Medial patellofemoral ligament reconstruction fixed with a cylindrical bone plug and a grafted semitendinosus tendon at the original femoral site for recurrent patellar dislocation

Results of medial patellofemoral ligament reconstruction with and without tibial tubercle osteotomy in patellar instability: a systematic review and single-arm meta-analysis

PURPOSE

To confirm which method provides lower rate of recurrent instability and superior clinical outcomes.

METHOD

We searched PubMed, Embase and Web of Science for the trials involving one intervention or both for patellar instability: medial patellofemoral ligament reconstruction (MPFLR) with and without tibial tubercle osteotomy (TTO). The postoperative Kujala score, Lysholm score, Tegner scores and the rate of recurrent instability (dislocation or subluxation) were analyzed as the primary clinical outcome parameters in a random or fixed effects meta-analysis.

RESULTS

In total, 43 articles met inclusion criteria after full-text review. A total of 2046 patients were analyzed. The overall mean age was 20.3 years (range, 9.5-60.0 years), with a mean follow-up time of 3.2 years (range, 1-8 years). The mean Kujala scores in MPFLR and MPFLR + TTO were 89.04 and 84.44, respectively. There was significant difference in Kujala scores between MPFLR and MPFLR + TTO (MD = 4.60, 95%CI: 1.07-8.13; P = 0.01). The mean Lysholm scores in MPFLR and MPFLR + TTO were 90.59 and 88.14, respectively. There was no significant difference in Lysholm scores between MPFLR and MPFLR + TTO (MD = 2.45, 95%CI: -3.20-8.10; P = 0.40). The mean Tegner scores in MPFLR and MPFLR + TTO were 5.30 and 4.88, respectively. There was no significant difference in Tegner scores between MPFLR and MPFLR + TTO (MD = 0.42, 95%CI: -0.39-1.23; P = 0.31). At final follow-up, the rates of recurrent instability in MPFLR and MPFLR + TTO were 3% and 4%, respectively. There was no significant difference in the rates between MPFLR and MPFLR + TTO (OR = 0.99, 95%CI: 0.96-1.02; P = 0.4848).

CONCLUSION

MPFLR and MPFLR + TTO are effective and reliable treatments in the setting of patellofemoral instability. MPFLR seems to show a better performance in functional outcomes than MPFLR + TTO. Moreover, their rates of recurrent instability are very low, and no significant difference exists.

A Case Report on Medial Patellofemoral Ligament Reconstruction Rehabilitation in a Cricket Player Through Targeted Agility Training

The medial patellofemoral ligament (MPFL) serves as a crucial stabilizer, preventing lateral dislocation of the patella. Surgery is usually advised after a second dislocation, with MPFL reconstruction being a common procedure. The primary objective of rehabilitation post-surgery is not just to relieve pain and restore range of motion (ROM), but also to combine proprioceptive neuromuscular training to help patients return to their prior functional level. Agility training is a crucial component in accomplishing this goal. The current case is of a 19-year-old male cricket player with a history of recurrent patellar dislocation who underwent surgery after the latest incident rendered him unable to bear weight. His rehabilitation program included standard protocols alongside the early implementation of agility drills, such as ladder exercises. Compared to traditional approaches, this case demonstrates significant improvement in the patient's functional ability following surgery. This report highlights the importance of comprehensive rehabilitation for patients undergoing MPFL reconstruction. It not only underscores the rationale behind the surgery but also lays the groundwork for comparing recovery times. Notably, this program incorporated early agility exercises from the very beginning, suggesting that such an approach might accelerate recovery compared to standard protocols. Further investigation is warranted to explore the potential benefits of early agility training in this patient population.

Isolated medial patellofemoral reconstruction outcomes: A systematic review and meta-analysis

BACKGROUND

Treatment of patellar instability remains up for debate, and a combination of tibial tubercle osteotomy and medial patellofemoral ligament reconstruction (MPFLr) of the medial patellofemoral ligament (MPFL) has become the mainstay treatment for recurrent lateral patellar dislocation. Due to limited small studies, there remains a variety of surgical techniques still being practiced. The use of MPFL reconstruction, in isolation, has demonstrated promise.

PURPOSE

The purpose of this systematic review and meta-analysis is to investigate if isolated medial patellofemoral ligament reconstruction (iMPFLr) can safely and efficaciously restore knee stability and to present the patient demographics, surgical techniques, graft choices, clinical outcomes, and complications after iMPFLr for recurrent patellar dislocation (RPD).

METHODS

A review of the current literature according to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, yielded 299 abstracts. Twenty-seven articles met the inclusion/exclusion criteria accounting for 1200 patients. Data was pooled and analyzed focusing on patient demographics, graft type used, Kujala, International Knee Documentation Committee (IKDC), Lysholm, Tegner, and complications.

RESULTS

Across all studies the weighted mean age was found to be an average of 24.5 years, BMI was 24.9 kg/m2, follow-up was 47.3 months, as 67% were female, TT-TG distance was 15.3 mm, and Caton Deschamps index 1.11. The pooled effect size difference of pre versus post assessment of Kujala was -2.8, IKDC was -4.5, Lysholm was -6.4, and Tegner was -0.74. The pooled complication rate was found to be 8% across all included studies. A subgroup analysis was also performed, specifically looking at how single bundle, double bundle, gracilis, semitendinosus and knee angle during fixation effect outcome data.

CONCLUSION

This systematic review and meta-analysis demonstrates that isolated MPFL reconstruction is a safe and effective treatment for recurrent patellar dislocations. Given the efficacy of isolated MPFL reconstruction, future investigations should aim to uncover the exact TT-TG distance, trochlear dysplasia, and patella alta grade for selecting patients to undergo this procedure. Furthermore, more primary research needs to be conducted on this topic due to the overall lack of published data from randomized controlled studies and no broad standardization of outcome measurements.

LEVEL OF EVIDENCE

(4) Systematic Review and Meta-Analysis.

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.

Clinical outcomes of medial patellofemoral ligament reconstruction using FiberTape and knotless SwiveLock anchors

BACKGROUND

We aimed to prospectively investigate the clinical outcomes of medial patellofemoral ligament (MPFL) reconstruction using polyester high-strength suture tape with knotless anchors.

METHOD

Forty-three patients (65 knees) were followed for at least 1 year postoperatively, with 27 patients (43 knees) followed for 2 years postoperatively. All patients underwent MPFL reconstruction using polyester high-strength suture tape (FiberTape®; Arthrex) with knotless anchors (SwiveLock®; Arthrex). Repeated dislocation and residual patellar apprehension signs were recorded, and congruence and tilting angles were measured. Changes in Knee Injury and Osteoarthritis Outcome Scale (KOOS) scores and their associations with the preoperative tibial tubercle-trochlear groove (TT-TG) distance were analyzed.

RESULTS

No repeat dislocations (0%) were observed. One (2.4%) residual positive patellar apprehension sign was noted. The mean tilting angle decreased from 24.8° to 10.7° (P < 0.001), and the mean congruence angle decreased from 24.9° to 4.3° (P < 0.001). At 2 years follow up, all KOOS subscales had improved: pain (92.0 ± 12.9), symptoms (90.2 ± 11.9), activities of daily living (95.7 ± 7.3), sports activity (85.7 ± 16.9), quality of life (87.7 ± 12.9), and patellofemoral (89.0 ± 9.6) outcomes. KOOS subscale scores improved regardless of the preoperative TT-TG distance (21.1 ± 3.5 mm; range, 13.8-29.9 mm).

CONCLUSIONS

MPFL reconstruction using FiberTape and knotless SwiveLock anchors was performed without sacrificing autologous tissue. No recurrent patellar dislocation was observed during the 2-year follow up period. All KOOS subscale scores improved using FiberTape and SwiveLock anchors in MPFL reconstruction.

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.

Influence of the Fluoroscopy Setting towards the Patient When Identifying the MPFL Insertion Point

(1) The malposition of the femoral tunnel in medial patellofemoral ligament (MPFL) reconstruction can lead to length changes in the MPFL graft, and an increase in medial peak pressure in the patellofemoral joint. It is the cause of 36% of all MPFL revisions. According to Schöttle et al., the creation of the drill canal should be performed in a strictly lateral radiograph. In this study, it was hypothesized that positioning the image receptor to the knee during intraoperative fluoroscopy would lead to a relevant mispositioning of the femoral tunnel, despite an always adjusted true-lateral view. (2) A total of 10 distal femurs were created from 10 knee CT scans using a 3D printer. First, true-lateral fluoroscopies were taken from lateral to medial at a 25 cm (LM25) distance from the image receptor, then from medial to lateral at a 5 cm (ML5) distance. Using the method from Schöttle, the femoral origin of the MPFL was determined when the femur was positioned distally, proximally, superiorly, and inferiorly to the image receptor. (3) The comparison of the selected MPFL insertion points according to Schöttle et al. revealed that the initial determination of the point in the ML5 view resulted in a distal and posterior shift of the point by 5.3 mm ± 1.2 mm when the point was checked in the LM25 view. In the opposite case, when the MPFL insertion was initially determined in the LM25 view and then redetermined in the ML5 view, there was a shift of 4.8 mm ± 2.2 mm anteriorly and proximally. The further positioning of the femur (distal, proximal, superior, and inferior) showed no relevant influence. (4) For fluoroscopic identification of the femoral MPFL, according to Schöttle et al., attention should be paid to the position of the fluoroscopy in addition to a true-lateral view.

