Mobile-Bearing Total Knee Arthroplasty Using Subvastus Approach With Lateral Retinacular Release for Valgus Knee Osteoarthritis With Permanent Dislocation of the Patella: A Case Report and Narrative Review.

Permanent dislocation of the patella (PDP) with valgus knee osteoarthritis is rare and challenging in total knee arthroplasty. A 55-year-old woman with PDP and valgus knee osteoarthritis underwent mobile-bearing posterior-stabilized total knee arthroplasty using the subvastus approach. Extensive lateral retinacular release and partial transverse division of the rectus femoris were required for stable patellar reduction and 90° of flexion. Independent ambulation was achieved at 3 months. At 1 year, knee flexion remained limited; however, the functional activities score on the 2011 Knee Society Score improved from 39 to 67, and the Forgotten Joint Score-12 from 20 to 40. No recurrent dislocation or radiographic complications occurred. This case demonstrates that this surgical strategy can provide stable patellar tracking and functional improvement in PDP with valgus knee osteoarthritis.