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

Promising results following derotational femoral osteotomy in patellofemoral instability with increased femoral anteversion: A systematic review on current indications, outcomes and complication rate

Purpose

Patellofemoral joint instability (PFJI) can surgically be treated with a multitude of approaches, depending on the underlying pathology. In the presence of increased femoral anteversion, some authors have reported good results with a derotational distal femoral osteotomy (DeDFO). The purpose of the study was to investigate the indications, outcomes and complication rate of DeDFO for PFJI.

Methods

A systematic review was performed according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) by searching Medline, Embase, Web of Science and Cochrane Library databases through 1 December 2023. Included were levels 1-4 clinical studies of skeletally mature patients undergoing a DeDFO for PFJI irrespective of concomitant procedures. Study characteristics, indications, radiological and clinical outcomes, surgical technique and concomitant procedures, re-dislocation and complication rate were all analysed, as was methodological quality.

Results

A total of 12 studies including 310 patients (325 knees) were included. Three studies were cohort studies, all others were case series. The mean patient age across the studies was 22 years, and the mean follow-up was 29.4 months. Femoral anteversion cut-off was between 20° and 30°. Every study included at least one concurrent soft tissue, bony or combined procedure. Across all studies, one case of re-dislocation was reported (0.3%) and four implant or osteotomy-related complications (1.2%) were reported. All studies reported a statistically significant increase in clinical scores.

Conclusion

This systematic review of DeDFO for patellofemoral instability in the presence of increased femoral anteversion demonstrates promising clinical results and an extremely low dislocation and complication rate. The heterogeneity of the cut-off in anteversion and concomitant procedures, especially tibial tubercle osteotomy with seemingly identical results, indicates the need for high-quality evidence for treating patellofemoral instability. Based upon this systematic review, we strongly recommend that DeDFO be added to the 'menu à la carte' of PFJI.

Level of Evidence

Level III Systematic Review.

Editorial Commentary: Absent Extreme Bony Malalignment: Medial Patellofemoral Reconstruction Is a Sufficient Primary Surgery for Adolescents With Recurrent Patella Instability

When planning an adolescent's primary surgery for recurrent patella instability, the surgeon must weigh the failure risk of performing medial patellofemoral reconstruction (MPFLR) versus the potential morbidity of adding a concomitant bony procedure, such as tibial tubercle osteotomy. In this age group, isolated MPFLR is an excellent operation with high clinical success, low failure rates, and favorable complication profile. Patients with high grade J-sign and severe trochlea dysplasia, apprehension into deep flexion, and extremes of bony malalignment, including elevated tibial tubercle-trochlear groove distance, may benefit from "doing more" than MPFLR alone. Other factors to be considered include patella alta, generalized ligament laxity, femoral rotation, tibial torsion, and valgus malalignment. In challenging situations, such as syndromic patients (e.g., neuromuscular disorders), congenital (habitual) patella dislocation, fixed dislocations, and failed prior to MPFLR, a combined surgical approach is likely needed. Patients who require "unloading" for symptomatic chondrosis also benefit from combined bony and soft tissue surgery. However, for the majority of patients with recurrent instability and no prior surgery, an isolated soft tissue reconstruction is a rational, safe, efficient, and evidence-based selection.

Medial Patellofemoral Ligament Reconstruction Using the Medial Third of the Patellar Tendon: Camanho's Technique

The reconstruction of the medial patellofemoral ligament (MPFL) is an essential procedure in the surgical treatment of patellar instability. The medial third of the patellar tendon is a good graft option for this reconstruction, maintaining the insertion of the graft in the patella, with no need for hardware for patellar fixation. The objective of this article is to describe the MPFL reconstruction technique with the patellar tendon graft.

Change in patellar height in medial and lateral unicompartmental knee arthroplasty: a clinical trial

INTRODUCTION

Evidence on patellar height changes following unicompartmental knee arthroplasty (UKA) is lacking. Therefore, this study compared the patella height in patients who underwent medial versus lateral UKA. Moreover, a subgroup analysis was conducted to investigate whether sex, age, and BMI of the patients exert an influence on the postoperative patellar height.

METHODS

Radiographs and hospital records of patients undergoing UKA were prospectively collected. Surgeries were performed by one author with long experience in UKA in a highly standardised fashion. The implants were fixed-bearing medial PPK (Zimmer Biomet, Warsaw, Indiana, USA) and fixed-bearing lateral ZUK (Lima Corporate, Udine, Italy). The patellar height was measured using the Insall-Salvati and Caton-Deschamps indices.

RESULTS

A total of 203 patients were included: 119 patients were included in the medial and 84 in the lateral UKA. The mean age of the patients was 68.9 ± 6.7 years, and the mean BMI was 28.1 ± 4.1 kg/m2. 54% (110 of 203 patients) were women. On admission, between-group comparability was found in age, BMI, sex, and length of the follow-up. No between-group and within-group difference was detected pre- and post-operatively in the Insall-Salvati and Caton-Deschamps indices in patients who have undergone medial versus lateral UKA. Concerning the subgroup analyses, no between-group and within-group difference was detected pre- and post-operatively in all comparisons according to sex, age, and BMI.

CONCLUSION

No difference was found in patella height in patients who have undergone medial compared to lateral UKA. Furthermore, there was no evidence of an association between patient characteristics (sex, age, BMI) and patella height between medial and lateral UKA.

Patellar tilt, congruence angle, and tibial tubercle-trochlear groove distance are correlated with positive J-sign in adolescents

PURPOSE

The J-sign is a clinical evaluation tool that assesses for patellar maltracking and is considered positive if lateral translation of the patella in extension, in the pattern of an inverted J is observed. This study aims to determine the association of clinical J-sign with imaging features noted on dynamic kinematic computed tomography (DKCT).

METHODS

A retrospective review was conducted by reviewing the clinical records of all patients aged 18 years or younger who had a CT patellar tracking scan done between 1 January 2005 to 31 December 2016 in a single institution. Patients who had the presence or absence of a 'J-sign' evaluated clinically were included. Radiographic parameters evaluated using the axial cuts include the patellar tilt angle, congruence angle, Dejour's classification, femoral sulcus angle, trochlear groove depth, and Wiberg's classification. Patients were then divided into two groups based on the presence or absence of J-sign on clinical examination. The radiographic measurements were then analyzed for association with the presence or absence of J-sign on clinical examination.

RESULTS

Patients with a positive J-sign had an increased patellar tilt of 23.3° ± 14.2° and an increased congruence angle of 47.1° ± 28.5° when measured in extension as compared to a patellar tilt of 18.3° ± 10.8° and a congruence angle of 32.1° ± 20.8° in patients with a negative J-sign (p = 0.024 and 0.004, respectively). Comparisons of the change in congruence angles with the knee in full extension and at 20° flexion also yielded significantly higher change of 28.0° ± 20.4° in patients with a positive J-sign as compared to 11.9° ± 17.5° in patients with a negative J-sign. Patients with a positive J-sign also had an increased TT-TG distance of 17.6 ± 5.6 mm as compared to a TT-TG distance of 14.7 ± 6.9 mm in patients with a negative J-sign (p = 0.01).

CONCLUSION

Patients with a positive J-sign had an increased patellar tilt and an increased congruence angle when measured in extension. Increased TT-TG distance was also significantly associated with positive J-sign. Patients with a positive J-sign also had a greater change in their congruence angle when measured with the knee in full extension and at 20° of flexion.

Isolated medial patellofemoral ligament reconstruction improves static bipedal balance control in young patients with recurrent lateral patellar instability

BACKGROUND

Knee stability can be safely and reliably restored using medial patellofemoral ligament (MPFL) reconstruction, which is widely recognized in patients with recurrent lateral patellar instability. However, the literature regarding its influence on static balance control is limited. Thus, this study aimed to assess the impact of MPFL reconstruction on balance control and determine its functional significance.

METHODS

The study comprised 26 patients with recurrent lateral patellar instability, scheduled for MPFL reconstruction, and 26 matched healthy controls who underwent double-leg stance static posturographic tests pre- and postoperatively on a vertical force platform. Four test conditions were performed with their eyes open and closed, without and with foam support to evaluate the balance control of all participants. The International Knee Documentation Committee subjective knee form, Lysholm knee scoring scale, Tampa scale for kinesiophobia, and active range of motion of the affected knee were synchronously obtained and assessed.

RESULTS

More postural sway was observed in patients compared to the healthy controls, 11 ± 5 days preoperatively (p < 0.01). However, 374 ± 23 days postoperatively, postural sway between the patients and control subjects was comparable (p > 0.05). Patients following MPFL reconstruction demonstrated better postural stability (p < 0.01). Significant ameliorations were found in all clinical assessments in the study patients postoperatively (p < 0.01).

CONCLUSIONS

Patients with recurrent lateral patellar instability have inefficient balance control. Static bipedal balance control can be improved under surface perturbation in these patients one year after isolated MPFL reconstruction that enhances the possibility of normal restoration of postural stability. Structural recovery of the ligament could help restore the sensorimotor efficiency and generate the compensatory and anticipatory balance regulation strategies, thereby improving joint function.

Concomitant Tibial Tubercle Osteotomy Reduces the Risk of Revision Surgery After Medial Patellofemoral Ligament Reconstruction for the Treatment of Patellar Instability

PURPOSE

To compare postoperative complication rates between patients who underwent medial patellofemoral ligament reconstruction (MPFLR) and those who underwent MPFLR with tibial tubercle osteotomy (TTO) in a large-scale study. A secondary goal was to investigate demographic associations with outcomes.

METHODS

Patients who underwent MPFLR (n = 3,480) or MPFLR-TTO (n = 615) for patellar instability were identified in the PearlDiver database. Rates of surgery for infection, procedures for knee stiffness, patellar fracture, and revision MPFLR within 2 years postoperatively were compared using multivariable logistic regression. Demographic associations with outcomes were also investigated.

RESULTS

The MPFLR-TTO cohort exhibited a significantly lower rate of revision surgery at 2 years (0.8% vs 1.9%; odds ratio [OR], 0.33; 95% confidence interval [CI], 0.10-0.80; P = .036) when compared with the MPFLR group. Independent of index procedure, patients younger than 21 years had significantly lower rates of requiring procedures for knee stiffness (OR, 0.35; 95% CI, 0.22-0.54; P < .001) and any complication at 2 years (OR, 0.59; 95% CI, 0.45-0.78; P < .001) when compared with older patients. Male patients displayed a significantly lower rate of requiring procedures for knee stiffness at 2 years than female patients (OR, 0.46; 95% CI, 0.25-0.78; P = .007). Tobacco use was associated with a significantly higher rate of postoperative infection at 2 years (OR, 2.35; 95% CI, 1.00-5.38; P = .046).

CONCLUSIONS

The MPFLR cohort exhibited higher rates of revision surgery at 2 years compared with the MPFLR-TTO cohort. Patient age under 21 years was associated with lower rates of any complication and requiring procedures for knee stiffness, male sex was associated with a lower rate of requiring procedures for knee stiffness, and tobacco use was associated with a higher rate of surgery for postoperative infection. This information can assist surgeons when counseling patients before these procedures are performed.

LEVEL OF EVIDENCE

Level III, retrospective, comparative prognostic trial.

Radiographic Changes After Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients Compared With an Age- and Sex-Matched Cohort

BACKGROUND

Despite recent evidence that medial patellofemoral ligament reconstruction (MPFLR) in the skeletally immature patient is both safe and effective, there are limited data evaluating postoperative coronal- and sagittal-plane growth and radiographic patellofemoral parameters in this population.

PURPOSE

The primary purpose was to assess radiographic measures of coronal-plane alignment, longitudinal growth, patellar congruence, and trochlear dysplasia after MPFLR in a skeletally immature population. A secondary purpose was to assess this population compared with a matched cohort with a focus on trochlear dysplasia prevalence and the effect of MPFLR on patellar height.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 28 children with a minimum 1-year follow-up who underwent isolated MPFLR were identified. All patients were skeletally immature, defined as fully open physes on both sides of the knee joint, at the time of surgery. The development of a limb length discrepancy or angular growth abnormalities were assessed on standing hip-to-ankle radiographs, patellar tilt and congruence were measured on the Merchant view of the knee, and the grade of trochlear dysplasia and patellar height were assessed on lateral knee radiographs. A sex- and age-matched group of patients who underwent anterior cruciate ligament reconstruction was formed as a control for patellar height and trochlear dysplasia measurements.

RESULTS

The mean patient age was 11.71 ± 2.02 years at the time of surgery with a mean follow-up of 23.54 ± 12.49 months. All but 1 patient in the MPFLR group had preoperative features consistent with trochlear dysplasia. There was no significant difference in limb length or coronal-plane alignment at final follow-up (P = .725 and P > .999, respectively). Both the MPFLR and the anterior cruciate ligament reconstruction groups had a statistically significant decrease in the Caton-Deschamps index between the preoperative and postoperative time points (mean, 0.18 ± 0.20 and 0.11 ± 0.14, respectively; P = .161).

CONCLUSION

MPFLR may be safely performed utilizing an epiphyseal femoral socket in a skeletally immature cohort without affecting normal longitudinal growth or coronal limb alignment. The previously reported effect of MPFLR in reducing patellar height may be related to physiological growth based on similar changes noted in a comparison cohort that did not undergo the procedure.

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.

Outcomes, Return to Sport, and Failures of MPFL Reconstruction Using Autografts in Children and Adolescents with Recurrent Patellofemoral Instability: A Systematic Review

INTRODUCTION

This study systematically reviews and updates the current evidence on the outcomes of medial patellofemoral ligament (MPFL) reconstruction using autografts in children and adolescents with recurrent patellofemoral instability. The outcomes of interest were improvements in patient reported outcomes measures (PROMs), return to sport rates, and the rates of surgical failure.