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.

Editorial Commentary: A Complex Network of Bony and Soft-Tissue Stabilizers-and Overall Limb Alignment-Determines Patellofemoral Stability

Patellofemoral stability is maintained through a complex network of static and dynamic soft-tissue stabilizers, the osseous structure of the patella and trochlea, and overall limb alignment. Thus, determining the risk of recurrent patellar instability must account for as many of these factors as possible in the clinical decision-making process. The tibial tubercle-trochlear groove distance is the most common parameter used for this evaluation but may be limited because of methodologic issues and because this distance is an absolute value. Indices that incorporate other predisposing factors, including trochlear dysplasia, increase the accuracy of predicting recurrent patellar instability and can be used to generate a patient-specific treatment plan.

Application of a true lateral virtual radiograph from 3D-CT to identify the femoral reference point of the medial patellofemoral ligament

PURPOSE

The purpose of this study is two-fold: (1) to describe the femoral reference point of the medial patellofemoral ligament (MPFL) on a virtual true lateral radiograph reconstructed from a three-dimensional computed tomography (3D-CT) image and (2) to compare this point with that of patients without patellofemoral instability and with Schöttle's point.

METHODS

A total of 26 consecutive patients (29 affected knees) with recurrent patellar dislocation (RPD), who underwent MPFL reconstruction were included in this study (4 males; 22 females; mean age, 24.0 years old). Using a true lateral 3DCT image, the MPFL femoral insertion was identified and marked with a 2-mm circle, and this image was reconstructed as a virtual true lateral radiograph. Following Schöttle's method, the point of intersection was described by their anterior-posterior and proximal-distal positions. As a control population, 29 age- and gender-matched patients with anterior cruciate ligament (ACL) injuries were also analysed.

RESULTS

The points in RPD patients were located significantly posterior (-2.5 ± 2.3 mm, p < 0.01) to the line representing an extension of the posterior cortex of the femur and distal (- 6.9 ± 2.4 mm, p < 0.01) to the posterior origin of the medial femoral condyle compared with those in the control population. The mean reference point of RPD patients was located in a 3.8-mm posterior and 4.4-mm distal position compared with Schöttle's point.

CONCLUSIONS

An anatomical and radiographic femoral reference point of the MPFL on a true lateral virtual radiograph was described with our method. In patients with RPD, this reference point was identified to be more posterior and distal to Schöttle's point. More anatomical and individualized MPFL reconstruction will be secured using our method.

LEVEL OF EVIDENCE

Level IV.

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.

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.

Interference Screw Versus Suture Anchors for Femoral Fixation in Medial Patellofemoral Ligament Reconstruction: A Biomechanical Study

Background:

Femoral-sided graft fixation in medial patellofemoral ligament (MPFL) reconstruction is commonly performed using an interference screw (IS). However, the IS method is associated with several clinical disadvantages that may be ameliorated by the use of suture anchors (SAs) for femoral fixation.

Purpose:

To compare the load to failure and stiffness of SAs versus an IS for the femoral fixation of a semitendinosus autograft in MPFL reconstruction.

Study Design:

Controlled laboratory study.

Methods:

Based on a priori power analysis, a total of 6 matched pairs of cadaveric knees were included. Specimens in each pair were randomly assigned to receive either SA or IS fixation. After an appropriate reconstruction procedure, the looped end of the MPFL graft was pulled laterally at a rate of 6 mm/s until construct failure. The best-fit slope of the load-displacement curve was then used to calculate the stiffness (N/mm) in a post hoc fashion. A paired t test was used to compare the mean load to failure and the mean stiffness between groups.

Results:

No significant difference in load to failure was observed between the IS and the SA fixation groups (294.0 ± 61.1 vs 250.0 ± 55.9; P = .352), although the mean stiffness was significantly higher in IS specimens (34.5 ± 9.6 vs 14.7 ± 1.2; P = .004). All IS reconstructions failed by graft pullout from the femoral tunnel, whereas 5 of the 6 SA reconstructions failed by anchor pullout.

Conclusion:

In this biomechanical study using a cadaveric model of MPFL reconstruction, SA femoral fixation was not significantly different from IS fixation in terms of load to failure. The mean load-to-failure values for both reconstruction techniques were greater than the literature-reported values for the native MPFL.

Clinical Relevance:

These results suggest that SAs are a biomechanically viable alternative for femoral-sided graft fixation in MPFL reconstruction.

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.

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.

Patellofemoral Contact Pressure for Medial Patellofemoral Ligament Reconstruction Using Suture Tape Varies With the Knee Flexion Angle: A Biomechanical Evaluation

PURPOSE

The purpose of this study was to evaluate the effect of the knee flexion angle during graft fixation on patellofemoral (PF) contact pressure in medial patellofemoral ligament (MPFL) reconstruction using polyester suture tape and knotless anchors.

METHODS

Nine human knees (mean age 74.9 ± 14.1 years) were used in this study. Polyester suture tape was fixed at the medial edge of the patella with two 3.5-mm knotless anchors, and then to the femur with a 4.75-mm knotless anchor at 4 different knee flexion angles (0°, 30°, 60°, and 90°). A pressure sensor was used to measure the maximum contact pressure (MCP) of the medial and lateral PF joints in the intact knee and in postreconstruction knees at each knee flexion angle (0°, 30°, 60°, and 90°). Each MCP was normalized to that of the intact knee. A statistical comparison was made between MCP in the intact and reconstructed knees.

RESULTS

The normalized MCP of the medial PF joint fixed at either 0° or 30° significantly increased at 60° of knee flexion (P = .036 and .042, respectively) and at 90° of knee flexion (P = .002 and .001, respectively). Conversely, the normalized MCP fixed at 60° and 90° remained at the same level as the intact knees at all angles of knee flexion. The normalized MCP of the lateral PF joint showed no significant difference at any fixation angle compared with intact knees.

CONCLUSION

To avoid excessive PF joint contact pressure after MPFL reconstruction, it may be best to fix polyester suture tape between 60° and 90° of knee flexion.

CLINICAL RELEVANCE

Fixation of the polyester suture tape with a knotless anchor for MPFL reconstruction should be at 60° to 90° of knee flexion to most closely restore PF joint contact pressures to that of the intact knee.

Isolated versus combined medial patellofemoral ligament reconstruction for lateral instability of the patella

INTRODUCTION

Medial patellofemoral ligament reconstruction (MPFLR) is regularly combined with a tibial tuberosity transfer (TTT) in cases of recurrent patellar instability with underlying structural deformity. However, these indications for a TTT have recently come into question. This study aimed to assess the traditional indications by comparing the outcomes of isolated and combined MPFLR for the treatment of recurrent lateral patellar dislocation.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies were those which reported the outcomes of either isolated or combined or both MPFLR. Studies were required to report at least one of the following: redislocation rate, revision due to instability, or the Kujala score.

RESULTS

We found no difference between isolated and combined MPFLR in terms of redislocation ( p = 0.48), revisions due to instability ( p = 0.36), positive apprehension tests ( p = 0.25), or the Kujala score ( p = 0.58). Combined reconstruction presented more complications compared to isolated procedures ( p = 0.05). Subgroup analysis revealed no significant difference between studies investigating isolated medial patellofemoral ligament reconstruction MPFLR performed in patients with normal tibial tuberosity-trochlear groove (TT-TG) distances only or in patients with both normal and elevated TT-TG distances.

CONCLUSIONS

According to the published data, there is no difference in outcomes between isolated and combined MPFLR. Underlying structural deformity did not demonstrate any significant effect on the success of the isolated MPFLR. Although there are definite indications for combined reconstruction, the current evidence suggests that our inclusion criteria may not be entirely correct. Further study is required to clarify and refine the true indications for combined MPFLR.

LEVEL OF EVIDENCE

III, meta-analysis of nonrandomized studies.

Selective bundle tensioning in double-bundle MPFL reconstruction to improve restoration of dynamic patellofemoral contact pressure

PURPOSE

To evaluate the optimal graft tension angles in a medial patellofemoral ligament (MPFL) reconstruction with selective bundle tensioning in order to restore patellofemoral contact pressure distributions closest to the native state.

METHODS

Twelve human cadaveric knee specimens were mounted with the femur on a custom-made fixation device allowing free range of motion in the knee joint for testing. Using a sensitive pressure film (Tekscan) patellofemoral contact pressure was measured in 15° intervals during a dynamic flexion movement from 0°-90° in the native state, in cut MPFL and after MPFL-reconstruction with a gracilis tendon. The graft was separated in two bundles and was fixed independently on the patella using two knotless anchors. Two groups were made with either the proximal or distal bundle fixed at the femur at a knee flexion angle of 30° and the corresponding other bundle subsequently fixed at the femur at 15°, 45°, 60°, 75° and 90° of knee flexion using extra-cortical fixation and controlled tension of 2N in both groups. The sequence of the flexion angles at the graft fixation was alternated. Pressure measurements were repeated after every fixation of the graft.

