This is a plain English summary of an original research article
A new casting technique called “close contact casting” is an alternative to surgery for older people with ankle fracture. Ankle function at six months was similar in people who had casting and those who had surgery but there are some disadvantages to both that patients and surgeons could consider.
This UK-based NIHR trial recruited 620 people aged over 60 years with an unstable ankle fracture that would usually be fixed with surgery.
People who had a cast were less likely to have infections or wound problems than those who had surgery. However, one in five people in the casting group had to undergo surgery later because their fracture was not healing in the right position.
Close contact casting was around £650 cheaper than surgery, and was very likely to be cost effective at current NHS thresholds.
Participants are being followed up for another year and a half to assess longer term outcomes such as arthritis and this will further help in balancing the benefits and harms of these options.
Why was this study needed?
People who fracture their ankle are treated either conservatively by stabilising the joint with a plaster cast or surgically to align the broken bones and fix them in place with metal screws or plates. If the fracture is ‘unstable’ – that is, the broken ends of the bone are no longer aligned – surgery to fix the boned in place with a metal plate and screws is currently the preferred treatment.
In older people, this surgery is associated with an increased risk of complications such as infection and wound problems. But using a cast doesn’t guarantee that the bones will heal in the correct alignment and it may be linked to plaster sores. In addition, it is not clear whether surgery or close contact casting is better in the long term.
The new casting technique is performed under anaesthetic. It uses less lining and padding than traditional casting methods, so is thought to be better at stabilising the fracture and may be less likely to damage the skin. The research was designed to provide more certainty for patients and orthopaedic surgeons.
What did this study do?
The Ankle Injury Management (AIM) randomised controlled trial recruited adults aged over 60 years from 24 hospitals in the UK. Participants had an unstable ankle fracture and would normally be offered surgery.
The 311 people randomly assigned to the casting group underwent close contact casting in theatre by an orthopaedic surgeon who had been specially trained in the technique. If the fracture did not appear to be healing in the correct alignment during the first three weeks after treatment, the person would then undergo surgery.
The 309 people in the surgery group had open reduction and internal fixation surgery by an orthopaedic surgeon.
Outcomes were assessed at six months after treatment using a validated patient-reported assessment of ankle function: the Olerud-Molander Ankle Score (OMAS), a 0 to 100 scale where higher scores indicate better ankle function. However, the researchers say that six months may be too early for all complications to appear.
What did it find?
- At six months, ankle function was similar in the casting group (64.5 points on OMAS) and the surgery group (66.0 points; mean difference −0.65 points, 95% confidence interval −3.98 to 2.68 points).
- One in five people who had casting had to undergo surgery later because the fracture was not healing in the right position. In addition, X-rays at six months showed that misaligned healing was more common in the casting group than in the surgery group (38/249 [15%] vs 8/274 [3%]).
- Infections or wound problems were more common in the surgery group than in the casting group (29/298 people [10%] vs 4/275 [1%]).
- At six months, the mean cost to the NHS was £6050 for casting, compared with £6694 for surgery (mean difference −£644, 95% confidence interval −£1390 to £76). The mean cost to society was £7320 for casting, compared with £8003 for surgery (mean difference −£683, 95% confidence interval −£1851 to £536).
- The probability that casting was cost effective at common willingness-to-pay thresholds was very high (>95% for NHS and 85% for society).
What does current guidance say on this issue?
The 2016 British Orthopaedic Association Standard for Trauma on management of ankle fractures recommends early surgery (on the day or day after injury) for the majority of people under 60 years who have unstable ankle fracture. Surgery should aim to realign and stabilise the ankle. It states that close contact casts are an option in people over 60 years, if bone alignment can be maintained.
The 2016 NICE guideline on non-complex fractures recommends surgery for ankle fractures. It does not make any recommendations on the use of close contact casting.
What are the implications?
This study suggests that many unstable ankle fractures in older people could be initially treated with close contact casting. This conservative approach does not compromise function compared with surgery and would be cheaper for the NHS. However, implementing the technique in UK hospitals would require some cost in terms of training healthcare staff and closer follow-up of patients after treatment.
The actual levels of ankle function were quite poor for both treatment groups, suggesting a considerable level of impairment irrespective of treatment in older people who fracture their ankle. More focus may be needed on recovery and rehabilitation of older people who fracture their ankle.
Citation and Funding
Keene DJ, Mistry D, Nam J, et al. The Ankle Injury Management (AIM) trial: a pragmatic, multicentre, equivalence randomised controlled trial and economic evaluation comparing close contact casting with open surgical reduction and internal fixation in the treatment of unstable ankle fractures in patients aged over 60 years. Health Technol Assess. 2016;20(75):1-158.
This project was funded by the National Institute for Health Research Health Technology Assessment Programme (project number 07/37/61).
British Orthopaedic Association Standards for Trauma. Management of ankle fractures. BOAST 12. London: British Orthopaedic Association Standards for Trauma; 2016.
Donken CC, Al-Khateeb H, Verhofstad MH, et al. Surgical versus conservative interventions for treating ankle fractures in adults. Cochrane Database Syst Rev. 2012;(8):CD008470.
NHS Choices. Broken ankle. London: Department of Health; 2015.
NICE. Fractures (non-complex): assessment and management. NG38. London: National Institute for Health and Care Excellence; 2016.
NIHR Dissemination Centre. Alternatives to open surgery. London: National Institute for Health Research Dissemination Centre; 2016.
Willett K, Keene DJ, Mistry D, et al. Close contact casting vs surgery for initial treatment of unstable ankle fractures in older adults: a randomized clinical trial. JAMA. 2016;316(14):1455-63.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre