University of Oulu

Kortekangas Tero, Haapasalo Heidi, Flinkkilä Tapio, Ohtonen Pasi, Nortunen Simo, Laine Heikki-Jussi et al. Three week versus six week immobilisation for stable Weber B type ankle fractures: randomised, multicentre, non-inferiority clinical trial BMJ 2019; 364 :k5432.

Three week versus six week immobilisation for stable Weber B type ankle fractures : randomised, multicentre, non-inferiority clinical trial

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Author: Kortekangas, Tero1,2; Haapasalo, Heidi3; Flinkkilä, Tapio1,2;
Organizations: 1Department of Surgery, Division of Orthopaedic and Trauma Surgery, Oulu University Hospital, Kajaanintie 50, PO Box 21, FI 90029 OYS, Oulu, Finland
2Medical Research Centre (MRC) Oulu, Oulu, Finland
3epartment of Orthopaedics, Tampere University Hospital, Tampere, Finland
4Division of Operative Care, Oulu University Hospital, Oulu, Finland
5Department of Orthopaedics, Tampere University Hospital, Tampere, Finland
6Finnish Centre for Evidence-Based Orthopaedics (FICEBO), Department of Orthopaedics, University of Helsinki, Helsinki, Finland
7Department of Orthopaedics and Traumatology, Helsinki University Hospital, Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.7 MB)
Persistent link:
Language: English
Published: BMJ, 2019
Publish Date: 2020-02-12


Objective: To determine whether treatment of isolated stable Weber B type ankle fractures with a cast or a simple orthotic device for three weeks produces non-inferior outcomes compared with conventional immobilisation in a cast for six weeks.

Design: Randomised, pragmatic, non-inferiority, clinical trial with blinded outcome assessment.

Setting: Two major trauma centres in Finland, 22 December 2012 to 6 June 2016.

Participants: 247 skeletally mature patients aged 16 years or older with an isolated Weber B type fibula fracture and congruent ankle mortise in static ankle radiographs.

Interventions: Participants were randomly allocated to conventional six week cast immobilisation (n=84) or three week treatment either in a cast (n=83) or in a simple orthosis (n=80).

Main outcome measures: The primary, non-inferiority, intention-to-treat outcome was the Olerud-Molander Ankle Score at 12 months (OMAS; range 0–100; higher scores indicate better outcomes and fewer symptoms). The predefined non-inferiority margin for the primary outcome was −8.8 points. Secondary outcomes were ankle function, pain, quality of life, ankle motion, and radiographic outcome. Follow-up assessments were performed at 6, 12, and 52 weeks.

Results: 212 of 247 randomised participants (86%) completed the study. At 52 weeks, the mean OMAS was 87.6 (SD 18.3) in the six week cast group, 91.7 (SD 12.9) in the three week cast group, and 89.8 (SD 18.4) in the three week orthosis group. The between group difference at 52 weeks for the three week cast versus six week cast was 3.6 points (95% confidence interval −1.9 to 9.1, P=0.20), and for the three week orthosis versus six week cast was 1.7 points (−4.0 to 7.3, P=0.56). In both comparisons, the confidence intervals did not include the predefined inferiority margin of −8.8 points. The only statistically significant between group differences observed in the secondary outcomes and harms in the two primary comparisons were slight improvement in ankle plantar flexion and incidence of deep vein thrombosis, both in the three week orthosis group versus six week cast group.

Conclusion: Immobilisation for three weeks with a cast or orthosis was non-inferior to conventional cast immobilisation for six weeks in the treatment of an isolated stable Weber B type fracture.

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Series: The BMJ
ISSN: 0959-8146
ISSN-E: 1756-1833
ISSN-L: 0959-8146
Volume: 364
Article number: k5432
DOI: 10.1136/bmj.k5432
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: This study was supported by state funding for university level health research (Oulu University Hospital; grant No EVO-VY 244770/24780 and Tampere University Hospital; grant Nos 9R006 and R9031).
Copyright information: This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: