Medial patellofemoral ligament reconstruction in children: do osseous abnormalities matter?

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

IV, systematic review of level III and IV studies.

Medial Patellofemoral Ligament Reconstruction With or Without Tibial Tubercle Osteotomy in Carefully Selected Patients Results in a 5% Revision Rate: A Preliminary Analysis

PURPOSE

The purpose was to assess the outcomes of medial patellofemoral ligament (MPFL) allograft reconstruction with or without tibial tubercle osteotomy (TTO) in adolescents, with a focus on evaluating demographic and imaging characteristics on outcomes.

METHODS

A single-institution retrospective study was performed of patients ages 12 to 19 years who underwent MPFL reconstruction +/- TTO for the treatment of lateral patellar instability. Demographic, clinical, surgical, and postoperative information was collected. All x-ray and magnetic resonance imaging measurements were completed independently by 2 surgeons. Patients were contacted to complete patient-reported outcomes at a minimum of 2 years following surgery. The primary outcome measure was recurrent instability resulting in revision surgery.

RESULTS

Seventy-eight knees in 74 patients, with a median age of 15.3 years (interquartile range: 14.4, 16.1), were included. Forty-five knees underwent isolated MPFL reconstruction and 33 knees had a combined MPFL + TTO. The knees that underwent MPFL + TTO had significantly greater tibial tubercle-trochlear groove distance (19.0 mm vs. 15.4 mm, P =0.015) and patellar tendon-lateral trochlear ridge distance (10.9 mm vs. 5.9 mm, P =0.018) than the knees treated with isolated MPFL reconstruction. Four knees (5.1%) underwent revision stabilization surgery, including 3 knees in the MPFL cohort (6.7%) and 1 knee in the MPFL + TTO cohort (3.0%). The rate of failure between the MPFL and MPFL + TTO knees was not significantly different, P =0.634. There were no differences in age, sex, body mass index, number of dislocations, or any imaging characteristics in patients who underwent revision versus those who did not. Patient-reported outcomes were collected on 50 knees at a median of 36 months (interquartile range: 24, 54) after surgery, and no differences were noted between cohorts.

CONCLUSIONS

Patellar stabilization surgery, including MPFL reconstruction and TTO in carefully selected patients, had excellent revision-free outcomes in 95% of this adolescent cohort. In this case series, those patients whose treatment included TTO had greater tibial tubercle-trochlear groove and patellar tendon-lateral trochlear ridge as compared to the isolated MPFL cohort. Despite previous literature suggesting demographic and imaging characteristics as risks for recurrent instability, we identified no characteristics within these two distinct surgical treatment groups to be predictive of the need for revision stabilization, regardless of the treatment group.

LEVEL OF EVIDENCE

Level III-retrospective comparison study.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

IV.

Patellar Dislocation: Workup and Decision-Making

Acute patellar dislocation (PD) is usually a problem of adolescents and young adults. In most cases, it is a sports-related injury. It is the result of an indirect force on the knee joint, which leads to valgus and external rotation of the tibia relative to the femur. PD is unlikely to occur on a knee with normal patellofemoral joint (PFJ) anatomy. Acute PD consists of an acute injury of the ligamentous medial patellar stabilizers in the background of factors predisposing to patellar instability. These factors are classified into three groups. The first group refers to the integrity of the ligamentous medial patellar restraints, particularly, the medial patellofemoral ligament (MPFL). The second group refers to an abnormal PFJ anatomy, which renders the patella inherently unstable inside the trochlea. The third group refers to the overall axial and torsional profile of the lower limb and to systemic factors, such as ligament laxity and neuromuscular coordination of movement. PD at a younger age is associated with an increased number and severity of patellar instability predisposing factors and lower stress to dislocate the patella. Acute primary PD is usually treated conservatively, while surgical treatment is reserved for recurrent PD. The aim of treatment is to restore the stability and function of the PFJ and to reduce the risk of patellar redislocation. Surgical procedures to treat patellar instability are classified into non-anatomic and anatomic procedures. Non-anatomic procedures are extensor mechanism realignment techniques that aim to center the patella into the trochlear groove. Anatomic procedures aim to restore the PFJ anatomy (ruptured ligaments, osteochondral fractures), which has been severed after the first incident of PD. Anatomic procedures, especially MPFL reconstruction, are more effective in preventing recurrent PD, compared with non-anatomic techniques. Theoretically, all factors that affect PFJ stability should be evaluated and, if possible, addressed. This is practically impossible. Considering that the MPFL ruptures in almost all PDs, MPFL reconstruction is the primary procedure, which is currently selected by most surgeons as a first-line treatment for patients with recurrent PD. Restoration of the axial and torsional alignment of the lower limbs is also increasingly implemented by surgeons. Non-anatomic surgical techniques, such as tibial-tuberosity osteotomy, are used as an adjunct to anatomic procedures. In the presence of multiple PFJ instability factors, acute MPFL reconstruction may be the treatment of choice for acute primary PD as well. Skeletal immaturity of the patient precludes osseous procedures to avoid premature physis closure and subsequent limb deformity. Unfortunately, restoration of the patient's previous activity level or participation in more strenuous sports is questionable and not easy to predict. In the case of competitive athletes, PD may prevent participation in elite levels of sports.

