BONE SURFACE PREPARATION IN CEMENTED JOINT REPLACEMENT

We studied the effects of nine techniques of bone surface preparation on cement penetration and shear strength at the cement-bone interface in a standard model of bovine cancellous bone. In unprepared bone the mean penetration was 0.2 mm and the mean shear strength of the interfa ce was 1.9 MPa, less than that of the underlying bone. Brushing with s urface irrigation gave mean penetrations of 0.6 to 1.4 mm and mean she ar strengths of 1.5 to 9.9 MPa. In 50% of specimens the interface was weaker than the underlying bone. The use of pressurised lavage resulte d in mean penetrations of 4.8 to 7.9 mm and mean shear strengths of 26 .5 to 36.1 MPa, which were greater than those of the cancellous bone i n all specimens. Pressurised lavage was equally effective alone or in combination with brushing, and its efficacy was not altered by using p ulsed or continuous jets, or by changing the temperature of the soluti on from 21-degrees-C to 37-degrees-C.