The CLS uncemented expansion shell, when used with a structural femoral head autograft, provides a reliable reconstruction, augments deficient acetabular bone stock, and allows placement of the socket at or close to the anatomic center of hip rotation in patients undergoing total hip arthroplasty to treat the sequelae of congenital hip disease.

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PURPOSE OF THE STUDYTo evaluate the results of primary total hip replacement with the CLS acetabular cup at a minimum of 15 years of follow-up. MATERIAL AND METHODSA total of 105 patients, with 112 hips, undergoing hip arthroplasty with the use of CLS acetabular cup between 1991 and 1993 were evaluated. The group comprised of 33 men and 72 women with an average age of 51.3 years (range, 28 to 66) at the time of surgery. All patients received the CLS expansion cup with a polyethylene Sulen-type liner. Cemented femoral stems were used in 75 hips and uncemented CLS stems were implanted in 37 hips. Ceramic heads of the femoral component were used in 86 hips and metal heads were used in 26 hips. The clinical outcome was assessed by the Merle d'Aubigné and Postel score and the Harris hip score, and the radiological results were evaluated on anterior posterior X-ray films of the pelvis and the affected hip. RESULTSThe average follow-up was 16.2 years (range, 15 to 17). The average Merle d'Aubigné and Postel score increased from 8.1 (range, 5.7 to 9.8) pre-operatively to 14.6 (range, 14.1 to 16.8) post-operatively. The average Harris hip score improved from 42 to 86 points (range, 71 to 99). The complications requiring revision arthroplasty included aseptic loosening in two hips, fracture of the CLS shell in three, dislocation in three and replacement of the liner due to high wear in two hips. The cumulative proportion of clinical survivorship with revision for any reason was 92 %. Fixation by bone ingrowth, assessed by the method of Engh et al. occurred in 98 cases, fibrous tissue fixation was found in ten hips. Unstable fixation was recorded in four hips (two with aseptic loosening and two with fracture of the shell). There were no signs of rarefaction of bone along acetabular shell in 98 hips. No noticeable migration was found in the stable cups. Only in ten cups from 112, polyethylene wear exceeded 4 mm. Cumulative probability of radiological survivorship of the CLS acetabular cup with any radiological sign of loosening was 86.6 %. DISCUSSIONThe causes of fracture of the CLS cup can be explained by insufficient bone support or bone resorption in the proximallateral part of the acetabulum in patients with developmental hip dysplasia, by low bone quality due to severe osteoporosis or by insufficient primary stability of the cup. The advantages of the CLS cup include removal of a small amout of bone and favourable force distribution in circumferential anchorage. The cup showed good osteointegration even in a bone of lower quality and with defects of the acetabular bottom. CONCLUSIONSThe CLS acetabular cup shows good results at 16-year follow-up period. No increase in fractures of the shell, migration or radiolucent lines, or in bone rarefaction or osteolysis was recorded with time. The reliability of this implant has been recently increased with the use of cross-linked polyethylene (Durasul).

The aim of our study is to assess the outcomes using the uncemented CLS expansion shell in revision hip surgery for aseptic loosening of the acetabular component. Between 1991 and 2000 we used the CLS expansion shell in revision hip surgery in 215 patients (230 hips). We were able to evaluate 196 patients (211 hips) with failed acetabular components. The male/female ratio was 82/114 and the mean age of the patients was 63 years (range 38-71). The main reason for revision was aseptic loosening of the PE cup (184 patients). There were 79 hips with Paprosky defect of the acetabulum type I, 62 hips with type 2A, 57 hips with type 2B and 13 hips with type 2C in the study. The mean follow-up was 8.5 years (range 5-14). Plain radiographs using an AP view of the pelvis and AP and lateral views of the affected hip were taken immediately after surgery and at the latest follow-up. Clinical outcomes were determined using the Merle dAubigne' and Postel score and the Harris Hip score. The mean preoperative Merle dAubigne' score was 7.8 points (range 6.9 to 9.9); at the latest follow-up it was 14.9 points (range: 12.5 to 15.9). The mean preoperative Harris Hip score was 38.6 points (range: 32 to 59); at the latest follow-up it was 82.5 points (range: 38 to 95). Osteointegration of the CLS expansion shell was present in 149 hips (70.6%) at the latest follow-up. There were 31 complications (15%) requiring a second revision. Clinical survivorship of the CLS expansion shell was 90% at five years and 84% at 8.5 years after revision surgery. Radiological survivorship was 78% at five years and 70% at 8.5 years after revision surgery. The CLS expansion shell offers a viable alternative for revision hip surgery with lower bone quality, insufficient bone at the bottom and cavitary defects of the acetabulum.;

PURPOSE OF THE STUDYThe aim of the study was to evaluate the results of primary total hip arthroplasty with the use of the CLS stem at 11 to 17 years after implantation. MATERIAL AND METHODSA total of 108 patients (122 hips) in whom a CLS stem was used in the 1991-1996 period were evaluated. The group included 34 men and 74 women, with an average age of 48 years (range, 28-63). The CLS stem with a neck-shaft angle of 145° and the CLS expansion cup were used in all patients. Clinical outcomes were evaluated by Merle d'Aubigné-Postel score and Harris hip score, radiological examination was completed on AP and lateral views of the pelvis and the operated hip. RESULTSThe average follow-up was 16.4 years (range, 11-17). The average Merle d'Aubigné-Postel score was 14.5 (range, 13.9-17.0) points and the average Harris hip score was 84.8 (range, 70-99) points. Very good or good outcomes were found in 81% of the patients. Three patients underwent revision surgery, in one for septic loosening, in one for aseptic loosening and in one for varus stem position leading to instability. The radiographs evaluated as described by Engh showed 116 stable stems, three fibrous stable and three unstable stems. Subsidence of more than 3 mm, without any further deterioration, was found in five hips at 12 months post-operatively. Seven hips showed one radiolucent line, four showed two radiolucent lines and three hips showed three radiolucent lines, all of them being less than 2 mm wide. DISCUSSIONRadiographic evidence of a stable stem in 116 hips (116/122) suggests a high reliability of the implant. Assessment of radiolucent lines showed 108 hips without radiographic demarcation and 11 hips with slight demarcation. The signs of stress-shielding grade 1 were found in 28 hips. Good results of arthroplasty with the CLS stem can be attributed to its threedimensional wedge-shaped design that allows for an optimal press-fit in the metaphyseal region. The porous surface provides reliable osteointegration. Stress-shielding is prevented by optimal stress distribution in the metaphyseal region and by a modulus of elasticity of titanium alloy which closely approximates the modulus of elasticity of bone. CONCLUSIONSAt 15 years post-operatively, the cumulative probability of clinical survivorship of the CLS stem was 98.3 %, and cumulative probability of radiographic survivorship was 87.7 %. The advantages of this stem include a technically simple implantation, reliable osteointegration and long-term stability even in high demanding patients.