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 dislocat ed or severely dysplastic hips. There were 45 hips with complete dislo cation, 27 of which were cases after Schanz osteotomy. Technical solut ions for various deformities are presented here. The acetabular compon ent was placed at the level of the original cotyloid cavity or some ro wer position. In hips after total dislocation a metaphyseal shortening osteotomy was combined with distal advancement of the greater trochan ter with intact attachment of the abductor muscles. This method was ap propriate 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 lo w, metaphyseal segmental shortening with angular correction was perfor med and the stem was used as an intramedullary nail. Special attention was paid to achieve sufficient abduction strength to balance the pelv is and abolish Trendelenburg limp and to restore leg length. The clini cal and radiographic results of the consecutive series were assessed t hree to five years after the arthroplasty. Pain relief and the functio nal results including improvement of gait were generally good, primary complications were few, but the loosening and revision rate of the sm ooth-threaded acetabular component was unacceptably high. There were n o problems with the press-fit cups. In general the outcomes were good even when reoperation was required.