METHODS

This systematic review was performed according to the 2020 PRISMA guidelines. The following electronic databases were accessed in October 2022: PubMed, Scopus, Web of Science. All the clinical studies which investigated the outcomes of MPFL reconstruction using autografts in children and adolescents with recurrent patellofemoral instability were accessed. Only studies which included patients younger than 18 years were considered. Techniques, case reports, guidelines, comments, editorials, letters, protocols, reviews, and meta-analyses were excluded. Studies which included patients with congenital or acute patellofemoral instability were not eligible, nor were those which focused exclusively on hyperlaxity.

RESULTS

Data from 477 patients (510 procedures) were retrieved. Of the patients, 41% (196 of 477) were women. The mean length of follow-up was 33.7 ± 28.8 months. The mean age of the patients was 14.6 ± 1.6 years. At the last follow-up, all PROMs of interest were statistically improved. The mean time to return to sport was 6.1 ± 1.1 months. Of the patients, 27% reduced their level of activity after surgical stabilization. A total of 87% of patients returned to practice sport. A total of 5% (26 of 477) and 2% (9 of 363) of patients experienced further dislocations and subluxations, respectively, during the follow-up period. Moreover, 4% (16 of 403) of patients underwent a further surgical procedure for patellofemoral instability within the follow-up period.

CONCLUSION

MPFL reconstruction using autografts is effective in children and adolescents with recurrent patellofemoral instability.

Patellofemoral articular cartilage damage is associated with poorer patient-reported outcomes following isolated medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to investigate the impact of articular cartilage damage on outcomes following medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Record review identified 160 patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. Patient demographics, patellofemoral articular cartilage status at surgery, and patient anatomical measures from imaging were obtained via chart review. Patients were contacted and outcomes assessed through collection of Norwich Patellar Instability (NPI) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity score as well as an assessment for recurrent patellar dislocation. Outcomes of patients with grade 0-II patellofemoral cartilage damage were compared to those of patients with grade III-IV cartilage damage.

RESULTS

One hundred twenty-two patients (76%) with a minimum of one year follow-up were contacted at a mean of 4.8 years post-operatively. A total of 63 patients (52%) had grade III or IV patellofemoral chondral damage at the time of surgery. The majority of the defects was on the medial patella (46 patients-72%) and the mean patellar defect size was 2.8 cm². Among 93 patients who completed patient-reported outcome scores, the 52 with grade III or IV chondral damage reported a significantly poorer KOOS Quality of Life than the 44 patients with grade 0 to II chondral damage (p = 0.041), controlling for patient age, sex, BMI, and anatomical factors.

CONCLUSION

Patients with grade III or IV articular cartilage damage of the patellofemoral joint at the time of MPFL reconstruction demonstrated poorer KOOS knee-related quality of life than patients without grade III or IV articular cartilage damage at a mean of 4.8 years following isolated MPFL reconstruction.

LEVEL OF EVIDENCE

Level II.

Return to Play Considerations After Patellar Instability

PURPOSE OF REVIEW

To discuss the treatment options and rehabilitation protocols after non-operative and operative treatment of patellar instability, and to discuss expected return to play outcomes and functional performance with non-operative and operative treatment of patellar instability.

RECENT FINDINGS

A criterion-based program assessing range of motion, joint effusion, strength, neuromuscular control, proprioception, agility, and power are critical measures to assess when rehabilitating this population. A series of functional tests including quadriceps strength testing, single-limb hop testing, lateral step-down test, the side hop test, the lateral leap and catch test, the Y-balance test, and the depth jump should be considered when determining an athlete's return to sport clearance. These objective measures combined with psychological readiness and a comprehensive understanding of the sports-specific tasks required for participation should be considered when evaluating an athlete's ability to safely and successfully return to sport. We discuss rehabilitation management when working with non-operative and operative management of patellar instability and provide considerations for clinicians working with these athletes to facilitate safe return to sport.

Synthetic graft for medial patellofemoral ligament reconstruction: a systematic review

Background

This systematic review investigates the role of synthetic graft for primary medial patellofemoral ligament (MPFL) reconstruction in patients with recurrent patellofemoral instability, focusing on clinical scores and the rate of complications.

Methods

This systematic review was conducted according to the PRISMA statement. The main online databases were accessed in January 2022 without time constraints. All clinical studies investigating the use of synthetic grafts for MPFL reconstruction were accessed. Revision settings were not considered. Only articles reporting data on patients with recurrent patellofemoral instability were eligible. Studies regarding congenital or acute patellofemoral dislocation were excluded. Only studies performing a follow-up longer than 24 months were considered.

