How does patellofemoral joint replacement differ from total knee replacement in indications and technique?

• A. Indicated for isolated patellofemoral arthritis or patellar failure; implants focus on the patellofemoral joint; tibiofemoral compartments may be preserved.
• B. It replaces all compartments of the knee; more invasive.
• C. It uses larger implants to replace the tibiofemoral joint.
• D. It is identical to total knee but uses different cement.

Answer: (A)

Patellofemoral joint replacement targets disease confined to the patellofemoral articulation, meaning it’s chosen for isolated patellofemoral arthritis or patellar maltracking/failure with preserved tibiofemoral compartments. The implants resurface only the patella and the trochlear groove, while the tibiofemoral joints are left largely untouched. This keeps the rest of the knee mechanics, ligaments, and bone stock intact and focuses the surgery on restoring smooth patellofemoral motion and tracking.

In contrast, a total knee replacement replaces all compartments of the knee—the patellofemoral surfaces plus the femorotibial articulations—creating a more extensive reconstruction. The technique involves resecting bone from both the femur and tibia and placing implants across the entire knee to address wear in all compartments, which is why the procedure is more invasive and carries a broader rehabilitation course.

So, the main distinction is that patellofemoral joint replacement is indicated for isolated patellofemoral pathology with tibiofemoral compartments preserved and involves resurfacing only the patellofemoral joint, whereas a total knee replacement addresses disease in all knee compartments with corresponding implant components. The other descriptions describe total knee replacement or mischaracterize the procedure’s scope and cement use.