The Influence of Porous Coating Level on Proximal Femoral Remodeling: A Postmortem Analysis

James P. McAuley, MD, Christi J. Sychterz, MSE, Charles A. Engh, Sr., MD

Background/Methods: This study used autopsy-retrieved femora to compare the extent and location of bone remodeling in four patients implanted with proximally porous-coated femoral prostheses to a matched group of four patients implanted with extensively porous-coated femoral prostheses. The contralateral normal femur of each patient was also retrieved, implanted with an identical prosthesis, and used as a control. Dual energy x-ray absorptiometry (DEXA) analysis demonstrated marked loss of bone mineral content in both groups of patients.

Results: The extensively coated group had less bone loss on average (18.4%) than the proximally coated group (38.6%, p=0.13). There was no relationship between the extent of coating and the location of bone mineral loss; specifically, proximal coating did not protect against loss of bone mineral content proximally or distally in the femur. Videodensitometric analysis of cross sections of periprosthetic bone also showed that the extensively coated group tended to have less decrease in bone density than the proximally coated group (14.3% versus 28.4%).

Conclusions: The results in this small group of cases challenge the common assumption that reducing the extent of porous surface and obtaining more proximal fixation results in less proximal femoral bone loss.

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