Results

Data on 199 patients [mean age 22.3 (range 19.0–28.0) years] were collected. The mean follow-up was 60.5 (39.0–142.8) months. All the scores of interest improved at last follow-up: Kujala (+ 24.8; P = 0.0002), Lysholm (+ 42.0; P = 0.02), Tegner (+ 1.2; P = 0.03), IKDC (+ 20.9; P = 0.02). Post-operatively, a positive apprehension test was detected in 6.1% (7/115) of patients, and a sensation of instability was reported by 1.5% (3/199) of patients. The rate of re-dislocations was 2.5% (5 of 199 patients), and revision procedures were performed in less than 1% (1 of 199) of patients.

Conclusion

Synthetic graft may be reliable and feasible for primary MPFL reconstruction in patients with recurrent patellofemoral instability.

Interference Screws Are Biomechanically Superior to Suture Anchors for Medial Patellofemoral Ligament Reconstruction: A Systematic Review and Meta-Analysis

Purpose

To systematically review the literature to evaluate the biomechanical properties of the interference screw (IS) versus suture anchor (SA) techniques for patellar and femoral fixation of medial patellofemoral ligament (MPFL) reconstruction.

Methods

A systematic review was performed by searching PubMed, the Cochrane library, and Embase using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify studies that analyzed the biomechanical properties of IS and SA techniques for MPFL reconstruction. The search phrase implemented was “medial patellofemoral ligament reconstruction biomechanics.” Evaluated outcomes included ultimate load to failure (N), stiffness (N/mm), and mode of failure. Forest plots were created for statistical analysis and heterogeneity was assessed via I² statistic.

Results

Six studies met inclusion criteria, including a total of 108 cadaveric specimens, for MPFL patellar fixation, and 3 studies met inclusion criteria, including a total of 50 cadaveric specimens, for MPFL femoral fixation. Pooled analysis from 5 studies reporting on stiffness for MPFL patellar fixation revealed a statistically significant difference in favor of IS compared with SA (P = .007). Pooled analysis from 3 studies reporting on ultimate load to failure of femoral fixation revealed a statistically significant difference in favor of IS compared with SA (P = .043).

Conclusions

The use of IS was associated with a greater stiffness compared with the use of SA in MPFL patellar fixation, but there was no difference in load to failure between IS and SA. The use of IS was associated with a greater load to failure compared with the use of SA in MPFL femoral fixation, but there was no difference in stiffness between IS and SA.

Clinical Relevance

There have been multiple individual biomechanical studies conducted comparing IS and SA fixation for MPFL patellar and femoral fixation; however, they have yielded conflicting results, with small sample sizes. Pooling the data from these studies in a meta-analysis may allow for more meaningful biomechanical data to coincide with the existing, albeit scarce, clinical data, this may help to inform clinical decision making for surgeons managing these injuries.

High Rates of Damage to the Medial Patellofemoral Ligament, Lateral Trochlea, and Patellar Crest After Acute Patellar Dislocation: Magnetic Resonance Imaging Analysis

PURPOSE

The primary outcome of interest of this study was to determine the frequency, location, and extent of chondral injuries and medial patellofemoral ligament (MPFL) tears, along with the rate of loose bodies, in the knee after acute primary patellar dislocation. The secondary outcome of interest was to conduct a multivariate analysis to investigate whether the presence of pathoanatomic abnormalities, including structural differences in the knees of the patients, is associated with the features of the lesions.

METHODS

Patients who underwent magnetic resonance imaging after primary acute patellar dislocation were identified from our institutional databases. We analyzed a total of 175 magnetic resonance imaging scans of patients aged between 14 and 25 years who were eligible for inclusion.

RESULTS

Chondral damage to the medial facet of the patella was present in 36 patients; patellar crest, 78 patients; and lateral patellar facet, 28 patients. One patient presented with chondral defects in the medial trochlear facet, whereas 118 patients showed chondral defects in the lateral trochlear facet. Loose bodies were present in 142 patients. A total of 161 patients (92%) showed MPFL damage. The patellar portion was affected in 119 patients. Of the patients, 28 showed a partially damaged MPFL (<50%), 42 showed MPFL damage greater than 50%, and 49 presented with a complete tear of the MPFL. MPFL lesions were observed on the femoral side in 42 patients. Fourteen patients presented with an avulsion fracture on the patellar side; 28 patients, on the femoral side.

