Aseptic Loosening of Boneloc Cemented Exeter Total Hip Replacement. A 5 Year Follow-Up of the First 100 Hips

To evaluate the midterm performance of Boneloc cemented primary Exeter hip arthroplasty we examined the first 100 hips in 93 patients, who were alive at a median 56.6 (50–62) months after the operation. During the follow-up period 2 femoral stems and 2 acetabular cups were revised because of aseptic loosening from 3–5 years after the operation. A third acetabular cup was revised at the same time as a loose femoral stem, but was not found loose. The 5-year survival of both the stem and the cup was 98 per cent and for the surviving 98 hips the average Harris Hip Score was 87.6 (43–100) and the average pain score was 42.2 (10–44). Eighty nine per cent of patients were very satisfied or satisfied with their hip prosthesis and the patients’ own evaluations correlated well with the Harris Hip Scores. Follow-up radiographs revealed definite loosening of 3 stems and 2 cups, probably loosening of one stem and 2 cups, and possibly loosening of 2 stems and one cup. The Exeter stem subsided significantly within the cement mantle by median 3.3 (0–19) mm. In a subgroup of patients subsidence diminished significantly from the first 28 months compared to the last 31 months. Subsidence at the cement bone interface was only seen in 4 hips, where cement fractures had developed. Poor quality cementation, and valgus position of the femoral stem, significantly increased the risk of aseptic loosening, as did osteolysis and cement fracture. Poor cementing technique and continuous radiolucent lines at follow-up radiographs were positively correlated with acetabular cup loosening. The rather good midterm results with the Exeter femoral stem can probably be ascribed to the collarless, polished, double tapered stem design.