Background: In Weber B/SER2-4 ankle fractures, assessment with weightbearing radiographs to ascertain stability of the ankle mortise has been advised. However, no previous studies report whether this method leads to preservation of normal ankle congruence. The purpose is to evaluate equivalence of ankle congruence of injured ankles after fracture union, vs the uninjured side, for stable SER2 and partially unstable SER4a fracture types. Methods: We conducted a prospective case-control study designed as an equivalence trial to evaluate if weightbearing radiographs predict whether stable/SER2 and partially unstable/SER4a Weber B ankle fractures reach union with preserved normal tibiotalar congruence and without a concomitant increase of treatment failure. A total of 149 patients with a Weber B fracture stable on weightbearing radiographs were recruited into the trial. All participants were treated with a functional orthosis and weightbearing allowed. Results from gravity stress radiographs classified ankles as SER2 or SER4a fracture types. We defined an equivalence margin in medial clear space difference of 1.0 mm. We also evaluated the reliability of obtaining measurements from weightbearing radiographs. Results: No differences in medial clear space between the injured and uninjured ankles were observed after fracture union for the SER2 group (mean difference 0.1 mm, 95% confidence interval [CI] −0.3, 0.0; P = .056), or the SER4a group (mean difference 0.0 mm (95% CI −0.1, 0.1; P = .797). No between-group differences were observed (mean difference 0.0 mm, 95% CI −0.2, 0.2; P = .842). These findings were consistent with equivalence. CIs for the intraclass correlation coefficients indicated excellent reliability. Conclusions: Assessment of stability of Weber B SER2/4a ankle fractures, with weightbearing radiographs, also predicts preservation of normal ankle congruence in those deemed stable, with no difference between SER2 and SER4a fracture types. Further, excellent reproducibility of the method of obtaining medial clear space measurements was demonstrated. Level of Evidence: Level III, case-control.

Background: Deltoid ligament injury occurs often with supination-external rotation (SER) ankle trauma. SER fibula fractures with concomitant deltoid ligament injury are considered unstable—requiring operative fixation. Recent studies have questioned this general practice with emphasis on better defining the medial side ankle ligamentous injury. The function of the individual bands of the deltoid ligament, and the interplay between them, are not fully understood. We undertook this study to develop a better understanding of these complex ligamentous structures and ultimately aid assessment and treatment choice of SER ankle fractures with concomitant deltoid ligament injuries. Methods: Ten fresh-frozen cadaveric foot and ankle specimens were studied. We identified the various ligament bands and did a functional analysis by assessment of ligament length and tension at predefined angles of ankle dorsi-plantarflexion combined with valgus/varus and rotation. The results were determined by manual evaluation with calipers and goniometers, manual stress, and direct visualization. Results: We recorded primarily 5 different bands of the deltoid ligament: the tibionavicular (TNL; 10/10) tibiospring (TSL; 9/10), tibiocalcaneal (TCL; 10/10), deep anterior tibiotalar (dATTL; 9/10), and deep posterior tibiotalar (dPTTL; 10/10) ligaments. The tibiospring ligament was tense in plantarflexion, while the tibiocalcaneal and deep posterior tibiotalar ligaments were tense in dorsiflexion. The superficial layer ligaments and the deep anterior tibiotalar ligament length and tension were largely affected by changes in varus/valgus and rotation. The deep posterior tibiotalar ligament length and tension was altered predominantly by changes in dorsi-plantarflexion; varus/valgus positioning had a minor effect on this band. Conclusions: We confirmed the finding of previous studies that dorsi-plantarflexion affects the tensile engagement of the separate ligament bands differently. Likewise, combined movements with varus/valgus and rotation seem to affect the separate ligament bands differently. Our results suggest that the TNL, TSL, and dATTL are at risk of injury, whereas the TCL and particularly the dPTTL are protected in the event of an SER-type ankle fracture mechanism of injury. Level of Evidence Level V, cadaveric study.

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.