Failure of isolated medial patellofemoral ligament reconstruction in children: Risk factors and management

Background

Patellofemoral instability is a frequent cause of referral in pediatric sports medicine. Isolated medial patellofemoral ligament reconstruction is widely used and provides satisfactory outcomes with a low failure rate. Given the success of this surgical technique, the literature on medial patellofemoral ligament reconstruction failures in the pediatric population is limited. Moreover, given the multifactorial nature of patellofemoral instability, the heterogeneity of the current literature, and the paucity of pediatric studies, medial patellofemoral ligament reconstruction failures are often difficult to analyze.

Methods

The purpose of this study was to retrospectively review the associated risk factors, surgical management, and the clinical outcomes at 2-year follow-up of skeletally immature patients that presented to our clinic with a failed medial patellofemoral ligament reconstruction.

Results

Of the 181 cases in 155 patients included in this study, treatment failed in 12 (7%). All 12 patients presented with at least one risk factor for patellofemoral instability, the most common being trochlear dysplasia and a high-grade J sign.

Conclusions

We conclude that isolated medial patellofemoral ligament reconstruction for patellofemoral instability in children has a low failure rate. Clinicians must assess pre-operative risk factors before surgical treatment is considered. A high-grade J sign and high-grade trochlear dysplasia were associated with medial patellofemoral ligament reconstruction failure in this cohort. Tailoring treatment to patients' associated risk factors selection may improve outcomes.

Return to sports and short-term follow-up of 101 cases of medial patellofemoral ligament reconstruction using gracilis tendon autograft in children and adolescents

INTRODUCTION

An acute patellofemoral dislocation is the most common acute knee injury in children. Recent studies suggest up to 40% of immature patients may develop recurrent instability. MPFL reconstruction has become a mainstay for the treatment of patellofemoral instability. Aim of the recent study is to show our experiences of MPFL reconstruction in patellar instability in immature patients using a gracilis autograft in respect to return to sport, growth plate disorders and short-term results.

MATERIALS AND METHODS

A total of 101 patients (50 females, 51 males) were included in this retrospective study. Mean age at time of operation was 14.8 ± 1.6 years. Primary outcome measures included patient satisfaction, Kujala score, recurrent instability, return to normal activity, return to sports, clinical leg axis and complications. Mann-Whitney U test was used for statistical analysis and alpha was set at p < 0.05 to declare significance.

RESULTS

At a mean follow-up of 32.0 ± 12.1 months 90/101 patients could be followed-up. 84% of all patients were satisfied or very satisfied with the result at latest follow-up. 86.6% of all patients were able to return to sports, 2.3% had a relevant deviation of the clinical leg axis, but symmetrical. In sum complication rate was 2.9%. Redislocation rate was 0.9% (1/101). Kujala Score improved significantly from 47.1 preoperatively to 85.3 postoperatively (p < 0.01).

CONCLUSION

Anatomic MPFL reconstruction using gracilis tendon allograft tissue is a safe procedure in children and adolescents with low risk of recurrent instability.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

PURPOSE/HYPOTHESIS

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

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

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

RESULTS

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

CONCLUSION

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

IV, case series.

Midterm Results After Isolated Medial Patellofemoral Ligament Reconstruction as First-Line Surgical Treatment in Skeletally Immature Patients Irrespective of Patellar Height and Trochlear Dysplasia

BACKGROUND

Medial patellofemoral ligament reconstruction in skeletally immature patients who experience lateral patellar dislocation has been reported to yield good results. Whether bony abnormalities such as patellar height and trochlear dysplasia should be addressed additionally is a topic of discussion.

PURPOSE

To evaluate patient-reported outcomes and redislocation rates after isolated medial patellofemoral ligament reconstruction as first-line surgical treatment for lateral patellar dislocation in skeletally immature patients. Further, to analyze epidemiological, intraoperative, and radiographical factors influencing redislocation and clinical outcome.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Prospectively collected data were retrospectively analyzed for adolescent patients younger than 16 years who underwent medial patellofemoral ligament reconstruction between 2014 and 2018. Inclusion criteria were isolated medial patellofemoral ligament reconstruction with gracilis tendon and availability of accurate pre- and postoperative radiographs with the presence of open physes. The patients were questioned regarding further surgery, redislocation, and clinical outcomes using the Tegner Activity Scale, International Knee Documentation Committee (IKDC) Subjective Knee Form, Lysholm score, and Kujala score. The influence of diverse epidemiological, intraoperative, and radiographical parameters on the redislocation rates and clinical outcome was analyzed.

