Plaster cast not superior to removable brace for ankle fractures in adults

Use of traditional plaster casting is not better than functional bracing in adults with an ankle fracture, a recent study has found. Olerud Molander ankle scores are comparable between the two intervention arms at week 16.

“This trial provides strong evidence for no statistically significant difference between traditional cast immobilization and removable bracing for ankle fractures in adults,” the researchers said.

This multicentre randomized controlled trial was conducted in 20 trauma units in the UK National Health Service and randomly assigned 669 adults aged ≥18 years with an acute ankle fracture suitable for cast immobilization to either a plaster cast (n=334) or a removable brace (n=335). A below-the-knee cast was used upon cast removal. The removable brace was fitted, and ankle range of movement exercises were initiated immediately.

The researchers performed an intention-to-treat analysis to determine the Olerud Molander ankle score at 16 weeks, the primary outcome. Other outcomes assessed were complications, quality of life, disability rating index, Manchester-Oxford foot questionnaire at 6, 10, and 16 weeks.

Of the participants (mean age 46 years, 381 [57 percent] women), 502 (75 percent) completed the study. There was no statistically significant difference noted in the Olerud Molander ankle score between the cast and removable brace groups at 16 weeks (mean difference, 1.8, 95 percent confidence interval, –2.0 to 5.6 in favour of brace). [BMJ 2021;374:n1506]

Likewise, no clinically significant differences were seen in the Olerud Molander ankle scores at 6 and 10 weeks in the secondary unadjusted, imputed, or per-protocol analyses.

Complications were also comparable between the two trial arms. In the cast group, major complications included deep vein thrombosis (n=3), pulmonary embolism (n=1), chronic regional pain syndromes (n=2), and further surgery (n=4), namely revision surgery for failed primary fixation (n=1), elective removal of metal work (n=2), and removal of metal work secondary to infection (n=1).

Significant complications in the removable brace group were as follows: deep vein thrombosis (n=3), pulmonary embolism (n=1), chronic regional pain syndrome (n=1), problems with fracture healing (n=1), and further surgery (n=8), namely revision surgery for failed primary fixation (n=1), elective removal of metal work (n=4), and removal of metal work secondary to infection (n=3).

“This trial did not find any clinically relevant differences between traditional cast compared with removable brace management at any time point, in keeping with previous trials,” the researchers said.

A Cochrane review assessed 10 trials comparing a removable type of immobilization and early movement with a case and no early movement. In this updated search, four subsequent trials were identified. None of these trials saw a difference in safety profiles between a plaster cast and a removable brace. [Cochrane Database Syst Rev 2012;11:CD005595; Injury 2018;49:1607-1611; Pilot Feasibility Stud 2019;5:55; J Orthop Trauma 2016;30:345-352; BMJ 2019;364:k5432]

The current study was limited by the 25-percent loss to follow-up and potential bias due to those who did not complete the trial, according to the researchers, noting that future research should consider the importance of later stage rehabilitation after the initial immobilization phase.