CONCLUSIONS

The MPFL was injured in 92% of 175 patients after a first-time acute patellar dislocation. Chondral damage was most frequent at the patellar crest, followed by the lateral femoral epicondyle. No association was found between patella alta, the sulcus angle, the Q angle, the tibial tubercle-trochlear groove distance, trochlear and patellar dysplasia, and soft-tissue damage.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

A Simple Instrument for Intraoperative Fluoroscopic Localization of Anatomic Insertions in Medial Patellofemoral Ligament Reconstruction

Medial patellofemoral ligament (MPFL) reconstruction is the most common operation for treating patellofemoral joint instability. Accurately identifying the fluoroscopic location of the MPFL anatomical insertion point is critical in this procedure. However, current radiographic localization has some limitations, such as inaccuracy and radiation exposure. We recommend a simpler and more accurate instrument for intraoperative fluoroscopic positioning.

Combined MPFL reconstruction and tibial tuberosity transfer avoid focal patella overload in the setting of elevated TT-TG distances

PURPOSE

Objectives are (1) to evaluate the biomechanical effect of isolated medial patellofemoral ligament (MPFL) reconstruction in the setting of increased tibial tuberosity-trochlear groove distance (TTTG), in terms of patella contact pressures, contact area and lateral displacement; (2) to describe the threshold of TTTG up to which MPFL reconstruction should be performed alone or in combination with tibial tuberosity transfer.

METHODS

A finite element model of the knee was developed and validated. The model was modified to simulate isolated MPFL reconstruction, tibial tuberosity transfer and MPFL reconstruction combined with tibial tuberosity transfer for patella malalignment. Two TT-TG distances (17 mm and 22 mm) were simulated. Patella contact pressure, contact area and lateral displacement were analysed.

RESULTS

Isolated MPFL reconstruction, at early degrees of flexion, restored normal patella contact pressure when TTTG was 17 mm, but not when TTTG was 22 mm. After 60° of flexion, the TTTG distance was the main factor influencing contact pressure. Isolated MPFL reconstruction for both TTTG 17 mm and 22 mm showed higher contact area and lower lateral displacement than normal throughout knee flexion. Tibial tuberosity transfer, at early degrees of flexion, reduced the contact pressure, but did not restore the normal contact pressure. After 60° of flexion, the TTTG distance was the main factor influencing contact pressure. Tibial tuberosity transfer maintained lower contact area than normal throughout knee flexion. The lateral displacement was higher than normal between 0° and 30° of flexion (< 0.5 mm). MPFL reconstruction combined with tibial tuberosity transfer produced the same contact mechanics and kinematics of the normal condition.

CONCLUSION

This study highlights the importance of considering to correct alignment in lateral tracking patella to avoid focal patella overload. Our results showed that isolated MPFL reconstruction corrects patella kinematics regardless of TTTG distance. However, isolated MPFL reconstruction would not restore normal patella contact pressure when TTTG is 22 mm. For TTTG 22 mm, the combined procedure of MPFL reconstruction and tibial tuberosity transfer provided an adequate patellofemoral contact mechanics and kinematics, restoring normal biomechanics. This data supports the use of MPFL reconstruction when the patient has normal alignment and the use of combined MPFL reconstruction and tibial tuberosity transfer in patients with elevated TT-TG distances to avoid focal overload.

Dynamic versus static medial patellofemoral ligament reconstruction technique in the treatment of recurrent patellar dislocation: a randomized clinical trial protocol

BACKGROUND

The redislocation rate of conservatively treated patella instability is high. One of the leading surgical strategies is medial patellofemoral ligament reconstruction. Over-tensioning is one of the most challenging complications in static medial patellofemoral ligament reconstruction as the graft used for reconstruction is isometric and the anatomical MPFL is a mostly dynamic structure. As an alternative to established static reconstruction techniques, dynamic graft techniques have been introduced for stabilizing the patella with the aim of providing a more physiological reconstruction of the medial patellofemoral ligament. To date, data on clinical outcomes are scarce and on biomechanical outcomes of the dynamic MPFL reconstruction are lacking. Here, we present the protocol of a randomized clinical trial for comparing clinical and biomechanical outcomes of dynamic versus static medial patellofemoral ligament reconstruction.

METHODS

This study is a prospective, single blinded, randomized, multicenter, multimodal (clinical and biomechanical) clinical trial. Patients with recurrent patella dislocation requiring isolated MPFL reconstruction will be recruited and randomized to the dynamic or static reconstruction technique. Participants will be followed up for 2 years with a total of five follow-ups. Preoperative magnetic resonance imaging, upright radiographs, surgical reports and patient records will be evaluated, and clinical and functional outcomes will be measured. Patient-reported knee function and anterior knee pain as assessed with the Kujala score will serve as primary outcome. For biomechanical outcome, pre- and postoperative evaluations will be performed to assess isokinetic muscle strength, gait asymmetry, joint kinematics and kinetics, and timing of muscle activity.

