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

Background: No clear guidelines or widespread consensus has defined a threshold value of tibial tuberosity–trochlear groove (TT-TG) distance for choosing the appropriate surgical procedures when additional tibial tuberosity osteotomy (TTO) should be added to augment medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability. Purpose: To compare the clinical outcomes between MPFL reconstruction and MPFL reconstruction with TTO for patients who have patellar instability with a TT-TG distance of 15 to 25 mm. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively analyzed 81 patients who underwent surgical treatment using either MPFL reconstruction or MPFL reconstruction with TTO for recurrent patellar instability with a TT-TG distance of 15 to 25 mm; the mean follow-up was 25.2 months (range, 12.0-53.0 months). The patients were divided into 2 groups: isolated MPFL reconstruction (iMPFL group; n = 36) performed by 2 surgeons and MPFL reconstruction with TTO (TTO group; n = 45) performed by another 2 surgeons. Clinical outcomes were assessed using the Kujala score, Knee injury and Osteoarthritis Outcome Score, and Tegner activity score. Radiological parameters, including patellar height, TT-TG distance, patellar tilt, and congruence angle were compared between the 2 groups. Functional failure based on clinical apprehension sign, repeat subluxation or dislocation, and subjective instability and complications was assessed at the final follow-up. We also compared clinical outcomes based on subgroups of preoperative TT-TG distance (15 mm ≤ TT-TG ≤ 20 mm vs 20 mm < TT-TG ≤ 25 mm). Results: All of the clinical outcome parameters significantly improved in both groups at the final follow-up ( P < .001), with no significant differences between groups. The radiological parameters also showed no significant differences between the 2 groups. The incidence of functional failure was similar between the 2 groups (3 failures in the TTO group and 2 failures in the iMPFL group; P = .42). In the TTO group, 1 patient experienced a repeat dislocation postoperatively and 2 patients had subjective instability; in the iMPFL group, 2 patients had subjective instability. The prevalence of complications did not differ between the 2 groups ( P = .410). In the subgroup analysis based on TT-TG distance, we did not note any differences in clinical outcomes between iMPFL and TTO groups in subgroups of 15 mm ≤ TT-TG ≤ 20 mm and 20 mm < TT-TG ≤ 25 mm. Conclusion: MPFL reconstruction with and without TTO provided similar, satisfactory clinical outcomes and low redislocation rates for patients who had patellar instability with a TT-TG distance of 15 to 25 mm, without statistical difference. Thus, our findings suggest that iMPFL reconstruction is a safe and reliable treatment for patients with recurrent patellar dislocation with a TT-TG distance of 15 to 25 mm, without the disadvantages derived from TTO.

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

Background Medial patellofemoral ligament (MPFL) reconstruction combined with tibial tubercle osteotomy (TTO) and lateral retinacular release (LRR) is one of the main treatment methods for patellar instability. So far, few studies have evaluated the clinical effectiveness and assessed potential risk factors for recurrent patellar instability. Purpose To report the clinical outcomes of MPFL reconstruction combined with TTO and LRR at least three years after operation and to identify potential risk factors for recurrent patellar instability. Methods A retrospective analysis of medical records for patients treated with MPFL, TTO and LRR from 2013 to 2017 was performed. Preoperative assessment for imaging examination included trochlear dysplasia according to Dejour classification, patella alta with the Caton-Deschamps index (CDI), tibial tubercle–trochlear groove distance. Postoperative assessment for knee function included Kujala, IKDC and Tegner scores. Failure rate which was defined by a postoperative dislocation was also reported. Results A total of 108 knees in 98 patients were included in the study. The mean age at operation was 19.2 ± 6.1 years (range, 13–40 years), and the mean follow-up was 61.3 ± 15.4 months (range, 36–92 months). All patients included had trochlear dysplasia (A, 24%; B, 17%; C, 35%; D, 24%), and 67% had patellar alta. The mean postoperative scores of Tegner, Kujala and IKDC were 5.3 ± 1.3 (2–8), 90.5 ± 15.5 (24–100) and 72.7 ± 12.1 (26–86). Postoperative dislocation happened in 6 patients (5.6%). Female gender was a risk factor for lower IKDC (70.7 vs 78.1, P = 0.006), Tegner (5.1 vs 6.0, P = 0.006) and Kujala (88.2 vs 96.6, P = 0.008). Age (p = 0.011) and trochlear dysplasia (p = 0.016) were considered to be two failure factors for MPFL combined with TTO and LRR. Conclusion As a surgical method, MPFL combined with TTO and LRR would be a reliable choice with a low failure rate (5.6%). Female gender was a risk factor for worse postoperative outcomes. Preoperative failure risk factors in this study were age and trochlear dysplasia. Level of Evidence Level IV; Case series

