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Particulate wear debris is associated with periprosthetic inflammation and loosening in total joint arthroplasty. We tested the effects of titanium alloy (Ti-alloy) and PMMA particles on monocyte/macrophage expression of the C-C chemokines, monocyte chemoattractant protein-1 (MCP-1), monocyte inflammatory protein-1 alpha (MIP-1␣), and regulated upon activation normal T expressed and secreted protein (RANTES). Periprosthetic granulomatous tissue was analysed for expression of macrophage chemokines by immunohistochemistry. Chemokine expression in human monocytes/macrophages exposed to Ti-alloy and PMMA particles in vitro was determined by RT-PCR, ELISA and monocyte migration.We observed MCP-1 and MIP-1␣ expression in all tissue samples from failed arthroplasties. Ti-alloy and PMMA particles increased expression of MCP-1 and MIP-1␣ in macrophages in vitro in a dose-and time-dependent manner whereas RANTES was not detected. mRNA signal levels for MCP-1 and MIP-1␣ were also observed in cells after exposure to particles. Monocyte migration was stimulated by culture medium collected from macrophages exposed to Ti-alloy and PMMA particles. Antibodies to MCP-1 and MIP-1␣ inhibited chemotactic activity of the culture medium samples.Release of C-C chemokines by macrophages in response to wear particles may contribute to chronic inflammation at the bone-implant interface in total joint arthroplasty.J Bone Joint Surg [Br] 1999;81-B:155-62.

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We modified the posterior approach by preserving the external rotator muscles to enhance joint stability after primary THA. We asked whether this modified posterior approach would have a lower dislocation rate than the conventional posterior approach, with and without a repair of external rotator muscles. We retrospectively divided 557 patients (670 hips) who had undergone primary THA into three groups based on how the external rotator muscles had been treated during surgery: (1) not repaired after sectioning, (2) repaired after sectioning, or (3) not sectioned and preserved. The minimum followup was 1 year. In the group with preserved external rotator muscles, we observed no dislocations; in comparison, the dislocation rates for the repaired rotator group and the no-repair group were 3.9% and 5.3%, respectively. This modified posterior approach, which preserves the short external rotator muscles, seemed effective in preventing early dislocation after primary THA. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.