Comparison of Drop Jumps and Sport-Specific Sidestep Cutting

Abstract

Background: Anterior cruciate ligament (ACL) injuries are a serious problem, with a high incidence and serious consequences. Published clinical screening tests are based on 2-legged and controlled drop jumps, but ACL injuries are known to occur in single-legged landings and sidestep cutting, where the load is predominantly distributed to a single leg. Purpose: To describe knee kinematics and kinetics in drop jumps and sidestep cutting and investigate the rank correlation of knee valgus angles and knee abduction moments between and within these movements. Study Design: Controlled laboratory study. Methods: A total of 120 elite female handball players (mean ± SD: age, 22.4 ± 7.1 years; height, 171 ± 7 cm; weight, 67 ± 7 kg), each performed 3 drop jumps and 3 sport-specific sidestep cuts to each side. Kinematics and kinetics were calculated from high-speed 3-dimensional motion analysis. Results: Knee kinematics and kinetics were significantly different between drop jumps and sidestep cutting. The knee abduction moment was 6 times higher in sidestep cutting (1.58 ± 0.60 Nm/kg vs 0.25 ± 0.16 Nm/kg). There was a poor correlation between knee abduction moments (ρ = 0.135) in the 2 tasks, but a moderate correlation (ρ = 0.706) for knee valgus angles. There was a poor correlation between knee valgus angles in drop jumps and knee abduction moments in sidestep cuts (ρ = 0.238). Conclusion: Motion patterns are different between drop jumps and sidestep cutting. There is a moderate correlation for knee abduction moments between the 2 tasks, but knee abduction moments are less consistent across tasks. Clinical Relevance: Knee valgus angles during drop jumps do not predict knee abduction moments during sidestep cutting. The moderate correlation of knee valgus angles in drop jumps and sidestep cutting indicates that this measure may be more relevant for screening efforts.