RESULTS

Cutting the MPFL resulted in significantly reduced patellofemoral contact pressure at all flexion angles. After MPFL reconstruction the patellofemoral contact pressure remained significantly reduced during dynamic knee flexion in all tested double-bundle combinations (p < 0.05) except for fixation of the proximal bundle in 30° and the distal bundle in 75°. Selective evaluation of lateral patellofemoral contact pressure, however, showed significant reduction in all tested double-bundle combinations (p < 0.05) from 15° to 90°. Evaluation of isolated medial patellofemoral pressure changes showed no significant difference in all tested combinations compared to the intact knee. Furthermore, evaluation of the isolated proximal and distal patellofemoral contact pressure also revealed a significantly reduced contact pressure in all tested double-bundle combinations (p < 0.05) except for fixation of the proximal bundle in 30° and the distal bundle in 75°.

CONCLUSION

According to this study, selective bundle tensioning in anatomic MPFL-reconstruction should be considered as an easy and more anatomic alternative to current popular techniques to restore patella kinematics and give clear recommendation about knee flexion angle and tension during fixation. Although tensioning two bundles separately may further improve clinical results. If performed, fixation of the graft is recommended under low tension (2N) with the proximal bundle at 30° and the distal bundle at 75° of knee flexion.

Arthroscopic assessment of patella tracking correlates with recurrent patellar instability

PURPOSE

For recurrent lateral patellar instability surgical algorithm, an arthroscopic assessment of patellar tracking can aid with the decision of adding a tibial tubercle transfer procedure based on knee flexion angle at which patella centrally engages in its groove. Tibial tubercle-trochlear groove distance is variable in normal values and has discrepancies between imaging modalities. The aims of our study were to assess correlation of arthroscopic patellar tracking technique with recurrent patellar instability, and to assess the accuracy and reproducibility of this technique.

METHODS

157 patients were evaluated, 64 control patients with no patellar instability, and 93 patients with recurrent patellar instability. This included 57 consecutive knee arthroscopy procedures evaluated for accuracy and reproducibility of our technique. The technique involved low flow arthroscopy and anterolateral viewing portal. Patients' knees were extended from a flexed position of 120°, and paused when the patella disengaged from its groove. The KFA was then estimated by the primary surgeon, and compared with a goniometer measurement. The assisting surgeon, blinded to the primary surgeon measurements, repeated this process. For the primary outcome, goniometer readings for KFA from the primary surgeon were used to correlate with patellar instability diagnosis.

RESULTS

Patients with patellar instability had a mean KFA of 118° compared to 44°for patients without patellar instability (p < 0.001). The mean difference between goniometer reading and estimation of KFA by each surgeon was 5° (p < 0.001) with intra-class correlation of 0.99. The mean difference between the two surgeons' goniometer readings was 8° (p < 0.001) with intra-class correlation of 0.99.

CONCLUSION

This study confirms arthroscopic assessment of patella tracking is accurate, reproducible, and a knee flexion angle of greater than 44° correlates with patellar instability diagnosis. Patella tracking can be used as an adjunct or an alternative assessment method to tibial tubercle-trochlear groove distance to determine the need for tibial tubercle transfer in patellar stabilisation surgery.

LEVEL OF EVIDENCE

Prospective Cohort Study, Level III.

The modified semi-tunnel bone bridge technique achieved statistically better knee function than the suture anchor technique

PURPOSE

The purpose of this study was to evaluate and compare the clinical outcomes of two different fixation techniques for anatomic medial patellofemoral ligament (MPFL) reconstruction.

METHODS

A retrospective study was undertaken between 2012 and 2018 of 60 cases of patellar dislocation who underwent surgical reconstruction between 2007 and 2010: 30 patients were treated with modified semi-tunnel bone bridge fixation (group A) and 30 patients with suture anchor fixation (group B). All patients had computed tomography scans available to review the patellar tilt angle and lateral patellar angle (LPA). In addition, a physical examination was performed, and the patellar apprehension sign and patellar stability were evaluated. Knee function was also evaluated using the Kujala score and Lysholm score.

RESULTS

At a minimum 5-year follow-up, the patellar tilt angle and LPA were restored to the normal range, and a significant difference was observed between the groups. There was a significant improvement in knee function in the Kujala and Lysholm scores after surgery in both groups. At the final follow-up, the mean Kujala and Lysholm scores in groups A and B were significantly different.

CONCLUSION

Both the semi-tunnel bone bridge and suture anchor fixation for double-bundle anatomic reconstruction of the MPFL can effectively restore patellar stability and improve knee function. The semi-tunnel bone bridge technique achieved statistically better knee function than the suture anchor technique at a minimum 5-year follow-up.

LEVEL OF EVIDENCE

III.

Graft choice for isolated MPFL reconstruction: gracilis versus semitendinosus

INTRODUCTION

After the first patellar dislocation, most patients report damage of the medio-patellofemoral ligament (MPFL) and surgical reconstruction is required. The purpose of this study is to systematically review current evidence and to clarify the role of the gracilis and semitendinosus tendons as graft for isolated MPFL reconstruction.

MATERIALS AND METHODS

The present systematic review was conducted according to the PRISMA guidelines. The literature search was conducted in October 2019. All clinical trials using the semitendinosus and/or gracilis tendon grafts for isolated MPFL reconstruction in patients with patellofemoral instability were considered for inclusion. Only articles reporting a minimum of 12-month follow-up were considered. The PEDro score was used for the methodological quality assessment.

RESULTS

Data from 1491 procedures were collected. The mean follow-up was 36.12 months. There was comparability among the patient baseline. All the scores of interests (Kujala, Tegner, Lysholm) and range of motion scored better in the semitendinosus group. Moreover, in favour of the semitendinosus group, a statistically significant reduction of the revision surgeries and re-dislocations were evidenced. Apprehension test and persistent instability sensation found any statistical correlations.

CONCLUSION

Isolated MPFL reconstruction through semitendinosus tendon graft performed better than the gracilis in selected patients suffering from recurrent patellofemoral instability.

Treatment of patellar dislocation with arthroscopic medial patellofemoral ligament reconstruction using gracilis tendon autograft and modified double-patellar tunnel technique: minimum 5-year patient-reported outcomes

BACKGROUND

The purpose of this study was to retrospectively analyze the clinical outcomes of patients with recurrent patellar dislocation who underwent arthroscopic medial patellofemoral ligament (MPFL) reconstruction using gracilis tendon autograft and a modified double-patellar tunnel method. We hypothesized that our modified method would provide good clinical outcomes.

METHODS

Patients who underwent arthroscopic MPFL reconstruction with autograft gracilis tendon and modified double-patellar tunnels technique for recurrent patellar dislocation and were followed up for a minimum of 5 years were identified, and the clinical and follow-up data were retrospectively analyzed. Preoperatively, joint hypermobility was assessed with the Beighton score. The Insall-Salvati ratio, TT-TG distance, and Q angle were measured on radiographic images. Patient-reported outcomes including the Kujala, Lysholm, and Tegner scores were collected preoperatively and postoperatively. Patient satisfaction was assessed at the end of 5 years. Complications and recurrent dislocation occurring after surgery were recorded.

RESULTS

A total of 79 patients (94 knees) were enrolled; of these, 13 (16.5%) were lost to follow-up. The data of 66 patients (80 knees) were available for final analysis. Mean age at surgery was 21.3 ± 7.8 years. Mean follow-up time was 66.1 ± 5.5 months (range, 60-78 months). Postoperative patient-reported outcome was not associated with Beighton score, Insall-Salvati ratio, or TT-TG distance. Q angle was negatively correlated to Kujala scores and Lysholm scores. Severity of trochlear dysplasia was not associated with postoperative patient-reported outcome. The mean Kujala score increased from 69.4 ± 7.9 to 96.1 ± 1.9, the mean Tegner score increased from 3.1 ± 1.3 to 5.9 ± 1.3, and the mean Lysholm score increased from 73.5 ± 14.6 to 95.3 ± 3.4. Two patients experienced recurrent patellar dislocation during follow-up.

CONCLUSIONS

MPFL reconstruction using autologous gracilis tendon under arthroscopy appears to be a reliable and safe method for treating recurrent patellar dislocation.

LEVEL OF EVIDENCE

Level IV.

Single- versus double-bundle patellar graft insertion for isolated MPFL reconstruction in patients with patellofemoral instability: a systematic review of the literature

INTRODUCTION

The MPFL reconstruction is performed either via a single-bundle (SB) or double-bundle (DB) procedure. The purpose of this study is to perform a systematic review comparing SB versus DB graft for recurrent patellofemoral instability, to summarize current evidence, and to clarify the role of both techniques. We focused on clinical scores, physical examination, complications, revision surgeries, and failures.

MATERIAL AND METHODS

In May of 2019 the main online databases were accessed. All the clinical studies treating isolated MPFL reconstruction for patellofemoral instability through a single and/or double-bundle graft were enrolled in the present systematic review. Only articles reporting primary isolated MPFL reconstruction, reporting a minimum of 12-months follow-up were considered for inclusion.

