Abstract
Aim: To assess the impact of three different entry points of the femoral canal preparation with regard to cement mantle thickness in the saggital plane.
Methods: We reviewed the literature to find that little has been written on the cement mantle thickness in the saggital plane. We reviewed randomly 60 total hip replacements performed at our institution to discover a common error of a thin cement mantle anteriorly (proximally) and posteriorly (distally) in the saggital plane.
We used standard saw-bone preparations of two prosthetic hip systems: Friendly (Lima) and Exeter (Stryker). In each hip system we performed five preparations for each entry point (trochanteric fossa, posterolateral corner and mid point of the cut neck). The only variable was the entry point. Preparation was performed according to the manufacturers’ recommendations. The preparations were x-rayed and cement mantle alignment and thickness were measured on the x-rays. Saggital sections with digital imaging and radial measurements were also performed.
Results: The results showed a strong trend towards neutral alignment (antero-posterior (AP) and saggital) and a uniform cement mantle with trochanteric fossa preparation. There was an increasing trend to varus alignment (AP), angled anterior to posterior alignment (saggital) and incomplete cement mantles with postero-lateral corner and mid point of cut neck preparation.
Conclusions: We conclude that in cemented femoral replacement, the entry point for canal preparation should be as far lateral and posterior as possible and the trochanteric fossa is the best to achieve neutral alignment and the complete cement mantle.
The abstracts were prepared by Professor A. J. Thurston. Correspondence should be addressed to him at the Department of Surgery, Wellington School of Medicine, PO Box 7343, Wellington South, New Zealand
(Financial support has been provided by Lima and Stryker Osteonics for this study).
