The influence of risk factors on clinical outcomes following anatomical medial patellofemoral ligament (MPFL) reconstruction using the gracilis tendon

Fear of Reinjury, Psychological Factors, and Sport Played Have Negative Impact on Return to Sport Following Medial Patellofemoral Ligament Reconstruction for Patellar Instability

PURPOSE

To analyze factors that affect return to sport after medial patellofemoral ligament reconstruction (MPFLR), such as psychological factors, sport played, and a positive apprehension test following surgery, and to determine the average return to sport rates and time to return to sport.

METHODS

A literature search was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies met the following criteria: patients underwent MPFLR for patellar instability, return to sport was recorded, and a factor that affected return to sport was mentioned. Search terms included medial patellofemoral ligament, tibial tubercle osteotomy, tibial tubercle transfer, return to play, and return to sport.

RESULTS

Eighteen of 632 identified studies met inclusion criteria, and 1,072 patients who underwent MFPLR were recorded. Return-to-sport rates and mean/median time ranged from 60.0% to 100% and 3 to 10.4 months, respectively. Of the patients, 55.6% to 84.0% returned to sport without decreasing the level of competition. Six of 12 studies (50.0%) reported fear of reinjury as the top reason for patients not returning or returning at a lower level of sport. Volleyball/handball had the lowest return to the same level following surgery (18.2%-50.0%).

CONCLUSIONS

Athletes who underwent MPFLR following recurrent patellar instability returned to sport at a range of 60.0% to 100%. Return to sport at the same level or higher was found to have a lower maximum rate at 55.6% to 84.0%. Fear of reinjury and sport played were found to have a substantial impact on ability to return to sport. Surgeons can use this information to advise patients on expectations following surgery.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

A Combined Surgical Approach for Recurrent Patellar Dislocation in Adolescents With Patella Alta and Increased Tibial Tuberosity-Trochlear Groove Distance: Improved Clinical Outcomes but Decreased Posterior Tibial Slopes in Skeletally Immature Patients at Minimum 4-Year Follow-Up

PURPOSE

(1) To report the clinical and radiological outcomes of a surgical technique combining anatomic medial patellofemoral ligament reconstruction and tibia tuberosity transfer in adolescents with patella alta and elevated tibial tuberosity-trochlear groove (TT-TG) distance in the treatment of recurrent patellar dislocation; and (2) to investigate the potential risks of growth arrest or developmental deformities associated with this combined technique.

METHODS

Medical records of patients who underwent the combined surgery from 2015 to 2019 were reviewed. This study included adolescents aged between 14 and 18 years with a Caton-Deschamps index (CDI) > 1.30 and TT-TG distance >20 mm, with a minimum follow-up of 4 years. Radiological examinations including lateral views and full-length posteroanterior standing radiographs were investigated to assess patella height by CDI, posterior tibial slope (PTS) angle, side-to-side difference in bone length, and lower extremity alignment by hip-knee-ankle angle; computed tomography scans and magnetic resonance imaging profiles were investigated to evaluate TT-TG distance and staging of growth plate closure. Other evaluations included preoperative and postoperative physical examination, Kujala score, and Tegner activity score. The patients were stratified into 3 subgroups according to an magnetic resonance imaging-based staging system of the growth plate closure, and each outcome was analyzed. A cohort-specific minimal clinically important difference estimation was performed using standard error of measurement.

RESULTS

The average age at the time of surgery was 16.1 years (range, 14.1-17.8). The average follow-up was 5.6 years (range, 4.0-7.6). No recurrent dislocation occurred, and no clinically significant deformity or axis deviation was encountered. Postoperative patellar height by CDI was 1.00 ± 0.11 (range, 0.81-1.15). No significant differences were found in the preoperative and postoperative hip-knee-ankle angle or side-to-side difference in femur/tibia length among all subgroups. A significantly decreased PTS angle was found in patients with open growth plates, from 10.2° ± 1.7° before surgery to 8.1° ± 1.0° after surgery (P = .015). The Kujala score and Tegner score both significantly improved, from 65.5 ± 13.9 before surgery to 90.4 ± 7.2 after surgery in the Kujala score (P < .001) and from 4.0 ± 1.1 before surgery to 4.7 ± 1.3 after surgery in the Tegner score (P < .001). Of the whole cohort, 63.1%, 100%, 47.1%, and 94.1% of patients achieved the minimal clinically important difference for PTS angle, CDI, Tegner score, and Kujala score, respectively.

CONCLUSIONS

This combined technique is safe and effective in treating recurrent patellar dislocation in skeletally mature adolescents with concurrent patella alta (CDI > 1.30) and TT-TG distance >20 mm, permitting patients to have improved knee function and low complication rates. Nonetheless, patients with open growth plates demonstrated a decrease in PTS, which might predispose the knee to recurvatum and osteoarthritis in the long term.

LEVEL OF EVIDENCE

Level IV, controlled case series.

Reconstruction of the medial patellofemoral ligament through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation

PURPOSE

The present study aimed to assess the clinical efficacy and imaging results of reconstruction of the medial patellofemoral ligament through a double bundle of single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation.

METHODS

Twenty-three patients with recurrent patellar dislocation, including ten males and 13 females, with 23 knee joints were enrolled according to the relevant criteria. Reconstruction of the medial patellofemoral ligament was performed through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity. Knee function was evaluated using visual analog scale (VAS) score, International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner score, and Kujala score at pre- and postoperative stages. Patellar stability was assessed by CT scans measuring tibial tuberosity-trochlear groove (TT-TG) distance, lateral patella displacement (LPD), congruence angle (CA), and patellar tilt angle (PTA).

RESULTS

All 23 patients were effectively followed up for 13-28 months (mean: 21.91 ± 4.14 months). At the last follow-up, the postoperative VAS score, IKDC score, Lysholm score, Tegner score, and Kujala score of 23 patients were 1.13 ± 0.82, 87.35 ± 3.17, 90.22 ± 1.28, 4.35 ± 0.65, and 89.26 ± 1.96, respectively, as compared to the preoperative values of 5.91 ± 1.13, 30.96 ± 5.09, 30.30 ± 2.98, 1.26 ± 0.62, and 27.87 ± 3.46, respectively, and these differences were statistically significant (P < 0.001). At the last follow-up, the postoperative TT-TG, LPD, CA, and PTA values of the 23 patients were 8.80 ± 1.85 mm, 6.01 ± 1.77 mm, 11.32 ± 6.18°, and 9.35 ± 2.88°, respectively, compared to the preoperative values of 18.77 ± 1.74 mm, 14.90 ± 4.07 mm, 37.82 ± 5.71°, and 23.58 ± 3.24°, respectively, and the differences were statistically significant (P < 0.001). No relevant complications were observed in the 23 patients.

CONCLUSIONS

Reconstruction of the medial patellofemoral ligament through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation showed satisfactory medium-term efficacy, and further investigations are required to confirm the long-term efficacy of this approach.

Medial Patellofemoral Complex Reconstruction (Combined Reconstruction of Medial Patellofemoral Ligament and Medial Quadriceps Tendon-Femoral Ligament) With Semitendinosus Autograft Resulted in Similar Clinical and Radiographic Outcomes to Medial Patellofemoral Ligament Reconstruction in Treating Recurrent Patellar Dislocation

PURPOSE

To compare clinical and radiographic outcomes of medial patellofemoral ligament reconstruction (MPFL-R) and medial patellofemoral complex reconstruction (MPFC-R) for recurrent patellar dislocation. Outcome measures were compared based on the Insall-Salvati index.

METHODS

Patients who were diagnosed with recurrent patellar dislocation and underwent either MPFL-R or MPFC-R (combined reconstruction of MPFL and medial quadriceps tendon-femoral ligament) were retrospectively analyzed. Group allocation was based on surgical procedure and patient characteristics were collected. Clinical assessments included patient-reported outcome measures (PROMs) and return-to-sports rates. Minimal clinically important difference analysis was performed. A subgroup analysis of PROMs was carried out between patients with an Insall-Salvati index ≤1.2 versus >1.2. The patellar tilt angle, lateral patellar displacement, and bisect offset ratio were measured pre- and postsurgery. Functional failures and complications were assessed.

RESULTS

Overall, 70 patients (72 knees) in the MPFL-R group and 58 patients (61 knees) in the MPFC-R group were included. Patient characteristics were comparable between the groups. At a minimum follow-up of 24 (mean, 50.6 ± 22.1) months, all PROMs were substantially improved (P < .001), without significant intergroup differences. The percentages of patients reaching the minimal clinically important difference were similar after MPFL-R and MPFC-R: 98.6% versus 93.4% (International Knee Documentation Committee), 97.2% versus 98.4% (Lysholm), 98.6% versus 100% (Kujala), and 77.8% versus 72.1% (Tegner). The subgroup analysis based on patellar height and the return-to-sport rates also suggested comparable results. Radiographic evaluation demonstrated significantly smaller lateral patellar displacements (P = .004) and bisect offset ratios (P < .001) but similar patellar tilt angles after MPFC-R. Four (5.6%) patients receiving MPFL-R and 2 (3.3%) patients receiving MPFC-R reported recurrence of functional instability, without statistically significant difference.

CONCLUSIONS

MPFC-R resulted in similar overall clinical and radiographic outcomes to MPFL-R in treating recurrent patellar dislocation. MPFC-R might not provide additional benefits for patients with an Insall-Salvati index >1.2.

LEVEL OF EVIDENCE

Level IV, therapeutic, retrospective cohort study.

Medial Patellofemoral Ligament Reconstruction Using Pedicled Quadriceps Tendon Autograft Yields Similar Clinical and Patient-Reported Outcomes but Less Donor-Site Morbidity Compared With Gracilis Tendon Autograft

PURPOSE

To compare clinical and patient-reported outcome measures (PROMs) in patients with recurrent patellar dislocation after medial patellofemoral ligament (MPFL) reconstruction using either a gracilis tendon (GT) or quadriceps tendon autograft (QT).

METHODS

All MPFL reconstruction performed between 2017 and 2019 were reviewed retrospectively. Only patients with isolated MPFL reconstruction, without any major patellofemoral risk factors and a minimum follow-up of 24 months, were included in the study. Patients were matched with respect to sex, age, and body mass index. All patients were evaluated clinically and using PROMs.

RESULTS

A total of 64 patients with an average follow up of 28.7 ± 7.5 months were included in this study. The mean Kujala score (GT: 84.8 ± 12.9, QT: 88.9 ± 10.1), Lysholm score (GT: 89.4 ± 10.2, QT: 88.4 ± 5.0), and visual analog scale score for pain (GT: 1.9 ± 1.8, QT: 1.1 ± 1.3) did not significantly differ between both groups. Tegner activity level was significantly greater (P = .027) in the QT group (5.5 ± 1.9) compared with the GT group (4.6 ± 1.8), but within the minimal clinically important differences. Occasional patellar instability events, but no recurrent dislocation, were reported in 12.5% in the GT group and 6.3% in the QT group (P = .39). Of all patients, 90.6% in the QT and 68.8% in the HT group exceeded the PASS for the Kujala score (P = .06). Significantly more patients (59.4%) treated with GT reported donor-site morbidity in the form of sensitivity deficit at the lower leg compared with those treated with QT (3.1%, P = .001).