RESULTS

The scores of interest were in favour of the DB cohort: Kujala (+ 3.2, P = 0.03), Lysholm (+ 5.1, P = 0.001), Tegner (+ 0.3, P = 0.2), IKDC (+ 5.4, P = 0.01), VAS (+ 0.8, P = 0.3), ROM (+ 9.96, P = 0.04). In the DB graft, a reduction of overall complications (OR 0.59; P = 0.1), further surgeries (OR 0.64; P = 0.12) and re-dislocations (OR 0.61; P = 0.16) was observed. The SB group reported a reduction in the post-operative apprehension test (OR 2.42; P = 0.24).

CONCLUSION

Current study support the use of double-bundle tendon graft for isolated MPFL reconstruction in selected patients with recurrent patellofemoral instability.

Medial patellofemoral ligament reconstruction using an autograft or allograft for patellar dislocation: a systematic review

Purposes

The purpose of this study is to review the use of an allograft or autograft in medial patellofemoral ligament (MPFL) reconstruction.

Materials and methods

Various electronic databases were searched for relevant articles published from January 2000 to September 2017 that evaluated clinical outcomes of MPFL reconstruction using an autograft or allograft. Data search, extraction, analysis, and quality assessments were performed based on Cochrane Collaboration guidelines.

Results

The study of 21 autografts and one allograft was included in this review. Although direct comparative studies were unavailable, the Kujala score and subjective results were reported in the majority of these studies. While the use of an autograft for MPFL reconstruction yielded satisfactory clinical outcomes with few perioperative complications, no new outcome has been drawn from the use of allografts.

Conclusions

Although many studies have shown favorable clinical results for MPFL reconstruction using an autograft, the clinical results of MPFL reconstruction using an allograft have not yet been sufficient to achieve meaningful clinical results due to low levels of evidence. Direct comparisons were not conducted because there were very few studies on allografts; thus, further research in this area should be performed in the future.

Electronic supplementary material

The online version of this article (10.1186/s43019-019-0008-0) contains supplementary material, which is available to authorized users.

Knee Flexion Angle During Graft Fixation for Medial Patellofemoral Ligament Reconstruction: A Systematic Review of Outcomes and Complications

PURPOSE

To determine the effect of knee flexion angle during graft fixation on outcomes and complications following medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Three databases (PubMed, EMBASE, and MEDLINE) were searched from database inception to January 2018. After screening based on inclusion and exclusion criteria, patient demographics, fixation technique, graft selection, outcomes, and complications were extracted from the included studies. The studies were grouped based on flexion angle used during graft fixation: low (0°-30°) and high (45°-90°) flexion angle group. Methodological Index for Non-Randomized Studies criteria were used to assess the quality of each included study. Descriptive statistics are presented.

RESULTS

Seventeen studies (of 3,399) were included and were either cohort (n = 1) or case series (n = 17) study designs. A total of 556 patients with a mean age of 23.6 years (range, 10-60 years) underwent MPFL reconstructions, with 458 patients in the 0° to 30° fixation group and 98 in the 45° to 90° fixation group. The mean Kujala score improved from 45 to 72.9 (365 patients) preoperatively to 83 to 94.5 (460 patients) postoperatively for the 0° to 30° fixation group and from 53.3 to 72 preoperatively to 92.2 to 95.2 postoperatively for the 45° to 90° fixation group (98 patients).

CONCLUSIONS

The knee flexion angle during MPFL graft fixation ranges from 20° to 90°. Graft fixation at low and high knee flexion angles during MPFL reconstruction showed excellent patient-reported outcomes and low patellar redislocation rates overall, with no clear differences between the 2 groups based on the currently available data.

LEVEL OF EVIDENCE

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

Systematic Review of Medial Patellofemoral Ligament Reconstruction Techniques: Comparison of Patellar Bone Socket and Cortical Surface Fixation Techniques

PURPOSE

To compare patellar bone socket and cortical surface fixation techniques for isolated medial patellofemoral ligament (MPFL) reconstruction and determine whether there was a difference in (1) complication rates, including fracture of the patella; (2) redislocation rates; or (3) patient-reported outcomes.

METHODS

A literature search was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included patients who underwent isolated MPFL reconstruction for recurrent patellar instability. Patients with confirmed concomitant or prior ipsilateral knee procedures, multiligament injury, or less than 3 months of follow-up were excluded. Risk-of-bias assessment was performed using the Methodological Index for Non-randomized Studies (MINORS) system. Studies were classified by surgical technique (patellar bone socket group [group S] vs cortical fixation group [group F]), and complications, redislocations, and patient-reported outcomes were collected.

RESULTS

A total of 29 studies yielded 981 patients with MPFL reconstruction for inclusion. Of the patients, 620 underwent a patellar bone socket technique and 361 underwent a cortical fixation technique. Patients ranged in age from 11 to 68 years. Patellar fracture rates ranged from 0% to 17% in group S and were 0% in all group F studies. Mean Kujala scores ranged from 83.5 to 93.6 in group S and from 84.4 to 94.5 in group F. Mean Lysholm scores ranged from 84.6 to 91.7 in group S and from 83.5 to 95 in group F. Redislocation rates ranged from 0% to 21% in group S and from 0% to 13% in group F. Although heterogeneous in nature, complication rates ranged from 0% to 28% in group S and from 0% to 4% in group F.

CONCLUSIONS

MPFL reconstruction techniques with patellar bone sockets showed a larger range of complication rates than cortical fixation techniques, although overall, complications remained uncommon. Clinically, the bone socket group had comparable postoperative redislocation rates and patient outcomes to the group treated with cortical fixation techniques.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I through IV studies.

A 2-year follow-up of isolated Medial Patellofemoral Ligament Reconstruction by using soft suture anchor and adjustable cortical fixation system

Purpose

Numerous surgical techniques and fixation methods have been described in medial patellofemoral ligament (MPFL) reconstruction such as choice of graft, graft fixation method of patella/femur and initial tension. We describe short term clinical results of MPFL reconstruction by using soft suture anchor and adjustable cortical fixation system.

Methods

Twenty-four patients who underwent isolated MPFL reconstruction by using soft suture anchor and adjustable cortical fixation system were included in this study. All patients were followed up for at least 2 years, and pre-operative and 2 years post-operative Kujala score, IKDC score and Knee Injury and Osteoarthritis Outcome Score were used to assess clinical outcome. Radiographic evaluation included the Q angle, congruence angle and patellar tilt angle. Pre- and post-operative changes were evaluated by Mann-Whitney U test.

Results

There were no complications including re-dislocation, patella fracture, infection, and joint contracture. The apprehension test was positive in 4.2% post-operatively. A statistically significant improvement in clinical scores and radiographic evaluation were evident after surgery.

Conclusions

Isolated MPFL Reconstruction using soft suture anchor and adjustable cortical fixation system led good restoration of patellar stability and significant improvement of knee function in short-term results. This surgical technique can reduce complications such as patella fractures, and can be done safely.

Clinical relevance

This technique may be a treatment option with little associated complications in the treatment for patellar instability.

Level of Evidence

Case series, Level IV.

Single- and double-bundle medial patellofemoral ligament reconstruction procedures result in similar recurrent dislocation rates and improvements in knee function: a systematic review

PURPOSE

To evaluate medial patellofemoral ligament (MPFL) reconstruction using hamstring tendon autografts using single-bundle (SB) and double-bundle (DB) techniques, and compare the clinical outcomes including the Kujala score, postoperative apprehension, recurrent subluxation or dislocation, and complications.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched for relevant literature using the terms ''medial patellofemoral ligament'' and ''MPFL''. The pooled mean values of improvement in the Kujala score were calculated by random effects meta-analysis. Unweighted estimates for the rates of postoperative apprehension, recurrent subluxation or dislocation, and complications were determined by dividing the total number of occurrences by the total number of knees.

RESULTS

Thirty-one articles were included, involving 1063 patients (1116 knees). Two hundred and forty-four patients (254 knees) underwent SB reconstruction, while 819 patients (862 knees) underwent DB reconstruction. The pooled mean values of Kujala score improvement were similar in the SB group (30.1; 95% CI 26.6-33.6) and DB group (30.7; 95% CI 27.7-33.7). The SB group had a significantly greater rate of postoperative apprehension (7.9%) than the DB group (4.1%; P = 0.014). There were no significant differences between the two groups in the rates of recurrent subluxation or dislocation (1.2 and 1.6%) and complications (10.6 and 7.7%).

CONCLUSION

With variability in patient populations and surgical techniques, the DB procedure for isolated MPFL reconstruction demonstrates similar outcomes to the SB technique regarding improvement of knee function, recurrent subluxation or dislocation, and complications. The SB technique may have a greater risk of postoperative apprehension, whereas the DB technique may cause more stiffness.

LEVEL OF EVIDENCE

IV.

Return-to-Play Guidelines After Medial Patellofemoral Ligament Surgery for Recurrent Patellar Instability: A Systematic Review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction and repair continue to gain acceptance as viable treatment options for recurrent patellar instability in patients who wish to return to sports after surgery. Return-to-play guidelines with objective or subjective criteria for athletes after MPFL surgery, however, have not been uniformly defined.

PURPOSE

To determine whether a concise and objective protocol exists that may help athletes return to their sport more safely after MPFL surgery.

STUDY DESIGN

Systematic review.

METHODS

The clinical evidence for return to play after MPFL reconstruction was evaluated through a systematic review of the literature. Studies that measured outcomes for isolated MPFL surgery with greater than a 12-month follow-up were included in our study. We analyzed each study for a return-to-play timeline, rehabilitation protocol, and any measurements used to determine a safe return to play after surgery.

