For physiotherapists working in orthopedics and trauma rehabilitation, ankle fractures are among the most frequently encountered lower limb injuries. Specifically, the management of isolated Weber B fibula fractures has long been a subject of clinical debate. While stable fractures are routinely managed conservatively, fractures deemed unstable—typically defined by mortise incongruency or positive stress testing—have traditionally been funneled toward open reduction and internal plate fixation (ORIF). A groundbreaking new Randomized Controlled Trial (RCT), the SUPER-FIN trial published in the BMJ, challenges this dogma, suggesting that conservative management may be just as effective, and safer, for a specific subset of these patients.
The Clinical Dilemma: Defining Instability
The crux of the issue lies in the definition of instability. The “grey zone” often involves patients who present with a congruent mortise on initial static radiography but demonstrate instability during external rotation stress testing under fluoroscopy. Is surgical stabilization truly necessary to prevent post-traumatic arthritis and ensure optimal function, or are we over-treating these injuries?
The SUPER-FIN trial sought to answer this by comparing conventional cast immobilization against surgical fixation in skeletally mature patients with isolated Weber B fractures. These participants had congruent static X-rays but were confirmed unstable via stress testing. A total of 126 patients were randomized to receive either a cast for six weeks or surgery followed by a cast for six weeks.
Outcomes: Functionality and Non-Inferiority
The primary outcome measure was the Olerud-Molander Ankle Score (OMAS) at the two-year follow-up mark. The OMAS is a validated tool assessing symptoms and function, with higher scores indicating better outcomes. The results were compelling for advocates of conservative care.
In the intention-to-treat analysis, the mean OMAS was 89 in the cast immobilization group compared to 87 in the surgery group. With a mean difference of only 1.3 points, the study confirmed that non-operative management was non-inferior to surgery. Furthermore, there were no statistically significant differences between the groups regarding secondary outcomes, including ankle range of motion, pain levels, or health-related quality of life.
Adverse Events and Rehabilitation Implications
For the physiotherapy profession, the adverse event profile is perhaps the most significant takeaway. While functional outcomes were similar, the surgical group faced a higher burden of complications. In the surgery arm, nine participants required subsequent procedures for hardware removal, and two developed postoperative infections (one deep, one superficial). Conversely, the cast group experienced fewer treatment-related harms.
This data suggests that for patients with a congruent mortise on static X-ray—even if stress positive—surgery introduces risks of infection, wound healing issues, and future hardware removal surgeries without delivering superior functional gains. Avoiding surgery eliminates scar tissue formation from the incision and hardware-related irritation, potentially streamlining the rehabilitation process once immobilization is removed.
Conclusion
The SUPER-FIN trial provides high-quality evidence that cast immobilization is a viable, safe, and cost-effective alternative to surgery for unimalleolar Weber B fractures that appear stable on static imaging but unstable on stress testing. For physiotherapists, this may signal a shift in referral patterns and a reduction in post-surgical rehabilitation cases for this specific demographic, emphasizing instead the importance of progressive loading and mobilization following conservative casting.
References
Kortekangas, T., Lehtola, R., Leskelä, H. V., Taimela, S., Ohtonen, P., Savola, O., Järvinen, T. L. N., & Pakarinen, H. (2026). Cast immobilisation versus surgery for unstable lateral malleolus fractures (SUPER-FIN): randomised non-inferiority clinical trial. BMJ (Clinical research ed.).
https://pubmed.ncbi.nlm.nih.gov/41534905/
