Abstract
Purpose of the study: Loss of acetabular bone stock is a very common finding at revision total hip arthroplasty (rTHA). The acetabular bone defect can be filled with an autograft or with cyropreserved or lyophilized and radiated allografts. The permanent availability lypophylized radiated allografts is a certain advantage. For more than ten years (1994), we have used Phoenix® (TBF) lyophylized radiated bone grafts.
Material and methods: We conducted a retrospective study of all patients who underwent rTHA for aseptic loosening between 1994 and 1999 with replacment of the acetabular implant requiring use of a lyophyilized radiated allograft (TBF, Phoenix®) fashioned from femoral heads and cut to fit. Grafts were impacted followed by acetabulra replacement with a cemented polyethylene (PE) cup or a Kerboull retaining ring, or an ace-tabular grid as needed. This procedure was used for 18 hips (16 patients). The Postel-Merle-d’Aubigné (PMA) clinical score and radiographic assessment were noted at five years with the Paprovsky classification. In addition, the status of the allograft (homogeneous aspect) and the presence of a lucent line between the host bone and the allograft were noted.
Results: One patient was lost to follow-up. The analysis thus included 17 of 18 hips. Mean age was 63 years at rTHA surgery and 55 years at primary surgery. The reason for revision was cup loosening (n=13), isolated PE wear (n=4) with acetabular bone defects. The mean preoperative PMA score was 10.4 (range 5–18). At three months, the PMA score was 15.2 (range 12–18), at one year 16.2 (range 15–18), and at five years 17.2 (range 16–18). Implant migration was not observed on the five-year x-rays. Allografts were incorporated for seven hips which presented a homogeneous graft image. Five hips presented a partial lucent line and five a complete lucent line but with no evidence of implant instability. None of the patients required surgical revision to change the implant or for a new bone graft.
Discussion: Acetabular revisions are often associated with bone defects which can be filled with allografts. This study demonstrated the good incorporation of lyophilized radiated allografts. This incorporation is progressive with good implant stability at more than five years. Use of this graft material for filling acetabular defects can correct for the bone deficiency.
Conclusion: Use of lyophilized grafts gives satisfactory results with reliable outcome at five years comparable with other bone replacement methods, particularly cyropreserved femoral grafts used before 1994.
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