INTRODUCTION: Headless compression screws are a popular fixation construct for scaphoid fractures as they can maintain reduction and provide fracture compression without implant prominence. The purpose of this study is to characterize fracture compression in models of proximal, waist, and distal scaphoid fractures for 3 types of headless compression screws.
METHODS: Three Sawbones models representing proximal, waist, and distal fractures were used to test the biomechanical properties of three 20-mm screws (Acumed Acutrak 3 Mini, Arthrex Compression FT Mini, Medartis Cannulated HD10). Screws were inserted in an antegrade fashion at a rate of 30 rpm using a DC motor mounted to the actuator of an Instron load frame. Compressive force was recorded at the point of flush insertion and compared using analysis of variance and Student t test.
RESULTS: Acutrak 3 achieved the highest compression in models of proximal and waist fractures, and the Acutrak 3 and Arthrex FT screws demonstrated similar compression in models of distal fractures with antegrade insertion. Both the Acutrak 3 and Arthrex FT screws demonstrated significantly less compression in distal fractures when compared with proximal and waist fractures.
CONCLUSIONS: As measured at the flush insertion point, the Acutrak 3 screw demonstrated the highest compressive force for models of proximal and waist fractures. Fully threaded variable pitch screw design resulted in greater simulated fracture compression than Herbert-style screws, which do not have central threads. Understanding the interplay of screw characteristics with various fracture patterns is important when selecting an operative construct that optimizes fracture stability.
Read the article: PubMed · Publisher (DOI)