CLINICAL OUTCOMES AFTER MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION UTILIZING ALLOGRAFT TISSUE IN PEDIATRIC AND ADOLESCENT PATIENTS: MINIMUM 2-YEAR FOLLOW-UP

Background: Medial patellofemoral ligament (MPFL) reconstruction has gained popularity as a tool to manage recurrent patellar instability. The use of allograft for reconstruction includes benefits of quicker surgical time and obviating donor-site morbidity. In anterior cruciate ligament (ACL) reconstruction hesitancy exists to use allograft in younger patients based on data demonstrating higher graft failure rates. However, a similar trend of allograft failure has not been demonstrated for reconstruction of the MPFL, which has a lower tensile strength than that of the ACL. Hypothesis/Purpose: The purpose of this study is to evaluate outcomes including recurrent instability after MPFL reconstruction utilizing allograft tissue in pediatric and adolescent patients. Methods: A retrospective review was performed to identify patients of a single surgeon with MPFL reconstructions with allograft for recurrent patellar instability with minimum two-year follow-up. Surgical management was recommended after minimum six weeks of nonoperative management including bracing, physical therapy, and activity modification. Pre-operative x-rays were evaluated to assess physeal closure, lower extremity alignment and trochlear morphology, and Insall-Salvati and Caton-Deschamps ratios. MRIs were reviewed to evaluate the MPFL, trochlear morphology, and tibial tubercle trochlear groove distance (TT-TG). The allograft was fixed with a bioabsorbable screw. Descriptive statistics were used to characterize data. The primary outcome was recurrent instability. Results: 20 patients (23 knees) 14 females (17 knees) with average age 15.8 years (range: 11.5-19.6 years) underwent MPFL reconstruction with allograft with average follow-up of 3.6 years (range: 2.2-5.9 years). Physes were open in 8 knees. Average Insall-Salvati ratio was 1.08 ± 0.16 and Caton-Deschamps index was 1.18 ± 0.15. Eighteen patients were noted to have trochlear dysplasia pre-operatively and TT-TG was 15.4 ± 3.9 mm. The three knees (13.0%) with complications had open physes – two (8.7%) had recurrent instability requiring subsequent operation and one sustained a patella fracture requiring open reduction internal fixation. The average Insall-Salvati of these three patients was 1.26 ± 0.21, Caton-Deschamps was 1.18 ± 0.21, and TT-TG was 18.3 ± 3.5mm. There were no growth disturbances noted post-operatively. Conclusion: MPFL reconstruction using allograft tissue may be performed safely in the pediatric and adolescent population with good outcomes at mid-term follow-up with few complications and low rate of recurrent instability. Anatomic factors for may contribute to recurrent instability and complications post-operatively, though larger numbers are needed for statistical analyses. Further prospective and randomized evaluation comparing autograft to allograft reconstruction is warranted to understand graft failure rates.

