The Cementless Fibre Mesh Coated Anatomic Femoral Stem: 12 to 23 Years Clinical and Radiological Outcome Study

Abstract

Introduction The aim of this study was to assess the long-term clinical and radiographic results, and possible reasons for failure of two versions of the cementless fibre-metal coated anatomical femoral component. Methods 99 patients (119 hips) were evaluated at an average of 16.7 years (range, 12 to 23 years) following primary THA. Developmental dysplasia of the hip (DDH) was the most common pathology (n = 37 hips). Structural femoral head autografts were used to increase cup coverage in 23 hips. Vertical and horizontal migration of acetabular and femoral components and osteolysis around the components were assessed using conventional radiolography. For clinical evaluation, the Harris Hip Score and Merle D'Aubigne scale were used pre-operatively and at final follow up. Implant survival was calculated according to the Kaplan-Meier survivorship analysis and failure was defined as component's revision for any reason. Results The cumulative survival rate of the anatomical femoral stem was 64.2% at 19.8 years, with a worst-case scenario of 41%. The cumulative survival rate of the total hip arthroplasty was 51% at 19.8 years, with a worse case scenario of 38%. The mean pre-operative Harris Hip Score of 42 points improved to 88 postoperatively. The mean pre-operative Merle D'Aubigne functional score of 3.5 improved to 5.2 points at the time of final follow-up. In 36 hips (41.6%) osteolysis was found in Gruen zone 1, proximal to the ingrowth surface. Conclusions The cementless fibre-metal coated anatomical femoral component showed favourable long-term clinical and radiological results. Proximal coating seems to protect bone implant interface from wear debris induced osteolysis during the second decade.