Three-Year Follow-up of a Trial of Close Contact Casting vs Surgery for Initial Treatment of Unstable Ankle Fractures in Older Adults

A randomized clinical trial of close contact casting vs the usual practice of surgery for treating unstable ankle fractures in older adults found equivalent ankle function outcomes at 6 months.¹ Higher rates of radiological ankle malunion in the casting vs surgical groups (15% vs 3%, respectively) and nonunion (medial malleolus: 7% vs 1%, respectively) suggested that equivalence between the 2 groups may be lost if symptoms or functional limitations from posttraumatic arthritis manifest later.² A follow-up at least 3 years after randomization was conducted to determine if equivalence persisted over time.

This study was a prespecified extended follow-up of a pragmatic, multicenter, equivalence randomized clinical trial.¹ The National Research Ethics Service, Oxfordshire, gave approval; written informed consent was obtained. Participants were adults older than 60 years with acute unstable malleolar fracture(s) from 24 UK centers. Participants had received surgery (usual local practice internal fixation) or close contact casting, in which a minimally padded cast was applied after closed fracture reduction by an orthopedic surgeon in an operating room under anesthesia. Data were collected for at least 3 years after randomization using patient-reported postal questionnaires.

The primary outcome measure for the original trial was the Olerud and Molander Ankle Score (OMAS; range, 0-100, higher scores = better ankle function) at 6 months,³ with a prespecified equivalence margin of ±6 points. Extended follow-up used the same primary outcome and equivalence margin and assessed quality of life and pain as secondary outcomes (Table 1). A post hoc analysis of additional operations after 6 months was also conducted. Per-protocol primary analysis was used, consistent with the main trial.¹ Random-effects models estimated mean differences and 95% CIs between treatments adjusted for age, sex, fracture pattern, baseline score, and time to follow-up, including the center variable as a random effect. The random-effects model was also used post hoc to assess differences in OMAS for participants with vs without radiological malunion and nonunion at 6 months. Change from baseline score was analyzed for outcomes without normal distribution. The primary outcome at extended follow-up assessed equivalence with the null hypothesis that the 2 groups were not equivalent. For all other outcomes, tests were 2-sided with a P value of .05 or less for significance. Analyses were conducted with Stata (StataCorp), version 15.0.

From September 2013 through November 2016, 450 of the 620 randomized participants (73%) responded to follow-up at a median of 3 years (range, 2.9-9.5). Responders and nonresponders had similar characteristics (Table 1). Most responders lived in their own home (209 of 222 participants [94%] in the surgery group and 196 of 206 participants [95%] in the casting group).

Surgery and casting participants had equivalent ankle function (mean OMAS: 79.4 in the surgery group vs 76.3 in the casting group; difference, −1.3 [95% CI, −5.6 to 3.0]) and no significant differences in quality of life or pain (Table 2). Twenty-two of 222 surgery participants (10%) and 17 of 206 casting participants (8%) had operations after 6 months, including surgical implant removals (15 in the surgery group [7%] vs 8 in the casting group [4%]), arthrodesis (1 in the surgery group [0.5%] vs 3 in the casting group [1.5%]), arthroplasty (1 in the surgery group [0.5%] and 1 in the casting group [0.5%]), and infection-related procedures (2 in the surgery group [1%] and 0 in the casting group). Five casting participants (2%) had internal fixations for nonunion after 6 months. There was 1 internal fixation revision, 1 arthroscopy, and 1 hindfoot osteotomy among surgery participants. In post hoc analysis, from randomization to extended follow-up, mean total operating room procedures per participant (per protocol) were 1.2 (SD, 0.5) in the surgery group and 1.3 (SD, 0.6) in the casting group, and mean total surgical procedures per participant were 1.2 (SD, 0.5) in the surgery group and 0.3 (SD, 0.6) in the casting group.

Of 67 participants with radiological abnormalities at 6 months, 43 (64%) provided extended follow-up data. Those with malleolar malunion at 6 months had significantly lower OMAS scores (n = 30; mean, 58.7 [SD, 33.1]) than those without (n = 372; mean, 79.8 [SD, 23.5]; mean difference, −16.4 [95% CI, −25.0 to −7.8]; P < .001). Participants with medial malleolar nonunion at 6 months also had significantly lower OMAS scores (n = 13; mean, 55.4 [SD, 38.5]) than those without (n = 388; mean, 79.1 [SD, 23.9]; mean difference, −13.9 [95% CI, −26.6 to −1.2]; P = .03). Treatment was not a significant covariate in these analyses.

Equivalence in function between casting and immediate surgery strategies was maintained at 3 years. In post hoc analyses, participants with radiological malunion and medial malleolar nonunion at 6 months had lower OMAS scores at 3-year follow-up. These longer-term outcomes will support surgeon and patient decision making. The findings indicate that treatment of ankle fractures in older adults should focus on obtaining and maintaining a reduction until union, by the most conservative means possible.

The study was limited by its reliance on self-reported events requiring participant recall and by loss to follow-up. However, there were sufficient data to estimate and conclude equivalence in the primary outcome.

Accepted for Publication: January 23, 2018.

Corresponding Author: David J. Keene, DPhil, Kadoorie Centre for Critical Care Research and Education, Level 3, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom (david.keene@ndorms.ox.ac.uk).

Author Contributions: Mr Willett had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Keene, Lamb, Tutton, Handley, Willett.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Keene, Lamb, Mistry, Tutton, Willett.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Lamb, Mistry, Lall.

Obtained funding: Keene, Lamb, Tutton, Willett.

Administrative, technical, or material support: Keene, Willett.

Supervision: Willett.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Lamb reported being a member of the National Institute of Health Research (NIHR) Health Technology Assessment (HTA) program’s additional capacity funding board, end of life care and add-on studies, prioritization group, and trauma board. Mr Willett reported receiving design royalties from ZIMMER for intramedullary bone fixation implants. No other disclosures were reported.

Funding/Support: The Ankle Injury Management (AIM) trial was funded by the NIHR HTA program (project number 07/37/61). This article was supported by the NIHR Biomedical Research Centre, Oxford, and NIHR postdoctoral fellowship program (Dr Keene; PDF-2016-09-056). Dr Lamb receives funding from the NIHR Collaboration for Leadership in Applied Health Research and Care Oxford at Oxford Health National Health Service (NHS) Foundation Trust.

Role of the Funder/Sponsor: The sponsor and funders monitored the study but were not involved in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The views and opinions expressed herein are those of the authors and do not necessarily reflect those of the Health Technology Assessment program, NIHR, NHS, or the Department of Health.

Additional Contributions: We thank Lesley Morgan, Emma Roberts, BA, Susan Wagland, PhD, and Scott Parsons, DPhil (all from the University of Oxford), who coordinated the study; Louise Spoors, MSc, and Kathryn Lewis, BA, PGDip (all from the Oxford University Hospitals NHS Foundation Trust), for their assistance with participant telephone follow-up; and Jennifer A. de Beyer, DPhil (University of Oxford), for English language editing. They did not receive compensation for their contributions.

Group Information: The AIM trial group members were reported previously.¹