CAST ankle sprain trial

Mechanical supports for acute, severe ankle sprain: a pragmatic, multicentre, randomised controlled trial

Lamb SE, Marsh JL, Hutton JL, et al. Lancet (London, England) 2009 · PMID 19217992 · doi:10.1016/s0140-6736(09)60206-3

Question

For severe acute ankle sprains, which form of mechanical support gives the fastest recovery of ankle function?

Design

Pragmatic multicentre RCT with blinded outcome assessment in eight UK emergency departments (Collaborative Ankle Support Trial).

Patients

Adults attending UK emergency departments with a severe acute ankle sprain.

Intervention

Below-knee cast for 10 days, Aircast brace, or Bledsoe boot

Comparison

Double tubular compression bandage

Primary outcome

Quality of ankle function (Foot and Ankle Score) at 3 months

Key result

A short period in a below-knee cast gave a faster recovery than tubular bandage, with the Aircast brace also beneficial; the Bledsoe boot did not show benefit. Differences narrowed by 9 months.

Limitations

Participants could not be blinded to their support (although outcome assessment was blinded); severity was judged clinically rather than by imaging.

Impact on practice

Tubular bandage alone is a poor choice for severe sprains; a brief cast or a brace is reasonable to speed early recovery.