DISCUSSION

The results of the study will clarify whether the reported surgery success for patella stabilization via dynamic MPFL reconstruction is due to muscle contraction or to the passive tenodesis effect combined with clinical outcome measures. With this study, we will provide much needed information on knee biomechanics after dynamic versus static MPFL reconstruction to provide evidence to support orthopedic surgeons in evidence-based decision-making in their quest for surgical techniques most favorable for their patients. Trial registration The study protocol was registered at clinicaltrials.gov (NCT04849130). Registered 19 April 2021, https://clinicaltrials.gov/ct2/show/NCT04849130 .

YouTube Videos Lack Efficacy as a Patient Education Tool for Rehabilitation and Return to Play Following Medial Patellofemoral Ligament Reconstruction

Purpose

To investigate the efficacy of YouTube videos as a patient education resource related to rehabilitation and return to play following medial patellofemoral ligament (MPFL) reconstruction.

Methods

YouTube was queried using 6 predetermined search terms. Videos were included if they met the following criteria: (1) written in the English language; and (2) within the first 100 videos for each search term. Videos were excluded if they met any of the following criteria: (1) not written in the English language; (2) did not include medial patellofemoral ligament/MPFL in the title; (3) duplicate videos; (4) part of a multivideo series such a vlogs; (5) advertisements; and (6) videos <1 minute. The remaining videos were evaluated by 2 independent viewers and scored using 4 distinct scoring systems: Global Quality Scale, The Patient Education Materials Assessment Tool for Audiovisual Materials (PEMAT), MPFL Rehabilitation and Return to Play Score, and the Journal of the American Medical Association benchmark criteria. The data was analyzed with IBM SPSS Statistics, version 27). The Kruskal–Wallis test was used to compare quality scores and video analytics to their assigned categories. Results where P < .05 were considered statistically significant and pairwise comparison analysis was completed to determine the video categories with statistically significant differences. Correlation of categorical variables with video analytics (views, video power index, duration, and days since publication) and quality scores was determined using the Pearson Correlation coefficient.

Results

Of the initial 600 videos, 58 met inclusion criteria, which were subsequently reviewed and scored. Most videos scored on the low-end of the possible scoring ranges with a mean Global Quality Scale score of 1.61 (standard deviation [SD] 0.81), PEMAT Understandability score of 59.40 (SD 17.54), PEMAT Actionability score of 18.20 (SD 29.92), MPFL Rehabilitation and Return to Play Score of 1.64 (SD 2.13), and Journal of the American Medical Association benchmark score of 2.08 (SD 0.75).

Conclusions

The videos in YouTube’s library received low scores in quality, reliability, understandability and actionability. Therefore, YouTube is currently a poor source of information for patients regarding postoperative rehabilitation and return to play following MPFL reconstruction.

Clinical Relevance

Patients increasingly view medical information online. YouTube is second only to Google as the most used search engine. It is important to understand the quality of information patients receive on YouTube following MPFL reconstruction so orthopaedic surgeons know to guide patients to higher-quality alternatives.

Hardware-free MPFL reconstruction in patients with recurrent patellofemoral instability is safe and effective

PURPOSE

This systematic review evaluated the clinical outcomes of hardware-free MPFL reconstruction techniques in patients with recurrent patellofemoral instability, focusing on patient-reported outcome measures (PROMs), redislocation rate, and complications. The hypothesis was that hardware-free MPFL reconstruction in patients with recurrent patellofemoral instability is safe and effective.

METHODS

This systematic review was conducted following the PRISMA guidelines. PubMed, Scopus, and Virtual Health Library databases were accessed in October 2021. All the clinical studies investigating the efficacy and feasibility of hardware-free MPFL reconstruction were screened for inclusion. Only studies with a minimum 24-month follow-up were considered eligible. Kujala Anterior Knee Pain Scale improvement and redislocation rate after surgical treatment were evaluated as primary outcomes. The rate of postoperative complications was evaluated as a secondary outcome. The quality of the methodological assessment was assessed using the Modified Coleman Methodology Score.

RESULTS

Eight studies were included in the present systematic review. The quality of the methodological assessment was moderate. Short- to long-term improvement of Kujala score was observed in all included studies. Mean score improvement ranged from + 13.2/100 to + 54/100, with mean postoperative scores ranging from 82/100 to 94/100. Patellar redislocation was observed in 8.33% (8 of 96) patients.

