Reliability and methodological concerns of vertical drop jumping and sidestep cutting tasks: implications for ACL injury risk screening

Abstract

Vertical drop jumping (VDJ) and sidestep cutting tasks have been suggested as movement screening tasks to identify players with increased risk for ACL injury. Previous studies have investigated the reliability of kinematics and kinetics in the two tasks, however the validity is questionable because of small sample sizes or inappropriate statistical methods. The common method for assessing motion characteristics in such tasks is marker-based 3D motion analysis. However, soft tissue artifacts, particularly at the thigh segment, may largely influence the measurements. Thigh marker placement is typically not standardized and the influence on the measured knee kinematics are not yet quantified. It is commonly assumed that movement screening tasks may be improved by making them more challenging, e.g. by adding an overhead target to the VDJ test, in order to distract the focus from keeping proper knee control, while attempting to reach the target. The overhead target can thus possibly provoke knee loading and increase the sensitivity of the task to assess ACL injury risk, but this has not yet been showed in a scientific study. The aims of this thesis were therefore to investigate the reliability of the selected lower limb biomechanical measurements from the VDJ and sidestep cutting tasks, as well as the effect of thigh marker placement, and the inclusion of an overhead target on joint kinetics and kinematics.

Paper I: Reliability of knee biomechanics during a vertical drop jump in elite female athletes. Submitted to Gait & Posture

Paper II: Reliability of lower limb biomechanics in two sport-specific sidestep cutting tasks. Submitted to Gait & Posture

Paper III: The effect of thigh marker placement on knee valgus angles in vertical drop jumps and sidestep cutting. Journal of Applied Biomechanics 2015:31(4):269-274.

Paper IV: The effect of overhead target on the lower limb biomechanics during a vertical drop jump test in elite female athletes. Resubmitted with major changes to Scandinavian Journal of Medicine and Science in Sports