CONCLUSIONS

GT and QT MPFL reconstruction have comparable PROMs and patellar redislocation rates 2 years' postoperatively. Significantly more patients treated with GT reported lower-leg sensitivity deficit compared with those treated with QT.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Tibial tuberosity-trochlear groove distance is significantly decreased by medial closing wedge distal femoral osteotomy

PURPOSE

While medial closing wedge distal femoral osteotomy (MCWDFO) has been used to address patella instability combined with valgus malalignment, its impact on patellofemoral parameters remains uncharted. Hence, this study seeks to establish a three-dimensional (3D) planning of MCWDFO and measure its effect on the tibial tubercle - trochlear groove distance (TTTG) through simulation and calculation.

METHODS

MCWDFO with a stepwise increment of one-degree varisation (1°-15°) was performed on 3D surface models of 14 lower extremities with valgus malalignment and 24 lower extremities with neutral alignment of the lower limb, resulting in a total of 608 simulations. Anatomic landmarks were employed to measure hip-knee-ankle angle (HKA), TTTG, and femoral torsion for each simulation. A mathematical formula was adopted to calculate TTTG changes following MCWDFO, and subsequently the mean simulated and calculated TTTG values were compared. Following a standardised protocol, MCWDFO was performed without rotational changes.

RESULTS

MCWDFO exhibited an almost linear reduction in TTTG, at a rate of approximately -1.05 ± 0.13 mm per 1° of varisation, demonstrating a strong negative correlation (R = -0.83; p < 0.001). Limb alignment did not exert an influence on TTTG change; however, it correlated with tibial plateau width. The mean difference between the simulated and calculated TTTG values amounted to 0.03 ± 0.03 mm per 1° varisation (p < 0.001).

CONCLUSION

The TTTG distance is linearly reduced by 1.05 mm for every 1° of varisation within the varus correction range of 0°-15° during MCWDFO. Patients with combined valgus and patellar instability may benefit from MCWDFO due to frequently pathological TTTG.

LEVEL OF EVIDENCE

Level III, descriptive laboratory study.

The 100 Top-Cited Articles on Medial Patellofemoral Ligament: A Bibliometric Analysis and Review

Background

The medial patellofemoral ligament (MPFL) has been investigated widely in the past 30 years, resulting in many research achievements in this field.

Purpose

To perform a comprehensive bibliometric analysis to evaluate the 100 top-cited articles on the MPFL.

Study Design

Cross-sectional study.

Methods

We searched the Scopus database in December 2022 using the terms "medial patellofemoral ligament" OR "MPFL." The search was confined to English-language articles, including technical notes, systematic reviews on clinical outcomes and/or complications, clinical studies, studies regarding complications, and basic science articles (either cadaveric or biomechanical); we excluded letters, case reports, personal opinions, guidelines, editorials, and narrative or other types of reviews. Analysis of the 100 top-cited articles was performed according to total number of citations, average citations per year (ACY), study type, country of origin, journal of publication, affiliated institution, and most published authors.

Results

The total number of citations was 16,358 (range of citations per article, 72-692). The majority of articles were published as clinical studies (54%), with cadaveric studies being the second most common (21%). Most studies originated in the United States (32%), with Japan (15%) and Germany (13%) following. The American Journal of Sports Medicine published the majority of the 100 top-cited articles (37/100; 6304 citations) as well as the 10 top-cited articles according to ACY (7/10; mean, 285.14 citations). The most prolific authors were Nomura (8 articles); Burks (6 articles); and Inoue, Sillanpää, and Dreyhaupt (5 articles each).

Conclusion

By analyzing the characteristics of the 100 top-cited articles, this study demonstrated that the MPFL is a growing and popular area of research, with the focus varying through timeline trends. Questions regarding MPFL anatomy, isometry, and biomechanics might have been answered adequately, but research regarding optimal fixation technique under various circumstances is still ongoing.

PROMIS physical function and pain perform poorly psychometrically in patients undergoing medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to assess the validity, floor and ceiling effects, and dimensionality of PROMIS Physical Function (PF) and Pain compared to legacy patient reported outcome (PRO) measures in patients undergoing medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Patients who underwent MPFL reconstruction between 2018 to 2020 were retrospectively reviewed. Preoperatively, patients completed the IKDC, VR-12, Kujala, SF-12, KOOS JR, PROMIS PF and Pain surveys. Inter-survey convergence was assessed with Spearman correlations. Psychometric analysis included investigations of inter-survey convergent validity, intra-survey floor and ceiling effects, and Rasch analyses with person-item fit and iterative question elimination model fit testing.

RESULTS

A total of 76 patients (mean age: 22.6 ± 8.4 years) who completed preoperative surveys were included (compliance: 91.7-96.2%). Preoperatively, age was significantly associated with both PROMIS PF (coefficient:  - 0.291, P = 0.005) and Pain scores (coefficient: 0.294, P = 0.002). PROMIS PF had a Very Good correlation with IKDC and PROMIS Pain had a Very Good correlation with KOOS JR. Other correlations ranged from Poor to Good. No significant floor or ceiling effects were observed for any PRO. On iterative question elimination Rasch modelling, only two questions from PROMIS PF remained after 6 rounds of elimination while PROMIS Pain had no questions remaining after 3 rounds of elimination.

CONCLUSION

Preoperative PROMIS PF and Pain provided only Fair to Good correlations with most legacy PROs. Although no significant floor and ceiling effects were observed, PROMIS PF and Pain did not perform well psychometrically in this population of patients undergoing MPFL reconstruction. These results suggest PROMIS questionnaires should be used with caution in this population, especially if used in isolation, when discussing clinical expectations with patients. The authors recommend continued use of legacy PROs specific to assessment of patellar instability and function that have established validity in patellar instability populations.

LEVEL OF EVIDENCE

Level IV.

Sulcus-Deepening Trochleoplasty for High-Grade Trochlear Dysplasia: Demystifying the Procedure-a Review of the Current Literature

PURPOSE OF REVIEW

The most common and biomechanically influential pathoanatomic risk factor for recurrent patellofemoral instability is trochlear dysplasia. Sulcus-deepening trochleoplasty is a procedure developed to address high-grade trochlear dysplasia in the setting of patellofemoral instability. The purpose of this paper is to outline the current classification and surgical management of trochlear dysplasia as well as to review the current literature on the clinical outcomes and complications of sulcus-deepening trochleoplasty.

RECENT FINDINGS

This review outlines the most recent literature reporting evidence behind the decision-making to perform a trochleoplasty in the setting of patellofemoral instability and high-grade trochlear dysplasia. Critical parameters include grade of trochlear dysplasia, severity of symptoms, pertinent physical examination findings, surgical techniques, modifications for skeletally immature patients, and considerations for the revision setting. Historic studies have elicited concerns regarding high reported complication rates for trochleoplasty; however, recent studies consistently report good clinical outcomes and acceptable complication rates, similar to those of other patellar stabilizing procedures. The addition of a trochleoplasty in patients with high-grade dysplasia results in a lower re-dislocation rate, significant improvements in patient-reported outcome measures (PROMs) as well as high levels of patient satisfaction and return to sport. The use of sulcus-deepening trochleoplasty for the treatment of high-grade dysplasia and recurrent patellofemoral instability is a well-established technique with good outcomes and an acceptable complication profile. In patients with high-grade dysplasia, trochleoplasty results in lower re-dislocation rates, high patient satisfaction scores, and good clinical and functional outcomes. An understanding of trochleoplasty and its indications should be in the armamentarium of surgeons treating patellofemoral instability.

Is combined MPFL reconstruction and tubercule tibial osteotomy superior to isolated reconstruction? A systematic review and meta-analysis

Purpose

There is no consensus for management of patellar instability, even in the case of malalignment. The purpose of the review is to evaluate outcomes in the literature of MPFL reconstruction with and without tibial tubercle osteotomy.

Methods

Two databases PubMed and Scopus were searched for studies comparing MPFL reconstruction with and without concomitant tibial tuberosity osteotomy. PRISMA guidelines were followed. Data on functional outcomes via Kujala score, redislocation rates and return to sport rates were reported.

Results

9 studies included data from 806 knees: 463 submitted to isolated MPFL reconstruction, and 343 submitted to the combined surgery. Patients submitted to the combined procedure had all TT-TG values superior to 18, while the ones with isolated reconstruction had more heterogeneous values, varying between 13 and 20 mm. 77.78% of the studies reported on postoperative Kujala scores, with a mean value of 83.53 in patients who underwent MPFL reconstruction alone and 83.72 in those who underwent the combined procedure. The mean difference between the two groups was -0.83, with the improvement of the score statistically significant in 22.22% of the studies, regardless of the surgery. Concerning redislocation rate, odds ratio comparing both procedures was 0.84 (p = 0.67).

Conclusion

The principal finding is that the MPFL reconstruction with or without TTO resulted in similar functional outcomes, assessed by the Kujala score, and low complications concerning recurrent patellar dislocation. More robust literature is needed in the setting of a high TT-TG distance.

Level of evidence

IV.

Patella alta and increased TT-TG distance do not adversely affect patient-reported outcomes following isolated MPFL reconstruction: A systematic review

OBJECTIVES

To analyze the effect of patellofemoral anatomical variations (patella alta, increased tibial tubercle-trochlear groove [TT-TG] distance, and trochlear dysplasia) on clinical outcomes after isolated medial patellofemoral ligament (MPFL) reconstruction.

METHODS

A comprehensive search from PubMed, Embase, and the Cochrane Library databases was conducted to identify studies that compared outcomes based on the presence or absence of patella alta, elevated tibial tubercle-trochlear groove (TT-TG) distance, and/or trochlear dysplasia. Exclusion criteria included reviews and meta-analyses, studies that included patients who underwent associated bony procedures, and those reporting outcomes after isolated MPFL reconstruction with no comparison between varying anatomical groups.

RESULTS

After application of selection criteria, 19 studies were included. Patella alta was not predictive of failure or poorer outcomes among 13 studies; however, 2 studies demonstrated poorer patient-reported outcome scores and/or higher failure rates with increasing patellar height. Increasing TT-TG distance demonstrated a statistically significant correlation with poorer outcomes in only one study, whereas 12 other studies showed no association. Trochlear dysplasia resulted in worse outcomes and greater failure rates in 6 studies, while 10 studies showed no statistically significant correlation between trochlear dysplasia and postoperative outcomes.

CONCLUSION

Patella alta and increased TT-TG distance did not adversely affect outcomes following isolated MPFL reconstruction in the preponderance of reviewed studies. Data are mixed regarding the impact of trochlear dysplasia on the outcomes of isolated MPFL reconstruction.

LEVEL OF EVIDENCE

IV.

Adding Tibial Tuberosity Medialization to Medial Patellofemoral Ligament Reconstruction Reduces Lateral Patellar Maltracking During Multidirectional Motion in a Computational Simulation Model

Purpose

To determine whether adding tibial tuberosity medialization to medial patellofemoral ligament (MPFL) reconstruction reduces lateral patellar maltracking during a dynamic multidirectional activity and to investigate when medial patellofemoral contact pressures are elevated during daily activities, such as squatting.

Methods

Seven computational models representing knees with patellar instability, including lateral patellar maltracking, were evaluated following simulated MPFL reconstruction (bisect offset index > .75). Tibial tuberosity medialization was added to MPFL reconstruction for each model. Patellar tracking during multidirectional motion was evaluated by simulating pivot landing. Analysis of pivoting focused on early flexion (5° to 40°). Patellofemoral contact pressures during daily function were evaluated by simulating knee squatting. Data were analyzed with paired comparisons between MPFL reconstruction with and without tuberosity medialization.

