There is a growing consensus among foot and ankle surgeons to support that trans-syndesmotic distal fibula fractures without medial column injury are stable fractures and could be safely treated by functional bracing and early weight bearing (10–12). This consensus was further strengthened by the findings of the recently published Combined Randomised and Observational Study of Surgery for type-B Ankle Fracture Treatment (CROSSBAT) (13) and the British Orthopaedic Association Standards for Trauma (BOAST) guidelines published in 2016 (14). Both recommend the use of functional bracing and weight bearing as tolerated in ankle orthotic.
However, some understandable concern remains among trauma surgeons regarding identification of stable ankle fracture. As such fractures may still displace if patients are allowed to weight bear in a brace. This concern arises from that fact that a seemingly stable supination external rotation (SER) stage II fracture according to Lange-Hansen classification may look identical to the unstable SER stage IV fracture on the initial radiographs (15). Hence, identifying unstable fractures is necessary if we are to adopt these recommendations.
Various methods were proposed to assess the stability of isolated trans-syndesmotic distal fibula fractures. These include medial tenderness, medial ecchymosis, gravity stress radiographs, manual stress radiographs and weight bearing radiographs. Medial tenderness and ecchymosis could be a result of an injury to the superficial part of the deltoid ligament, the ankle stability is not usually compromised in this situation as the deep part of the deltoid ligament is intact (16). Despite this unreliability, medial tenderness and bruising remain the only clinical sign of possible instability. Stress radiographs (manual and gravity) are difficult to obtain, poorly tolerated by patients and could lead to over-diagnosis of ankle instability (17, 18). Weight bearing radiographs have also been examined for their ability to detect ankle instability. Weight bearing radiographs were reported to result in significant reduction in the need for operative management for SER fractures when used. In his series of 57 patients, Weber et al stated that weightbearing radiographs are “easy, pain-free, safe and reliable” in detecting instability. (19, 20).
In our study, all patients who had weight bearing radiographs to examine for the ankle stability were allowed early weightbearing. Our observation is consistent with the findings of other published studies that weight bearing radiographs facilitated the functional treatment of ankle fractures (21–23).
Our results did not show statistical difference in the fracture union or patient reported outcome score (Olerud - Morander Score) regardless of the method of immoblisation or the weight bearing status. However, the benefit of functional bracing was clear. Functional bracing and early weight bearing have resulted in less outpatient appointments, fewer number of radiographs needed and less complications.
Cost of treatment is a significant ongoing concern in the UK National Health System (NHS) and any other health system. One outpatient appointment costs the NHS £36 (minimum), while one radiograph costs approximately £25. At the current rates, the ankle orthotic (boot) used by our trust costs £21, while polymer casts (which need to be changed at least once through the course of treatment) cost approximately £32 each. Therefore, if all our 123 patients were treated according to BOAST guidelines (one outpatient appointment and discharged, weight bearing in a boot), we estimate potential saving of over £10000 that could have been saved within 6 months.
This study is not without limitations, the retrospective nature of the data collection, the lack of randomisation and relatively short follow-up period are the main limitations. We recommend a prospective randomised controlled trial with longer follow-up to help answer this clinically relevant question. We also recommend a thorough investigation of the value of obtaining weight-bearing radiographs in these situations. One could argue that weight bearing radiographs could be obtained on the first visit to the emergency department, functional bracing and early weight bearing could be decided at this stage. To our knowledge, there are two ongoing trials, currently recruiting, with the aim to answer these issues (24, 25).