Impaction allografting with cement for revision of the femoral component. A minimum four-year follow-up study with use of a precoated femoral stem.

BACKGROUND: Cancellous impaction allografting with cement for revision of the femoral component has conventionally been performed with a polished, tapered implant, which was designed to allow subsidence of the component. However, subsidence has been associated with pain in the thigh, dislocation of the hip, and revision of the component. This prospective study tested the hypothesis that good clinical results can be achieved--without subsidence of the component--with use of impaction allografting and a precoated, collared, straight stem for difficult femoral revisions.
METHODS: Twenty-nine patients had revision of the femoral component with use of impaction allografting with cement and a Harris Precoat stem. Impaction allografting was performed when loss of metaphyseal and diaphyseal bone precluded revision with more straightforward techniques or when reconstitution of bone was considered a specific goal of the reconstruction (as was sometimes the case with revision of the component in younger patients). The patients were followed prospectively and were evaluated with use of the Harris hip score and serial radiographs. The patients were followed for a minimum of four years (mean, sixty-three months), except for four who died.
RESULTS: Four patients died before the minimum four-year follow-up period had elapsed; all four had the prosthesis in place at the time of death. The Harris hip scores improved from a preoperative mean of 54 points (poor) (range, 21 to 91 points) to a mean of 87 points (good) (range, 41 to 100 points) at the time of the most recent follow-up. Kaplan-Meier survivorship analysis, with aseptic loosening as the end point, was 92 percent (95 percent confidence interval, 82 to 100 percent) at six years; one additional hip failed because of a hematogenous infection at seventy-three months postoperatively, for an overall failure rate of 12 percent (three of twenty-five patients) at the time of the most recent follow-up. Two hips needed a repeat revision; one was revised because of subsidence of the stem with recurrent osteolysis and the other, in a patient who had hemodialysis, because of late sepsis. A third femoral component subsided and failed but was not revised. Radiographic evidence of bone-stock reconstitution was observed in six (29 percent) of the twenty-one patients for whom radiographs were available. As in other series of patients managed with impaction allografting, the complication rate was high; excluding the revisions, three reoperations were performed, and six patients had either intraoperative femoral fracture or perforation necessitating cerclage wiring or cortical strut allografting and cerclage wiring at the time of the procedure. There were six nonunions in eighteen patients who had been operated on with a transtrochanteric approach.
CONCLUSIONS: Difficult revisions of the femoral component with use of impaction allografting and a precoated stem provided satisfactory clinical and radiographic results at the time of intermediate-term follow-up. However, the high rate of complications in our series led us to refine our indications for the procedure.