Measurement of bone mineral density by dual-energy X-ray absorptiometry around an uncemented knee prosthesis.

Dual-energy x-ray absorptiometry allows the measurement of bone mineral density (BMD) around an uncemented hip prosthesis, but has not so far been widely used to measure BMD around a knee prosthesis. We studied 16 patients undergoing total knee replacement using a Miller-Galante uncemented prosthesis for either osteoarthritis or rheumatoid arthritis of the knee. The precision of the measurement was improved by using a leg brace. The pattern of bone loss differed in the lateral projection by region (P = .001). There was significant loss of bone from the distal femur but not from the patella or proximal tibia over the 6-month period after insertion of a knee prosthesis.