Comparison of AO type-B and type-C volar shearing fractures of the distal part of the radius

Abstract

Background: Fractures of the volar articular margin of the distal part of the radius with volar radiocarpal subluxation (volar shearing, or Barton, fractures) can be accompanied by a fracture of the dorsal metaphyseal cortex. We tested the null hypothesis that there is no difference in wrist function or health status after open reduction and plate-and-screw fixation between volar shearing fractures with a dorsal cortical fracture (complete articular, AO Type C) and those without a dorsal cortical fracture (partial articular, AO Type B). Methods: In a multicenter cohort study, fifty-seven patients with a volar marginal shearing fracture of the distal part of the radius and volar radiocarpal subluxation were followed for at least one year following plate-and-screw fixation. Thirtyseven patients who also had a dorsal metaphyseal cortical fracture (Type-C fracture) were compared with twenty patients who had a partial articular (Type-B) fracture. The two cohorts were analyzed for differences in wrist and forearm motion, grip strength, pain, and the Gartland and Werley, Disabilities of the Arm, Shoulder and Hand (DASH), and Short Form-36 (SF-36) scores at six, twelve, and twenty-four months postoperatively. Differences in mean values and their change over time were determined. Results: There were no significant differences between patients with a Type-B fracture and those with a Type-C fracture with respect to motion, grip strength, or the Gartland and Werley or DASH score at any time point. At six months after the surgery, the patients with a Type-B volar shearing fracture reported a mean score for pain in motion of 0.5 point on a 10-point visual analogue scale compared with 2.2 points for patients with a Type-C fracture (difference in means, 1.7 points [95% confidence interval, 0.7 to 2.6 points]; p < 0.001), but no significant difference was seen at twelve or twenty-four months. Conclusions: Volar shearing fractures are usually complete articular, Type-C injuries. Patients with a Type-C volar shearing fracture experience more pain during early recovery, but ultimately their outcome is comparable with that for patients with a Type-B (partial articular) volar shearing fracture. Level of Evidence: Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence. Copyright © 2009 by The Journal of Bone and Joint Surgery, Incorporated.