Abstract
Impaction allografting is increasingly used for the treatment of failed total hip replacements. In six human cadaveric femurs the impaction allografting procedure was performed to comprehensively describe the postoperative morphology of impaction allografting. After the procedure, the specimens were sectioned and prepared for histomorphometric analysis. The graft porosity was lowest in Gruen zone four (52%) and highest in Gruen zone one (76%). At the level of Gruen zone six and two, virtually the entire cross-section was filled with bone cement. The presented data will serve as a baseline for future investigations of the impaction allografting.
Impaction allografting is an attractive procedure for the treatment of failed total hip replacements. The purpose of this study was to comprehensively describe the morphology of impaction allografting post operatively to form a baseline for further investigations.
Three experienced surgeons performed the impaction allografting procedure on six cadaveric femurs. After the procedure, the femurs were cut in 6mm thick transverse sections and processed for histomorphometric analysis.
The porosity of the impacted graft was highest proximally in Gruen zone one (76%) and lowest in Gruen zone four (52%). Below the tip of the stem (Gruen zone four), the mean cement penetration was significantly lower compared to the proximal part of the femur. The averaged residual impacted graft layer in Gruen zone six and two was (0.5mm SD 0.4mm) significantly thinner compared with Gruen zone’s one, 7/1, and four.
In the region of Gruen zone six and two the entire cross-section was penetrated with bone cement with almost no residual graft layer (Figure). Even the simulated lytic defects in this region were filled with the graft cement composite which may not be remodelled by the host bone.
The graft porosity was found to be highest proximally and lowest distally. In the region of Gruen zone six and two the entire cross-section was penetrated with bone cement with almost no residual graft layer.
This investigation will serve as a baseline for future studies of the mechanical and biological processes that make the impaction allografting a successful procedure.
Funding: Stryker Howmedica and DePuy for provided implants and instruments.
Please contact author for figures and/or diagrams.
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
