Which PF joint involvement is most commonly seen in patellofemoral osteoarthritis?

• A. Knee
• B. Anterior
• C. Lateral
• D. Posterior

Answer: (C)

Patellofemoral osteoarthritis most often targets the lateral facet of the patellofemoral joint. When the knee bends, the patella tracks within the femoral trochlea, and this tracking tends to load the lateral facet more heavily, especially in people with maltracking tendencies such as a larger Q angle, valgus alignment, or tight lateral structures. That repetitive lateral contact compresses and wears the cartilage there, leading to OA changes on that facet. Clinically, this explains pain with activities that load the PF joint (stairs, squatting, kneeling) and why the lateral portion is the most commonly affected. The terms describing the whole knee or other directions don’t specify this facet-level involvement, making the lateral facet the best described site.