By Jeffrey R. Baker, DPM, FACFAS
In medical school, we were taught that Weber B ankle fractures required the 6-week cast immobilization protocol. But for many of us, that protocol has felt excessive due to concerns of increased ankle stiffness, decreased ankle strength, and the possibility of a thrombotic event. However, the thought of possible suboptimal healing of the fracture [malunion or nonunion] with less than 6 weeks of immobilization or use of less rigid forms of immobilization provided anxiety to many of us treating physicians. Despite the anxiety, there has been a trend among foot and ankle physicians toward earlier mobilization for this common fracture subset.
And now, a recent article1 in the British Medical Journal has arrived to soothe that anxiety. The Finnish study reported on the comparison of immobilization techniques for stable unimalleolar Weber B ankle fractures.
This well designed, randomized, blinded, and high patient number clinical trial provides excellent clinical evidence for the decision to treat stable unimalleolar Weber B ankle fractures with options other than long-term immobilization of up to 6 weeks. In the study, patients were randomized into 3 groups: a 6-week cast group (84), a 3-week cast group (83), and a 3-week orthosis group (80). The 6-week cast group served as a control group and the authors compared the 3-week cast group to the 6-week cast group and the orthosis group to the 6-week cast group. The authors were looking to see if treatment of these fractures with immobilization in a cast for 3 weeks or immobilization with the use of an orthosis for 3 weeks produced non-inferior results as compared to 6 weeks of cast immobilization. Study participants were seen at 3 weeks, 6 weeks, 12 weeks, and 52 weeks. The study results showed that 3 weeks of cast immobilization or 3 weeks of immobilization with the use of a prefabricated ankle-foot orthosis provide the same clinical outcome as immobilization of 6 weeks with a cast for these fractures. This is the result of enhancement of fracture healing with early mechanical stimulation.
For the foot and ankle physician the article provides significant value. It answers and provides substantive evidence for aggressive worry-free treatment for patients with stable unimalleolar Weber B ankle fractures. This is important as the option to treat these fractures with a shorter duration of immobilization and with less rigid immobilization significantly improves patient compliance. Within the study there were no issues of compliance with either the 3-week cast immobilization group or the orthosis group; however, within the 6-week cast group there was a 7% noncompliance as 6 participants had a protocol violation as they refused continued cast treatment beyond the 3-week study visit.
Furthermore, the major precentral consultation concerns were addressed within the article. A deep vein thrombosis (DVT) was diagnosed in a total of 8 patients. No patients within the orthosis group developed a DVT, whereas 5 patients in the 6-week cast group and 3 patients in the 3-week cast group developed a DVT. A nonunion at 52 weeks was only noted in 2 patients, both within the 3-week cast group. Both nonunions were atrophic, suggesting to the authors that this was a random phenomenon as opposed to secondary to insufficient immobilization. They theorized that if the 2 nonunions were truly secondary to instability, they would have been hypertrophic in nature.
Over the last 15 years in practice, I have progressed in my treatment of stable unimalleolar Weber B ankle fractures from 6 weeks of non-weight-bearing with a cast to a protocol of 3 weeks of partial weight-bearing with a below-the-knee fracture boot and crutch gait assistance with transition at 3 weeks to full weight-bearing with the use of the fracture boot for a total of 6 weeks of immobilization. The results of this clinical trial not only support my current treatment protocol for these injuries, but they also provide evidence that even my current treatment protocol is too conservative and that I can be more aggressive with these injuries without worry for potential nonunion.
The treatment of all musculoskeletal injuries has had a shift toward early range of motion in recent times. The ability of the patients to move early and not limit joint function improves overall time to recovery from injuries as well as patient compliance. Therefore, this clinical trial provides an excellent resource and support for foot and ankle physicians to provide adequate and appropriate care for stable unimalleolar Weber B ankle fractures without the need for long-term immobilization in a cast.
Jeffrey R. Baker, DPM, FACFAS, is a podiatrist and foot and ankle surgeon with the Weil Foot and Ankle Institute in Chicago, IL.
- Kortekangas T, Haapasola H, Flinkkila, et al. Three week versus six week immobilization for stable Weber B type ankle fractures: randomized, multicenter, non-inferiority clinical trial. BMJ. 2019;364:k5432.