THA with hydroxyapatite granules at cement-bone interface: 15- to 20-year results.

UNLABELLED: To augment cement-bone bonding, we interposed hydroxyapatite granules at the cement-bone interface (bioactive bone cement technique). Hydroxyapatite granules (2-3 g) were smeared on the bone surface of the acetabulum and femur just before cementing. We used porous hydroxyapatite granules 300 to 500 microm in diameter from 1986 to 1988 (first generation) and granules 100 to 300 microm in diameter from 1989 to 1991 (second generation). We followed 151 patients (222 hips) in the first generation and 170 patients (252 hips) in the second generation. The minimum followup was 15 years (mean, 17.3 years; range, 15-20 years). Radiolucent lines or spaces less than 1 mm were observed in four hips (1.8%) in the first generation and in 15 hips (6.2%) in the second generation. Osteolysis was observed in one hip (0.5%) in the first generation and six hips (1.6%) in the second generation. We observed loosening in two cups (0.8%) in the second generation. The long-term clinical results suggest the interface bioactive bone cement technique combined with our other techniques results in low incidences of radiolucent lines (spaces) and osteolysis, and may increase the longevity of cemented THA. The data suggest the larger hydroxyapatite granules performed better than smaller ones. LEVEL OF EVIDENCE: Level III, therapeutic retrospective cohort series. See the Guidelines for Authors for a complete description of levels of evidence.