Results

The patella dislocated during pivoting for 2 models with an isolated MPFL reconstruction and for 1 model including tibial tuberosity medialization. Adding tibial tuberosity medialization to MPFL reconstruction significantly decreased bisect offset index by ∼0.1 from 5° to 40° (P < .03). For knee squatting, medializing the tibial tuberosity significantly increased maximum medial contract pressure by ∼0.5 MPa from 30° to 85° (P < .05) but did not significantly influence maximum lateral pressure.

Conclusions

In this study of simulated multidirectional motion, MPFL reconstruction did not sufficiently constrain the patella for some knees. Adding tibial tuberosity medialization to MPFL reconstruction in these models reduced lateral patellar maltracking during multidirectional motion but increased pressure applied to medial cartilage during squatting.

Clinical Relevance

After establishing the influence of tibial tuberosity medialization on patellar maltracking for an idealized population, as was done in the current study, future simulation studies can be performed to better determine the anatomical characteristics of patients for whom tibial tuberosity medialization is needed to reduce the risk of postoperative patellar maltracking.

Isolated Medial Patellofemoral Ligament Reconstruction in Patellar Instability: Does the Distance Between Tibial Tuberosity-Trochlear Groove Make a Difference?

Introduction

Medial patellofemoral ligament reconstruction (MPFLR) is used in most patellar instability surgeries, there is controversy on adding a tibial tuberosity osteotomy (TTO).

Objective

To describe the results of isolated MPFLR in patellar instability according to the Tibial Tuberosity-Trochlear Groove distance (TT-TG).

Methods

Retrospective study of patients with patellar instability with a mature skeleton in one center between 2016 and 2021, using isolated MPFLR. Patients with incomplete clinical and/or radiological records and less than one year follow-up were excluded. Pre-surgical demographic and radiological data (TT-TG, Caton-Deschamps (CD) index, patellar tilt, trochlear dysplasia) were recorded. Patients were divided into three groups according to TT-TG distance (Group 1: < 17 mm, Group 2: 17-19, Group 3: ≥ 20 mm). A pre and post-surgical Kujala score was performed. Local complications, satisfaction, recurrence and/or reintervention were recorded. Pre-surgical variables between groups, intra and inter-group Kujala differences were compared using Bartlett's test. Consent from the patients and approval from the local ethics committee were obtained.

Results

67 patients met the selection criteria, mean age of 23 years, 70% were women. There were no pre surgical, radiological nor follow-up differences between the groups (average 27 months). Pre and post-surgical Kujala score, respectively: Group 1: 37-78, Group 2: 37-78, Group 3: 39-79. All groups had a significant improvement (p < 0.05), there were no significant differences in improvement between groups (p > 0.05). There were three patients with a redislocation episode, all in group 1. One patient had a mobilization under anesthesia due to an arthrofibrosis (Group 2). 97% of all cases reported being satisfied.

Conclusion

Isolated MPFLR in patellar instability presents a functional improvement, with a low rate of complications and failure, regardless of the pre surgical TT-TG.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43465-023-00906-6.

Differences in the Severity and Location of Patellofemoral Cartilage Damage Between Instability Patients With and Without Patella Alta

Background

Patella alta is a risk factor for recurrent patellar instability. Differences in chondral injury in patients with patellar instability between patella alta and patella norma have not been evaluated.

Purpose

To analyze whether preoperative cartilage damage differs in severity and location between patellar instability patients with and without patella alta.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients with patellar instability who underwent patellar realignment surgery at a single institution with preoperative magnetic resonance imaging (MRI) scans were included. After measurement of Caton-Deschamps index (CDI) on MRI, patients were divided into patella alta (CDI ≥1.3) and patella norma groups. The area measurement and depth and underlying structures (AMADEUS) score was used to quantify cartilage defect severity on MRI.

Results

A total of 121 patients were divided into patella alta (n = 50) and patella norma (n = 71) groups. The groups did not differ significantly in sex ratio, age at MRI, body mass index, mean reported number of previous dislocations, or mean interval between first reported dislocation and date of MRI. A total of 34 (68%) of the patella alta group and 44 (62%) of the patella norma group had chondral defects (P = .625) with no significant between-group differences in defect size (P = .419). In both groups, chondral injuries most affected the medial patellar facet (55% in patella alta vs 52% in patella norma), followed by the lateral facet (25% vs 18%), and lateral femoral condyle (10% vs 14%). A smaller proportion of patients had full-thickness defects in the patella alta compared with the patella norma group (60% vs 82%; P = .030). The overall AMADEUS score was higher for the patella alta versus the patella norma group (68.9 vs 62.1; P = .023), indicating superior articular cartilage status.

Conclusion

Patients with patella alta had less severe cartilage injury after patellar instability, including a lower proportion with full-thickness defects and better overall cartilage grade. The location of injury when present was similar between alta and norma, with most defects affecting the medial facet, lateral facet, and lateral femoral condyle in descending frequency.

The Top 50 Most Cited Articles on the Medial Patellofemoral Ligament (MPFL): A Bibliometric Analysis

Objectives

To determine which original articles on the topic of the medial patellofemoral ligament (MPFL) have been cited the most in the literature utilizing a bibliometric approach. Secondarily, to determine temporal trends between article types.

Methods

Articles on the topic of the MPFL were identified by utilizing the Web of Science Database. The search yielded 1596 results and the top 50 cited original articles were collected for further analysis. The following information was gathered for all included articles: title, first author's name, journal name, year of publication, impact factor of the journal in 2021, total number of citations of the article, average citations per year (ACY), geographic origin, institutions, research theme, and keywords. Articles were then grouped into one of three categories: cadaveric/anatomic, clinical, and radiologic.

Results

The total number of citations was 10,393. Most were published between the years 2000-2009 (66%) and in the journal, American Journal of Sports Medicine (34%). The mean ACY was 11.73 ± standard deviation 5.86 and the Kawasaki Municipal Hospital was the institution with the most articles included in the top 50 (n = 6, 12%). The top-cited articles focused on 3 themes: cadaveric/anatomic (n = 18, 36%), clinical (n = 25, 50%), and radiologic (n = 7, 14%). Cadaveric/anatomic articles had the highest average number of citations at 271.4 ± 153.9, followed by radiologic (173.3 ± 53.0) and clinical articles (171.8 ± 102.4). Over time, clinical articles were more likely to be included in the top 50 list, compared to cadaveric/anatomic/radiologic articles.

Conclusion

The most impactful MPFL articles relate to cadaveric/anatomic articles; however, over time, clinical articles became more prevalent.

Medial patellofemoral ligament reconstruction and tibial tuberosity transfer can be used to successfully manage patellofemoral instability in the setting of trochlea dysplasia

BACKGROUND

Management of patella instability remains a challenge particularly in the presence of trochlea dysplasia. The aim of this study is to assess the recurrence rates of those with patellar instability who have undergone a combined tibial tuberosity transfer (TTT) and medial patellofemoral ligament reconstruction (MPFLR) in the setting of trochlea dysplasia.

METHODS

All skeletally mature patients who underwent combined TTT and MPFLR for recurrent patella instability were identified between January 2009 and December 2019. A retrospective review was conducted, with information regarding re-dislocation/subluxation and complications collected.

RESULTS

Seventy patients with a mean age 25.3 years were identified and evaluated. Thirteen patients were found to have low-grade dysplasia (Dejour A), with 57 patients having high-grade dysplasia (Dejour B/C/D). No patients in the low,grade dysplasia group suffered a recurrence of their symptoms, with four in the high-grade group suffering episodes of re-dislocation/subluxation. Three patients subsequently underwent a trochleoplasty, with the other patient managed successfully non-operatively. There were a total of 13 complications in 11 patients.

CONCLUSIONS

A combined procedure of MPFLR and TTT can be used to manage patellofemoral instability even in the setting of trochlea dysplasia with a low rate of recurrence. Trochlea dysplasia, however, remains an anatomical risk factor for recurrence and patients should be counselled accordingly. The anatomical risk factors should be assessed in all patients to allow for the development of the most appropriate management plan, of which this combined procedure represents a potentially successful option.

LEVEL OF EVIDENCE

IV (Case Series).

Complication Rates After Medial Patellofemoral Ligament Reconstruction Range From 0% to 32% With 0% to 11% Recurrent Instability: A Systematic Review

PURPOSE

To review the incidence of complications following primary medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability.

METHODS

A literature search was conducted by querying PubMed and Scopus databases from database inception through August 2022 according to the 2020 Preferred Reporting Items for Systematic Review and Meta-analysis guidelines using the terms "Medial Patellofemoral Ligament," "MPFL," "reconstruction," "patellar," and "instability." Inclusion criteria included studies reporting complications following primary MPFL reconstruction for recurrent patellar instability. Exclusion criteria consisted of studies reporting on patients undergoing concurrent osteotomy procedures, revision reconstruction, and biomechanical or anatomic studies. The incidence of specific complications was aggregated from the included studies.

RESULTS

Twenty-eight studies, consisting of 1,478 patients (n = 1521 knees), with a mean age of 23.3 years (mean range, 19-34.3 years) were identified. The overall incidence of complications ranged from 0% to 32.3% of knees. Failure ranged from 0% to 10.7% of knees, whereas patellar fractures occurred in 0% to 8.3% of knees, primarily in patients treated with full-length transverse tunnel or 2-tunnel techniques. All patellar fractures occurred in patients with patellar tunnels ranging from 4.5 to 6.0 mm in diameter. The incidence of postoperative knee stiffness/range of motion deficit ranged from 0% to 20%. Persistent anterior knee pain, ranged from 0% to 32.3%.

CONCLUSIONS

Complications following primary MPFL reconstruction ranged from 0% to 32.3% of knees, primarily consisting of residual anterior knee pain. Failure ranged from 0% to 10.7% of knees, whereas patellar fractures were reported in 0% to 8.3% of knees. Fractures primarily occurred with a full-length transverse tunnel or 2-tunnel techniques, whereas all fractures occurred with patellar tunnels ranging from 4.5 mm to 6.0 mm in diameter.

LEVEL OF EVIDENCE

IV; Systematic Review of Level I-IV studies.

The remaining parameters of patellar instability could be affected for osteoarthritic change after medial patellofemoral ligament reconstruction with or without anteromedialization of the tibial tubercle osteotomy for patellar instability: a retrospective cohort study

BACKGROUND

In literature, studies evaluating the factors associated the postoperative progression of patellofemoral (PF) osteoarthritis (OA) following patellar stabilization surgery are limited. This study aimed to compare the clinical outcomes after medial patellofemoral ligament reconstruction (MPFLR) as an isolated procedure (iMPFLR) and in combination with anteromedialization (AMZ) of the tibial tubercle osteotomy (TTO) and investigate the factors related to the postoperative progression of PFOA after patellar stabilization surgery.

METHODS

Between 2009 and 2020, 30 knees of 23 consecutive patients underwent MPFLR with or without AMZ, using an autologous semitendinosus tendon graft; they were followed up for more than 2 years in the retrospective nature of the study. iMPFLR was performed in cases of recurrent patellar dislocation with normal tibial tubercle-trochlear groove (TT-TG) distance and no PFOA, and MPFLR+AMZ was performed for cases of excessive TT-TG distance, preoperative PFOA of recurrent patellar dislocation, or habitual patellar dislocation. Clinical findings and radiographs of the PF joint were evaluated pre- and postoperatively with PF alignment parameters and PFOA and were compared between surgical procedures. Factors for the postoperative progression of PFOA were compared between the OA progression and non-progression groups.

RESULTS

Postoperative clinical score, radiographic parameters except for sulcus angle, TT-TG distance, and progression of PFOA were not significantly different between the iMPFLR and MPFLR+AMZ groups. Postoperative lateral patellar displacement (p = 0.001) and congruence angle (p = 0.017) were significantly different between the OA progression and non-progression groups.

