The relationship between femoral bone mineral density and hip joint loads in osteoarthritis.

摘要

The relationship between mechanical loading and its effect on bone mass is well accepted. Over the years, numerous experimental and theoretical studies have investigated bone's response to increased and decreased mechanical stimuli. However, the relationships between bone and joint loading during daily activities such as walking and their role in disease processes such as osteoarthritis are unclear and are currently the topic of many investigations.; The relationship between bone mineral density (BMD), assessed by dual energy x-ray absorptiometry, and joint loading, assessed by gait analysis, was examined in osteoarthritic and normal subjects. Three specific aims were investigated to understand the mechanical influences at the hip joint and their impact on the underlying bone. Aim 1 determined how to correct for differences in stature, body weight and gender when using gait data. Two commonly used normalization methods were tested. Both methods, normalizing to body weight times height and body mass, significantly reduced the variance in the moments ascribed to height, weight, and gender with the exception of the hip adduction and ankle dorsiflexion moments. Aim 2 determined if and how proximal femoral BMD and joint loading during walking were correlated in a normal population likely to have peak bone mass. A study of 31 normal subjects from 30--49 years demonstrated that joint moments during walking and jogging were significantly correlated with BMD of the proximal femur. Specifically, 25% to 40% of the variance in BMD at the femoral neck and greater trochanter was explained by the hip internal and external rotation moments. Aim 3 focused on how BMD and joint loading were related in the nonsurgical hip of subjects scheduled for total hip arthroplasty of the contralateral hip. Investigating the nonsurgical hip provided a population where the earlier stages of the disease could be investigated. For the nonsurgical hips with no definitive radiographic changes, no relationship was found between BMD and loading, while both positive and negative correlations were found for the nonsurgical hips with definitive radiographic changes. The lack of a relationship and the unexpected negative correlations are most likely due to confounding factors such as aging, gender issues, varying activity levels, and various pain and functional levels.