Abstract
During hip revision removal of old cement mantle is a major problem. In cases of satisfactory bond between cement mantle and the underlying bone, cementing the revision stem into the old mantle is regarded as a highly attractive option. The aim was the analysis of the shearing strength of the interface between two layers of poly-methylmethacrylate cement in the presence of fluid.
A laboratory, two-dimensional model of the interface was used. Effect of different viscosity fluids and volumes on its strength was checked. 6 variants (control monoblock, dry surface, surface stained with small or large volume of water or highly viscous fluid) containing 7 repeats were exposed to a single shearing stress to failure.
Large volume of viscous fluid prevented bonding completely in two cases and significantly weakened the other samples showing mean failure stress of 5.53 MPa. This was significantly lower compared with control monoblock (19.8MPa), dry surface variant (16.9MPa) and the stain with small amount high viscosity fluid (16.01MPa). Interestingly, presence of a large volume of low viscosity fluid did not significantly reduce resistance to shear stress (17.05MPa).
In all but large volume of viscous fluid variants, the failure occurred away from the interface between two cement layers. Large amount of viscous fluid weakened significantly this interface. If such a viscous fluid could be eliminated by copious water irrigation it is likely that strength of the cement-cement bond will be maintained. Our observations suggest that cement-in-cement technique seems to be biomechanically acceptable
Correspondence should be addressed to Anastasia C. Tilentzoglou MD, General Secretary of the Board of Directors of HAOST, 20 A. Fleming Str. (N.Filothei), Gr. 15123 Maroussi, Athens Greece. E-mail: info@eexot.gr
