DEVELOPMENTS IN FEMORAL IMPACTION GRAFTING AT REVISION HIP REPLACEMENT AND RESULTS USING RADIOSTEREOMETRIC ANALYSIS

Abstract

Introduction: In the past, surgeons have found impaction bone grafting technically difficult leading to its limited use. This paper reviews the long term results and developments in instrumentation and techniques aimed at simplifying femoral impaction grafting at revision hip replacement. The expanded indications for this procedure are reviewed and recent results of stem fixation using radiostereometric analysis (RSA) are reported.

Methods: The impaction bone grafting procedure, using a cemented collarless polished double taper stem, has been used in 66 hips (median patient age 63yrs) since 1993. The technique has undergone numerous developments. Modular tamps have been used in the last 29 hips and in the last seven hips, a pneumatic mechanical vibration device has been used in place of manual impaction. Stem subsidence at both the prosthesis-cement and cement-graft/bone interfaces was measured, more recently using radiostereometric analysis.

Results: There was a high early incidence of failure in the initial cases but there have been no further revisions for mechanical failure at up to 15 years. Technique developments have resulted in dramatic improvements in stem fixation achieved. In the modular tamp cases, the mean stem subsidence at the cement-bone interface at 12 months was 0.07mm (0 to 0.7mm) at 12 months. The stem subsidence in the hips where the mechanical vibration device was used was 0.05mm (0 to 0.06mm). Femoral impaction grafting offers special advantages in younger patients include standard femoral stem revision and at the second stage of two stage revision for infection.

Discussion and Conclusion: A stable cement-bone interface is achieved using advanced techniques of femoral impaction grafting that includes the use of modular impaction instruments. Early results of mechanical vibration impaction are encouraging. Femoral impaction grafting restores bone and new techniques simplify the femoral revision procedure.