CONCLUSION

Similar to MPFLR for recurrent cases, MPFLR with AMZ can improve the clinical and radiographic outcomes in severe cases. The remaining parameters of patellar instability could be affected in the postoperative progression of PFOA after MPFL reconstruction with or without AMZ of TTO for patellar instability.

Arthroscopic Anatomical Double-Bundle Medial Patellofemoral Complex Reconstruction Improves Clinical Outcomes in Treating Recurrent Patellar Dislocation Despite Trochlear Dysplasia, Elevated Tibial Tubercle-Trochlear Groove Distance, and Patellar Alta

PURPOSE

To evaluate the clinical outcomes of arthroscopically assisted double-bundle medial patellofemoral complex reconstruction (MPFC-R).

METHODS

A retrospective review was carried out among adult patients who experienced at least 2 patellar dislocations and underwent primary arthroscopically assisted MPFC-R between January 2014 and November 2019. Dejour classification, tibial tubercle-trochlear groove (TT-TG) distance, and patellar height (with Insall-Salvati index) were measured. Pre- and postoperative patellar tilt were compared. Information on outcome scores, ability to return to sports, postoperative recurrent dislocations, and complications was recorded.

RESULTS

A total of 42 MPFC-Rs in 39 patients were included. Mean age at surgery was 22.2 ± 7.6 years; 69.2% of patients were female. Mean follow-up was 47.3 ± 20.2 months. Seventy-four percent of cases had Dejour B (19.0%), C (33.3%), and D (21.4%) trochlear dysplasia; mean TT-TG distance was 19.6 ± 3.5 mm, and mean Insall-Salvati index was 1.21 ± 0.17. Mean patellar tilt decreased from 27.6 ± 11.6° to 9.4 ± 6.5° (P < .001). All patients had statistically significant (P < .001) improvement in mean International Knee Documentation Committee (IKDC) (44.9 ± 18.2 to 87.5 ± 6.9), Lysholm (61.4 ± 16.6 to 94.1 ± 6.4), Kujala (56.0 ± 16.8 to 92.9 ± 5.3), and Tegner score (2.7 ± 1.3 to 4.6 ± 1.4). The majority of patients (96.9%) returned to sports, with 90.3% returning to the same or greater level of activity. No postoperative dislocations or subluxations were reported.

CONCLUSIONS

Arthroscopically assisted double-bundle MPFC-R is a promising procedure to treat recurrent patellar instability at 2- to 7-year mid-term follow-up, despite the presence of trochlear dysplasia, elevated TT-TG distance and patellar alta. The improvement of IKDC score exceeded the minimal clinically important difference in 95.2% patients, and 66.7% surpassed the patient acceptable symptomatic state based on postoperative IKDC score with no redislocations being reported at latest follow-up.

LEVEL OF EVIDENCE

Level IV, case series, retrospective.

Isolated medial patellofemoral ligament reconstruction results in similar postoperative outcomes as medial patellofemoral ligament reconstruction and tibial-tubercle osteotomy: a systematic review and meta-analysis

PURPOSE

To determine the effect of isolated medial patellofemoral ligament reconstruction (MPFLR) versus concomitant MPFLR and tibial-tubercle osteotomy (TTO) on patient-reported functional outcomes, rate of patellar redislocation, and rate of return to sport in skeletally mature patients with recurrent patellar instability and lateralization as defined by elevated tibial-tubercle trochlear groove (TT-TG) distance.

METHODS

Three databases MEDLINE, PubMed and EMBASE were searched from inception to July 10th, 2022 for literature outlining the management of patients with TT-TG indices greater than 15 mm with either isolated MPFLR or concomitant MPFLR and TTO procedures. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on functional outcomes via the Kujala anterior knee pain score, redislocation rates, return to sport rates, and complications were recorded. The MINORS score was used for all studies to perform a quality assessment of included studies.

RESULTS

A total of 31 studies comprising 1405 patients (1452 knees) were included in this review. The mean Kujala score in 13 studies comprising 848 total patients in the isolated MPFLR group was 85.0 (range 80.9-97.5) compared to a score of 83.7 (range 77.2-94.0) in 14 studies comprising 459 patients in the concomitant group. The mean pooled redislocation rate in 19 studies examining isolated MPFLR procedures comprising 948 patients was 3.1% (95% CI 2.1-4.4%, I² = 7%) as opposed to 3.2% (95% CI 1.9-5.0%, I² = 0%) in 15 studies comprising 486 patients in the concomitant group. The mean pooled return to sport rate in seven studies with 472 total patients in the isolated MPFLR group was 82% (95% CI 78-86%, I² = 16%) compared to a score of 92% (95% CI 78-99%, I² = 58%) in four studies comprising 54 patients in the concomitant group. There were similar complication rates between both treatment groups, including range of motion deficits, fractures, infections, and graft failures.

CONCLUSION

Isolated MPFLR leads to similar anterior knee pain, similar redislocation rates and lower return to sport rates than concomitant MPFLR and TTO procedures in patients with TT-TG distances greater than 15 mm. Information from this review can aid surgeons in their decision to choose MPFLR versus concomitant procedures for this patient population, and can also guide future studies on this topic.

LEVEL OF EVIDENCE

Level IV.

Quality of life following medial patellofemoral ligament reconstruction combined with medial tibial tubercle transfer in patients with recurrent patellar dislocation: a retrospective comparative study

Background

Because the patients undergoing medial patellofemoral ligament reconstruction (MPFLr) combined with medial tibial tubercle transfer (TTT) procedure are usually young and active, the quality of life (QoL) is also an important prognostic factor for patients with recurrent patellar dislocation. Assessing QoL can provide more useful and accurate evidence for the effects of this procedure. This study aimed to evaluate QoL following MPFLr combined with TTT, compared with isolated MPFLr (iMPFLr).

Methods

Fifty-one patients who underwent iMPFLr + TTT and 48 patients who underwent iMPFLr were included. Clinical evaluation included QoL (EQ-5D-5L and EQ-5D VAS), functional outcomes (Kujala, Lysholm and Tegner activity scores), physical examinations (patellar apprehension test and range of motion) and redislocation rates. Radiological evaluation included patellar tilt angle and bisect offset. These preoperative and postoperative results were compared between groups at baseline and the final follow-up. The paired and independent t tests were used for the data following a normal distribution. Otherwise, the Wilcoxon and Mann–Whitney U tests were used to analyze the differences. Categorical variables were compared by chi-square or Fisher’s exact test.

Results

All of the QoL (EQ-5D-5L and EQ-5D VAS), clinical results and radiological outcomes significantly improved in both groups at the final follow-up, with no significant differences between groups. There was no significant difference in five dimensions of EQ-5D at the final follow-up, although percentages of people with problems of mobility and pain/discomfort were higher in the MPFLr + TTT group. Female patients had lower EQ-5D index and EQ-5D VAS compared with male patients in both groups at the final follow-up, but there was only a significant difference in the EQ-5D VAS.

Conclusions

Both MPFLr + TTT and iMPFLr groups obtained similar and satisfactory improvements in the QoL, clinical results and radiological outcomes, indicating that MPFLr combined with TTT is a safe and effective procedure, which can significantly improve the QoL for patients with recurrent patellar dislocation in cases of pathologically lateralized TT. However, female patients obtained lower QoL than males.

Trochleoplasty for severe trochlear dysplasia significantly improves the quality of life of patients with symptomatic patellar instability

BACKGROUND

Trochleoplasty is a recognized surgical technique to address severe trochlear dysplasia. The clinical and radiological outcomes of trochleoplasty surgery in trochlear dysplasia have been well reported. There is a paucity in literature regarding the correlation between trochleoplasty and quality of life (QoL). The aim of this study is to measure the improvement in QoL, in patients with severe trochlear dysplasia and recurrent patellar instability following trochleoplasty.

METHODS

Between 2013 and 2019, 51 trochleoplasty cases were performed in 48 patients. They were identified from our prospectively kept database. All operations were performed by a fellowship trained consultant sports knee surgeon. Functional outcomes and QoL scores were assessed using Kujala, IKDC and EQ-5D index. Objective outcomes were obtained following each patient's latest follow-up assessment.

RESULTS

The mean age at operation was 22y (SD ± 4.7, range 14-37y) and the mean follow-up period was 21.6 months (SD ± 15.2, range 12-60 months). The mean Kujala score improved from 58.1 (SD 14.9) to 77.9 (SD 17.3) at latest follow-up (p < 0.001). The mean IKDC score improved from 40.5 (SD 14.2) to 69.5 (SD 22.8) at latest follow up (p < 0.001). The mean EQ-5D index also improved from 0.593 (SD 0.257) to 0.824 (SD 0.189) at latest follow-up (p = 0.003). A higher Body Mass Index (BMI; >30 kg/m²) was associated with inferior outcomes.

CONCLUSION

Trochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear dysplasia. BMI can be used to predict post-operative outcomes.

Protocols of rehabilitation and return to sport, and clinical outcomes after medial patellofemoral ligament reconstruction with and without tibial tuberosity osteotomy: a systematic review

PURPOSE

No consensus exists on rehabilitation programmes after medial patellofemoral ligament reconstruction (MPFLR) with or without tibial tuberosity osteotomy (TTO). This systematic review examined the content and timeline of rehabilitation (weightbearing, range of motion [ROM] and exercise therapy) and return to sport (RTS), as well as patient-reported outcomes after MPFLR with or without TTO.

METHODS

The PubMed, Cochrane Library, Web of Sciences, CINAHL and SPORTDiscus databases were searched from inception to December 2021. Studies that reported postoperative rehabilitation programmes and patient-reported outcomes for patients aged ≥ 18 years who underwent MPFLR with or without concomitant TTO were included.

RESULTS

Eighty-five studies were included, 57 of which were case series and only one randomised controlled trial on rehabilitation programmes. Non-weightbearing was set within one week post-operatively in approximately 80% of weightbearing programmes for MPFLR without and with TTO. Joint immobilisation was set within one week post-operatively in 65.3% and 93.8% of programmes for MPFLR without and with TTO, respectively. Weightbearing and ROM (≤ 90°) restriction were within three weeks post-operatively for > 50% of the programmes. Quadriceps strengthening was the most cited exercise therapy (33 programmes), most often initiated within two weeks post-operatively. However, few other exercise programmes were cited (only nine programmes). RTS was mostly noted at six months post-operatively (35 programmes). The weighted mean Kujala score was 87.4 points.

CONCLUSION

Regardless of TTO addition to MPFLR, most studies restricted weightbearing and ROM only in the early post-operative period, with seemingly favourable clinical results. Limited information was available on post-operative exercise therapy.

Medial patellofemoral ligament reconstruction for recurrent patellar dislocation allows a good rate to return to sport

PURPOSE

Recurrent patellar dislocation is a frequent knee disorders in young, active patients. Medial patellofemoral ligament reconstruction (MPFLR) can restore knee stability and function, but the rate of return to sports is less clear. The aim of this study was to evaluate rate of return to sport following treatment of recurrent patellar dislocation with isolated MPFLR.

METHODS

Between 2011 and 2018, 113 patients with recurrent patellar dislocation were treated with isolated MPFLR at an academic center. Pre-injury sports participation and Tegner score, pre-operative subjective IKDC score, time to return to sports, and post-operative Tegner and subjective IKDC scores were collected, with a minimum of follow-up of 2 years.

