Impact of plate placement position on the efficacy and safety of derotational distal femoral osteotomy combined with medial patellofemoral ligament reconstruction in treating recurrent.

objectiveTo analyze the effects of different plate placement positions on the efficacy and safety of Derotational Distal Femoral Osteotomy (DDFO) combined with Medial Patellofemoral Ligament Reconstruction (MPFL) surgery in the treatment of Recurrent Patellar Dislocation (RPD).

methodsA retrospective analysis was conducted on 33 patients with Recurrent Patellar Dislocation (RPD) who underwent surgical treatment from January 2020 to January 2022. Preoperative general data were collected for both groups, as well as J-sign grading, VAS scores, Caton index, femoral anteversion angle, patellar tilt angle, TT–TG value, Tegner score, Kujala score, and Lysholm score measured preoperatively and at 1.5 years postoperatively. Bone healing was evaluated on follow-up radiographs, and the time to bone union was defined as the duration from surgery to the presence of continuous cortical bridging at the osteotomy site on at least three cortices. Delayed union was defined as bone union exceeding six months after surgery. In addition, effect sizes (Cohen’s h/d) and post hoc power analyses were performed to further evaluate the adequacy of the sample size, particularly for the comparisons between medial and lateral plating.

resultsAt 1.5 years postoperatively, the incidence of discomfort related to plate placement was significantly lower in the medial plate group compared with the lateral plate group (P < 0.05). Additionally, the rate of plate removal was significantly lower in the medial plate group than in the lateral plate group (P < 0.05). Both groups showed significant improvements in J-sign grading, VAS scores, Caton index, femoral anteversion angle, patellar tilt angle, TT–TG value, Tegner score, Kujala score, and Lysholm score at 1.5 years postoperatively compared with preoperative values (P < 0.001). All osteotomy sites achieved bone union without nonunion, and the mean time to bone union was 5.9 ± 1.1 months in the medial plate group and 5.8 ± 0.5 months in the lateral plate group (P = 0.71). All patient incisions healed at stage I, and there were no complications such as knee joint stiffness, infection, or recurrent patellar dislocation. Post hoc power analysis further confirmed adequate statistical power (Cohen’s h = 1.01 for discomfort; 0.87 for plate removal, both with > 99% power).

conclusionFor patients with RPD and FAA ≥ 30°, DDFO combined with MPFL-R appears to be an effective treatment option, with meaningful improvements in knee pain and function. Patients with a lateral incision reported a higher incidence of discomfort related to plate placement compared with those with a medial incision.