Subvastus approach improves intraoperative patellofemoral tracking in total knee arthroplasty for varus deformities – An <i>in vivo</i> study

Objectives: The subvastus approach has the theoretical advantages of protecting the extensor mechanism while securing the patellar blood supply, enhanced patellofemoral tracking, faster recovery, decreased post-operative pain, and shortened length of hospital stay at the expense of longer operative and tourniquet times. This study aimed to evaluate the effect of the subvastus approach on patellofemoral tracking. We hypothesize that being a more anatomical approach, the subvastus approach may improve patellofemoral tracking intraoperatively and decrease the necessity to release the lateral retinaculum during total knee replacement (TKR). Methods: In 54 consecutive cases presented with advanced varus osteoarthritis knee in a high-volume arthroplasty hospital from January 2022 to April 2022 and scheduled for cemented posterior stabilized TKR, patellofemoral tracking and the tightness of lateral retinaculum were evaluated intra-operatively all through the whole range of motion (ROM) of the knee by “No thumb test” and “Vertical patella test” subsequent doing the whole tibial and femoral bony cuts, proper sizing, completing soft-tissue release and gap balancing, and reaching the full ROM. Results: The “No thumb test” and “Vertical patella test” were negative in all the patients, and there was no intra-operative dislocation or subluxation. In addition, there was no need to release the lateral retinaculum in any of them. Conclusion: Implementing the subvastus approach during TKR surgeries, with subsequent preservation of the patellar attachment of the vastus medialis oblique muscle, allows for better tracking of the patella over the femur during surgery, resulting in a reduction in the necessity of performing lateral retinaculum release intraoperatively.