Total knee arthroplasty with "Collar Tightening Technique" for advanced knee osteoarthritis with concurrent chronic posterolateral knee dislocation and lateral patellar dislocation: A case report.

Chronic posterolateral knee dislocation with concurrent lateral patellar dislocation is a rare and challenging pathology. Without appropriate treatment, it invariably leads to advanced osteoarthritis, frequently necessitating total knee arthroplasty. However, achieving optimal patellofemoral tracking remains a primary challenge, and no consensus on a definitive surgical technique exists. In this article, we introduce a novel "Collar Tightening Technique" to address this complex clinical scenario. A 66-year-old male with a complex medical history, including prior right knee medial collateral ligament/posterior cruciate ligament reconstruction, presented with chronic right knee pain with difficulty in ambulation. Imaging revealed advanced osteoarthritis, posterolateral knee dislocation, and lateral patellar dislocation with a fixed 20-degree tibial external rotation deformity. The patient underwent total knee arthroplasty, during which the collar tightening technique was employed to restore patellofemoral stability. This technique consisted of three key components: (1) an extensive lateral release, (2) distal and lateral advancement of the quadriceps tendon, and (3) medialization of the patellar component. A hinged prosthesis was utilized to address the underlying global instability. Postoperatively, the patient could walk smoothly with single cane assistance. In conclusion, restoring stable patellofemoral tracking is of paramount importance in complex total knee arthroplasty. The collar tightening technique provides an effective solution by combining dynamic stabilization from muscle advancement with static stabilization from component positioning. This comprehensive approach warrants consideration when a simple lateral retinacular release is insufficient to achieve proper patellofemoral alignment.