Outcomes of Surgical Interventions for Patellofemoral Instability in the Presence of Trochlear Dysplasia: A Systematic Review and Meta-analysis

Background: Patellar instability is frequently encountered by orthopaedic surgeons. One of the major risk factors of this condition is underlying trochlear dysplasia (TD). Recent trends have indicated the use of multiple procedures to correct patellar instability under these conditions. Medial patellofemoral ligament reconstruction (MPFLR) and trochleoplasty (TP) are surgical strategies that have demonstrated successful outcomes. However, it is unclear whether isolated MPFLR suffices for patellar instability in the presence of severe TD. Furthermore, the need for TP or a combined approach, considering its invasiveness and technical demands, to achieve better clinical outcomes and patellofemoral stability remains uncertain. Purpose: To compare the outcomes of 3 surgical interventions for addressing patellar instability due to TD: MPFLR, TP, and combined MPFLR and TP. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: Studies reporting the clinical outcomes of MPFLR, TP, and both in combination, regardless of additional procedures, were identified using the MEDLINE, PubMed, Embase, Scopus, Cochrane Library, Cochrane Central Register of Controlled Trials, and Cumulative Index to Nursing and Allied Health Literature databases. An important inclusion criterion was that studies should include the mean preoperative and postoperative Kujala scores and any complications. A random-effects model was used for the meta-analysis. Results: Overall, 30 studies were included: 10 describing the outcomes of TP, 13 describing the outcomes of MPFLR, and 7 describing the outcomes of combined TP and MPFLR. Furthermore, 1457 patients (1571 knees) were evaluated with a mean follow-up of 42.4 ± 32.8 months. No statistically significant differences were found between the 3 methods regarding the mean difference using the Kujala score. However, combined MPFLR and TP had the highest weighted mean difference compared with the other 2 procedures (28.5 points; P < .001). Evidential analysis revealed a robust log-likelihood ratio ( S = 3.2) supporting the superiority of the combined procedure when comparing this mean and the weighted grand mean of 23.7. The redislocation rate after patellar stabilization remained minimal, irrespective of the surgical procedure (mean, 0.7%). However, the rate of residual patellar instability was the highest in the TP group (mean, 13.5%). Conclusion: This study found no statistically significant difference between the outcomes of the 3 procedures. However, the combined approach of MPFLR and TP was associated with the most promising clinical outcomes and a low redislocation rate in patients with varying severities of TD.