Abstract
Introduction: Many mini compression screws are now available for fixation in procedures such as metatarsal osteotomies or arthrodeses of the foot.
The aim of the current study is to compare the compression forces achieved by mini compression screws on cortical and cancellous bone models.
Material and Methods: The screws that were tested are listed in the table below. The compression forces were tested by inserting a pressures load measurement cell between longitudinally-split sheep tibia as a cortical bone model and longitudinally split retrieved femoral heads as a cancellous bone model.
Results: The Headed AO 3.5 mm cortical screw gave the best compression force and the Bold was the weakest, both in cortical and cancellous bone. The relative compression forces of the other tested screws were different between cortical and cancellous bone. Compression with the headless screws was lost as soon as the screw penetrated through the cortex in the cortrical bone model.
Conclusions: The indications for using headless self-tapping screws should be reserved for fixation of cancellous bone or of metatarsal or Akin osteotomies where compression is not required for union. When compression is important, such as in MPJ, tarso-metatarsal or talonavicular arthrodeses, Headed AO 3.5 mm or 2.7 mm cortical or 4 mm cancellous screws, which give better compression, should be used.
Correspondence should be addressed to the Honorary Secretary, BOFSS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
