Reduction of a dislocation of the hip due to developmental dysplasia. Implications for the need for future surgery.

BACKGROUND Recent reports on the treatment of a dislocation of the hip due to developmental dysplasia have documented conflicting data on the importance of the ossific nucleus in the development of postreduction ischemic necrosis. Delaying reduction until the ossific nucleus is present bypasses the time-period of maximal osseous remodeling of the hip, thereby possibly increasing the need for future operations. We hypothesized that hips with an ossific nucleus are more likely to have subsequent reconstructive procedures. METHODS A retrospective review of the medical records at two tertiary-care children's hospitals was completed to identify all patients who had had reduction of a dislocation of the hip due to developmental dysplasia, performed between 1979 and 1993, when they were less than two years old. Patients were excluded if the medical records or radiographs were inadequate, the duration of follow-up was less than three years after the final reduction, a previous reduction had been performed at an outside facility, or the patient had a neuromuscular disease or a teratologic dislocation. We identified 124 patients (153 hips) who satisfied the criteria for inclusion. The average age at the time of the reduction was eleven months, and the average duration of follow-up was 7.2 years. RESULTS Overall, fourteen of the sixty-three hips without an ossific nucleus had a reconstructive procedure: thirteen had a varus rotational osteotomy of the proximal part of the femur and one had a combined pelvic and varus rotational femoral osteotomy. Forty of the ninety hips with an ossific nucleus had a reconstructive procedure: twenty-seven had a varus rotational osteotomy, eight had a pelvic osteotomy, and five had a combined pelvic and varus rotational osteotomy (p < 0.05). In addition, secondary reconstructive procedures were performed in 17% (ten) of the fifty-nine patients who were less than six months old and in 35% (thirty-three) of the ninety-four patients who were at least six months old, which was a greater than twofold increase. The effect of age was further emphasized at the other age cutoff points. CONCLUSION Delaying the reduction of a dislocated hip until the appearance of the ossific nucleus more than doubles the need for future surgery to make the hip as anatomically normal as possible. Despite finding a slight increase in the rate of ischemic necrosis after reduction of the hips without an ossific nucleus, we advocate early reduction of a dislocation of a hip due to developmental dysplasia to optimize the development of the hip with the minimum number of operations