Outcomes of total knee arthroplasty combined with the modified "overlap" technique in the treatment of knee osteoarthritis with permanent patellar dislocation

Abstract

Objective: To investigate the clinical outcomes of total knee arthroplasty (TKA) combined with the modified "overlap" technique in the treatment of end-stage knee osteoarthritis with fixed patellar dislocation. Methods: This is a retrospective case series study. Clinical data of 19 patients (22 knees) who underwent TKA combined with the modified "overlap" technique for the treatment of end-stage knee osteoarthritis with permanent patellar dislocation from January 2011 to January 2022 in the Department of Orthopaedics, the First Affiliated Hospital of Xinjiang Medical University were retrospectively analyzed. The cohort included 5 males (6 knees) and 14 females (16 knees), with an age of (60.6±12.2) years (range:33 to 77 years) and a body mass index of (25.4±4.1) kg/m² (range:20.0 to 33.0 kg/m²). Among them, 11 cases (12 knee) had valgus deformity, with Keblish classification showing mild in 2 cases (2 knees), moderate in 6 cases (6 knees), and severe in 4 cases (4 knees). All cases were treated using a medial parapatellar approach, with lateral retinaculum release combined with the "overlap" technique to restore the patellar trajectory. Knee function was evaluated using the American Knee Society (KSS) Score. Paired sample t tests were used for intergroup comparisons. Results: All patients successfully completed the surgery. Postoperatively, patellar dislocation, knee valgus deformity, flexion contracture deformity, and extensor lag were all corrected. All patients were followed up, with a follow-up duration of (63.8±35.2) months (range:24 to 136 months). One patient experienced periprosthetic infection 2 weeks postoperatively, 1 patient had recurrent patellar dislocation 2 months postoperatively, 1 patient developed knee stiffness 3 months postoperatively and underwent closed manipulation. No other patients exhibited signs of patellar dislocation or subluxation. At the last follow-up, the KSS clinical score improved from (36.4±12.7) points preoperatively to (83.4±6.3) points postoperatively (t=-15.15, P<0.01), and the KSS functional score improved from (30.7±11.1) points preoperatively to (77.6±8.3) points postoperatively (t=-14.37, P<0.01). The range of motion of the knee increased from 81.7°±19.6° preoperatively to 107.6°±12.5° postoperatively (t=-4.85, P<0.01). Conclusion: TKA combined with the modified "overlap" technique is an effective surgical option for the treatment of end-stage knee osteoarthritis with permanent patellar dislocation, demonstrating satisfactory clinical outcomes.