RESULTS

Fifty-three studies met the inclusion criteria, with a total of 1756 patients and 1838 knees. The most commonly cited rehabilitation guidelines included weightbearing restrictions and range of motion restrictions in 90.6% and 84.9% of studies, respectively. Thirty-five of 53 studies (66.0%) included an expected timeline for either return to play or return to full activity. Ten of 53 studies (18.9%) in our analysis included either objective or subjective criteria to determine return to activity within their rehabilitation protocol.

CONCLUSION

Most studies in our analysis utilized time-based criteria for determining return to play after MPFL surgery, while only a minority utilized objective or subjective patient-centric criteria. Further investigation is needed to determine safe and effective guidelines for return to play after MPFL reconstruction and repair.

Return to Sports After Tibial Tubercle Osteotomy for Patellofemoral Pain and Osteoarthritis

PURPOSE

To determine the rate of return to sports and clinical outcomes after anteromedialization (AMZ) tibial tubercle osteotomy (TTO) for patients with patellofemoral pain and/or osteoarthritis.

METHODS

This study is a retrospective case series of consecutive patients who underwent unilateral or staged bilateral AMZ TTO for a primary diagnosis of patellofemoral pain or arthritis. Included were all patients with minimum 1-year follow-up. The indication for surgery was failure of at least 6 months of nonoperative treatment. Simultaneous tubercle distalization or proximal-medial soft-tissue procedures were excluded; however, prior patellar instability procedures did not prohibit inclusion if there was no recurrence. A diagnostic arthroscopy was performed to evaluate the cartilage surfaces; AMZ TTO was performed by use of a freehand technique and two 4.5-mm fully threaded screws for fixation. A gradual return to activities was permitted at 6 months; however, contact sports were prohibited until 9 months postoperatively. Patients were evaluated retrospectively for participation in sports using a questionnaire about the level of participation, return to sporting activities, and Kujala score. Statistical analysis included 1-way analysis of variance and χ² or Fisher exact and paired t tests.

RESULTS

Forty-eight patients played sports within 3 years before surgery. The majority were female patients (84.2%). The average age at surgery was 29.6 years, with an average follow-up period of 4.6 years. The average Kujala score improved from 51.2 to 82.6 (P < .0001); the average pain score improved from 4.1 to 1.8 (P < .001). Of the patients, 83.3% returned to at least 1 sport on average 7.8 months postoperatively. Of these, 77.5% believed they returned to sports at the same level or a higher level.

CONCLUSIONS

Patients undergoing AMZ TTO for patellofemoral pain or arthritis had an 83.3% rate of return to 1 or more sporting activities at an average of 7.8 months after surgery, with many patients returning at the same level or a higher level of intensity compared with their preoperative state.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Graft Choice in Isolated Medial Patellofemoral Ligament Reconstruction: A Systematic Review With Meta-analysis of Rates of Recurrent Instability and Patient-Reported Outcomes for Autograft, Allograft, and Synthetic Options

PURPOSE

To determine whether graft selection or patient age affects the following after isolated medial patellofemoral ligament (MPFL) reconstruction: (1) rates of recurrent instability, (2) rates of postoperative complications (other than instability), and (3) subjective symptom improvement.

METHODS

A systematic search identified studies reporting outcomes for isolated MPFL reconstruction. Rates of recurrent instability, subjective Kujala knee function scores, and complications were tabulated. Symptom improvement was defined as change in Kujala score (preoperative evaluation to final follow-up).

RESULTS

Forty-five studies were included with 27 documented cases of recurrent instability among 1,504 patients (1.8%); instability rates ranged from 0% to 20.0% overall; among autograft in adults, 0% to 11.1% (1.4%, 18/1,260); among autograft in adolescents, 0% to 20% (10.0%, 8/80); among allograft, 0% (0/65 cases); and among synthetic, 0% to 3.3% (1.3%, 1/76). Among autograft choices in adults, rates of recurrent instability were low; recurrence with gracilis ranged from 0% to 11.1% (0.9%, 1/116); with semitendinosus, 0% to 6.3% (0.6%, 4/676); with quad or patellar tendon, 0% (0/65); and with adductor tendon, 5.6% to 8.3% (6.7%, 2/30). Complication rates ranged from 0% to 34.4%. All included studies reported significant improvement in Kujala scores after surgery (P < .01). There was significant heterogeneity in effect size and evidence of reporting bias among small studies, precluding reliable pooled analysis of treatment effect.

CONCLUSIONS

Autograft is not superior to allograft or synthetic grafts for isolated reconstruction of the MPFL, and rates of recurrent instability are generally low. Isolated MPFL reconstruction can provide significant symptom relief regardless of graft selection, although there is a bias toward reporting better than expected results among smaller studies. Pediatric patients and patients treated with adductor tendon autograft have higher recurrent instability rates. While caution should be used in making definitive recommendations secondary to the small number of allograft and synthetic studies, selection of graft type based on surgeon preference, comfort, and prior experience remains appropriate.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I to IV studies.

Medial Patellofemoral Ligament Reconstruction: Impact of Knee Flexion Angle During Graft Fixation on Dynamic Patellofemoral Contact Pressure-A Biomechanical Study

PURPOSE

Objective evaluation of the optimal graft tension angle to fully restore patellofemoral contact pressure in reconstruction of the medial patellofemoral ligament (MPFL) in comparison to the native knee.

METHODS

Twelve cadaveric knee specimens were fixed in a custom-made fixation device. A sensitive pressure film (Tekscan) was fixed in the patellofemoral joint, and patellofemoral contact pressure was assessed during a dynamic flexion movement from 0° to 90°. The MPFL was cut and measurements were repeated. Reconstruction of the MPFL was performed with the gracilis tendon subsequently fixed in the femur at 15°, 30°, 45°, 60°, 75°, and 90° of knee flexion under controlled tension (2 N). The sequence of the flexion angles was alternated. Pressure measurements were repeated after every fixation of the graft.

RESULTS

No significant differences were seen in the overall patellofemoral contact pressure compared to the native knee (P > .05). However, medial patellofemoral pressure showed a significant increased patellofemoral contact pressure after MPFL reconstruction at a knee flexion angle during graft fixation of 15° (P = .027), 45° (P = .050, P = .044), and 75° (P = .039). Moreover, proximal/distal patellofemoral contact pressure revealed a significantly reduced contact pressure at 15° (P = .003), 30° (P = .009), 45° (P = .025), 75° (P = .021), and 90° (P = .022) of flexion distal after MPFL reconstruction compared with the intact knee. Lateral patellofemoral contact pressure was significantly reduced in all performed reconstructions (P < .05).

CONCLUSIONS

The flexion angle during graft fixation for MPFL reconstruction did not have a significant impact on the overall patellofemoral contact pressure. However, selective medial, proximal, distal, and lateral patellofemoral contact pressure was significantly altered for all reconstructions. Fixation of the MPFL graft at 60° of flexion was able to most closely restore patellofemoral contact pressure compared with the intact knee.

CLINICAL RELEVANCE

Based on the findings of the present study, fixation of the graft in anatomic reconstruction of the MPFL should be considered in 60° of flexion under low tension (2 N) to most closely restore patellofemoral contact pressure compared with the native knee.

Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability Among Patients With Trochlear Dysplasia

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction has become one of the most common and widely used procedures to regain stability among patients with recurrent lateral patellar dislocation. While recent studies demonstrated low recurrence rates, improved patient-reported outcome measures, and a high rate of return to sports, limited literature explored its effectiveness as an isolated intervention in the context of trochlear dysplasia.

PURPOSE

To determine the efficacy of isolated MPFL reconstruction in treating patellar instability in the setting of trochlear dysplasia.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This was a retrospective review of consecutive patients who underwent uni- or bilateral medial patellofemoral ligament reconstruction for patellofemoral instability with a minimum 2-year follow-up. No osteotomies were included. Pre- and postoperative assessment included ligamentous laxity, patellar crepitus, tilt, translation, apprehension, and radiographic features, including tibial tubercle-trochlear groove (TT-TG) distance, Dejour classification, and Caton-Deschamps index.

RESULTS

A total of 121 MPFL reconstructions were included. Mean age at surgery was 23.8 years, and 4.4 dislocation events occurred before surgery. Mean follow-up was 44 months; 76% of patients were female. Mean preoperative TT-TG ratio was 13.5, and mean Caton-Deschamps ratio was 1.2; 92% of patients had Dejour B, C, or D trochlear dysplasia. Kujala score improved from 55.0 preoperatively to 90.0 ( P < .001). Almost all patients (94.5%) were able to return to sports at 1 year, with 74% returning to the same or higher level of play. Only 3 patients reported a postoperative dislocation or subluxation event.

DISCUSSION

For patients without significantly elevated TT-TG distances or significant patella alta, isolated MPFL reconstruction provides a safe and effective treatment for patellofemoral instability, despite the presence of trochlear dysplasia. Most patients are able to return to sports by 1 year postoperatively at the same or higher level of play.

