HIP MOTION AND MOMENTS DURING GAIT RELATE DIRECTLY TO PROXIMAL FEMORAL BONE-MINERAL DENSITY IN PATIENTS WITH HIP OSTEOARTHRITIS

The present study examined the loads at the hip joint during gait and the bone mineral density of the proximal femur in 25 patients with end -stage hip osteoarthritis. Dual energy X-ray absorptiometry was used t o determine the bone mineral density of the greater trochanter, femora l neck and Ward's triangle of the osteoarthritic group. The bone miner al density was normalized for the patient's age, gender, weight and et hnic origin (Z score). Gait analysis was used to determine the externa l hip joint moments and motion during walking for the osteoarthritic g roup and a control group of 21 normal subjects. The gait parameters of the osteoarthritic group which were significantly diminished compared to the normal group (p < 0.001) accounted for as much as 42% (p < 0.0 01) of the variation in the normalized bone mineral density. Specifica lly, the dynamic sagittal plane hip motion during gait (maximum flexio n minus maximum extension) and peak external rotation and adduction mo ments were significantly correlated with greater trochanter (R = 0.429 -0.648, p = 0.032-0.0001) and Ward's triangle (R = 0.415-0.532, p = 0. 038-0.006) normalized bone mineral density while the adduction moment was also significantly correlated with the femoral neck normalized bon e mineral density (R = 0.5394, p = 0.005). The normalized bone mineral density of the femoral neck and Ward's triangle was elevated while th at of the greater trochanter was decreased as compared to normal refer ence values. The significant correlation between the hip joint moments during gait and femoral bone mineral density indicate that hip joint loads need to be included when explaining local variation in bone mine ral density in hip osteoarthritis. (C) 1998 Elsevier Science Ltd. All rights reserved.