Trochleoplasty versus MPFL-Reconstruction in Severe Trochlear Dysplasia. A Systematic Review and Meta-Analysis

AIMS AND OBJECTIVES: Reconstruction of the medial patellofemoral ligament (MPFL) is an established operative procedure for the treatment of lateral patellar dislocation yielding good to excellent results with low rates of redislocation. However, few studies indicated less favourable results after an isolated MPFL reconstruction in patients with a severe trochlear dysplasia (Type B-D according to Dejour). In addition, some articles recommended the more invasive and demanding trochleoplasty (TP) as an additional procedure as the treatment of choice for those particular patients but the current literature lacks studies directly comparing both treatment strategies. Thus, the aim of this systematic review and meta-analysis was to evaluate the results of MPFL-reconstruction techniques compared to TP-procedures with special emphasis on severe trochlear dysplasia and to assess the available scientific evidence. MATERIALS AND METHODS: A systematic review (MEDline) was performed using the following mesh terms: #1. Patellar instability; #2. Patellar dislocation; #3. Patell* dislocation; #4. Trochlear dysplasia; #5. Luxating patella; #6. Luxating patellar; #7. Medial patellofemoral; #8. Medial patello-femoral; #9. Trochleoplasty; #10.Trochleoplasties; #11. MPFL. The final search algorithm (#1 OR #2 OR #3 OR #4 OR #5) AND (#7 OR #8 OR #9 OR #10 OR #11) yielded 425 articles. Two physicians independently screened all articles with decision reached by consensus. After applying the inclusion criteria (human study; MPFL reconstruction or TP procedure; exact documented pre- and postoperative validated knee score; and type of trochlear dysplasia) 8 Studies (2 MPFL studies; 6 TP studies) were available for further analysis. Statistical evaluation was performed with a random-effect meta-analysis including inverse variance weighting of pre- and postoperative mean differences. RESULTS: All available studies were case-series (level of evidence IV). Overall, 419 knees were included in the meta-analysis. The MPFL study group consisted of 231 knees with a trochlear dysplasia type B and C; the TP study group consisted of 188 knees with a trochlear dysplasia type B and D. The mean Kujala-score increased by 23.75 points (95%CI 10,41; 37,09) to 83.35 points (p=0.0005) postoperatively in the MPFL group, and by 28.57 points (95%CI 21,03; 36,11) to 84.36 points (p<0.00001) postoperatively in the TP study group. Though the mean postoperative Kujala score was identical in both groups, the mean increase was more pronounced in the TP group (MPFL 23.75 vs. TP 28.57). The redislocation rate was 1/231 (=0,4%) for the MPFL group and 1/188 (=0,5%) for the TP group. CONCLUSION: This analysis found significant postoperative improvement both in patients undergoing TP procedures and in those undergoing MPFL reconstructions for the treatment of patellar instability caused by severe trochlear dysplasia. However, low levels of evidence and significant sources of selection bias were present in the selected studies.