Medial Unicompartmental Knee Arthroplasty After Previous Patellectomy: A Case-Based Review and Technical Considerations

The patella plays an essential role in optimizing the biomechanics of the knee extensor mechanism.Patellectomy disrupts force transmission within the extensor apparatus, leading to diminished extension strength, altered joint stability, and a higher risk of developing tibiofemoral osteoarthritis.Surgical treatment of degenerative changes in patellectomized knees remains challenging, and evidence regarding the use of unicompartmental knee arthroplasty (UKA) in these patients is limited.We present the case of a 66-year-old man who developed persistent anteromedial knee pain and functional impairment more than two decades after total patellectomy.Imaging studies demonstrated isolated osteoarthritis of the medial compartment.The patient underwent medial mobile-bearing UKA using the standard anteromedial surgical approach.Postoperative management included early mobilization and gradual progression to full weight-bearing.At the 36-month follow-up, the patient reported no pain and achieved a knee range of motion of 0-140°, with quadriceps strength comparable to that of the contralateral side.Radiographs demonstrated appropriate implant positioning without evidence of loosening, misalignment, or progression of degenerative changes in the remaining compartments.This case suggests that patellectomy may not be a contraindication to UKA in carefully selected patients with isolated medial disease and intact ligamentous stability and that UKA may provide durable mid-term outcomes.