CONCLUSION

Hardware-free MPFL reconstruction with or without associated soft-tissue or bony realignment procedures provided reliable clinical improvements and was associated with a low rate of redislocation in patients with recurrent patellofemoral instability. Advantages such as safety, femoral physis preservation, and comparable complication profiles with implant-based techniques endorse its implementation. Orthopedic surgeons in cost-sensitive environments may also benefit their patients with lower costs, no need for implants, lack of implant-related complications, or surgery for implant removal.

LEVEL OF EVIDENCE

Level IV.

Anatomical Double-Bundle Medial Patellofemoral Ligament Reconstruction With Autologous Semitendinosus, a Single Patellar Tunnel Technique

Patellofemoral instability is one of the knee problems that can be found in up to 3% of knee injuries, especially in younger aged females. Recent biomechanical studies showed that the main soft tissue stabilizer for patellofemoral stability is the medial patellofemoral ligament (MPFL). More than 200 articles on MPFL reconstruction have been published. Some surgical techniques create multiple holes in the patellar area that may increase the risk of patellar fractures. This technique that we present here attempts to reduce the chance of patella-related complications, while maintaining stability of the reconstructed construct, reducing the use of a lengthy tendon graft within the patella and covering the footprint at the border of the patella closed to the native anatomy of the MPFL.

Changes in patellar morphology following surgical correction of recurrent patellar dislocation in children

Background

The aim of this study was to evaluate patellar morphological changes following surgical correction of recurrent patellar dislocation in children.

Methods

A total of 35 immature children aged 5 to 10 years who suffered from bilateral recurrent patellar dislocation associated with abnormal patella morphology were enrolled in this study. The knees with the most frequent dislocations (treated with medial patellar retinacular plasty) were selected as the study group (SG), and those undergoing conservative treatment for the contralateral knee were selected as the control group (CG). Computed tomography (CT) scans were performed on all children preoperatively and at the last follow-up to evaluate morphological characteristics of the patella.

Results

All the radiological parameters of the patella showed no significant difference between the two groups preoperatively. At the last follow-up for CT scans, no significant differences were found for the relative patellar width (SG, 54.61%; CG, 52.87%; P = 0.086) and the relative patellar thickness (SG, 26.07%; CG, 25.02%; P = 0.243). The radiological parameters including Wiberg angle (SG, 136.25°; CG, 122.65°; P < 0.001), modified Wiberg index (SG, 1.23; CG, 2.65; P < 0.001), and lateral patellar facet angle (SG, 23.35°; CG, 15.26°; P < 0.001) showed statistical differences between the two groups.

Conclusions

The patellar morphology can be improved by early surgical correction in children with recurrent patellar dislocation. Therefore, early intervention is of great importance for children diagnosed with recurrent patellar dislocation.

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.

Age at surgery is correlated with pain scores following trochlear osteotomy in lateral patellar instability: a cross-sectional study of 113 cases

Background

A trochlear osteotomy aims to restore patellar stability in patients with recurrent patellar instability and trochlear dysplasia. The age of patients at time of surgery could be a relevant factor which influences outcome. We hypothesized that lower age at time of surgery is associated with better patient-reported outcomes.

Methods

A retrospective study was conducted on patients with patellar instability and trochlear dysplasia. Patients were contacted by phone for informed consent and were then asked to complete online patient-reported outcome measurements (PROMs). The PROMs consisted of the Kujala Knee Score (KKS) (Kujala et al., Arthroscopy 9(2):159-63, 1993; Kievit et al. Knee Surg Sports Traumatol Arthrosc. 21(11):2647-53, 2013), the Short Form 36-item health survey (SF-36v1) (Ware, Med Care 73-83, 1992; Aaronson et al., J Clin Epidemiol. 51(11):1055-68, 1998), and visual analog scale (VAS) scoring pain, instability, disability, and satisfaction on a 0–100 scale. Multivariable linear regression models were used to study the effect of age on the PROM scores.

Results

For this study, 125 surgical procedures in 113 patients were included. Mean VAS pain at rest was 19 and at activity 38; mean Kujala score was 73. Multivariable regression analysis revealed that age at the time of surgery was correlated with VAS pain at rest, with a 0.95 increase of VAS score (scale 0–100) for every year of age. Recurrence of instability was observed in 13 (10%) knees.

Conclusion

In this cross-sectional study, pain scores of 113 patients who have undergone a lateral facet elevating trochlear osteotomy for patellar instability were reported. Age at time of surgery was correlated with an increased pain score at rest with an average of 9.5 points (scale 0–100) for every 10 years of age. Age at time of surgery was not correlated with overall satisfaction.