RESULTS

One hundred and three patients (91%) were evaluated at a mean of 4.5 ± 2.5-year post-operative. 92 patients (89%) participated in sports prior to onset of patellar instability. At final follow-up, 84 of these 92 patients (91%) were able to return to sports. The mean time from surgery to return to sports was 10.4 ± 8.6 months (range: 2-48 months). 62 patients (67%) returned to the same (50 patients) or higher (12 patients) level. 22 patients (26%) returned at a lower level. 19 of these patients attributed this decreased participation to ongoing knee problems. The median Tegner score was noted to decrease from 5 pre-injury to 4 post-operatively (p = 0.02).

CONCLUSION

Isolated MPFL reconstruction allowed return to pre-injury sports in 91% of patients, with 67% of patients returning to the same or higher level than pre-injury. Mean time to return to sports was 10 months and post-operative Tegner score was noted to be modestly decreased from pre-injury level.

LEVEL OF EVIDENCE

IV.

Research Hotspots and Trends Analysis of Patellar Instability: A Bibliometric Analysis from 2001 to 2021

Background

Patellar instability is a common multifactorial disease in orthopedics, which seriously affects the quality of life. Because of the unified pathogeny, diagnosis and treatment, patellar instability has gradually attracted the interest of more scholars these years, resulting in an explosive growth in the research output. This study aims to summarize the knowledge structure and development trend in the field from the perspective of bibliometrics.

Methods

The data of articles and reviews on patellar instability was extracted from the Web of Science database. The Microsoft Excel, R-bibliometrix, CiteSpace, VOSviewer, Pajek software are comprehensively used to scientifically analyze the data quantitatively and qualitatively.

Results

Totally, 2,155 papers were identified, mainly from North America, Western Europe and East Asia. Until December 31, 2021, the United States has contributed the most articles (1,828) and the highest total citations (17,931). Hospital for Special Surgery and professor Andrew A Amis are the most prolific institutions and the most influential authors respectively. Through the analysis of citations and keywords based on a large number of literatures, “medial patellofemoral ligament construction”, “tibial tubercle-trochlear groove (TT-TG) distance”, “epidemiological prevalence”, “multifactor analysis of etiology, clinical outcome and radiographic landmarks “ were identified to be the most promising research directions.

Conclusions

This is the first bibliometric study to comprehensively summarize the research trend and development of patellar instability. The result of our research provides the updated perspective for scholars to understand the key information in this field, and promote future research to a great extent.

Inconsistencies in Reporting Risk Factors for Medial Patellofemoral Ligament Reconstruction Failure: A Systematic Review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a common surgical treatment for patients with recurrent patellar instability. A variety of risk factors, such as age, trochlear dysplasia, patella alta, and increased tibial tubercle-trochlear groove (TT-TG) distance, have been identified and may lead to postoperative failure or poor outcomes.

PURPOSE

While a large number of risk factors have been identified, significant heterogeneity exists in evaluating and reporting these risk factors in the literature. The goal of this study was to perform a systematic review to determine risk factors associated with worse outcomes after MPFL reconstruction and their consistency of being controlled for or analyzed among studies.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of the literature was performed using the MEDLINE database to identify relevant clinical outcome studies after MPFL reconstruction for recurrent patellar instability. Eligible studies were evaluated for risk factors that were associated with MPFL failure, defined as recurrent instability or lack of improvement on patient-reported outcome (PRO) scores. Each study was then evaluated for inclusion of these risk factors.

RESULTS

Ten studies were included in the final analysis, comprising 1287 knees from 1275 patients who underwent isolated MPFL reconstruction. Of these 10 studies, 8 defined outcomes based on PROs and 3 defined outcomes based on postoperative recurrent instability (1 study included both outcomes). In the PRO failure group, 12 risk factors were found across all studies: trochlear dysplasia, trochlear bump height, elevated TT-TG, patellar tilt, hyperlaxity, age at first dislocation, age at surgery, body mass index, bilateral symptoms, WARPS/STAID score (weak atraumatic, risky anatomy, pain, and subluxation/strong, traumatic, anatomy normal, instability, and dislocation), femoral tunnel malposition, and femoral tunnel widening. In the recurrent instability failure group, 7 risk factors were found across all studies: trochlear dysplasia, bump height, patella alta, higher sulcus angle, higher congruence angle, preoperative J sign, and femoral tunnel malposition. Trochlear dysplasia and femoral tunnel malposition were consistently cited in several studies as risk factors for worse PROs and higher rates of recurrent instability. Patella alta was indicated as a significant risk factor for recurrent instability in 1 of 2 studies analyzing postoperative instability failures and was not associated with worse PROs in any of the studies analyzed. Similarly, elevated TT-TG distance was not a significant risk factor in any of the studies that analyzed recurrent instability as the failure endpoint.

CONCLUSION

While various risk factors are postulated to affect outcomes after MPFL reconstruction, there remains inconsistency within the literature regarding the inclusion of all risk factors in a given analysis. Furthermore, the significance of these risk factors varies among studies in terms of whether they affect postoperative outcomes. We found that more severe trochlear dysplasia (types C and D) and femoral tunnel malposition (>10 mm from Schöttle's point) appear to have the most consistent effect on producing higher rates of recurrent dislocation as well as worse PROs. Despite this, the role of concomitant bony procedures to adjust certain pathoanatomic risk factors in addition to MPFL reconstruction remains unknown. Future high-level studies must be conducted that respect the multifactorial nature of patellar instability and should analyze all risk factors (demographic, anatomic, and radiographic) reported to affect outcomes.

Effect of Isolated Medial Patellofemoral Ligament Reconstruction in Patellofemoral Instability Regardless of Predisposing Factors

The purpose of this study was to evaluate the outcomes of isolated medial patellofemoral ligament (MPFL) reconstruction, regardless of the presence of predisposing factors. A total of 21 knees that underwent isolated MPFL reconstruction from March 2014 to August 2017 were included in this retrospective series. Radiographs of the series of the knee at flexion angles of 20, 40, and 60 degrees were acquired. The patellar position was evaluated using the patellar tilt angle, sulcus angle, congruence angle (CA), and Caton-Deschamps and Blackburne-Peel ratios. To evaluate the clinical outcome, the preoperative and postoperative International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales were analyzed. To evaluate the postoperative outcomes based on the predisposing factors, the results were separately analyzed for each group. Regarding radiologic outcomes, 20-degree CA was significantly reduced from 10.37 ± 5.96° preoperatively to -0.94 ± 4.11° postoperatively (p = 0.001). In addition, regardless of the predisposing factors, delta values of pre- and postoperation of 20-degree CA were not significantly different in both groups. The IKDC score improved from 53.71 (range: 18-74) preoperatively to 94.71 (range: 86-100) at the last follow-up (p = 0.004), and the Lysholm score improved from 54.28 (range: 10-81) preoperatively to 94.14 (range: 86-100) at the last follow-up (p = 0.010). Isolated MPFL reconstruction provides a safe and effective treatment for patellofemoral instability, even in the presence of mild predisposing factors, such as trochlear dysplasia, increased patella height, increased TT-TG distance, or valgus alignment. This is a Level 4, case series study.

Return to Sport After Medial Patellofemoral Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

Patellar instability is frequently encountered in the athletic population. Medial patellofemoral ligament (MPFL) reconstruction is a common strategy to treat recurrent patellar dislocation and demonstrates good clinical outcomes.

PURPOSE/HYPOTHESIS

The purpose was to examine return to sport after MPFL reconstruction for patellar instability. We hypothesized that patients would resume athletic activity at a high rate and that a large proportion would return to their preoperative level of performance.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of the literature was conducted using PubMed and Cochrane Library databases to identify articles reporting return to sport after MPFL reconstruction for recurrent patellar dislocation. Athletes were defined as those reporting a preoperative sport. A random-effects model was used to evaluate return to sport rates, subsequent level, and rate of instability recurrence. Meta-regression was used to compare return to sport rates in patients undergoing MPFL reconstruction without osteotomy compared with those treated with simultaneous tibial tubercle osteotomy or trochleoplasty.

RESULTS

In total, 23 articles met inclusion criteria after full-text review. A total of 930 patients were analyzed, including 786 athletes. Women represented 61.3% of all patients. The overall mean age was 21.1 years (range, 9.5-60.0 years), with a mean follow-up time of 3.0 years (range, 0.8-8.5 years). The return to sport rate was 92.8% (95% CI, 86.4-97.6). Patients returned to or surpassed their preoperative level of activity in 71.3% (95% CI, 63.7-78.4) of cases. An osteotomy was performed on 10.5% of athletes. Return to sport did not differ significantly in patients undergoing MPFL reconstruction without osteotomy versus those receiving additional osteotomy (95.4% vs 86.9%; P = .22). Patients returned to sport at a mean of 6.7 months (range, 3.0-6.4 months) postoperatively. Osteotomy did not affect return time. Complications occurred at an overall rate of 8.8%. The most common complication was recurrence of instability (1.9%; 95% CI, 0.4-4.0). The Kujala score was reported by 13 studies, with pre- and postoperative combined means of 60.3 and 90.0, respectively.

CONCLUSION

MPFL reconstruction is an effective and reliable treatment in the setting of patellofemoral instability. Surgeons can counsel their patients that they can expect a high rate of return to sport after MPFL reconstruction surgery alone or with concomitant osteotomy.

Allograft Medial Patellofemoral Ligament Reconstruction in Adolescent Patients Results in a Low Recurrence Rate of Patellar Dislocation or Subluxation at Midterm Follow-Up

PURPOSE

To evaluate rates of recurrent instability in adolescent patients with medial patellofemoral ligament (MPFL) reconstruction with allograft and associations of anatomic risk factors with complications.

METHODS

A retrospective review identified patients of a single surgeon who underwent MPFL reconstruction with allograft for recurrent patellar instability with minimum 2-year follow-up. Surgical management was recommended after a minimum 6 weeks of nonoperative management and included MPFL reconstruction with gracilis allograft using a double-bundle technique. Preoperative radiographs were evaluated to assess physeal closure, lower-extremity alignment, trochlear morphology, and Insall-Salvati and Caton-Deschamps ratios. Magnetic resonance images were reviewed to evaluate the MPFL, trochlear morphology, and tibial tubercle trochlear groove distance (TT-TG). Descriptive statistics were used to characterize data. The primary outcome was recurrent instability.

RESULTS

20 patients (24 knees; 18 knees in 14 females and 6 knees in 6 males; average age 15.7 years; range 11.5 to 19.6) underwent MPFL reconstruction with allograft (mean ± standard deviation follow-up 5.2 ± 1.7 years; range 2.2 to 8.1). Physes were open in 9 knees. The Insall-Salvati ratio was 1.09 ± 0.16, and the Caton-Deschamps index was 1.17 ± 0.15. Preoperatively, 19 patients were noted to have trochlear dysplasia, and TT-TG was 15.3 ± 3.9 mm. Three of 4 knees (16.7%) with non-hardware-related complications had open physes: 3 (12.5%) had recurrent instability, 2 of which underwent subsequent operation, and 1 sustained a patella fracture after a fall, requiring open reduction and internal fixation. The average Insall-Salvati ratio of these 4 patients was 1.21 ± 0.20, Caton-Deschamps index was 1.18 ± 0.17, and TT-TG was 17.5 ± 3.3 mm, none of which were statistically different from the group without complications. There were no clinically noted growth disturbances postoperatively.

CONCLUSIONS

MPFL reconstruction using allograft tissue may be performed safely in the pediatric and adolescent population with good outcomes at midterm follow-up, few complications, and a low rate of recurrent instability.

LEVEL OF EVIDENCE

IV, case series.

