Abstract
We have prospectively followed up 191 consecutive primary total hip replacements utilising a collarless polished tapered (CPT) femoral stem, implanted in 175 patients between November 1992 and November 1995.
At a mean follow-up of 15.9 years (range 14 – 17.5) 86 patients (95 hips) were still alive (25 men and 61 women) and available for routine follow up. Clinical outcome was determined from a combination of the Harris (HHS) and Oxford (OHS) hip scores. Radiological assessment was with antero-posterior radiographs of both hips and a lateral radiograph of the operated hip. The radiographs were evaluated using well-recognised assessment techniques.
There was no loss to follow up, with clinical data available on all 95 hips. Five patients were too frail to undergo radiographic assessment, therefore radiological assessment was performed on 90 hips (95%). At the latest follow-up, the mean HHS was 78 (range 28 – 100) and the mean OHS was 36 (range 15 – 48). Stems subsided within the cement mantle, with a mean total subsidence of 2.1mm (range 0.4 – 24). Higher grades of heterotopic bone formation were significantly associated with males (p<0.001) and hypertrophic osteoarthritis (p<0.001). Acetabular wear was associated with increased weight (p<0.001) and male sex (p=0.005). Amongst the cohort, only 1 stem (1.1%) has been revised due to aseptic loosening. This patient required reaming of their canal prior to implantation, as a result of a previous femoral osteotomy. The rate of stem revision for any cause was 7.4% (7 stems), of which 4.2% (4 stems) resulted from infection following revision of the acetabular component. Twenty patients (21.1%) required some sort of revision procedure; all except 3 of these resulted from failure of the acetabular component. Cemented cups had a significantly lower revision burden (2.7%) than Harris Galante uncemented components (21.8%) (p<0.001).
The CPT stem continues to provide excellent radiological and clinical outcomes at 15 years following implantation. Its results are consistent with other polished tapered stem designs. Cup failure remains a problem and is related in part to inadequate bearings and biological abnormalities.
