Effect of Semi-Rigid and Soft Ankle Braces on Static and Dynamic Postural Stability in Young Male Adults

Ankle braces have been suggested to protect ankle joints from a sprain by restricting inversion and improving proprioception. However, the difference in effects between a semi-rigid brace and a soft brace regarding dynamic postural control after landing is not known. The aim of the present study was to compare the effect of soft (SB) and semi-rigid (SRB) ankle braces on static and dynamic postural stability in healthy young men. Altogether, 21 male adults (mean age 24.0 ± 1.5 years) were assessed for one leg while wearing non-brace (NB), SB or SRB. Balance in single-limb stance on a single-force platform with open eyes and closed eyes were assessed for the non-dominant leg under SB, SRB, and NB conditions. Locus length/second (mm/s) and the enveloped area (mm·s-2) surrounded by the circumference of the wave pattern during postural sway were calculated. For assessing dynamic postural stability, the participant jumped and landed on one leg on a force platform, and the Dynamic Postural Stability Index (DPSI) and the maximum vertical ground reaction force (vGRFmax) were measured. The data were compared among the three conditions with repeated-measures analysis of variance. The correlations between locus length/second, enveloped area, DPSI values (DPSI, Anterior-Posterior Stability Index, Medial-Lateral Stability Index, and Vertical Stability Index), and vGRFmax were then calculated. The results indicated that locus length/second and enveloped area with open eyes and closed eyes were not significantly different for each condition. However, a significant lower in the DPSI and Vertical Stability Index were observed with the SRB in comparison to the SB and NB. A significant improvement in vGRFmax was also observed with the SRB in comparison to NB. SRB demonstrated a positive effect on dynamic postural stability after landing on a single leg and may improve balance by increasing dynamic postural stability. Key points This study examined the effect of ankle braces on healthy young individuals during dynamic postural stability using the DPSI. The semi-rigid brace improved dynamic postural stability compared with the soft brace and no brace. Key words: Ankle brace, static postural balance, dynamic postural balance, Dynamic Postural Stability Index Introduction Ankle sprain occurs commonly among athletes in sports (Hootman et al., 2007; Mack et al., 1982; van den Bekerom et al., 2012). An ankle sprain accounts for 14.8% of all injuries in collegiate sports, and the athletes who participate in activities that involves jumping and landing, such as basketball and volleyball, have a higher chance of ankle sprain (Hootman et al., 2007). Pain, decreased range of motion, and functional instability occur as a result of ankle sprains (Ivins et al., 2006). Yeung et al. (1994) reported that 30.2% of patients experience pain. Ankle sprains recur at a high rate (56t74%) (McKay et al., 2001), and repeated ankle sprain leads to chronic ankle instability. Because chronic ankle instability incurs enormous economic and social costs, preventing lateral ankle sprain recurrence is important. Ankle braces are used as one of the preventive measures against ankle sprains. The benefit of the ankle brace includes: 1) decreasing anterior tibial shear force; 2) decreasing range of motion in ankle and subtalar joints; 3) improving ankle proprioception facilitated by mechanoreceptors; and 4) maintaining dynamic balance ability (Hardy et al., 2008). An ideal ankle brace should protect the ankle from lateral ligament injury without restraining its normal movement. There are various ankle braces, including soft braces, semi-rigid braces, and rigid braces. The braces are prescribed widely to prevent sports injuries during athletic practice or competitions and treat them if they do sustain an injury. Sitler et al. (1994) reported that use of a semi-rigid brace (SRB) could significantly reduce the frequency of ankle injuries. Clinically, SRBs are believed to help athletes with functional ankle instability by improving neuromuscular control and mechanical stability. The ability of ankle braces to prevent ankle sprain, however, is still debatable (McGuine et al., 2012). Although a number of studies have investigated the effect of ankle braces on postural control, evidence on the effects of ankle braces on postural control is still inconclusive. Guskiewicz and Perrin (1996) and Baier and Hopf (1998) reported the positive effects of ankle braces on postural control. To the best of our knowledge, however, there have been no comparisons of the effects of soft braces (SB) and SRBs on static or dynamic postural control after landing. Dynamic postural control can be assessed using the Dynamic Postural Stability Index (DPSI) (Wikstrom et al., 2006). The DPSI assesses balance while the subject transits from a dynamic to static state in single-leg hop stabilization maneuver. Thus it is a functional measurement of neuromuscular control (Wikstrom et al., 2006). The effects of the SB, SRB, and no brace (NB) on static and dynamic balance could have implications for athletes, trainers, and rehabilitation staff. The difference in the effects of SRB and SB on static and dynamic postural control after landing is not known. The purpose of this study was to compare the effects of SBs and SRBs on static and dynamic postural control. We hypothesized that there are no difference between interventions in static postural sway and dynamic postural stability.