Effects of nonweight bearing on the hip

To evaluate the effects of nonweight bearing on joints (weight-free range, five to 92 months), bilateral hips of 20 patients with amputated lower limbs or nonunion of the femur were studied clinically and roentgenographically. The nonweight-bearing side showed a roentgenographic narrowing of the joint space of 10% or more as compared with the weight-bearing side in one half of the patients, and marked narrowing of 30% or more was observed in six patients. The degree of narrowing correlated with the degree of osteopenia expressed as a femur score. The joint space narrowing was notable in those who had onset of the nonweight-bearing state at ages younger than 20 years. None of the patients who showed narrowing of the joint space had pain or motor restriction of the hip. These findings suggest that a nonweight-bearing state of normally weight-bearing joints causes deranged homeostasis of articular cartilage, which leads to its thinning.