RESULTS

A total of 54 medial patellofemoral ligament reconstructions (49 patients) met the inclusion criteria. After 4.3 ± 1.7 years (range, 2.0-7.3 years), 45 reconstructions (83.3%) in 41 patients were available for follow-up. The distribution of trochlear dysplasia was as follows: type A and B, 19 cases (42.2%) each; type C, 6 cases (13.3%); and type D, 1 case (2.2%). Patellar redislocation occurred in 3 patients (6.7%). The mean Tegner, subjective IKDC, Lysholm, and Kujala scores at follow-up were 6.3 ± 1.6 (range, 3-9), 93.6 ± 8.8, 95.9 ± 7.4, and 97.9 ± 7.1, respectively. Patellar height and trochlear dysplasia had no influence on redislocation or clinical scores. The Lysholm score was lower in knees with intraoperative retropatellar chondral lesion grade ≥III versus grade <III (89.0 ± 19.2 vs 96.9 ± 3.6, respectively; P = .023); likewise, the Kujala score was lower in knees that were grade ≥III versus grade <III (90.0 ± 19.7 vs 98.1 ± 2.1, respectively; P = .015).

CONCLUSION

Isolated medial patellofemoral ligament reconstruction as first-line surgical treatment in skeletally immature patients yields excellent midterm results, irrespective of patellar height and trochlear dysplasia. Redislocation still occurs in a certain number of patients, and a higher degree of retropatellar chondral lesion is a predictor for a worse clinical outcome.

Complications and Recurrence of Patellar Instability after Medial Patellofemoral Ligament Reconstruction in Children and Adolescents: A Systematic Review

Background: This study aimed to review the data available in the current literature concerning the complications and recurrence of instability following medial patellofemoral ligament (MPFL) reconstruction for patellar instability in young and adolescent patients (those <20 years old). Methods: A systematic review was performed based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Two independent reviewers searched the PubMed, Scopus, EMBASE, and Cochrane databases. The terms “medial patellofemoral ligament” or “MPFL” and “reconstruction” and “young” or “adolescents” or “children” were used. The inclusion criteria for the literature review comprised studies that reported the complications and recurrences of instability in patients who had undergone MPFL reconstruction for patellar instability. Results: In all, 332 patients were included in the review, of which 195 were females (63.5%) and 112 were males (36.5%), and they totaled 352 treated knees. The mean age at the time of the surgery was 14.28 years, and the mean follow-up duration was 30.17 months. A total of 16 (4.5%) complications were reported: one (0.3%) patella fracture, one (0.3%) screw removal due to intolerance, one (0.3%) infection, five (1.4%) wound complications, six (1.7%) subluxations and two (0.6%) instances of post-operative stiffness. A total of 18 (5.1%) recurrences of patellar instability were recorded. Conclusions: MPFL reconstruction in young patients can be considered an effective and safe treatment leading to clinical improvement in terms of recurrence of dislocation. No major complications related to the technique were reported, but a high level of research evidence is required to better evaluate the clinical results in a long-term follow-up.

Failure Analysis in Patients With Patellar Redislocation After Primary Isolated Medial Patellofemoral Ligament Reconstruction

Background:

Reconstruction of the medial patellofemoral ligament (MPFL) has become a popular surgical procedure to address patellofemoral instability. As a consequence of the growing number of MPFL reconstructions performed, a higher rate of failures and revision procedures has been seen.

Purpose:

To perform a failure analysis in patients with patellar redislocation after primary isolated MPFL reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients undergoing revision surgery for reinstability after primary isolated MPFL reconstruction were included. Clinical notes were reviewed to collect demographic data, information on the primary surgery, and the mechanism of patellar redislocation (traumatic vs nontraumatic). Preoperative imaging was analyzed regarding femoral tunnel position and the prevalence of anatomic risk factors (ARFs) associated with patellofemoral instability: trochlear dysplasia (types B through D), patella alta (Caton-Deschamps index >1.2, patellotrochlear index <0.28), lateralization of the tibial tuberosity (tibial tuberosity–trochlear groove distance >20 mm, tibial tuberosity–posterior cruciate ligament [TT-PCL] distance >24 mm), valgus malalignment (mechanical valgus axis >5°), and torsional deformity (internal femoral torsion >25°, external tibial torsion >35°). The prevalence of ARF was compared between patients with traumatic and nontraumatic redislocations and between patients with anatomic and nonanatomic femoral tunnel position.

