Prognostic value of the CURL classification system for proximal ulna fracture dislocations of the elbow

Proximal ulna fracture dislocations comprise a wide spectrum of injury. The Coronoid, proximal Ulna, Radius and Ligaments (CURL) classification is a simple framework designed to aid surgical decision-making by focusing attention on the key components of the injury and their relative severity. It has been demonstrated to have a high interobserver and intraobserver reliability. The aim of this study was to analyze the prognostic value of the CURL classification with respect to patient outcome.

The CURL framework was applied retrospectively to 182 patients treated surgically for a proximal ulna fracture dislocation in a level 1 trauma center. Patient outcomes collected included complication rate, reoperations, patient satisfaction, and Oxford Elbow Score (OES). The CURL score overall and each individual component were assessed for the effect on outcome. Appropriateness of surgical fixation was also assessed and correlated with outcome.

Of 182 patients, 69 (37.9%) had at least 1 major or minor complication and the overall CURL score was associated with a higher rate of complications (r = 0.85, P = .02). The presence of a coronoid fracture as well as the radial head and ligament components was associated with increased complications (coronoid: r = 0.26, P < .01; radial head: r = 0.36, P < .01; ligament: r = 0.38, P < .01). The complication rate was higher as the CURL value increased for both coronoid and radial head components (coronoid score 0 = 30.9%, coronoid score 1 = 54.6%, coronoid score 2 = 69.2% and radial head score 0 = 26.1%, radial head score 1 = 50.0%, radial head score 2 = 73.3%). The median OES was 43, and the total CURL score was correlated with inferior OES (r = -0.89, P = .01) as were the coronoid, radial head, and ligament components (coronoid: r = -0.43, P < .01; radial head: r = -0.38, P < .01; ligament: r = -0.42, P < .01). The proximal ulna fracture severity was not correlated with increased complication rate or OES. Patients deemed to have inappropriate fixation (20.8%) had a significantly higher complication rate (65.8% vs. 30.5%, P ≤ .001), with the 9 patients with inadequate coronoid fixation demonstrating a 100.0% complication rate.

Proximal ulna fracture dislocations have a high complication rate and are intolerant to inadequate fixation. The CURL system demonstrates prognostic value with the coronoid component most influential on outcome.