Interference screws vs. suture anchors for isolated medial patellofemoral ligament femoral fixation: A systematic review

PURPOSE

The present study aimed to systematically review and compare 2 femoral autograft fixation techniques, namely, interference screws and suture anchors, for isolated medial patellofemoral ligament reconstruction in patients with recurrent patellofemoral instability at mid- to long-term follow-up.

METHODS

A literature search was performed in September 2020. All studies reporting the outcomes of primary isolated medial patellofemoral ligament reconstruction for recurrent patellofemoral instability were considered for inclusion. Only studies reporting the type of femoral autograft fixation under examination were considered. Studies reporting data from patients with elevated tibial tuberosity-tibial groove, patella alta, and/or Dejour's trochlear dysplasia types C and D, were not included. Only articles reporting data with a minimum follow-up period of 18 months were considered.

RESULTS

Data from 19 studies (615 patients) were retrieved. The overall age was 24.4 ± 6.7 years (mean ± SD). The mean follow-up was 46.5 ± 20.9 months. There were 76 patients in the anchor group and 539 in the screw group. Comparability was found with regard to age and follow-up duration between the 2 study groups. There was comparability between the Kujala, Lysholm, and Tegner scores at baseline. At the last follow-up, no worthy differences were found in terms of mean Kujala (+2.1%; p = 0.04), Lysholm (+1.7%; p = 0.05), and Tegner (+15.8%; p = 0.05) scores. Although complications occurred almost exclusively in the screw cohort, no statistically significant difference was found.

CONCLUSION

Femoral autograft fixation through interference screws or suture anchors report similar clinical scores and rate of apprehension test, persistent joint instability, re-dislocations, and revisions. These results must be interpreted within the limitations of the present study.

Chondral and Soft Tissue Injuries Associated to Acute Patellar Dislocation: A Systematic Review

INTRODUCTION

Chondral and soft tissue injuries can be associated with first time patellar dislocation, but it is unclear how common they are, and which tissues are affected. A systematic review of the literature was performed to investigate the frequency, location, and extent of chondral and medial patellofemoral ligament (MPFL) injuries in patients following first time patellar dislocation.

METHODS

This systematic review was conducted according to the PRISMA guidelines. PubMed, Google Scholar, Embase, and Web of Science databases were accessed in November 2021. All the published clinical studies reporting the frequency, location, and extent of soft tissue lesions following first time patellar dislocation were accessed. Studies reporting data on habitual, congenital, or recurrent patellofemoral instability were excluded.

RESULTS

Data from 42 articles (2254 patients, mean age 21.6 ± 7.3 years) were retrieved. Ninety-eight percent of patients who experienced first time patellar dislocation demonstrated MPFL rupture at MRI. Forty-eight percent of MPFL ruptures were located at the patellar side, 34% at the femoral insertion site, and 18% in the midportion. Eighty-five percent of patients showed signs of patellar chondral damage at MRI, and trochlear chondral injuries were evidenced in 47% of patients. Intra-articular loose bodies were observed in 11.5% of patients. At arthroscopy, the medial facet and the crest of the patella more commonly exhibited chondral lesions than the lateral facet and femoral trochlea.

CONCLUSIONS

Most patients suffer chondral damage and MPFL tears following after a first time patellar dislocation.

Strong Agreement Between Magnetic Resonance Imaging and Radiographs for Caton-Deschamps Index in Patients With Patellofemoral Instability

PURPOSE

To compare the measurements of the Caton-Deschamps index on preoperative magnetic resonance imaging and radiographs of patients undergoing operative management of patellar instability.

METHODS

Patients who underwent primary medial patellofemoral ligament reconstruction and/or tibial tubercle osteotomy between January 2015 and November 2019 were assessed. Caton-Deschamps indices were measured by 3 independent reviewers on both radiographs and magnetic resonance imaging. Intra- and interclass correlation coefficients and a Bland-Altman analysis were calculated to assess inter-rater reliability and measurement agreement between radiographic and magnetic resonance imaging.

RESULTS

Seventy-two patients (73 knees) were identified. The average Caton-Deschamps index was 1.23 ± 0.18 on radiograph and 1.26 ± 0.18 on magnetic resonance imaging. Strong inter-rater reliability was observed between reviewers for both radiographic and magnetic resonance imaging Caton-Deschamps indices (intraclass correlation coefficients 0.700 and 0.715, respectively). Pooled observer measurements revealed a moderate agreement between radiographic and magnetic resonance imaging for patella to tibia distance, weak agreement for patellar articular cartilage distance, and strong agreement for the Caton-Deschamps index (intraclass correlation coefficients 0.687, 0.485, and 0.749, respectively). Bland-Altman analysis demonstrated a mean difference in Caton-Deschamps index of -0.03 ± 0.15 (95% limits of agreement: -0.29 to 0.23) between radiographic and magnetic resonance imaging, meaning that Caton-Deschamps indices were on average 0.03 lower on radiographic than on magnetic resonance imaging.

CONCLUSIONS

The Caton-Deschamps index has strong agreement between radiographic and magnetic resonance imaging in patients undergoing patellar stabilization surgery. Either modality can be reliably used to preoperatively assess patellar height.

LEVEL OF EVIDENCE

Level IV, diagnostic case series.

Combined MPFL reconstruction and tibial tubercle osteotomy for patellar instability: A retrospective review of 23 patients

The primary objective of this retrospective study is to compare patient outcomes following a combined approach (MPFL reconstruction and TTT) to outcomes reported in the literature by patients who required either only an isolated TTT procedure to treat pathologic lateral patellar instability or isolated MPFL reconstruction to treat patellar dislocation due to MPFL insufficiency. Twenty-three patients (74%) were available for follow-up and are included in our analysis. MPFL reconstruction combined with TTT has a high rate of success for patients presenting with patellar instability and extensor mechanism mal-alignment. The risk of recurrence with this technique was low (4.3%).

Putting it all Together: Evaluating Patellar Instability Risk Factors and Revisiting the "Menu"

Management of the patient with multiple risk factors for recurrent patellar instability is complex. Surgeons must possess familiarity with the anatomic risk factors that are associated with first time and recurrent instability events and weigh them in the patient's individualized surgical "menu" options for surgical patellar stabilization. Addressing individual risk factors, pairing imaging findings with physical examination, and thoughts on prioritizing risk factors to determine which should be prioritized for surgical correction are discussed.

Ability of Medial Patellofemoral Ligament Reconstruction to Overcome Lateral Patellar Motion in the Presence of Trochlear Flattening: A Cadaveric Biomechanical Study

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is an established operative procedure to restore medial restraining force in patients with patellar instability. In the setting of a shallow sulcus, it is unclear whether an isolated MPFL reconstruction is sufficient to restore patellofemoral stability.

HYPOTHESIS

Progressively increasing the sulcus angle would have an adverse effect on the ability of an MPFL reconstruction to restrain lateral patellar motion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven fresh-frozen human cadaveric knees were harvested and prepared for experimentation. Each specimen was run through the following test conditions: native, lateral retinacular release, lateral retinacular repair, MPFL release, MPFL reconstruction, and MPFL reconstruction with trochlear flattening. Four 3-dimensional printed wedges (10°, 20°, 30°, and 40°) were created to insert beneath the native trochlea to raise the sulcus angle incrementally and simulate progressive trochlear flattening. For each test condition, the knee was positioned at 0°, 15°, 30°, and 45° of flexion, and the force required to displace the patella 1 cm laterally at 10 mm/s was measured. Group comparisons were made with repeated measures analysis of variance.

RESULTS

In the setting of an MPFL reconstruction, as the trochlear groove was incrementally flattened, the force required to laterally displace the patella progressively decreased. A 10° increase in the sulcus angle significantly reduced the force at 15° (P = .01) and 30° (P = .03) of knee flexion. The force required to laterally displace the patella was also significantly lower at all knee flexion angles after the addition of the 20°, 30°, and 40° wedges (P≤ .05). Specifically, a 20° increase in the sulcus angle reduced the force by 29% to 36%; a 30° increase, by 35% to 43%; and a 40° increase, by 40% to 47%.

CONCLUSION

Despite an MPFL reconstruction, the force required to laterally displace the patella decreased as the sulcus angle was increased in our cadaveric model.

CLINICAL RELEVANCE

An isolated MPFL reconstruction may not be sufficient to restore patellar stability in the setting of a shallow or flat trochlea. Patients with an abnormal sulcus angle may have recurrent instability postoperatively if treated with an isolated MPFL reconstruction.

Clinical Comparison of Medial Patellofemoral Ligament Reconstruction With or Without Tibial Tuberosity Transfer for Recurrent Patellar Instability

BACKGROUND

No clear guidelines or widespread consensus has defined a threshold value of tibial tuberosity-trochlear groove (TT-TG) distance for choosing the appropriate surgical procedures when additional tibial tuberosity osteotomy (TTO) should be added to augment medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability.

PURPOSE

To compare the clinical outcomes between MPFL reconstruction and MPFL reconstruction with TTO for patients who have patellar instability with a TT-TG distance of 15 to 25 mm.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We retrospectively analyzed 81 patients who underwent surgical treatment using either MPFL reconstruction or MPFL reconstruction with TTO for recurrent patellar instability with a TT-TG distance of 15 to 25 mm; the mean follow-up was 25.2 months (range, 12.0-53.0 months). The patients were divided into 2 groups: isolated MPFL reconstruction (iMPFL group; n = 36) performed by 2 surgeons and MPFL reconstruction with TTO (TTO group; n = 45) performed by another 2 surgeons. Clinical outcomes were assessed using the Kujala score, Knee injury and Osteoarthritis Outcome Score, and Tegner activity score. Radiological parameters, including patellar height, TT-TG distance, patellar tilt, and congruence angle were compared between the 2 groups. Functional failure based on clinical apprehension sign, repeat subluxation or dislocation, and subjective instability and complications was assessed at the final follow-up. We also compared clinical outcomes based on subgroups of preoperative TT-TG distance (15 mm ≤ TT-TG ≤ 20 mm vs 20 mm < TT-TG ≤ 25 mm).

RESULTS

All of the clinical outcome parameters significantly improved in both groups at the final follow-up (P < .001), with no significant differences between groups. The radiological parameters also showed no significant differences between the 2 groups. The incidence of functional failure was similar between the 2 groups (3 failures in the TTO group and 2 failures in the iMPFL group; P = .42). In the TTO group, 1 patient experienced a repeat dislocation postoperatively and 2 patients had subjective instability; in the iMPFL group, 2 patients had subjective instability. The prevalence of complications did not differ between the 2 groups (P = .410). In the subgroup analysis based on TT-TG distance, we did not note any differences in clinical outcomes between iMPFL and TTO groups in subgroups of 15 mm ≤ TT-TG ≤ 20 mm and 20 mm < TT-TG ≤ 25 mm.

CONCLUSION

MPFL reconstruction with and without TTO provided similar, satisfactory clinical outcomes and low redislocation rates for patients who had patellar instability with a TT-TG distance of 15 to 25 mm, without statistical difference. Thus, our findings suggest that iMPFL reconstruction is a safe and reliable treatment for patients with recurrent patellar dislocation with a TT-TG distance of 15 to 25 mm, without the disadvantages derived from TTO.

Factors Influencing Graft Function following MPFL Reconstruction: A Dynamic Simulation Study

Medial patellofemoral ligament (MPFL) reconstruction is currently the primary surgical procedure for treating recurrent lateral patellar instability. The understanding of graft function has largely been based on studies performed with normal knees. The current study was performed to characterize graft function following MPFL reconstruction, focusing on the influence of pathologic anatomy on graft tension, variations with knee flexion, and the influence on patellar tracking. Knee squatting was simulated with 15 multibody dynamic simulation models representing knees being treated for recurrent lateral patellar instability. Squatting was simulated in a preoperative condition and following MPFL reconstruction with a hamstrings tendon graft set to allow 0.5 quadrants of lateral patellar translation with the knee at 30 degrees of flexion. Linear regressions were performed to relate maximum tension in the graft to parameters of knee anatomy. Repeated measures comparisons evaluated variations in patellar tracking at 5-degree increments of knee flexion. Maximum graft tension was significantly correlated with a parameter characterizing lateral position of the tibial tuberosity (maximum lateral tibial tuberosity to posterior cruciate ligament attachment distance, r ² = 0.73, p < 0.001). No significant correlations were identified for parameters related to trochlear dysplasia (lateral trochlear inclination) or patella alta (Caton-Deschamps index and patellotrochlear index). Graft tension peaked at low flexion angles and was minimal by 30 degrees of flexion. MPFL reconstruction decreased lateral patellar shift (bisect offset index) compared with preoperative tracking at all flexion angles from 0 to 50 degrees of flexion, except 45 degrees. At 0 degrees, the average bisect offset index decreased from 0.81 for the preoperative condition to 0.71. The results indicate that tension within an MPFL graft increases with the lateral position of the tibial tuberosity. The graft tension peaks at low flexion angles and decreases lateral patellar maltracking. The factors that influence graft function following MPFL reconstruction need to be understood to limit patellar maltracking without overloading the graft or over constraining the patella.

Clinical outcomes and predictive factors for failure with MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release for recurrent patellar instability

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction combined with tibial tubercle osteotomy (TTO) and lateral retinacular release (LRR) is one of the main treatment methods for patellar instability. So far, few studies have evaluated the clinical effectiveness and assessed potential risk factors for recurrent patellar instability.

PURPOSE

To report the clinical outcomes of MPFL reconstruction combined with TTO and LRR at least three years after operation and to identify potential risk factors for recurrent patellar instability.

METHODS

A retrospective analysis of medical records for patients treated with MPFL, TTO and LRR from 2013 to 2017 was performed. Preoperative assessment for imaging examination included trochlear dysplasia according to Dejour classification, patella alta with the Caton-Deschamps index (CDI), tibial tubercle-trochlear groove distance. Postoperative assessment for knee function included Kujala, IKDC and Tegner scores. Failure rate which was defined by a postoperative dislocation was also reported.

RESULTS

A total of 108 knees in 98 patients were included in the study. The mean age at operation was 19.2 ± 6.1 years (range, 13-40 years), and the mean follow-up was 61.3 ± 15.4 months (range, 36-92 months). All patients included had trochlear dysplasia (A, 24%; B, 17%; C, 35%; D, 24%), and 67% had patellar alta. The mean postoperative scores of Tegner, Kujala and IKDC were 5.3 ± 1.3 (2-8), 90.5 ± 15.5 (24-100) and 72.7 ± 12.1 (26-86). Postoperative dislocation happened in 6 patients (5.6%). Female gender was a risk factor for lower IKDC (70.7 vs 78.1, P = 0.006), Tegner (5.1 vs 6.0, P = 0.006) and Kujala (88.2 vs 96.6, P = 0.008). Age (p = 0.011) and trochlear dysplasia (p = 0.016) were considered to be two failure factors for MPFL combined with TTO and LRR.

CONCLUSION

As a surgical method, MPFL combined with TTO and LRR would be a reliable choice with a low failure rate (5.6%). Female gender was a risk factor for worse postoperative outcomes. Preoperative failure risk factors in this study were age and trochlear dysplasia.

LEVEL OF EVIDENCE

Level IV; Case series.

Outcomes of MPFL reconstruction with tibial tubercle transfer for recurrent patellar instability with high grade trochlear dysplasia in Indian population

BACKGROUND

Patellar instability is a painful condition which affects the quality of life and mobility of young individuals. The aim of this study is to observe the results of medial patello-femoral ligament reconstruction with hamstring autograft along with a modified Fulkerson osteotomy, for recurrent instability of patella with high-grade trochlear dysplasia in Indian population.

MATERIALS & METHODS

We conducted a prospective observational study of 26 knees (21 patients) who attended our outpatient department from June 2014 to February 2019, with recurrent instability of the patella and high-grade trochlear dysplasia. All knees were treated with MPFL reconstruction with hamstring autograft and modified Fulkerson osteotomy.

RESULTS

The mean follow-up period was 30 months (range: 24-50). The mean Lysholm scores improved from 49.9 (range: 30-63) preoperatively to 82.5 (range: 51-100) (p < 0.05), Kujala scores from 55.5 (36-67) to 85.9 (55-100) and International Knee Documentation Committee (IKDC) scores from 50.2 (31.6-62.3) to 82.9 (54.7-98.3) (p < 0.05) at 2 years follow-up. TT-TG distance decreased from 21.2 mm (18-25) to 11.6 mm (10-13) (p < 0.05) and patellar tilt angle decreased from 24.2° (18°-35°) to 7.2° (5°-10°) (p < 0.05). One knee had superficial skin infection in immediate post-operative period. Three knees had postoperative stiffness, which improved on manipulation under anesthesia. Six knees had implant irritation from the osteotomy screws which were removed after bony union was achieved. Functional scores were low in two knees due to patello-femoral pain, but they did not have recurrent instability.

CONCLUSION

MPFL reconstruction with tibial tubercle transfer gives good functional outcomes in 92.3% patients with recurrent patellar instability, associated with high-grade trochlear dysplasia in Indian population.

MPFL reconstruction corrects patella alta: a cohort study

PURPOSE

Patella alta is an established risk factor for recurrent lateral patella dislocations. Medial patellofemoral ligament (MPFL) reconstruction has been shown to reduce patella height. Our hypothesis is that isolated MPFL reconstruction corrects patella alta, thereby reducing the risk of recurrent patella dislocation.

METHODS

A prospective cohort study of 33 knees which underwent MPFL reconstruction for recurrent patella dislocation. The pre-operative and post-operative patella height and Kujala knee outcome scores, as well as tibial tuberosity-trochlear groove (TT-TG) distance, and the grade of trochlear dysplasia were recorded.

RESULTS

The mean age was 21.5 years (16-34 years). There was significant reduction in patella height in all patients (p < 0.001), a 67% normalisation of patella alta (CD ≥ 1.2) (p < 0.004), and improvement in the Kujala scores 57.1 (pre-operatively) to 94.8 (post-operatively, p < 0.0001). The recurrent dislocation rate was 3%.

CONCLUSION

MPFL reconstruction alone results in correction in patella alta and improvement in clinical outcomes.

Conservative versus tailored surgical treatment in patients with first time lateral patella dislocation: a randomized-controlled trial

Background

Patellar instability has a high incidence and occurs particularly in young and female patients. If the patella dislocates for the first time, treatment is usually conservative. However, this cautious approach carries the risk of recurrence and of secondary pathologies such as osteochondral fractures. Moreover, there is also risk of continuous symptoms apparent, as recurrent patella dislocation is related to patellofemoral osteoarthritis as well. An initial surgical treatment could possibly avoid these consequences of recurrent patella dislocation.

Methods

A prospective, randomized-controlled trial design is applied. Patients with unilateral first-time patella dislocation will be considered for participation. Study participants will be randomized to either conservative treatment or to a tailored patella stabilizing treatment. In the conservative group, patients will use a knee brace and will be prescribed outpatient physical therapy. The surgical treatment will be performed in a tailored manner, addressing the pathologic anatomy that predisposes to patella dislocation.

The Banff Patellofemoral Instability-Instrument 2.0, recurrence rate, apprehension test, joint degeneration, and the Patella Instability Severity Score will serve as outcome parameters. The main analysis will focus on the difference in change of the scores between the two groups within a 2-year follow-up.

Statistical analysis will use linear mixed models. Power analysis was done for the comparison of the two study arms at 2-year follow-up with regard to the BPII Score. A sample size of N = 64 per study arm (128 overall) provides 80% power (alpha = 0.05, two-tailed) to detect a difference of 0.5 standard deviations in a t-test for independent samples.

Discussion

Although several studies have already dealt with this issue, there is still no consensus on the ideal treatment concept for primary patellar dislocation. Moreover, most of these studies show a unified surgical group, which means that all patients were treated with the same surgical procedure. This is regarded as a major limitation as surgical treatment of patella dislocation should depend on the patient’s anatomic pathologies leading to patellar instability. To our knowledge, this is the first study investigating whether patients with primary patella dislocation are better treated conservatively or operatively with tailored surgery to stabilize the patella.

Trial registration

The study will be prospectively registered in the publicly accessible database www.ClinicalTrials.gov.

Medial patellofemoral ligament reconstruction with and without trochleoplasty for patients with patella instability-correlation of trochlear dysplasia and patient outcome, classification and outcome measure in the past decade-a systematic review

PURPOSE

The primary aim of the study is to compare the patient outcome in medial patellofemoral ligament reconstruction (MPFLR) or MPFLR concurrent with trochleoplasty (MPFLR + TP) and correlate it with the degree of trochlear dysplasia (TD). The secondary aim is to review TD classification, outcome measure, chronological and geographical trend of such studies in the past decade.

METHODS

A systemic review of the literature in the past decade on studies of patients with patella instability and underwent either a MPFLR or MPFLR + TP. The degree of TD with the patient outcome was correlated and compared between the 2 groups. The TD classification, outcome measures, chronological and geographical trends of these studies were documented.

RESULTS

There is no statistical difference in the overall improvement in the compared outcome scores between the 2 groups. However, the MPFLR studies reported a total of 16 re-dislocation in contrast to none in the MPFLR + TP studies. The 24 selected studies in the current review utilized different TD classification as well as outcome measures. A more homogeneous subgroup of 12 studies utilized Dejour classification as well as Kujala score that enabled comparison and showed no significant difference in outcome. The highest number of MPFLR publications was in 2019 and was from North and South Americas, Asia and Europe. The MPFLR + TP studies were from Europe during 2013 to 2017.

CONCLUSION

Though there is an overall improvement in post-operative outcomes scores with no statistical significance between MPFLR and MPFLR + TP, the documented re-dislocations in the MPFLR studies suggested an undetermined zone where the choice of procedure could result in a different outcome. The current review did not show correlation between the degree of TD with the patient outcome to provide a clear indication for either procedure according to the degree of TD. The diverse TD classifications and varied outcome measures indicated the need for standardization and consistency in documentation to guide the treating clinician in the choice of procedure. MPFLR was more commonly performed and studied than MPFLR + TP in the past decade.

Prognostic factors for isolated medial patellofemoral ligament reconstruction: A systematic review

BACKGROUND

Evidence concerning the influence gender, age, and the time elapsed from the first dislocation to surgery in the outcomes of Medial Patella Femoral Ligament (MPFL) reconstruction are lacking. This systematic review was conducted to investigate whether patient characteristics have an influence in the clinical outcomes of MPFL reconstruction for patients with patellofemoral instability.

MATERIAL AND METHODS

This study followed the PRISMA guidelines. The main databases were accessed in February 2021. All the studies reporting outcomes of primary MPFL reconstruction in patients with recurrent patellofemoral instability were considered for inclusion. A multivariate analysis diagnostic tool was used to analyse the association between age, gender and time from injury to surgery and the surgical outcomes at last follow-up.

