No benefit of a proximal stem centralizer in cementing of a femoral prosthesis in human cadavers

Abstract

Background and purpose A proximal stem centralizer may be beneficial regarding cementing pressures, cement penetration, and stem alignment. We measured these parameters when cementing a mat-surfaced femoral component with and without the use of a proximal stem centralizer.

Material and methods 8 femoral prostheses with proximal centralizers and 8 femoral prostheses without proximal centralizers were cemented according to third-generation cementing technique in 8 pairs of embalmed cadaveric femora. We recorded intramedullary pressures (peak levels, the area under the pressure curves and mean pressure) with 6 pressure transducers during stem cementation. Computer tomographic scanning of specimens was performed to evaluate stem alignment after surgery. Thickness of the cement mantle, cement penetration, and stem centralization at the metaphyseal part of the femur were measured on cross sections using stereology.

Results There were no statistically significant differences in measured pressure and cement penetration values between the groups. There was similar cement distribution around the stems; however, in using a proximal centralizer, the cement mantle tended to be thinner laterally. Moreover, we found a larger variation in stem alignment on lateral projection in the proximal centralizer group.

Interpretation No benefits regarding intramedullary pressures and cement penetration were obtained from cementation of a straight stem with a proximal stem centralizer. However, there was an increased risk of inferior stem positioning in the reamed medullary cavity using the centralizing device.

JP contributed to study design, performance of surgical operations, data acquisition, data analysis, and preparation of the manuscript. TLH, RA, and JRN contributed to data acquisition, data analysis, and revision of the manuscript. PTN and KS contributed to study design and revision of the manuscript.

We thank Niels Trolle of the Department of Biostatistics, University of Aarhus, for his advice regarding statistical analysis. Biomet Denmark and NMS Inc. are also acknowledged for supplying the bone cement and cementing equipment. The study was financially supported by the following organizations: the North Jutland Medical Association Research Foundation, the Sahva Fundation, Speciallæge Heinrich Kopps legat 2006, the A P Møller and Chastine McKinney Møller Foundation for General Purposes, and the Villum Foundation.

No competing interests declared.