Poor results of the cementless total hip arthroplasty with a nonporous coated acetabular component: AcSys Shearer Cup

Background This study followed patients for a minimum of 7 years after primary total hip arthroplasty using cementless acetabular components and evaluated their outcomes. Methods We followed 73 patients (75 hips), who had undergone total hip arthroplasty with cementless nonporous coated acetabular components (3M AcSys Shearer Cup) for a mean of 9.8 years (range 7–13 years). There were 61 women and 12 men with a mean age of 53 years (range 27–69 years) at surgery. The diagnosis was primary osteoarthritis in 9 hips, osteoarthritis secondary to developmental dysplasia in 58 hips, osteonecrosis of the femoral head in 6 hips, and rheumatoid arthritis in 2 hips. Results Three cups were revised because of aseptic loosening, and one cup was revised following removal of the prosthesis due to deep infection. Radiographic loosening was observed in 22 hips at the latest follow-up. The survival rate at 10 years was 94.7% with revision as the endpoint and 72% with radiographic loosening as the endpoint. The Merle d'Aubigné and Postel hip score showed significant improvement postoperatively and was maintained well even in cases showing radiographic loosening. Conclusions The intermediate radiological results with the AcSys Shearer Cup were unsatisfactory because of the high loosening rate, although the revision rate was low. The nonporous outer surface and the poor fixation mechanism between the metal shell and liner may have contributed to the high failure rate. Regular radiological review is recommended when this cup is used because early loosening is often painless.