Use of Computed Tomography to Predict Union and Time to Union in Acute Scaphoid Fractures Treated Nonoperatively

Abstract

To use computed tomography to determine whether factors could be identified to predict union for acute scaphoid fractures treated nonoperatively. We used a radiology database at a tertiary care center to identify scaphoid computed tomography scans performed between 2004 and 2010. We noted fracture location, fracture orientation, translation between fragments, humpback deformity, comminution, cysts, and sclerosis. We determined the associations between imaging variables on union rates and time to achieve union with casting alone in a cohort of 219 patients (mean age, 31 y; 83% males). Most fractures were scaphoid waist fractures (173 of 219; 79%), of which 178 (81% of total group) were nondisplaced. There were 28 proximal pole fractures (13%) and 18 distal pole fractures (8%). The overall union rate was 95% (207 of 219). The odds of developing a nonunion were increased in fractures with translation (odds ratio, 3.4) or with a humpback deformity (odds ratio, 6.9). The presence of sclerosis or cysts did not correlate with union rates. There was no statistical association between successful union and fracture location, although, given the small number of proximal pole fractures, we were underpowered for this finding. Time to union was longer for proximal pole fractures (113 d) versus distal pole (53 d) and waist fractures (65 d) and for fractures with sclerosis (166 vs 67 d) or comminution (103 vs 66 d). We were able to identify a number of features that contributed to risk of nonunion or delayed union based on computed tomography scan. Factors such as fracture translation, comminution, and humpback were related to a higher risk of scaphoid nonunion. Factors such as sclerosis, comminution, translation, and location in the proximal pole were associated with longer times to union. These variables were independently significant in increasing the time required to achieve union and were shown to have an overall additive effect. Prognostic II.