Clavicle anatomy and the applicability of intramedullary midshaft fracture fixation

Background: This study investigated the morphologic safety and applicability of intramedullary fixation of midshaft clavicle fractures by analyzing the pertinent clavicle anatomy using 3-dimensional computer simulation. Materials and methods: Computed tomography was used to scan 22 skeletonized clavicles. Computer software was used to simulate middle-segment fracture fixation by fitting a cylindrical corridor within the clavicle in the area that intramedullary devices normally cross during surgery. The cylindrical corridor crossed the fracture line on both sides, and the number of cortical diameters that were bypassed was recorded. We assumed that 1 to 2 cortical diameters had to be bypassed to achieve adequate fixation. The medial and lateral exit points of the cylindrical corridor were measured and described in relation to the sternoclavicular and acromioclavicular ends respectively. Results: Simulation revealed that 15 of 22 clavicles could be bypassed by 2 cortical diameters on either side of the midline fracture, 6 clavicles could be bypassed by 1 cortical diameter medial to the fracture line, and 1 clavicle could not be bypassed by any cortical diameters medial to the fracture line. The medial exit point of the cylindrical corridor was anterior in 20 of 22 cases and an average of 44.2 mm lateral to the sternoclavicular end. The lateral exit point of the cylindrical corridor was posterosuperior in 16 of 22 cases and an average of 26.5 mm medial to the acromioclavicular end. Conclusion: In most clavicles, straight intramedullary fixation appears to be a morphologically safe and effective method of fixation.