Correlation of Fracture Energy With Sanders Classification and Post-traumatic Osteoarthritis After Displaced Intra-articular Calcaneus Fractures.

To quantify fracture severity for a series of displaced intra-articular calcaneal fractures (DIACFs) and to correlate it with Sanders classification, post-traumatic osteoarthritis (PTOA), and patient outcomes. Retrospective review and fracture severity analysis. Level 1 trauma center affiliated with the University of Iowa in Iowa City, IA. Thirty-six patients with 48 DIACFs were selected from 153 patients previously treated. All patients 18 years of age and older who had available electronic preop and postop computed tomography (CT) scans, good-quality postop and follow-up radiographs, and a follow-up ≥18 months were selected for study. Fractures were treated with percutaneous reduction, using multiple small stab incisions and fluoroscopy to guide manipulation of articular fragments using cork screws or Steinmann pins, with subsequent fixation using 3.5- and 4.0-mm screws. Preop CT scans were used to grade fractures according to the Sanders classification and to quantify fracture severity. Fracture severity was objectively quantified using a CT-based measure of fracture energy. PTOA was assessed on follow-up radiographs using the Kellgren-Lawrence scale. Patient outcomes were assessed using the Short Form 36 (SF-36) questionnaire and a visual analog scale pain score. Fracture energies for the 48 DIACFs ranged from 14.1 to 26.2 J (19.3 ± 3.1 J) and correlated with Sanders classification (rho = 0.53, P = 0.0001); type I (16.3 ± 0.9 J); type II (18.0 ± 2.7 J); type III (20.8 ± 2.8 J); and type IV (22.0 ± 0.7 J). Fracture energy was higher for fractures in which the subtalar joint developed PTOA (19.5 ± 2.7 J) than for those that did not (18.9 ± 3.3 J), but the difference did not reach statistical significance. The Sanders classification predicted PTOA risk [odds ratio (OR) = 4.04, 95% confidence interval = 1.43-11.39, P = 0.0084]. No relationship was observed between fracture energy and visual analog scale pain scores. Higher fracture energy correlated with lower SF-36 scores. Fracture energy positively correlates with Sanders classification for DIACFs, which can be used to identify more severe fractures at greater risk of progressing to PTOA. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.