Results:

A total of 26 patients (69% female) with a mean age of 25 ± 7 years were included. The cause of redislocation was traumatic in 31% and nontraumatic in 69%. Position of the femoral tunnel was considered nonanatomic in 50% of patients. Trochlear dysplasia was the most common ARF with a prevalence of 50%, followed by elevated TT-PCL distance (36%) and valgus malalignment (35%). The median number of ARFs per patient was 3 (range, 0-6), and 65% of patients had 2 or more ARFs. Patients with nontraumatic redislocations showed significantly more ARFs per patient, and the presence of 2 or more ARFs was significantly more common in this group. No significant difference was observed between patients with anatomic versus nonanatomic femoral tunnel position.

Conclusion:

Multiple anatomic risk factors and femoral tunnel malposition are commonly observed in patients with reinstability after primary MPFL reconstruction. Before revision surgery, a focused clinical examination and adequate imaging including radiographs, magnetic resonance imaging (MRI), standing full-leg radiographs, and torsional measurement with computed tomography or MRI are recommended to assess all relevant anatomic parameters to understand an individual patient’s risk profile. During revision surgery, care must be taken to ensure anatomic placement of the femoral tunnel through use of anatomic and/or radiographic landmarks.

Recurrent patellofemoral instability rates after MPFL reconstruction techniques are in the range of instability rates after other soft tissue realignment techniques

PURPOSE

Recurrent patellofemoral instability is a common knee injury in skeletally immature patients. Many surgical techniques have been described in the literature, all with different success rates. Purpose of this study was to perform a systematic review and meta-analysis of the available literature to assess recurrent patellofemoral instability rates after surgical treatment using MPFL reconstruction techniques and other soft tissue realignment techniques in skeletally immature patients.

METHODS

PubMed, Embase, Web of Science, and The Cochrane Library were searched to identify all original articles concerning the surgical treatment for patellofemoral instability in skeletally immature patients and that reported post-operative recurrent patellofemoral instability rates. Subsequently a risk of bias assessment was conducted and a meta-analysis was performed on reported post-operative recurrent patellofemoral instability rates after MPFL reconstruction techniques and other soft tissue realignment techniques.

RESULTS

Of the 21 eligible studies (448 knees in 389 patients), 10 studies reported on MPFL reconstruction techniques using different grafts and fixation techniques and 11 reported on other soft tissue realignment procedures. In total, 62 of the 448 (13.8%) treated knees showed recurrent patellofemoral instability during follow-up. The overall pooled recurrent patellofemoral instability rate was estimated to be 0.08 (95% CI 0.02-0.16). For MPFL reconstruction techniques, the pooled recurrent patellofemoral instability rate was estimated to be 0.02 (95% CI 0.00-0.09). For the other soft tissue realignment techniques, the pooled rate was estimated to be 0.15 (95% CI 0.04-0.31). No statistically significant difference in recurrent patellofemoral instability rates between MPFL reconstruction techniques and other soft tissue realignment techniques were found (n.s.). There was a large variation in treatment effects over different settings, including what effect is to be expected in future patients.

CONCLUSION

This systematic review and meta-analysis found that recurrent patellofemoral instability rates after MPFL reconstruction techniques are in the range of instability rates after other soft tissue realignment techniques. The clinical relevance of this study is that it provides clinicians with the best currently available evidence on recurrent patellofemoral instability rates after surgical treatment for patellofemoral instability in skeletally immature patients.

LEVEL OF EVIDENCE

IV.

Medial patellofemoral ligament reconstruction fails to correct mild patella alta in cases of patellofemoral instability-a case-control study

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is the gold standard in patella soft tissue surgery for patellofemoral instability. Although claimed, recent reports indicate that MPFL-R may fail to distalize the patella in mild cases of patella alta. The present study is a retrospective case-control study to compare radiographic patella height between MPFL-R and historical Insall's proximal realignment (IPR) pre- and post-operatively with respect to distalization and assess redislocation rates at a mid-term follow-up.

METHODS

Sixty-four patients were age/sex matched (1:1), yielding 32 patients for group 1 MPFL-R (cases) and 32 patients for group 2 IPR (controls). Insall-Salvati, Blackburne-Peel and Caton-Deschamps indices were analyzed for differences pre- and post-operatively. An additional inter-rater reliability analysis was performed by means of intra-class correlation (ICC). Redislocation rates were considered as treatment failures in this study.

RESULTS

ICC was excellent for all three patella indices. MPFL-R failed to show significant differences if compared to IPR with respect to distalization in mild stages of patella alta. Moreover, redislocation rates significantly favored MPFL-R (3.1%) over IPR (12.5%; p < 0.0001).

CONCLUSIONS

MPFL-R has become a popular option to restore native patellofemoral biomechanics after ligament rupture. However, the procedure's potential to correct concomitant patella alta should not be overestimated and indications considered carefully.