Supination external rotation ankle fractures A simpler pattern with better outcomes

Abstract

Background: Rotational injuries are the most common and usually classified as per the Lauge Hansen classification; with the most common subgroup being the supination external rotation (SER) mechanism. Isolated fractures of the distal fibula (SE2) without associated ligamentous injury are usually treated with a splint or brace and the patient may be allowed to weight bear as tolerated. This study reports the functional outcomes following a stable, low energy, rotational ankle fracture supination external rotation (SER2) when compared to unstable SER4 fractures treated operatively. Materials and Methods: 64 patients who were diagnosed and treated nonoperatively for a stable SER2 ankle fracture were followed prospectively. In the comparison group, 93 operatively treated fibular fractures were extracted from a prospectively collected database and evaluated comparison. Baseline characteristics obtained by trained interviewers at the time of injury included: Patient demographics, short form-36, short musculoskeletal functional assessment (SMFA) and American Orthopedic Foot and Ankle Society (AOFAS) questionnaires. Patients were followed at 3, 6 and 12 months postsurgery. Additional information obtained at each followup point included any complications or evidence on fracture healing. Data were analyzed by the Student's t-test and theFisher's Exact Test to compare demographic and functional outcomes between the two cohorts. P < 0.05 was considered to be significant. Results: The average of patients' age in the stable fracture cohort was 43 versus 45 in the SER4 group. Nearly 64% of the patient population was female when compared with 37% in the operative group. In the SER2 by 6 months all patients had returned to baseline functional status. There were 18 delayed unions (all healed by 6 months). Based on the functional outcome scores all patients had returned to preoperative level. In comparison, SE4 patients had less functional recovery at 3 and 6 months (P < 0.05) based on the SMFA scores and at 3, 6 and 12 months based on the AOFAS (P < 0.001) scores. There was no difference in pain levels between the two groups at all time points. There were three nonunions in the SE4 group and six delayed unions. Conclusions: An SER2 ankle fracture is a relatively benign injury with functional limitations resolving by 3 months while the need for surgical fixation in SER ankle fractures appears to affect lower extremity function to a greater degree for a longer time period. Patients should be counseled as to these expected outcomes.