Megaprosthesis is typically used to replace what?

• A. Large segments of bone (often in tumor resection or massive bone loss).
• B. A small portion of the joint cartilage only.
• C. The entire acetabulum only.
• D. The articular surface of a small finger joint.

Answer: (A)

Megaprosthesis is used to replace large segments of bone, typically when there has been tumor resection or massive bone loss that leaves too little bone for a conventional implant. These implants are designed to span long portions of a limb and restore both structural stability and joint function, often with long stems anchored into the remaining bone. This makes them ideal for reconstructions like the distal femur or proximal tibia after tumor removal or extensive bone loss. They aren’t intended for small cartilage defects or isolated joint surfaces, nor are they used to replace only an entire acetabulum or a tiny finger joint; those situations involve smaller joints or different reconstructive approaches. The essence is replacing a large bone segment to restore limb integrity and function when smaller implants wouldn’t be feasible.