A study of semi-rigid support on ankle supination sprain kinematics Y. M. Tang 1,5 , Z. H. Wu 2,5 , W. H. Liao 3 , K. M. Chan 4,5 1 Department of Industrial and Systems Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China, 2 Department of Civil Engineering, Shanghai University, Shanghai, China, 3 Department of Mechanical and Automation Engineering, Faculty of Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China, 4 The Hong Kong Jockey Club Sports Medicine and Health Sciences Centre, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China, 5 Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China [Corrections have been made to author affiliations after initial online publication.] Corresponding author: W. H. Liao, Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China. Tel: 852 2609 8341, Fax: 852 2603 6002, E-mail: whliao@mae.cuhk.edu.hk Accepted for publication 23 May 2009 Ankle sprain injury is very common in sports and the use of ankle support is crucial. This research investigated the effect of an ankle brace in reducing the ankle angular displacement and angular velocity during sudden supination. In the experiment, 11 healthy males were tested. The bracing condition, semi-rigid ankle braces were investigated. The angular displacement and angular velocity of the ankle were computed. The motion-capture system was adopted to capture the three-dimensional coordinates of the reflective markers. The coordinates of the reflective markers were used to compute the ankle kinematics during simulated ankle supination. A mechanical supination platform was used to simulate the sprain motions. Experimental results showed that the semi-rigid brace tested significantly reduced the ankle angular displacement and angular velocity com- pared with control conditions during sudden supination. In conclusion, the semi-rigid-type brace can provide significant restriction to reduce the magnitudes of the angular displace- ment and angular velocity of the ankle during sudden supination sprain. The semi-rigid-type brace is suggested as the prophylactic bracing for the ankle. Ankle injury is very common in sports (Galasko et al., 1982; Chan et al., 1984; Chan et al., 1993). Approximately 16% of sports injuries are an ankle injury (Purves & Chan, 1987; Fong et al., 2007). Ankle sprain is the most common injury, which accounts for 84% of the total ankle injuries (Purves & Chan, 1987; Fong et al., 2007). Ankle sprain is caused by excessive sudden supination torque at the ankle joint, and the use of ankle support is crucial for the treatment and prevention of an ankle sprain. Numerous researches have been conducted to deter- mine the effect of ankle support (Verhagen et al., 2000, 2001; Cordova et al., 2002). It was found that semi-rigid braces confer a significant restriction of ankle inversion motion. Ubell et al. (2003) evaluated the effect of ankle braces based on the ability of the braces to prevent forced ankle inversion. The semi- rigid braces proved to be more effective than the unbraced condition in preventing ankle inversion. Although the effect of ankle support in restricting the ankle range of motion (ROM) has been widely studied, little research has investigated the effect of ankle support in terms of ankle angular velocity and angular acceleration (Cordova et al., 2002). Evaluat- ing the effect of ankle support in reducing ankle angular velocity is important there exists good evi- dence to show that joint injuries were due to the rate of change of joint displacement over the limitation of tendons and ligaments rather than the displacement itself (Ozkaya & Nordin, 1998; Nordin et al., 2001). An investigation of angular velocity has been con- ducted by Cordova et al. (2007). They evaluated the effects of ankle bracing on rearfoot angular displace- ment and angular velocity during a sudden inversion movement. It was found that the semi-rigid ankle brace is better than the lace-up-style brace and bare- foot in restricting the angular displacement and angular velocity during a sudden inversion motion. Although numerous studies have focused on the ability of ankle supports to restrict ankle motion, the investigations were only focused on inversion mo- tion. The ankle stability and occurrence of ankle sprains were usually related to the functional anat- omy of the ankle (Hertel, 2002; Zwipp et al., 2002; Ferran, 2006), which was described as 231 of prona- tion and supination (Hertel, 2002). It remains unclear This article was published online on 17th September 2009. Errors were subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected as at 19th January 2010. Scand J Med Sci Sports 2010: 20: 822–826 & 2009 John Wiley & Sons A/S doi: 10.1111/j.1600-0838.2009.00991.x 822