Modified adductor sling technique: A surgical therapy for patellar instability in skeletally immature patients

BACKGROUND

Due to open femoral physis the therapy of patellar instability in skeletally immature patients is challenging. We developed a modified surgical technique of the 'Adductor-Sling-Approach' by Sillanpää. The purpose of this study was to evaluate the clinical outcome of the operative technique and to analyse the reasons for failure.

METHODS

Thirty 'modified adductor sling' reconstructions in 28 patients were included in the study. From 2010 to 2016 modified adductor sling reconstruction was performed by looping the gracilis or semitendinosus tendon around the adductor magnus tendon and attaching it at the medial facet of the patella. Clinical outcome was retrospectively evaluated at a mean follow up of 25.6months (range 12-43). The evaluation also included subjective International Knee Documentation Committee (IKDC), Lysholm Score, Kujala Score and Tegner Activity Score.

RESULTS

The average age at the time of operation was 15.10years (range 11-17). Eighty-seven percent of the patients, who underwent the modified adductor sling technique, gained a stable patella and excellent results in postoperative scores. Recurrent dislocation occurred in four of 30 cases (13%). Analysis showed that possible reasons for failure of the tendon graft could be maltracking of the patella due to patella alta, trochlear dysplasia or an elevated tibial tuberosity to trochlear groove distance.

CONCLUSION

The modified adductor sling technique for MPFL reconstruction in children and adolescents showed elevated redislocation rates. Only in absence of additional patellofemoral maltracking, caused by elevated tibial tubercle to trochlear groove distance (>15mm), patella alta or especially severe trochlear dysplasia, the modified adductor sling technique could be recommended.

Brain Activity Changes in Somatosensory and Emotion-Related Areas With Medial Patellofemoral Ligament Deficiency

BACKGROUND

Patellar instability with medial patellofemoral ligament (MPFL) deficiency is a common sports injury among young people. Although nonoperative and surgical treatment can provide stability of the patella, patients often have anxiety related to the knee. We speculate that neural dysfunction may be related to anxiety in these patients; however, the mechanism in the brain that generates this anxiety remains unknown.

QUESTIONS/PURPOSES

(1) How does brain activity in patients with MPFL deficiency change in the areas related to somatic sensation against lateral shift of the patella? (2) How does patella instability, which can lead to continuous fear or apprehension for dislocation, influence brain activity in the areas related to emotion?

METHODS

Nineteen patients with MPFL deficiency underwent surgical reconstruction in our hospital from April 2012 to March 2014. Excluding seven patients with osteochondral lesions, 12 patients (five males and seven females; mean age, 20 years) with MPFL deficiency were sequentially included in this study. Eleven control subjects (four males and seven females; mean age, 23 years) were recruited from medical students who had no history of knee injury. Diagnosis of the MPFL deficiency was made with MR images, which confirmed the rupture, and by proving the instability with a custom-made biomechanical device. Brain activity during passive lateral stress to the patella was assessed by functional MRI. Functional and anatomic images were analyzed using statistical parametric mapping. Differences in functional MRI outcome measures from the detected activated brain regions between the patients with MPFL deficiency and controls were assessed using t tests.

RESULTS

Intergroup analysis showed less activity in several sensorimotor cortical areas, including the contralateral primary somatosensory areas (% signal change for MPFL group 0.49% versus 1.1% for the control group; p < 0.001), thalamus (0.2% versus 0.41% for the MPFL versus control, respectively; p < 0.001), ipsilateral thalamus (0.02% versus 0.27% for the MPFL versus control, respectively; p < 0.001), and ipsilateral cerebellum (0.82% versus 1.25% for the MPFL versus control, respectively; p < 0.001) in the MPFL deficiency group than in the control group. In contrast, the MPFL deficiency group showed more activity in several areas, including the contralateral primary motor area (1.06% versus 0.6% for the MPFL versus control, respectively; p < 0.001), supplementary motor area (0.89% versus 0.52% for the MPFL versus control, respectively; p < 0.001), prefrontal cortex (1.09% versus 1.09% for the MPFL versus control, respectively; p < 0.001), inferior parietal lobule (0.89% versus 0.62% for the MPFL versus control, respectively; p < 0.001), anterior cingulate cortex (0.84% versus 0.08% for the MPFL versus control, respectively; p < 0.001), visual cortex (0.86% versus 0.14% for the MPFL versus control, respectively; p < 0.001), vermis (1.18% versus 0.37% for the MPFL versus control, respectively; p < 0.001), and ipsilateral prefrontal cortex (1.1% versus 0.75% for the MPFL versus control, respectively; p < 0.001) than did the control group.

CONCLUSIONS

Less activity in the contralateral somatosensory cortical areas suggested that MPFL deficiency may lead to diminished somatic sensation against lateral shift of the patella. In contrast, increased activity in the anterior cingulate cortex, prefrontal cortex, and inferior parietal lobule may indicate anxiety or fear resulting from patellar instability, which is recognized as an aversion similar to that toward chronic pain.

CLINICAL RELEVANCE

This study suggests that specific brain-area activity is increased in patients with MPFL deficiency relative to that in controls. Further longitudinal research to assess brain activity and proprioception between patients pre- and postreconstructive knee surgery may reveal more regarding how patella instability is related to brain function. We hope that based on such research, a neural approach to improve patella-instability-related brain function can be developed.

Influence of graft source and configuration on revision rate and patient-reported outcomes after MPFL reconstruction: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to determine the influence of graft source (allograft vs. autograft) and configuration (single-limbed vs. double-limbed) on failure rate and disease-specific patient-reported outcome (Kujala score) after medial patellofemoral ligament (MPFL) reconstruction for patellar instability.

METHODS

A systematic review of PubMed, Scopus, and the Cochrane Library was performed. A total of 31 studies met inclusion/exclusion criteria and were used to extract cohorts of patients who underwent ligament reconstruction with various allograft, autograft, single-limbed, and double-limbed constructs. Failure rates and postoperative improvements in Kujala scores were compared between cohorts using inverse-variance weighting in a random-effects analysis model and appropriate comparative statistical analyses (Chi-squared and independent samples t tests).

RESULTS

A total of 1065 MPFL reconstructions were identified in 31 studies. Autograft reconstructions were associated with greater postoperative improvements in Kujala scores when compared to allograft (32.2 vs. 22.5, p < 0.001), but there was no difference in recurrent instability (5.7 vs. 6.7 %, p = 0.74). Double-limbed reconstructions were associated with both improved postoperative Kujala scores (37.8 vs. 31.6, p < 0.001) and lower failure rate (10.6 vs. 5.5 %, p = 0.030).

CONCLUSION

MPFL reconstructions should be performed using double-limbed graft configurations. While autograft tendon may be associated with higher patient-reported outcomes in the absence of associated connective tissue disorders or ligamentous laxity, patient factors and allograft processing techniques should be carefully considered when selecting an MPFL graft source, as revision rates were no different between graft sources.

LEVEL OF EVIDENCE

IV.

The influence of medial patellofemoral ligament reconstruction on clinical results and sports activity level

OBJECTIVES

The aim of this study was to demonstrate postoperative outcomes and return to regular physical and sports activities at average of 6 years after patellar stabilization with medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Between November 2006 and January 2010, 31 isolated MPFL reconstructions in 29 patients with recurrent patellar dislocation were performed. Radiographs and magnetic resonance imaging were evaluated preoperatively. Knee function was assessed pre- and postoperative using Kujala score and the patient satisfaction, according to the International Knee Documentation Committee (IKDC) score. Tegner activity score was used for the evaluation of sports activity level.

RESULTS

The average follow-up was 6.4±1.2 years. All measured scores increased significantly at follow-up. The average Kujala score increased from 75±10 to 95±10, patient satisfaction according to IKDC score from 6.1±1.4 to 8.7±1.4 and Tegner activity score from 4.4±1.6 to 5.7±1.3. The Tegner activity score after surgery was significantly lower than the score before the patellar dislocation (6.7±1.3). There were no significant differences in Kujala postoperative score between women's and men's group (P=0.25). There was no significant correlation between body mass index and Kujala score postoperatively (P=0.11) and between age at surgery and Kujala scores postoperatively (P=0.56). Patients who were active in sports preoperatively had resumed sports activities in 88.5% after surgery, 69.6% of them returned to the same levels and 30.4% return to the lower levels.

CONCLUSION

Patellar stabilization with MPFL reconstruction is a safe and effective treatment method for all patients with patellofemoral instability and allows most patients to return to regular physical and sports activities after surgical intervention. Although sports activity level increased significantly after surgery, the same level of sports activity before the patellar dislocation has not been achieved.

Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction for the Treatment of Recurrent Lateral Patellar Dislocations: A Systematic Review and Meta-analysis

BACKGROUND

A patellar dislocation is a common knee injury in the young, athletic patient population. Recent trends indicate that the use of long-term nonoperative treatment is decreasing, and surgical intervention is more commonly recommended for those patients who fail initial nonoperative management with recurrent patellar dislocations. Medial patellofemoral ligament (MPFL) reconstruction has become increasingly utilized in this regard.

