Abstract
Aim To assess whether prosthetic femoral stem centralisers have a detrimental effect on the maroporosity of the cement mantle, and if so, whether this is independent of their design and the rate of implantation.
Methods 30 identical moulded prosthetic femora were divided into 3 groups. Group 1; no centraliser (control), Group 2; centraliser A, Group 3 centraliser B. Using third generation cementation techniques and pressure monitoring, Charnley C-stems +/− the appropriate centraliser were implanted to a constant depth. Half in each group were implanted as rapidly as possible and the other half over 90 seconds. The stems were removed and the cement mantle then underwent a preliminary arthroscopic examination prior to being sectioned transversely at 3 constant levels. Each level was then photographed and digitally enlarged to a known scale to allow examination and determination of any cement voids (macropores) surface area.
Results There were no significant pressure fluctuations between the groups. Preliminary arthroscopic examination revealed that cement voids appeared more common when a centraliser was used. This difference was statistically confirmed (p=0.002) following sectioning of the specimens with cement voids found in 85% of femora when a centraliser was used and only 20% in the control group. Centraliser B performed worst with cement voids of a larger volume and more frequent occurrence (p=0.002). The macroporosity of the cement mantle was independent of the rate of implantation (p=0.39).
Conclusion The use of femoral stem centralisers is helpful in preventing malposition of the implant but results in increased macroporosity of the cement mantle. This may have implications regarding the longevity of an implant in terms of early loosening and therefore their design and use must always be carefully considered.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
