The effect of different methods of stability assessment on the rate of fixation in SER2/4 ankle fractures

E.J. Dawe, R. Shafafy, J. Quayle, N. Gougoulias, A. Wee, A. Sakellariou

Introduction: Non weight-bearing plain radiographs are frequently unreliable in distinguishing between stable Supination-External Rotation (SER) 2 and unstable SER 4 injuries. Gravity stress radiographs and, more recently, weight-bearing radiographs have been introduced to aid surgical decision-making. The aim of this study was to assess the effect of different radiographic stability assessments on the rate of fracture fixation.

Methods: Radiographs of 1500 ankle injuries were assessed to identify SER 2/4 injuries. We determined inter- and intra-rater agreement of the need for stress radiography and divided patients into three groups. These were: Phase 1- the ‘before gravity stress views’ period (BS), phase 2- the ‘gravity stress view’ period (GS) and, phase 3 - the ‘weight-bearing radiograph’ period (WB). The rate of fixation was assessed based on the timeperiod and also the type of assessment.

Results: We indentified 558 patients with SER2/4 injuries. Minimum follow-up was 8 months. Of those, 327 were classified as SER2/4 on initial radiographs. Median age was 50 years (IQR 35 to 65). Mean Inter-observer agreement (Kappa) for the need for stress radiographs was 0.82 whilst intra-observer agreement was 0.85. Only 51% of patients requiring a stress view received one. Significantly fewer fractures were fixed during the BS and the WB period than during the GS period (8.9% and 7.0% vs 25.7%, Chi Squared P=0.0001). In the BS period, two patients underwent late fracture fixation. In the GS period, two patients underwent metalwork removal. In the WB period, no patient underwent re-operation. Thirty of 58 patients assessed with Gravity Stress underwent fixation, compared with 3 of 55, assessed with weight-bearing views.

Conclusion: Patients assessed with gravity-stress radiographs for SER2/4 fractures were eight times more likely to undergo surgery than those assessed with weight-bearing radiographs. We recommend the routine use of weight-bearing views in assessing the need for fixation.