SURGICAL MANAGEMENT OF PATELLAR INSTABILITY IN ADOLESCENTS WITH BODY MASS INDEX GREATER THAN 30

Background: Recurrent patellar instability is a common condition often requiring surgical stabilization in adolescents. Obesity, defined as body mass index (BMI) greater than 30 kg/m2 in adults, has been associated with poorer outcomes with many procedures including ACL reconstruction, spinal fusion, and joint arthroplasty. Data is limited regarding the results of surgery for patellar instability in adolescent patients with BMI > 30 kg/m2. Purpose: The purpose of this study was to report on rates of recurrent patellar instability following surgical management in adolescents with BMI >30 kg/m2 and to compare the rates of recurrent instability between different surgical procedures. Methods A retrospective review of patients who underwent surgical management of patellar instability at our institution was performed. Inclusion criteria included patients aged 19 and younger, with BMI >30 kg/m2 who were followed for least 12 months post procedure. Patients with underlying collagen or systemic disorders, a history of prior ipsilateral knee surgery, or an osteochondral fragment greater than 10mm were excluded. Complications were defined as any recurrent subluxation or dislocation, or need for subsequent instability surgery. A subgroup analysis was performed to compare recurrent instability rates within our cohort between patients who underwent medial retinacular plication versus all other procedures. Categorical variables were compared using Fisher’s exact test. Statistical significance of p<0.05 was applied. Results: Fifty-five patients were identified. Mean age was 15.6±2.4 years. Mean BMI for this cohort was 34.9± 4.3 kg/m2. 72.7% of patients were female. All patients underwent either medial retincular plication, tibial tubercle osteotomy, MPFL reconstruction or combined procedures (Table 1). At a mean of 3.8 years, 16.4% of all patients had any recurrent subluxation or dislocation including 12.7% who had a recurrent dislocation, and 7.3% who required a revision patellar stabilization procedure. Subgroup analysis revealed that obese patients who underwent isolated medial retinacular plication had higher rates of recurrent subluxation or dislocation (24% vs 10%, p=0.272) including recurrent dislocation (20% vs 6.7%, 0.226), and had significantly higher rates of subsequent instability surgery (16% vs 0%, p=0.037) (Table 2). Conclusion: Adolescents with BMI > 30 who undergo patellar stabilization surgery have notable rates of recurrent subluxation or dislocation and subsequent instability surgery though comparable to results in non-obese patients. Obese patients who underwent medial retinacular plication had higher rates of postoperative instability and significantly higher rates of revision instability surgery compared to those who underwent MPFL reconstruction, tibial tubercle osteotomy or combined procedures. Tables/Figures: [Table: see text][Table: see text]

Modified technique for medial patellofemoral ligament reconstruction – Its outcome with 2-year follow-up

Objectives: The purpose of this study was to present our modified technique for MPFL reconstruction. We also present its functional outcome, complications, and patients’ satisfaction from the procedure. Materials and Method: This study is a retrospective analysis of prospectively collected data during the period of July 2015 and March 2019. Forty cases in patients with recurrent symptomatic patellar instability without a patellar fracture and who underwent isolated MPFL reconstruction were included in the study. Kujala scoring was done to assess the functional outcome at follow-up. Post-operative dislocation and apprehension were recorded in each case along with any complication. Patients were asked to complete a subjective questionnaire postoperatively during follow-up, to assess their satisfaction with the surgical procedure. Results: Pre-operative Kujala score was 45.85 which improved to 92.72 postoperatively at the time follow-up. The improvement in Kujala score was found to be highly significant (P < 0.01). Subjective assessment of the procedure: 72.5% of the patients had an excellent outcome. About 15% of the patients had a good outcome whereas 10% had a fair outcome. Only one patient had a poor outcome. Conclusion: In properly selected patients with recurrent patellar instability, isolated MPFL reconstruction appears to be a safe and efficient surgical procedure for the stabilization of patella, with a low failure rate. Consistent good results with early rehabilitation can be obtained using suture anchors to fix the implant on patella and using the described technique.

Current Concepts Regarding Patellofemoral Trochlear Dysplasia

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