Effect of simulated lateral process talus "fracture excision" on its ligamentous attachments

Recent epidemiologic studies highlight lateral talar process fractures as snowboarder's fracture or snowboarder's ankle. Snowboarding is the fastest growing sport worldwide, so lateral talar process fractures are increasing in frequency and mandating a more careful assessment of injury patterns, surrounding tissue involvement, and treatment strategy. In this study, we evaluated the effects of lateral talar process fracture on the footprints of 3 lateral stabilizing ligaments of the ankle and subtalar joint-the lateral talocalcaneal ligament (LTCL), the anterior talofibular ligament (ATFL), and the posterior talofibular ligament (PTFL). The musculotendinous structures from 10 fresh cadaveric limbs were removed and the distal fibula reflected to provide visualization of the lateral talar process and ligamentous attachments. Length and width of the LTCL, ATFL, and PTFL footprints on the lateral process of the talus were measured with calipers before and after removal of a 1-cm(3) simulated fracture fragment. Relative changes in the attachment site areas for the 3 ligaments were determined. Mean pre-excision footprint areas were 80.57 mm(2) (LTCL), 224.38 mm(2) (ATFL), and 394.18 mm(2) (PTFL); mean postexcision footprint areas were 2.10 mm(2) (LTCL), 194.89 mm(2) (ATFL), and 335.18 mm(2) (PTFL); and mean decreases calculated as percentages of the original areas were 97.5% +/- 3.5% (LTCL), 11.7% +/- 13.0% (ATFL), and 14.3% +/- 12.3% (PTFL). Removal of a 1-cm(3) bony fragment from the lateral talar process involves 3 of the major lateral stabilizing ligaments: approximately 100% of LTCL and approximately 10% to 15% of ATFL and PTFL.