Bone mineral content assessed by dual photon absorptiometry in the proximal tibia: Normative data and measurements in orthopaedic conditions

Bone mineral content (BMC) assessed by dual photon absorptiometry was measured in the proximal end of the tibia in women with various orthopedic diseases and in 102 healthy women. Precision in vivo expressed as the coefficient of variation for BMC measurements was 1.8%. The mean BMC in healthy women showed a decrease from 5.30 g/cm in women of 20-29 years of age to 2.85 g/cm in women aged 80-89 years. In women with Colles' fracture, age-adjusted BMC was significantly lower compared to controls (p = 0.0003) and in patients with osteoarthrosis of the knee, BMC was significantly higher (p = 0.0002). Patients with ankle fractures had RMC within normal range at the time of the fracture, but after 6 months BMC was decreased by 18.3% compared with initial value (p = 0.003) and BMC was then significantly lower (p = 0.01) compared with normative data. In women with osteoarthrosis of the hip, BMC was decreased by 19.4% compared with the healthy contralateral legs (p = 0.004) and was significantly lower compared with BMC in healthy women (p = 0.02); BMC in the healthy legs was within normal range. In women with earlier lesions of the anterior cruciate ligament of the knee, BMC in the injured legs did not differ from normative data, but was decreased by 8.6% (p = 0.002) compared with the healthy contralateral legs. These findings indicate that BMC measurements in the proximal end of the tibia, which consists mainly of trabecular bone, is a very sensitive method for measuring disuse induced bone loss in the lower extremities.