Concomitant Unstable and Stable Gravity Stress Tests on Weight-Bearing Stable Weber B Ankle Fractures Treated Nonoperatively: A 2-Year Outcome Study

Abstract

Background: Replacing gravity stress tests with weight-bearing radiographs to evaluate the stability of Weber B (also called Lauge-Hansen supination-external rotation [SER]) ankle fractures results in a lower surgery rate, thus avoiding associated risks and complications. Still, nonoperative treatment of weight-bearing stable fractures is controversial because of the scarcity of strong evidence. We investigated the influence of a concomitant unstable gravity stress test compared with a stable gravity stress test on outcomes after nonoperative treatment of weight-bearing stable fractures.

Methods: We performed a prospective, noninferiority study on 149 patients with Weber B ankle fractures and stable weight-bearing radiographs. Gravity stress radiographs classified fractures as stable (SER2 [n = 88]) or partially unstable (SER4a [n = 61]). All were treated with a functional orthosis and weight-bearing was allowed; patients were followed for 2 years. The primary outcome was the Manchester-Oxford Foot and Ankle Questionnaire (MOXFQ), with a range from 0 to 100, in which lower scores indicate fewer symptoms. A noninferiority margin was prospectively defined as 7.5 points. The secondary outcomes included the Olerud-Molander Ankle Score, assessment of ankle congruence, and treatment-related adverse events.

Results: The primary outcome data were available for 144 (96.6%) of 149 participants at 2 years. The between-group difference in the MOXFQ score was 1.0 point (95% confidence interval, −1.4 to 3.4 points; p = 0.397) in favor of the SER2 group, consistent with noninferiority. We found no appreciable between-group differences for any other outcome.

Conclusions: In Weber B/SER ankle fractures that are stable on weight-bearing radiographs, are treated with removable orthoses, and are allowed to bear weight, a concomitant unstable gravity stress test (SER4a) was not associated with worse patient-reported or radiographic outcomes compared with a stable gravity stress test (SER2) at the 2-year follow-up. Thus, the identification of stress instability seems redundant, which questions the applicability of stress instability for surgical decision-making.

Level of Evidence: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.