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

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

Biomechanical Strength and Bulk Comparisons Between the Open-Book Technique and the Pulvertaft Method for Peroneal Tendon Transfer: A Pilot Study

Background: The Pulvertaft method has classically been used for the transfer of various tendon injuries owing to its biomechanical strength; however, this method has been shown to be bulky. We describe the open-book technique, which can offer comparable structural integrity with a decreased bulk. The purpose of this study was to determine whether the openbook technique is biomechanically equivalent to the Pulvertaft method for treating peroneal tendon injuries. Methods: We evaluated five pairs of human cadaveric ankles. Within each pair, one specimen was randomly assigned to either the Pulvertaft or the open-book group. Using sharp dissection, the tendons were severed in a standardized method. Transfer was performed using one of the two randomly assigned techniques. The transferred peroneal tendons were stressed on a mechanical tensioning device until failure. Data were recorded and analysis was performed. Results: There was a statistically significant difference (P \u3c 0.001) between the thickness of the Pulvertaft method (7.6 mm) and open-book technique (5.7 mm). There was also a statistically significant difference in elongation, with the Pulvertaft undergoing more elongation at yield (9.7 mm vs 3.7 mm, respectively; P = 0.04). No statistical difference was detected in elongation at peak (P = 0.52), load at yield (P = 0.9), or peak load (P = 0.69). Conclusions: The open-book technique appears to be a viable biomechanical alternative to the Pulvertaft method for peroneal tendon transfer. The peak load, load at yield, and elongation at peak were biomechanically equivalent. The open-book technique was found to provide a significant decrease in thickness, which could prove advantageous when dealing with anatomical locations