Osteoarthritis of the knee before and after replacement

Panel A shows a radiograph of a knee with osteoarthritis. Panel B shows the same knee after a total knee arthroplasty. In panel A, the arrow shows the narrowed space between the femur and the tibia. Marginal osteophytes are also present. In panel B, the femur and tibia each have new metal end-pieces. The arrow shows that the space between the two bones has been widened with a polyethylene spacer.