CORA ABSTRACT #II - 4

CERAMIC-ON-CERAMIC TOTAL HIP ARTHROPLASTY: THE RELEVANCE OF BONE REMODELING AND IMPLANT ALIGNMENT TO CLINICAL OUTCOME

S. Kaspar

J. DeBeer

N. Colterjohn

M. Winemaker

Cortical hypertrophy of the femur has frequently been described, particularly about the femoral stem in total hip arthroplasty (THA). While a causal relationship has not clearly been shown between distal cortical hypertrophy and thigh pain, proximal resorption or radiologic lucency at the calcar, there have been many suggestions that these all result from such factors as implant design, stress shielding, and excessive distal implant fixation.

We review about 30 papers addressing the subject of cortical hypertrophy in THA, then we present our own new data regarding cortical hypertrophy and femoral bone remodeling in a series of 50 ceramic-on-ceramic THA's. The following issues are explored in this study:

(1) Cortical hypertrophy occurs in THA, but to our knowledge, the extent and nature of it in ceramic implants has not been presented in the literature before. Comparison will be made of matched patients, who received either polyethylene or ceramic liners, with otherwise equal implants.

(2) Clinical correlation is emphasized, with analysis of standardized prospective longitudinal hip scores and their relationship to radiographic findings in follow-up. We concomitantly assess multiple factors including bone resorption, hypertrophy, heterotopic ossification, and implant alignment, and their relationship to clinical scores of function and pain.