Myelodysplasia. The influence of the quadriceps and hip abductor muscles on ambulatory function and stability of the hip.

In an analysis of motor function, ambulatory function, and hip stability in sixty-five patients with myelodysplasia, four motor-function groups based on the strength of the quadriceps and hip abductor muscles were identified. Retrospectively, it was evident that based on these groups, it would have been possible to predict which hips would remain stable, what level of ambulatory function the patients could achieve, and whether treatment to reduce and stabilize the hips was indicated. Fifty-seven of fifty-eight hips in the twenty-nine patients with functioning quadriceps muscles but non-functioning hip-abductor muscles were either subluxated or dislocated. Thirty-nine of the remaining forty-six patients with functioning quadriceps muscles could walk. In this series, three operative procedures were used to treat hip subluxation: varus osteotomy, varus osteotomy combined with iliopsoas transfer, and iliopsoas transfer alone. One shelf procedure was also done. Varus osteotomy was the best procedure for hip subluxation while posterior iliopsoas transfer, either alone or in combination with a varus osteotomy, was of questionable value. Treatment of hip instability (subluxation or dislocation) in patients without quadriceps function was not necessary.