Background: In patients with degenerative osteoarthritis of the subtalar joint, surgical treatment can include subtalar arthrodesis. Notably, mechanical factors such as compression and pull-out strength contribute to successful union, which can be achieved through use of headed or headless cannulate screws. The purpose of this study was to compare the resultant joint compressive force and pull-out strength between use of a headless 6.5-mm self-drilling cannulated compression screw and a more traditional headed 6.5- mm self-drilling cannulated compression screw.
Methods: This study used the calcaneus and talus from six paired fresh frozen specimens. The soft tissues were stripped and the joint was separated. Fujifilm Prescale Compression Paper (Minato, Tokyo, Japan) was placed in the subtalar joint, and both the talus and calcaneus were fixed with either traditional headed or a headless cannulated screw. Pull-out strength was measured by fixing the fused subtalar joints to a servohydraulic activator and measuring peak load at failure in distraction. Imaging analysis of the compression paper determined peak compression across the joint.
Results: The resultant joint compressive force and pull-out strength were not statistically different between use of headed and headless cannulated compression screws (P = 0.30 and P = 0.67, respectively).
Conclusions: In a small sample, use of headless cannulated compression screws offered equivalent joint compression as that of a headed screw in subtalar arthrodesis and showed equivalent resistance to pullout force.
Douthit, Christian; Matthew Blue; Adam N. Wooldridge; Micah Lierly-Chick; Kerry Gilbert; and Jerry Grimes. "Comparison of Joint Compression and Pull- Out Strength of 6.5-mm Self-Drilling Screws With Headed and Headless in Subtalar Arthrodesis: A Pilot Study." UNM Orthopaedic Research Journal 8, 1 (2019). https://digitalrepository.unm.edu/unm_jor/vol8/iss1/27