Studies in Osteoarthritis of the Hip: Part IV, * Biomechanics and clinical considerations

Present knowledge of hip biomechanics supports the contention that the stresses imposed on the hip on the side of the longer leg are greater than normal; those on the short side are comparably reduced. Indirect measurements by various authors have demonstrated greater stress on the hip if the pelvis is adducted, a persistent and chronic condition of the hip joint on the side of a long leg. Furthermore the pressure on the acetabulum will be displaced laterally in these circumstances. The consistent pattern of degeneration in unilateral superolateral O A hip is what would be expected if the consequences of leg-length disparity were as described. Leg-length inequality may be a major contributing factor in the development of unilateral degenerative disease of the hip of this type.A clinical method of estimating leg-length disparity is described. Clinical findings in patients support the hypothesis that hip stress is increased on the side of a longer leg.