PURPOSE

To evaluate outcomes, particularly return to sports and its relationship to postoperative instability, of isolated MPFL reconstruction for the treatment of recurrent patellar dislocations.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A review of the current literature was performed using the terms "medial patellofemoral ligament reconstruction" and "MPFL reconstruction" in the electronic search engines PubMed and EBSCOhost (CINAHL, MEDLINE, SPORTDiscus) on July 29, 2015, yielding 1113 abstracts for review. At the conclusion of the search, 14 articles met the inclusion criteria and were included in this review of the literature. Means were calculated for population size, age, follow-up time, and postoperative Tegner scores. Pooled estimates were calculated for postoperative Kujala scores, return to play, total risk of postoperative instability, risk of positive apprehension sign, and risk of reoperation.

RESULTS

The mean patient age associated with MPFL reconstruction was 24.4 years, with a mean postoperative Tegner score of 5.7. The pooled estimated mean postoperative Kujala score was 85.8 (95% CI, 81.6-90.0), with 84.1% (95% CI, 71.1%-97.1%) of patients returning to sports after surgery. The pooled total risk of recurrent instability after surgery was 1.2% (95% CI, 0.3%-2.1%), with a positive apprehension sign risk of 3.6% (95% CI, 0%-7.2%) and a reoperation risk of 3.1% (95% CI, 1.1%-5.0%).

CONCLUSION

A high percentage of young patients return to sports after isolated MPFL reconstruction for chronic patellar instability, with short-term results demonstrating a low incidence of recurrent instability, postoperative apprehension, and reoperations.

Knee biomechanics during walking in recurrent lateral patellar dislocation are normalized by 1 year after medial patellofemoral ligament reconstruction

PURPOSE

Gait kinematics and kinetics of the knee before and after medial patellofemoral ligament (MPFL) reconstruction in patients with recurrent lateral patellar dislocation (RPD) are unknown. The purpose of this study was to measure knee kinematics and kinetics during gait before and 1 year after anatomical MPFL reconstruction in patients with RPD and compare the results to healthy individuals.

METHODS

Eleven RPD patients were treated using an anatomical MPFL reconstruction procedure. Gait analysis was conducted before and at 3, 6, and 12 months after surgery. For comparison, 15 healthy volunteers with no history of orthopaedic problems in their lower limbs were included as the control group. Knee kinematics and kinetics were analysed during gait.

RESULTS

Before surgery, the internal knee extension moment in RPD patients was significantly lower than in controls (P = 0.025). At 3 months post-operatively, there was an additional decrease in knee extension moment compared to before surgery, and so it was still significantly lower than in the control group (P < 0.01). One year post-operatively, knee extension moment in the RPD group was significantly increased compared to 3 months post-operatively (P < 0.01). The knee flexion angle in the early stance phase in the RPD group at 3 months post-operatively was significantly lower than that of controls (P < 0.01). Knee kinematics and kinetics were similar to that of controls 1 year after surgery.

CONCLUSION

Initially, RPD patients had lower knee extension moments during gait compared with controls, but by 1 year after MPFL reconstruction, knee kinematics and kinetics of gait in the RPD patients had returned to normal. These observations indicate that MPFL reconstruction may help to delay prospective knee OA as long as possible by restoring the conformation of the patellofemoral joint and gait biomechanics by surgery.

An Algorithmic Approach to the Management of Recurrent Lateral Patellar Dislocation

High-level evidence supports nonoperative treatment for first-time lateral acute patellar dislocations. Surgical intervention is often indicated for recurrent dislocations. Recurrent instability is often multifactorial and can be the result of a combination of coronal limb malalignment, patella alta, malrotation secondary to internal femoral or external tibial torsion, a dysplastic trochlea, or disrupted and weakened medial soft tissue, including the medial patellofemoral ligament (MPFL) and the vastus medialis obliquus. MPFL reconstruction requires precise graft placement for restoration of anatomy and minimal graft tension. MPFL reconstruction is safe to perform in skeletally immature patients and in revision surgical settings. Distal realignment procedures should be implemented in recurrent instability associated with patella alta, increased tibial tubercle-trochlear groove distances, and lateral and distal patellar chondrosis. Groove-deepening trochleoplasty for Dejour type-B and type-D dysplasia or a lateral elevation or proximal recession trochleoplasty for Dejour type-C dysplasia may be a component of the treatment algorithm; however, clinical outcome data are lacking. In addition, trochleoplasty is technically challenging and has a risk of substantial complications.

"Basket weave technique" for medial patellofemoral ligament reconstruction: Clinical outcome of a prospective study

BACKGROUND

Bone tunneling and implants with rigid fixations for medial patellofemoral ligament (MPFL) reconstruction are known to compromise results and are avoidable, especially in skeletally immature subjects. This study was to assess if these deficiencies were overcome with the technique devised by the author which avoids implants and bone tunnels. Results were assessed for complication rate and outcome.

MATERIALS AND METHODS

Fifty six knees of recurrent lateral patellar dislocation were treated in the past 49 months by MPFL reconstruction. Thirty nine were female and 17 male knees. The mean age was 20.6 years (range 9-48 years). Mean followup was 26 months. Five knees had previously failed stabilization procedures. Thirty one cases had Dejours Type A or B and 12 had Type C trochlear dysplasia. Arthroscopy was performed for associated injuries and loose bodies. Seven knees required loose body removal. Five knees underwent lateral retinacular release. Four knees had tibial tuberosity transfer. One knee had an associated anterior cruciate ligament reconstruction. An anatomical MPFL reconstruction was performed using hamstring autograft without the need for intraoperative fluoroscopy. Only soft tissue fixation was necessary with this newly devised technique and suturing. A rapid rehabilitation protocol was implemented with monthly followup until normalcy and 6 monthly thereafter.

RESULTS

All achieved full range of motion and normal mediolateral stability. There was no recurrence of dislocation. No major surgery related complications. One patella fracture at 8 months was due to a fall developed terminal restriction of flexion. Those in sports could return to their sporting activities (Tegner 1-9). Cases with osteochondral fractures had occasional pain that subsided in 1 year. Mean Kujala score improved from 64.3 to 99.69 with KOOS score near normal in all.

CONCLUSION

This new method of MPFL reconstruction gives excellent results. It avoids complications related to bone tunneling and implants. It is a safe, effective, reliable and reproducible technique.

Radiographic Reference Points Are Inaccurate With and Without a True Lateral Radiograph: The Importance of Anatomy in Medial Patellofemoral Ligament Reconstruction

BACKGROUND

Studies have reported methods for radiographically delineating medial patellofemoral ligament (MPFL) femoral tunnel position on a true lateral knee radiograph. However, obtaining a true lateral fluoroscopic radiograph intraoperatively can be challenging, rendering radiographic methods for tunnel positioning potentially inaccurate.

PURPOSE

To quantify the magnitude of MPFL femoral tunnel malposition that occurs on true lateral and aberrant lateral knee radiographs when using a previously reported radiographic technique for MPFL femoral tunnel localization.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten fresh-frozen cadaveric knees were dissected to expose the MPFL femoral insertion and surrounding medial knee anatomy. True lateral and aberrant lateral knee radiographs at 2.5°, 5°, and 10° off-axis were obtained with a standard mini C-arm in 4 orientations: anterior to posterior, posterior to anterior, caudal, and cephalad. A previously reported radiographic method for MPFL femoral localization was performed on all radiographs and compared in reference to the anatomic MPFL attachment center.

RESULTS

The radiographic point, as previously described, was a mean distance of 4.1 mm from the anatomic MPFL attachment on a true lateral knee radiograph. The distance between the anatomic MPFL attachment center and the radiographic point significantly increased on aberrant lateral knee radiographs with as little as 5° of rotational error in 3 of 4 orientations of rotation when a standard mini C-arm was used. This corresponded to a malposition of 7.5, 9.2, and 8.1 mm on 5°-aberrant radiographs in the anterior-posterior, posterior-anterior, and cephalad orientations, respectively (P < .005). In the same 3 orientations of rotation, MPFL tunnel malposition on the femur exceeded 5 mm on 2.5° aberrant radiographs.

CONCLUSION

The commonly utilized radiographic point, as previously described for MPFL femoral tunnel placement, results in inaccurate tunnel localization on a true lateral radiograph, and this inaccuracy is perpetuated with aberrant radiography. Aberrant lateral knee imaging of as little as 5° off-axis from true lateral has a significant effect on placement of a commonly used radiographic point relative to the anatomic MPFL femoral attachment center and results in nonanatomic MPFL tunnel placement.

CLINICAL RELEVANCE

This study demonstrates that radiographic localization of the MPFL femoral tunnel results in inaccurate tunnel placement on a true lateral radiograph, particularly when there is deviation from a true lateral fluoroscopic image, which can be difficult to obtain intraoperatively. Assessing anatomy directly intraoperatively, rather than relying solely on radiographs, may help avoid MPFL tunnel malposition.

Patellar instability factors in isolated medial patellofemoral ligament reconstructions--what does the literature tell us? A systematic review

BACKGROUND

Many studies have demonstrated good results after medial patellofemoral ligament (MPFL) reconstruction for patients with patellar instability. The applicability of published studies to the clinical decision-making process for the individual patient with patellar instability, however, is not well elucidated.

HYPOTHESIS

There is inconsistency in the reporting of preoperative and postoperative variables, which limits the applicability of current studies to patients with patellar instability.

STUDY DESIGN

Systematic review.

