Failed cementless total hip arthroplasty for osteoarthrosis due to hip dysplasia. A minimum five-year follow-up study.

We performed cementless total hip arthroplasty on patients with secondary osteoarthrosis due to hip dysplasia. We conducted prospective radiographic and clinical studies on 75 hips with a minimum five-year follow-up. Aseptic loosening of the Dual geometry Microstructured cup used on the acetabular component was recognized in 2 of 75 hips within five years postoperatively, but neither case required revision. As for the femoral component, within five years of operation, in 9 of 28 (32%) and 11 of 31 (35%) patients, aseptic loosening was recognized in the Omnifit Normalized Smooth surfaced stem (FIT-N) and the Omniflex Normalized Smooth surfaced stem (FLEX-N), respectively, neither of which have a porous coating on their proximal end. Revisions of the stems have been conducted on three FIT-N and two FLEX-N stems. Aseptic loosening was recognized in 2 of 16 Omnifit Microstructured stems (FIT-M) with porous coating, but revisions have not yet been required in these cases. We conclude that stems without a porous surface coating should not be used for cementless total hip arthroplasty.