Of the 171 total hip replacements reported on previously that had had a
minimum length of follow-up of two years, 117 replacements in 104 patients
were analyzed at a minimum of five years postoperatively (average,
seventy-four months; range, sixty to ninety-four months) to assess the rate
of loosening of the femoral component. At the time of cementing of the
femoral component, the medullary canal had been plugged with a bolus of
bone cement and then filled with doughy Simplex-P methylmethacrylate in a
retrograde fashion using a cement gun. The femoral components, made of a
chromium-cobalt alloy, had a rectangular cross-sectional shape to the stem
and a medial collar. Three categories of loosening were used: definite
(requiring radiographic evidence of migration of the component or the
cement), probable (requiring evidence of a complete radiolucent zone at the
bone-cement interface on one radiograph or more), and possible (a
radiolucent zone at the cement-bone interface of more than 49 per cent but
less than 100 per cent on one radiograph or more). One femoral component
had been removed for aseptic loosening at another hospital, leaving the
patient with a resection arthroplasty. One other (1.7 per cent) was
definitely loose. No femoral component was categorized as probably loose,
and only two were possibly loose.