10-day below-knee cast for management of severe ankle sprains

Abstract

S E Lamb and colleagues (Feb 14, p 575)1Lamb SE Marsh JL Hutton JL Nakash R Cooke MW on behalf of the Collaborative Ankle Support Trial (CAST Group)Mechanical supports for acute, severe ankle sprain: a pragmatic, multicentre, randomised controlled trial.Lancet. 2009; 373: 575-581Summary Full Text Full Text PDF PubMed Scopus (146) Google Scholar investigated the effectiveness of three types of mechanical support for acute ankle sprains and found that a short period of immobilisation with a below-knee cast resulted in better ankle function than a tubular compression bandage. Clinically important benefits (foot and ankle score) were found at 3 months' follow-up with the below-knee cast; however, no self-perceived benefits were found at this time. To what extent, then, did the knee cast result in a faster recovery? A systematic review2van Rijn RM van Os AG Bernsen RM Luijsterburg PA Koes BW Bierma-Zeinstra SM What is the clinical course of acute ankle sprains? A systematic literature review.Am J Med. 2008; 121: 324-331Summary Full Text Full Text PDF PubMed Scopus (391) Google Scholar reported a resprain occurrence of 3–34% within 1 year of the initial injury. It is regrettable that Lamb and colleagues did not present the number of resprains that occurred during the follow-up period. It is plausible that the number of resprains is strongly correlated with self-perceived recovery. Another point of discussion is the patients' correct use of the mechanical supports. Lamb and colleagues report that they were unable to attain accurate reports on compliance with the bracings protocol, but they expected similar compliance across all groups. It is however probable that patients with a removable support such as the tubular compression bandage, the Bledsoe boot, and the Aircast are more likely to violate the protocol than patients with a below-knee cast that could not be removed. Incidentally, Lamb and colleagues report that 19 patients were wearing the below-knee cast at 1-month follow-up “now and then”. How is this possible for a non-removable support? Finally, Lamb and colleagues emphasise the importance of limiting movement of the ankle joint, but one might also argue the importance of the non-weight-bearing period. The weight-bearing period might be more guaranteed by the below-knee cast support and therefore account for the treatment effect. The number of resprains and the possible lack of compliance with the protocols could have overestimated the study effects; therefore, Lamb and colleagues' recommendation should be interpreted with some caution. We declare that we have no conflicts of interest. 10-day below-knee cast for management of severe ankle sprains – Authors' replyWe thank colleagues for their comments on our paper. Many of the judgments rest on an understanding of pragmatic trials. Full-Text PDF