A Biological Solution to a Bony Problem: Interposition Arthroplasty for Post-traumatic Patellofemoral Arthritis

Interposition arthroplasty is a joint-preserving surgical technique that involves the placement of biological or synthetic tissue between articulating surfaces to restore function and alleviate pain. Although rarely used in modern practice, it remains a valuable option in selected cases, particularly in young, active patients with complex post-traumatic joint pathology. We report the case of a man in his 40s who presented with persistent anterior knee pain and functional impairment due to isolated post-traumatic patellofemoral arthritis and a significant trochlear bone defect following distal femur fracture fixation. Imaging revealed extensive trochlear cartilage loss, bony irregularities, and a contained central defect. We performed an interposition arthroplasty utilising an ipsilateral suprapatellar synovial flap, in conjunction with bone grafting of the osseous defect, trochleaplasty, patelloplasty, and lateral patellar facetectomy. Postoperatively, the patient experienced substantial pain relief and functional recovery, maintained at two-year follow-up. This case demonstrates that interposition arthroplasty, though seldom employed today, can offer excellent outcomes in carefully selected patients with isolated patellofemoral arthritis.