There are some special features involving replacement surgery of totally dislocated or severely dysplastic hips (Eftekhar Stage C and D). To achieve abduction strength strong enough to balance the pelvis and reliable fixation of the acetabular component, the cup must be seated near the anatomic level or even lower. Therefore, the femoral component in most cases is to be mounted below the intertrochanteric level in order to get the prosthesis reduced and the greater trochanter with intact attachment of the gluteus medius muscle distally advanced. At these levels the femoral diaphysis is straight and requires a straight stem. We started these techniques over 15 years ago with Lord’s madreporic prosthesis, but the stem – especially the calcar part – was too curved. A totally straight cementless, collared stem was designed with Biomet Inc. and has been used since 1988. For this stem the femur was prepared with broaches, but it was far too easy to get a proximal split when rasping the cortical bone or inserting the stem. For this reason a new stem with a tapered, oval proximal part was designed in 1993. The femur is prepared with reamers and no broaches are needed. Because the stem is collarless, vertical/rotational stability is achieved by the oval wedge shape of the proximal stem, and not by the collar. Therefore, rotational instability and loosening of the stem are avoided. We present the operative methods. The collarless stem has been used since 1993 in 58 hips of 43 patients. Mean age of the patients was 54 years (range: 21 to 71). Only six of the patients were men. The most common cause of hip deformity was DDH (47 hips). Five hips had congenital coxa vara, two cases had tuberculosis of the hip, and two patients had diastrophic dysplasia. There was one arthrogryphosis multiplex patient and one congenital proximal femoral deficiency. Schanz osteotomy had been performed in 11 of the DDH cases. Forty-four of the 47 DDH hips were high dislocations (Eftekhar C or D). Complications: There were three dislocations, three late fractures of the greater trochanter fixed with a hookplate, two splits of the proximal diaphysis fixed with a cable, and one late fracture dislocation revised with a collared stem. Deep infection occurred in one case and removal of the prosthesis was necessary. In two cases the stem migrated 3 to 7 mm but stabilised spontaneously with osteointegration. In one case the stem migrated 15 mm. Fibrous union remained, but it is painless. The final outcome was good in all other cases, but the patient with deep infection is waiting for a rearthroplasty, and the case with fibrous union is likely to be revised when it becomes symptomatic. Pain relief and the functional results including improvement of gait and abduction strength were generally good. Most of the patients were highly satisfied.
We have reviewed retrospectively 68 revisions of the femoral component in arthroplasties of the hip in 65 patients, using impaction bone grafting, at a median of three years (1 month to 6 years). We employed the cemented Exeter X-Change technique in 36 patients and the uncemented Bi-Metric allografting method in 32. The 37 bone defects were grade 3 or grade 4 on the Endo-Klinik classification. The Mayo hip score improved from a mean of 32 ( The risk of intraoperative fracture was prevented by supporting the bone with wires in 16 hips, with reinforcement mesh in 18 and by a plate in six. Early migration of the stem of more than 10 mm during the first year indicated rotational instability; it occurred in three cases. In difficult revision cases with large defects of the femoral bone, bone-impaction techniques carry a high risk of complications.
We describe six patients with aggressive granulomatous lesions around cementless total hip prostheses. Two patients previously had a cemented prosthesis in the same hip. The Lord prosthesis was used in five patients, the PCA in one. Both prostheses were made of chrome-cobalt alloy. Pain on weight-bearing occurred on average 3.2 years after the cementless arthroplasty, and at that time radiography revealed aggressive granulomatosis around the proximal femoral stem and the acetabular component in five of the patients; one had a large solitary granuloma in the proximal femur. Revision was performed on average 4.8 years after the cementless arthroplasty. At that time all granulomas had grown large in size; while waiting for revision operation, two femoral stem components fractured. All the granulomas showed a uniform histopathology, which included histiocytosis; the cause for these lesions was thought to be plastic debris from the acetabular socket.
We report the short-term results of 100 cementless total hip replacements in 52 severely dysplastic and 48 totally dislocated hips, with some new technical solutions to the problems involved. In cases with a very narrow iliac bone, the acetabular screw ring is seated below the true cotyloid area. In hips with tight flexor and abductor muscles or with deformities of the proximal femur, various osteotomies were performed. Special attention was paid to careful pre-operative planning and precise operative technique. In spite of a high complication rate the results were generally good and even patients who required reoperation were satisfied with the final result.
