Medial Patellofemoral Ligament Reconstruction Using Allografts in Skeletally Immature Patients

Abstract

Background: Patellar instability has the highest incidence in adolescents aged between 14 and 18 years. The unique relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis in skeletally immature patients warrants precisely positioned MPFL graft insertion. A paucity of data are available evaluating the results of MPFL reconstruction using allograft tendon before skeletal maturity. Purposes: (1) To assess the results of MPFL reconstruction using allograft tendon in skeletally immature patients by analyzing redislocation and reoperation rates, radiological outcomes, and patient-reported outcomes and (2) to determine whether epidemiological, intraoperative, or radiographic factors influence recurrent instability and clinical outcomes. Study Design: Case series; Level of evidence, 4. Methods: Prospectively collected data were retrospectively analyzed for 69 skeletally immature patients who experienced a first-time or recurrent lateral patellar dislocation and were treated with anatomic MPFL reconstruction. Inclusion criteria were MPFL reconstruction using allograft and the availability of preoperative magnetic resonance imaging scans in the presence of open or partially open physes. Patients with <2 years of follow-up and patients with previous surgeries on the same knee were excluded from the study. Preoperative radiographic imaging was reviewed and analyzed. Trochlear dysplasia, tibial tubercle–trochlear groove distance, and patellar height were evaluated. Descriptive data, concomitant injuries, surgical procedure details, complications, and postoperative history were assessed via review of medical records and patient charts. Validated patient-reported and surgeon-measured outcomes were collected pre- and postoperatively, including Kujala score, Lysholm score, and Tegner activity score. Return-to-sports rate was assessed. The influence of epidemiological, intraoperative, and radiographic parameters on the redislocation rates and clinical outcomes was assessed using a multiple linear regression model. Results: A total of 79 physeal-sparing MPFL reconstructions (69 patients) met the inclusion criteria. The mean age of the patient cohort was 14.7 ± 1.8 years (range, 8.5-16.9 years). Within the mean follow-up time of 37.9 ± 12.1 months (range, 24-85 months after surgery, there were 12 patients with clinical failures resulting in reoperation. Eleven patients experienced a redislocation of the patella, and 1 patient sustained a transverse noncontact patellar fracture 6 months after index surgery that required operative fixation. No injuries to the distal femoral physes were clinically observed. At the final follow-up, patients had a mean Lysholm score (1-100) of 96.5 ± 6.7, a mean Kujala score (1-100) of 96.5 ± 7.4, and a mean Tegner Activity Scale score (1-10) of 4.9 ± 1.3. Patellar height and trochlear dysplasia did not influence redislocation or clinical scores. In total, 57 of the 63 patients (90.5%) who were engaged in sports before injury returned to the same or higher level of competition. In a subgroup analysis of patients who underwent isolated MPFL reconstruction (n = 44) without concomitant procedures, 9 patients (20.5%) experienced failure and had a redislocation. A univariate analysis of hazards for failure based on patient-specific variables was carried out. A body mass index ≥30 conveyed a hazard ratio of 2.51 (95% CI, 0.63-10.1; P = .19), and the tibial tubercle-trochlear groove distance by increments of 1 mm was associated with a hazard ratio of 2.02 (95% CI, 0.51-8.11; P = .32). Conclusion: Physeal-sparing anatomic reconstruction of the MPFL using an allograft tendon in skeletally immature patients was a safe and effective treatment for patellar instability, regardless of patellar height and trochlear dysplasia. Failure rates decreased when the MPFL reconstruction was performed concomitantly with a tibial tubercle osteotomy.

What’s New in Pediatric Orthopaedics

“…Reconstructing the medial patellofemoral ligament using an allograft in skeletally immature patients is safe using a physeal-sparing anatomic technique, although 12 of 79 patients required a reoperation for redislocation (11 of 12) or patellar fracture (1 of 12). No injuries to the physis were seen at a minimum follow-up of 2 years 38 .…”

Arthroscopic Patella Realignment for Children And Adolescents: A Single Incision Technique

“…MPFL reconstruction is probably a better solution due to its effectiveness and the use of a graft that restores the medial patellofemoral complex. 9 , 19 However, MPFL reconstruction has some limitations, such as the need for use of autograft with the associated morbidity and invasiveness, and the risk of complications, including a low risk for growth disturbance in skeletally immature patients. 13 , 20 As a result, in patients with patellofemoral symptoms of maltracking without frank instability, the arthroscopic patella realignment described above can be a safe and effective solution in a carefully selected patient population.…”

“… 4 , 5 , 6 , 7 Several different techniques have been described for recurrent patellofemoral instability, with medial patellofemoral ligament (MPFL) reconstruction recently gaining a leading role in the management of recurrent instability because of its effectiveness and ability to restore anatomy and isometry. 8 , 9 , 10 , 11 …”

Arthroscopically Assisted Double-Bundle Medial Patellofemoral Ligament Augmentation With Physeal-Sparing Suture Fixation for Recurrent Patellar Dislocation in Skeletally Immature Patients

“… 2 Despite various procedures being reported, including medial reefing, medial retinacular plasty, lateral release, medial patellofemoral ligament reconstruction (MPFL-R) using adductor-transfer or pedicled quadriceps tendon, and fluoroscopy-guided autograft MPFL-R, the optimal surgical treatment of recurrent patellar dislocation for pediatric population remains a debated issue. 3 , 4 , 5 , 6 …”