This study determined the areal bone mineral density (BMD) from the lumbar spine (L2-4), right distal radius and ulna, and the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and calcaneus of both extremities in 29 men who had a femur shaft fracture 10 years earlier. For evaluation of the patients' BMDs in the spine and distal forearm, 29 age-, weight-, and height-matched normal men were also measured. Compared with normal men (mean +/- SD = 1.123 +/- 0.153), the spinal BMDs of the patients were significantly (p = 0.0054) lower (1.018 +/- 0.119, -9.3%). Distal radius and distal ulna showed no significant group differences. In patients, the mean BMD of the injured extremity (compared with the uninjured side) was significantly lower in the distal femur (-6.8%; p = 0.0000), patella (-5.4%; p = 0.0000), proximal tibia (-4.7%; p = 0.0000), and calcaneus (-2.2%; p = 0.0259). In the proximal femur, this value was at the same level (femoral neck 1.3%, NS) or higher (trochanter area 6.3%, p = 0.0002) than that in the uninjured extremity. The relative BMDs of the injured extremity did not associate with the fracture type, fracture location, age, muscle strength, follow-up time, or non-weight-bearing time but showed significant (r = 0.33-0.64) positive correlation with low pain assessment and high functional scores of the injured extremity.(ABSTRACT TRUNCATED AT 250 WORDS)