The Effect Of Insertion Technique And Surgeon Experience On The Pullout Strength Of Orthopaedic Screws

Background:We tested the null hypothesis that the manner of orthopaedic screw insertion (hand-driven or electrically-driven) and the experience of the screw inserter (orthopaedic trainees or experienced orthopaedic surgeons) have no effect on the pullout strength of orthopaedic screws.Methods:Four fellowship-trained orthopaedic surgeons and four orthopaedic chief residents each inserted 10 cancellous bone screws into a polyurethane foam cancellous bone substitute. Five screws were inserted with a standard orthopaedic screw driver, and five screws were inserted with a battery-powered electric driver. Samples were loaded to failure, and pullout strength was measured using a electromechanical tensile tester. Analysis of variance was used to compare experimental groups.Results:No significant difference was found between the pullout strengths of screws inserted by hand and the pullout strengths of screws inserted with an electric driver. Screws inserted by experienced orthopaedic surgeons, however, demonstrated significantly higher pullout strengths than screws inserted by orthopaedic trainees.Conclusions:Hand-driven and electrically-driven screws demonstrate similar pullout strengths in a model for orthopaedic screw insertion into bone. Screws inserted by experienced surgeons, however, did exhibit increased pullout strength. This suggests a technical nuance that allows experienced surgeons to better insert screws. If identified, this nuance would be of interest to orthopaedists in general.