The effect of ankle bracing on joint dynamics in the lower limb during jumping tasks in elite female athletes

Abstract

Wearing ankle braces reduces the incidence of new and recurring ankle injuries in sports. Several studies have examined the effect of bracing on the mechanics of the ankle but little research has been done examining biomechanical changes at the knee and hip when ankle braces are used. The purpose of this study was to determine if the application of an ankle brace had an effect on the kinematics and kinetics of the ankle, knee and hip joints during two simulated athletic jumping manoeuvres. Eight members of the University of Saskatchewan Women’s Huskie Basketball team were recruited for this study. Each subject performed a series of single leg jump landing/takeoff manoeuvres in forward and sideways directions while their movements and ground reaction forces (GRF) were recorded. The participants performed the movements both with and without wearing a lace-up style ankle brace. Dependent variables for this study included ground reaction forces (GRF) and ankle, knee and hip joint angles and joint moments as well as ankle and knee joint stiffness. Comparisons were made between the braced and non-braced conditions using paired t-tests. Using a conservative statistical approach, significant changes were only observed for ankle joint kinematics, with the braced condition exhibiting significant decreased overall sagittal range of motion, and a significant increase in ankle external rotation. A strong trend for increased ankle inversion was also observed during both the forward and sideways manoeuvres. There were no significant differences for GRFs, in ankle knee or hip joint moments or knee and hip kinematics at the p<0.001 level for any time point during contact. During the braced condition the GRFs displayed a strong trend for increasing in magnitude as well as decreasing in time to peak magnitude, with the largest differences observed in the breaking and vertical GRFs at or near the time of impact. Trends were observed in ankle moments with an increase in the eversion moment, plantar flexor moment and external rotation moment at impact. Smaller kinematic changes were observed at the knee joint with trends indicating an increase in knee flexion at impact and a decrease in knee abduction angle. The hip did not display any difference with regards to kinematic changes however there was a trend for increased hip flexion moments at impact. There were no major differences observed for GRFs, ankle, knee or hip kinematics or kinetics during the propulsive phase of each movement. These results indicate that the largest ankle brace effect is primarily constrained to the time period surrounding impact with the ground and the largest change in joint mechanics occurs at the ankle.