RESULTS

A total of 50 articles (2037 procedures) were included. The mean follow-up was 40.90 ± 24.8 months. The mean age was 23.6 ± 3.9 years. 64.3% (1309 of 2037 patients) were female. The mean time from injury to surgery was 64.5 ± 48.9 months. Women showed no statistically significant association with the Kujala score or complications. Older patients had a reduced risk to incur re-dislocations (P = 0.01) and revisions (P = 0.01). Longer time from injury to surgery was associated with greater risk to incur re-dislocations (P = 0.01), and with lower Kujala score (P < 0.0001). No other statistically significant association was evidenced.

CONCLUSION

The time span from the first patellar dislocation to the surgical reconstruction was a negative prognostic factor, while sex had no influence on surgical outcomes. The role of patients age on surgical outcomes remains unclear.

Current Concepts Regarding Patellofemoral Trochlear Dysplasia

Optimal treatment of patients with patellofemoral trochlear dysplasia and recurrent patellar instability requires in-depth understanding of this complex structural anomaly. An extensive review of the literature suggests that dysplasia occurs as a result of aberrant forces applied to the patellofemoral joint in the majority of cases. Evidence supports surgical stabilization that reconstructs the medial patellofemoral and/or medial quadriceps tendon-femoral ligament without added trochleoplasty in the majority of patients with trochlear dysplasia and recurrent patellar instability. Adding tibial tubercle transfer distally, medially, or anteromedially in those who need it to treat specific deficits in alignment or articular cartilage can be beneficial in selected patients with trochlear dysplasia and recurrent patellar instability. Trochleoplasty may be appropriate in those few cases in which permanent stable patellofemoral tracking cannot be restored otherwise, but the indications are not yet clear, particularly as trochleoplasty adds risk to the articular cartilage. Improved understanding of imaging techniques and 3-dimensional reproductions of dysplastic patellofemoral joints are useful in surgical planning for patients with recurrent patellar instability and trochlear dysplasia.

Isolated medial patellofemoral ligament reconstruction for recurrent patellofemoral instability: analysis of outcomes and risk factors

Background

The medial patellofemoral ligament (MPFL) is always damaged after patellar dislocation. In selected patients, MPFL reconstruction is necessary to restore a correct patellar tracking. Despite the large number of different techniques reported to reconstruct the MPFL, there is no consensus concerning the optimal procedure, and debates is still ongoing. The present study analysed the results after isolated MPFL reconstruction in patients with patellofemoral instability. Furthermore, a subgroup analysis of patients presenting pathoanatomical risk factors was made.

Methods

In November 2020, the main electronic databases were accessed. All articles reporting the results of primary isolated MPFL reconstruction for recurrent patellofemoral instability were considered for inclusion. Only articles reporting a minimum 12-month follow-up were eligible.

Results

Data from a total of 1777 knees were collected. The mean age of the patients involved was 22.8 ± 3.4 years. The mean follow-up was 40.7 ± 25.8 months. Overall, the range of motion (+ 27.74; P < 0.0001) and all the other scores of interests improved at last follow-up: Kujala (+ 12.76; P = 0.0003), Lysholm (+ 15.69; P < 0.0001), Tegner score (+ 2.86; P = 0.006). Seventy-three of 1780 patients (4.1%) showed a positive apprehension test. Thirty of 1765 patients (1.7%) experienced re-dislocations, while 56 of 1778 patients (3.2%) showed persisting joint instability. Twenty-five of 1786 patients (1.4%) underwent revision surgeries.

Conclusion

Isolated MPFL reconstruction for recurrent patellofemoral instability provides reliable surgical outcomes. Patients with pathoanatomical predisposing factors reported worse surgical outcomes.

The presence of a preoperative high-grade J-sign and femoral tunnel malposition are associated with residual graft laxity after MPFL reconstruction

PURPOSE

The purpose of this study was to analyse the risk factors associated with residual graft laxity after medial patellofemoral ligament reconstruction (MPFL-R) in patients with recurrent patellar dislocation (RPD).

METHODS

A total of 312 consecutive patients (354 knees) with clinically diagnosed RPD who underwent MPFL-R from 2011 to 2015 were retrospectively analysed. Postoperative MPFL graft stability was assessed with patellofemoral stress radiography, and if the patellar central ridge surpassed the apex of the lateral femoral trochlea, the reconstructed MPFL was defined as having residual graft laxity. Finally, 15 patients who exhibited MPFL residual graft laxity (study group) were matched in a 1:2 fashion to 30 control participants (control group), who showed a normal postoperative patellar stability on stress radiography. Preoperative three-dimensional computed tomography (3D-CT) was used to identify patients with a high-grade J-sign. Femoral tunnel position was assessed using 3D-CT to identify cases with femoral tunnel malposition. Potential predictors of MPFL residual graft laxity, including age, sex, a preoperative high-grade J-sign, femoral tunnel malposition, and several radiological parameters, were assessed by logistic regression analysis.

RESULTS

A preoperative high-grade J-sign was identified in 66.7% of the study group, which was significantly higher than that the 13.3% in the control group (P = 0.001). In addition, the presence of a preoperative high-grade J-sign (odds ratio, 11.9 [95% CI, 1.7-82.8]; P = 0.012) and femoral tunnel malposition (odds ratio, 8.2 [95% CI, 1.2-58.0]; P = 0.036) were determined to be independent risk factors associated with residual graft laxity after MPFL-R.

CONCLUSION

The presence of a preoperative high-grade J-sign and femoral tunnel malposition are associated with residual graft laxity after MPFL-R in patients with RPD. These results may provide additional information for counselling patients on residual graft laxity after MPFL-R.

LEVEL OF EVIDENCE

Level III.

Return to Play After Medial Patellofemoral Ligament Reconstruction: A Systematic Review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is being performed more frequently in athletes experiencing recurrent patellar instability.

PURPOSE/HYPOTHESIS

The purpose was to systematically review the evidence in the orthopaedic sports medicine literature to determine both the rate and timing of return to play after MPFL reconstruction and the rate of further patellar instability. Our hypothesis was that there would be a high rate of return to play after MPFL reconstruction.

STUDY DESIGN

Systematic review.

METHODS

A systematic literature search was performed based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, which utilized EMBASE, MEDLINE, and the Cochrane Library databases. Inclusion criteria for literature included clinical studies reporting on return to play after MPFL reconstruction. Rate of return to play, level of return, timing of return, rate of recurrent instability, and patient-reported outcomes were evaluated. Statistical analysis was performed using SPSS.

RESULTS

Our review found 27 studies including 1278 patients meeting our inclusion criteria. The majority of patients were women (58%), and the total group had a mean age of 22.0 years and a mean follow-up of 39.3 months. The overall rate of return to play was 85.1%, with 68.3% returning to the same level of play. The average time to return to play was 7.0 months postoperatively. The rate of recurrent instability events following reconstruction was 5.4%. There was an improvement in both mean visual analog scale, pain scores (preoperative: 4.3, postoperative: 1.6) and Tegner activity scores (preoperative: 4.8, postoperative: 5.5).

CONCLUSION

The overall rate of return to play was high after MPFL reconstruction for the treatment of recurrent patellar instability. However, a relatively high percentage of those patients were unable to return to their preoperative level of sport. Additionally, there was a moderate time taken to return to play, at approximately 7 months after the procedure.

Patella alta is reduced following MPFL reconstruction but has no effect on quality-of-life outcomes in patients with patellofemoral instability

PURPOSE

The primary purpose of this study was to determine if isolated medial patellofemoral ligament (MPFL) reconstruction for lateral patellofemoral instability altered the patellar height ratio. Secondary purposes were to use disease-specific quality-of-life scores to determine if MPFL reconstruction is as successful in patients with patella alta, compared to those without; and whether the change in the patellar height ratio after MPFL reconstruction is influenced by demographic and clinical factors.

METHODS

Demographic and clinical data were collected pre-operatively on 283 patients with recurrent patellofemoral instability. Pre-operative and 6-month post-operative true-lateral radiographs were assessed to determine the patellar height ratio using the Caton-Deschamps index. A Caton-Deschamps index ≥ 1.2 was defined as patella alta. Paired t tests evaluated the effect of MPFL reconstruction on the Caton-Deschamps index. Using a two-sample t test, pre- and 24-month post-operative Banff Patellofemoral Instability Instrument (BPII) scores were assessed for differences in clinical outcomes between patients with and without patella alta. Pearson (for continuous variables) and Spearman rank correlations (for binary/ordinal variables) were calculated to determine the relationship between the patellar height ratio, demographic and pathoanatomic risk factors, and pre- and post-operative BPII scores.

RESULTS

Pre- and post-operative true-lateral radiographs were admissible for 229/283 patients (81%) following isolated MPFL reconstruction. A statistically significant difference in the Caton-Deschamps index was evident from pre- to post-operative for the entire cohort (p < 0.001). The mean decrease in ratio was 0.03, and the effect size was 0.27, classified as small. Pre-operatively 52/229 patients (22.7%) demonstrated a Caton-Deschamps index ≥ 1.2, mean = 1.27 (SD = 0.08); post-operatively 21/229 patients (9.2%) demonstrated patella alta, mean = 1.18, (SD = 0.10), p < 0.001 (two-tailed). The mean decrease in the Caton-Deschamps index for patients with pre-operative patella alta was 0.10; the effect size was 0.82, classified as large. Pearson r correlation of patella alta to the pre- and post-operative BPII scores demonstrated no statistically significant relationship.

CONCLUSION

This study has demonstrated that treatment of lateral patellofemoral instability with an isolated MPFL reconstruction results in a statistically significant decrease in patellar height ratio, with the effect size being greatest in patients with higher pre-operative Caton-Deschamps indices. In patients that presented with patella alta, normalization of the patellar height ratio occurred in 31/52 (59.6%) of the cases. Pre-operative patella alta was not associated with a statistically significant difference in disease-specific BPII outcome scores at any time point. Given these findings, the utility and results of tibial tubercle distalization in patients with patella alta should be a focus of further research. Level of evidence IV.

Lateral retinacular release combined with MPFL reconstruction for patellofemoral instability: a systematic review

INTRODUCTION

The role of the lateral retinaculum in patellofemoral instability is still debated. Lateral retinacular release (LRR), has been extensively performed in combination with different surgical procedures, including reconstruction of medio-patellofemoral ligament (MPFL). Despite controversial indications, the results from these studies seem promising. The present study conducts a systematic review about current biomechanical and clinical evidence concerning the role of LRR in combination with MPFL reconstruction. We performed a comprehensive literature research, comparing the outcomes of MPFL reconstruction with and without LRR.

MATERIALS AND METHODS

This systematic review was conducted according to the PRISMA guidelines. The literature search was performed in August 2020. All articles describing the outcome of isolated MPFL reconstruction alone or in combination with a LRR in patients with recurrent patellofemoral instability were considered for inclusion. Only articles reporting data on patients with a minimum of 12-month follow-up were included. Only articles reporting quantitative data under the outcomes of interest were included.

RESULTS

A total of 63 articles were eligible for this systematic review, including 2131 knees. The mean follow-up was 40.87 ± 24.1 months. All scores of interests improved in favour of the combined group: Kujala + 3.8% (P = 0.01), Lysholm + 4.2% (P = 0.004), Tegner + 0.8 points (P = 0.04), IKDC + 9.8% (P = 0.02). The ROM was comparable between the two groups (P = 0.4). Similarity was found in terms of positivity to the apprehension test (P = 0.05), rate of complications (P = 0.1), re-dislocations (P = 0.8), and revision surgeries (P = 0.1).

CONCLUSION

There is no evidence that adding a lateral release impacts positively on the outcome of MPFL reconstruction.

LEVEL OF EVIDENCE

IV, Systematic review.