Wearing a cast for six weeks is as effective as surgery for healing unstable ankle fractures and results in fewer treatment-related harms, according to a clinical trial from Finland published by The BMJ today. This finding could reshape treatment protocols for certain ankle injuries, providing a less invasive option for patients.
Around two-thirds of all ankle fractures involve a break in the fibula, known as Weber B fractures, which can leave the ankle either stable or unstable. Despite recent trials and guidelines increasingly supporting non-surgical options for selected patients, surgery remains the main treatment for unstable Weber B ankle fractures.
Examining the Effectiveness of Cast Immobilization
The Finnish study aimed to assess whether cast immobilization is “non-inferior” to surgery in adults with unstable Weber B ankle fractures. Researchers identified 126 participants aged 16 years or older with an unstable Weber B ankle fracture confirmed by an external rotation stress test at a specialist university hospital trauma center in Finland between January 2013 and July 2021.
Participants were randomly assigned to two groups: 62 underwent conventional cast immobilization for six weeks, while 64 received surgery followed by the same immobilization period. Both groups attended check-ups at two, six, and 12 weeks and met with a physiotherapist to guide rehabilitation.
Key Findings and Statistical Analysis
At the two-year mark, participants were assessed using the Olerud-Molander Ankle Score (OMAS), a scale from 0 to 100 where higher scores indicate better healing. An 8-point difference between groups was pre-set as the non-inferiority margin. The mean OMAS was 89 for the cast group and 87 for the surgery group, showing a mean difference of 1.3 points.
“No statistically significant between-group differences were seen in any of the other outcomes, and overall, fewer treatment-related harms occurred with cast immobilization compared with surgery.”
The authors noted that their trial was conducted at a single university hospital, which might limit generalizability. They also acknowledged the lack of consensus on using the external rotation stress test to determine fracture instability. However, they emphasized that this was a robust analysis with a high follow-up rate at two years, a time frame generally considered sufficient to capture longer-term outcomes.
Implications for Ankle Fracture Treatment
The findings support the evolving concept that treatment for ankle fractures should focus on maintaining a congruent ankle mortise until fracture union, using the most conservative means possible. “Together, our findings and those of previous studies show that a standard below-the-knee cast provides adequate stabilization of an isolated unimalleolar fibular fracture with a congruent ankle mortise,” the authors wrote.
UK researchers, in a linked editorial, praised the study for addressing an important clinical question and supporting treatment decisions and updates to clinical guidelines. They acknowledged some limitations but noted that this and other trials are advancing the evidence base for ankle fracture management.
“This team is to be commended for conducting a robust study which addresses an important clinical question, and will support treatment decisions and updates to clinical guidelines,” they stated.
Looking Forward: A Shift in Clinical Practice?
The results of this study could lead to a shift in clinical practice, encouraging healthcare providers to consider non-surgical options for certain patients with unstable ankle fractures. This approach not only reduces the risks associated with surgery but also aligns with a broader trend in medicine towards less invasive treatments.
As more studies contribute to the growing body of evidence, healthcare professionals may increasingly adopt cast immobilization as a standard treatment for specific types of ankle fractures. This change could improve patient outcomes while minimizing the risks and costs associated with surgical interventions.
The Finnish study underscores the importance of continued research and collaboration among trauma and orthopedic health professionals, researchers, and patient participants to refine and enhance treatment protocols for common injuries like ankle fractures.
