Mechanical properties of 7-10 mm bone grafts and small slurry grafts in impaction bone grafting

We compared the mechanical properties of morselized cancellous bone grafts of two sizes: 7-10 mm bone and small slurry bone (about 2 mm). The in vitro test was designed to simulate the hammer and impactor system for impaction bone grafting used in hip arthroplasty clinical practice. The 7-10 mm bone grafts showed higher height, elastic modulus, and massive extrusion strength than those of the small slurry bone grafts. No difference was found in yield strength. The bone mineral density of the 7-10 mm grafts continued to increase during impaction and became higher than that of the small slurry bone grafts after 10 impactions. Our results demonstrated that the small slurry bone grafts exhibit worse mechanical properties as compared with the 7-10 mm bone grafts, which implies that the use of this material in reconstruction of a bone defect in the acetabulum should be limited. (C) 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:1491-1495, 2011