Abstract
Introduction
Segmental defects of the femur present a major problem during revision hip arthroplasty. In particular, calcar segmental defects may compromise initial and long-tem femoral stem stability.
Objective
The objective of the present study is to assess mid-term clinical and radiographic follow-up results at least two years after femoral revision comprising reconstruction for calcar segmental defect using metal wire mesh and impacted morcellised allograft.
Methods
We performed 26 femoral revisions with calcar reconstruction in 24 patients between 2002 and 2010. The average age was 69.7 years, and the average follow-up period was 5 years and 1 month. All surgeries were performed using a cemented polished collarless tapered stem. The segmental calcar defect was reconstructed with metal wire mesh with doubled stainless wires. Large sized morcellised cancellous allograft was tightly impacted into the cavity between the phantom stem and the metal wire mesh. Nineteen hips were reconstructed with impaction bone grafting of the femur, and 7 hips with cement-in-cement technique except for the reconstructed calcar region.ã�� For clinical assessment, Merle d'Aubigné and Postel hip scores were recorded. For radiological assessment, antero-posterior hip radiographs were analyzed pre-operatively, and post-operatively at one month, 6 months and every 6 months thereafter. Clear lines around the femoral component using Gruen zone classification, stem subsidence in cement mantle, and change of stem axis were recorded. Kaplan-Meier survival analyses were performed with any re-operation of the femoral component or aseptic loosening as end points. In one case, the histological appearance of a biopsy specimen of the most proximal part of the reconstructed calcar, which was obtained at a later surgery for infection at 4 years after the revision, is described.
Results
For clinical assessment, the mean Merle d'Aubigné and Postel hip scores improved from 10.4 points before the operation to 14.7 points at the final follow-up. For radiological assessment, no clear lines at the cement-bone interface and no stem axis changes were detected. Twenty-five of 26 hips showed less than 2 mm of stem subsidence at the final follow-up and one hip showed 2.2 mm stem subsidence. Both hips of one female patient underwent a one stage stem exchange because of an infection that occurred 48 months after revision. No cases showed aseptic loosening up to and including the last follow-up. The Kaplan-Meier survival analysis revealed that the survival rate at five years after revision was 88.0% with any type of re-operation on the femoral side as the endpoint and 100% with aseptic stem loosening as the endpoint, respectively. A biopsy specimen taken from the most proximal part of the reconstructed calcar region at 4 years after surgery in the infected case showed almost complete regeneration of viable bone with normal marrow spaces with partially formed granulation tissue.
Conclusion
Reconstruction using metal wire mesh and tightly impacted morcellised allograft is a favorable method for the correction a calcar segmental defect. The procedure is simple and reliable, achieving initial and mid-term stem stability even for femurs with a complete calcar defect.
