Abstract
Purpose: The purpose of the study was to compare the maximum compression force of three different 6.5 mm cancellous screws commonly used in hindfoot fusions.
Materials and methods: Screw 1 was a solid core standard fragment partially threaded cancellous screw (Smith and Nephew).
Screw 2 was a titanium cannulated screw with a medium thread pitch (Asnis III, Stryker).
Screw 3 was also a titanium cannulated screw with a large core diameter but with a small thread pitch (Ace, DePuy).
Four different densities of polyurethane foams were used simulating cancellous bone and the compression
Results: Screw 3 had the highest compression force in tests with the low density foams (p< 0.05) and screw 1 performed better in higher density foams (p< 0.05). In medium density foams, both screws 1 and 3 showed significantly more compression than screw 2 (p< 0.05).
Clinical relevance: The results indicate that the 6.5 mm standard fragment non-cannulated cancellous screw may provide more compression in a normal density bone whereas in an osteoporotic bone a cannulated titanium screw may be preferred for producing better compression during arthrodesis.
Correspondence should be addressed to: D. Singh, BOFAS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
