DIFFERENCES IN LOWER EXTREMITY MECHANICS OF ACL RECONSTRUCTED AND NON-INJURED RUGBY UNION PLAYERS PERFORMING SIDESTEPS WITH AND WITHOUT A BALL CATCH

Abstract

Research has identified sidesteps, frequently performed evasive manoeuvres in field sports such as rugby union, as a mechanism of non-contact ACL injury but limited insight into the influence of ball catching during a sidestep upon the risks of ACL injury exists. This aim of this study was to enhance understanding of the biomechanical responses of non-injured and ACL reconstructed rugby union players’ during sidestep performance with and without a ball catch. The overall purpose of the research was to inform ACL rehabilitation programs in rugby union and assist the development of criteria for a safe return to competition after ACL reconstruction. Three ACL rehabilitated (ACLR) athletes (mean ± SD age 20.2 ± 1.9 yrs, height 181.4 ± 7.4 cm, mass 78.7 ± 7.9 kg) and three non-injured (NI) athletes (age 20.5 ± 1.1, height 180.6 ± 7.1 cm and mass 83.8 ± 9.9) completed three sidestep, and three sidestep and catch trials to 45° off both legs. CODA motion (200 Hz) and force plate (1000 Hz) analysis were used to obtain three dimensional kinematic and kinetic data of sidesteps. ACLR athletes demonstrated significantly greater (p=0.043) knee extension angles than NI athletes during sidestep and catch conditions. Both ACLR and NI athletes displayed greater hip abduction during sidesteps with a catch. ACLR athletes exhibited significantly higher (p=0.023) peak knee joint flexion moments of -2.61 N•m•kg-1 during the sidestep and catch condition when compared to NI athletes moments of -2.56 N•m•kg-1. Higher knee extension and hip abduction angles alongside higher peak knee moments suggested greater ACL injury risks. Catching a ball during a sidestep may increase the risks of ACL injury due to changes in kinematics and kinetics. Athletes may be guided to include hamstring conditioning during prevention and rehabilitation protocols to reduce knee extension angles during sidesteps to safer levels.