Cementless total hip arthroplasty for congenitally dislocated or dysplastic hips. Technique for replacement with a straight femoral component.

A new straight cementless stem was used for replacement of 67 dislocated or severely dysplastic hips. There were 45 hips with complete dislocation, 27 of which were cases after Schanz osteotomy. Technical solutions for various deformities are presented here. The acetabular component was placed at the level of the original cotyloid cavity or some lower position. In hips after total dislocation a metaphyseal shortening osteotomy was combined with distal advancement of the greater trochanter with intact attachment of the abductor muscles. This method was appropriate also for the femora, where high-seated Schanz osteotomy was previously performed. If the diaphysis was too narrow for the stem, it was split about 10 cm both anteriorly and posteriorly. In cases with unilateral total dislocation where Schanz osteotomy had been seated low, metaphyseal segmental shortening with angular correction was performed and the stem was used as an intramedullary nail. Special attention was paid to achieve sufficient abduction strength to balance the pelvis and abolish Trendelenburg limp and to restore leg length. The clinical and radiographic results of the consecutive series were assessed three to five years after the arthroplasty. Pain relief and the functional results including improvement of gait were generally good, primary complications were few, but the loosening and revision rate of the smooth-threaded acetabular component was unacceptably high. There were no problems with the press-fit cups. In general the outcomes were good even when reoperation was required.