Pyomyositis of the obturator muscles is a rare condition, characterised by pain in the hip and features of systemic infection. It may follow minor trauma to the hip, sometimes in the presence of an apparently innocuous infective source. All previously reported cases have been diagnosed conclusively on the initial CT or MR scan. We present a case of obturator pyomyositis in a 21-year-old football player in which the first MR scan was misleading. A radiolabelled, white blood cell scan was also negative and the resultant delay in diagnosis proved dangerous. The crucial importance of careful and repeated clinical examination is emphasised.

We have studied aseptic loosening of the femoral component in 76 patients with primary total hip replacement using the Capital prosthesis. The mean follow-up was 26 months (10 to 37).

Twelve femoral components (16%) were definitely and eight (10%) were possibly loose. They were characterised by a thin cement mantle (p < 0.001) and excessive residual cancellous bone in the proximomedial region (p < 0.01).

We recommend that the cement mantle around the prosthesis should be 2 to 3 mm and that further long-term studies are needed to evaluate the wear properties of titanium-nitride-coated titanium femoral heads.