Abstract
Introduction. Some cement restrictors in current use in hip arthroplasty have documented failings in pressurization, canal occlusion and distal migration and we have set out to design an apparatus to test some restrictors which are currently available and present our preliminary results.
Method. Using the Instron 8874 machine for reproducibility of prosthesis insertion and a specially designed jig, we tested several commercially available cement restrictors (Hardinge, Rex, Cemlock and Amberflex) for pressurization, canal occlusion and distal migration in sawbone femora. These were subsequently radiographed.
Results. The Rex cement restrictor allows the greatest distal pressure generation (439 kPa) and demonstrated the least distal migration of all the restrictors (0.07mm). The Amberflex (276 kPa, 0.57 mm) and Hardinge (318 kPa,1.34 mm) restrictors gave lower pressures and slightly more distal migration. The lowest distal pressures and greatest distal migration was observed in the Cemlock restrctor.
Discussion. We have demonstrated a method of testing cement restrictors in vitro with reproducible results and these suggest that the Rex Cement Restrictor is as effective as the best designs available in current use in terms of pressurization and distal migration.
Broomfield Hospital Department of Orthopaedics and Anglia Polytechnic University
The abstracts were prepared by Mr Peter Kay, Editorial Secretary. Correspondence should be addressed to British Hip Society, The Hip Centre, Wrightington Hospital, Appley Bridge, Wigan, Lancashire WN6 9EP.