METHODS

A systematic review of the literature was conducted using the search term medial patellofemoral ligament reconstruction to identify studies with cohorts of patients with isolated MPFL reconstruction. A combination of inclusion and exclusion criteria resulted in 24 studies being reviewed for a variety of preoperative demographics, physical examination findings, and imaging findings, as well as postoperative outcomes, including redislocation and responses to subjective questionnaires.

RESULTS

A physical examination of lateral patellar translation was reported in 42% of studies, by reporting an apprehension sign (n = 9), reporting quadrant translation (n = 7), or both. For patellar instability factors on imaging, patellar height was reported as a preoperative variable in 75% of studies, and trochlear dysplasia was reported in 83% of studies. The tibial tubercle-trochlear groove distance was reported as a preoperative variable in 42% of studies. The rate of redislocation after index surgery was reported in 92% of studies. Patient-related outcome measures were reported in all of the studies; the Kujala score was the most common. A homogeneous population was selected as part of the authors' surgical indications for "isolated" MPFL in 67% of studies, and a heterogeneous population was selected in 33% of studies.

CONCLUSION

Current literature on MPFL reconstruction contains diverse methods of recording preoperative and postoperative variables. Most studies report on a homogeneous population, with inconsistent applicability to the broad spectrum of patients with patellar instability. Outcomes reporting in our current literature needs more clarity and consistency regarding reporting methodology to be of value for the treating clinician.

Widespread Implementation of Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability Maintains Functional Outcomes at Midterm to Long-Term Follow-up While Decreasing Complication Rates: A Systematic Review

PURPOSE

Our primary purpose was to evaluate whether complications have increased or functional outcomes have changed as medial patellofemoral ligament (MPFL) reconstruction has been adopted by more surgeons at more institutions over recent years. Our secondary purpose was to further define the complication profile of MPFL reconstruction.

METHODS

A systematic review of the literature was performed on January 12, 2014, using the keywords "medial patellofemoral ligament reconstruction," "patellar instability reconstruction," "patellofemoral ligament reconstruction," and "MPFL." Articles meeting our inclusion criteria were reviewed. Outcome measures, functional failures, complications, graft choice, and surgical technique were recorded and analyzed.

RESULTS

Thirty-four articles met our exclusion and inclusion criteria and were reviewed. Nineteen articles were "new" additions to the literature, whereas 15 had previously been reported on in prior analyses ("old"). The 19 new articles reported a statistically significant decrease in functional failure rates, from 9.55% in older studies to 4.77% in more recent studies (P < .001). The major complication rate dropped from 2.01% to 0.46% in the newer studies (P = .005), and the minor complication rate decreased from 6.53% to 4.00% (P = .06). Postoperative Kujala scores did not show a statistically significant change between newer and older publications (89.0 [SD, 3.7] and 89.4 [SD, 4.9], respectively; P = .55). Comparing results by fixation type, as well as by graft choice, showed no statistically significant differences in terms of outcomes or complication profile.

CONCLUSIONS

With nearly twice the number of medical centers performing reconstruction of the MPFL and outcomes reported on nearly double the number of patients in recent years, functional outcomes remain favorable as complication and failure profiles are improving. Furthermore, despite a wide array of fixation techniques, as well as multiple options for graft constructs, there are no statistically or clinically significant differences in functional outcomes over time. This finding highlights the efficacy and adoptability of MPFL reconstruction for the treatment of recurrent patellar instability.

LEVEL OF EVIDENCE

Level IV, systematic review of mixed-level studies.

MPFL reconstruction: technique and results

Patellar instability is a common problem, and medial patellofemoral ligament (MPFL) injury is inherent with traumatic patellar dislocations. Initial nonoperative management is focused on reconditioning and strengthening the dynamic stabilizers of the patella. For those patients who progress to recurrent instability, further investigation into the predisposing factors is required. MPFL reconstruction is indicated in patients with recurrent instability and insufficient medial restraint due to MPFL injury. A technique of MPFL reconstruction is outlined. This procedure may also be performed in combination with other realignment procedures.

Patellar instability

Patellar instability is a common injury that can result in significant limitations of activity and long-term arthritis. There is a high risk of recurrence in patients and operative management is often indicated. Advances in the understanding of patellofemoral anatomy, such as knowledge about the medial patellofemoral ligament, tibial tubercle-trochlear groove distance, and trochlear dysplasia may allow improved surgical management of patellar instability. However, techniques such as MPFL reconstruction are technically demanding and may result in significant complication. The role of trochleoplasty remains unclear.

MPFL reconstruction using a quadriceps tendon graft: part 1: biomechanical properties of quadriceps tendon MPFL reconstruction in comparison to the Intact MPFL. A human cadaveric study

BACKGROUND

The aim of this study was to analyze the structural properties of the original MPFL and to compare it to a MPFL-reconstruction-technique using a strip of quadriceps tendon.

METHODS

In 13 human cadaver knees the MPFLs were dissected protecting their insertion at the patellar border. The MPFL was loaded to failure after preconditioning with 10 cycles in a uniaxial testing machine evaluating stiffness, yield load and maximum load to failure. In the second part Quadriceps-MPFL-reconstruction was performed and tested in a uniaxial testing machine. Following preconditioning, the constructs were cyclically loaded 1000 times between 5 and 50 N measuring the maximum elongation. After cyclic testing, the constructs have been loaded to failure measuring stiffness, yield load and maximum load. For statistical analysis a repeated measures (RM) one-way ANOVA for multiple comparisons was used. The significance was set at P<0.05.

RESULTS

During the load to failure tests of the original MPFL the following results were measured: stiffness 29.4 N/mm (+9.8), yield load 167.8 N (+80) and maximum load to failure 190.7 N (+82.8). The results in the QT-technique group were as follows: maximum elongation after 1000 cycles 2.1 mm (+0.8), stiffness 33.6 N/mm (+6.8), yield load 147.1 N (+65.1) and maximum load to failure 205 N (+77.8). There were no significant differences in all tested parameters.

CONCLUSIONS

In a human cadaveric model using a strip of quadriceps-tendon 10 mm wide and 3mm deep, the biomechanical properties match those of the original MPFL when tested as a reconstruction.

CLINICAL RELEVANCE

The tested QT-technique shows sufficient primary stability with comparable biomechanical parameters to the intact MPFL.

Medial patellofemoral ligament reconstruction as an isolated or combined procedure for recurrent patellar instability

PURPOSE

The principal aim of this study was to report the outcomes of medial patellofemoral ligament (MPFL) reconstruction, used as either an isolated procedure or in combination with another stabilization procedure, for the primary treatment of recurrent patellar instability.

METHODS

Between 2007 and 2012, 45 patients with recurrent patellar instability and no prior stabilization surgery had an MPFL reconstruction by a single surgeon, either as an isolated procedure or in combination with another stabilization procedure. Questionnaires detailing patellar instability since surgery, knee pain, ability to negotiate stairs, and sports participation were completed, and data regarding examination and radiological findings were collected from the medical record.

RESULTS

A total of 36 (80%) patients completed the questionnaire at a mean of 3.1 years (minimum 1 year), whilst a further 11% had clinical follow-up of greater than 1 year. Four patients were excluded due to lack of adequate follow-up. Thirty-one patients had an isolated MPFL reconstruction and none had further patellar instability. Of the ten patients who had a combined procedure, one experienced recurrent instability. Return to sport rates were 81 and 57% for the isolated and combined groups, respectively, with the majority returning to strenuous sport (81 and 57%, respectively). Most patients (96 and 80%) could negotiate stairs without difficulty, whilst 38 and 40% reported some degree of anterior knee pain.

CONCLUSIONS

This study shows that satisfactory results can be obtained using MPFL reconstruction either in isolation or in combination to treat recurrent patellar instability. Whether the indications for an isolated MPFL can be extended further remains unclear.

LEVEL OF EVIDENCE

III.

The horizontal Y-shaped graft with respective graft tension angles in anatomical two-bundle medial patellofemoral ligament reconstruction

PURPOSE

Various techniques for medial patellofemoral ligament (MPFL) reconstruction have been described with two bundles of graft tensioned simultaneously. The present study was to introduce an anatomical reconstruction procedure using a horizontal Y-shaped graft with respective graft tension angles and report the preliminary results.

METHODS

A surgical technique for MPFL reconstruction using a horizontal Y-shaped semitendinosus tendon autograft with two bundles tensioned at 0° and 30° of knee flexion was described in detail. The patellar stability was evaluated with the apprehension test and an axial computed tomography (CT) scan at 30° of knee flexion. The knee function was evaluated using the Lysholm and Kujala scores.

RESULTS

No recurrent dislocation or subluxation was reported for 45 patients at a mean of 33.7-month follow-up. On CT images, congruence angle, patellar tilt angle, lateral patellar angle and lateral displacement were restored to the normal range. At the last follow-up, the mean Lysholm score improved from 51.8±6.2 to 91.7±4.1 and mean Kujala score was from 53.4±5.3 to 90.9±6.6 (P<0.01).

CONCLUSIONS

The present anatomical MPFL reconstruction technique with a horizontal Y-shaped two-bundle graft tensioned at respective knee flexion angles could not only recreate the fan-shape of MPFL but also mimic the function bundles of native ligament. Clinical follow-up confirms the good restoration of the patellar stability and significant improvement of knee function without special complications.

LEVEL OF EVIDENCE

Therapeutic, Level IV.