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Stiff landings in vertical drop jump test associated with increased risk of ACL injury
Young female basketball and floorball players who demonstrated stiff landings with less knee flexion and greater vertical ground-reaction force in a vertical drop jump test had a greater risk of ACL injury, according to results.
Mari Leppänen, MSc, and colleagues analyzed knee valgus angles at initial contact, peak knee abduction moment, knee flexion angle at initial contact, peak knee flexion angle, peak vertical ground-reaction force and medial knee displacement in 171 female basketball and floorball players who participated in a vertical drop jump test using 3-D motion analysis. Researchers recorded all new ACL injuries, as well as match and training exposure for 1 year to 3 years.
During the study period, results showed 15 new ACL injuries occurred. Researchers noted factors associated with increased risk of ACL injury included lower peak knee flexion angle and higher peak vertical ground-reaction force. An area under the curve of 0.6 and 0.7 for peak knee flexion and vertical ground-reaction force, respectively, indicated a failed-to-fair combined sensitivity and specificity of the test, according to results of a receiver operating characteristic curve analysis. – by Casey Tingle
Disclosure: This study was financially supported by the Finnish Ministry of Education and Culture, by the Finnish Olympic Committee and by the Competitive State Research Financing of the Expert Responsibility Area of Tampere University Hospital.
Perspective
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Leppanen and colleagues in a longitudinal prospective study found female athletes who go on to tear their ACL land with higher vertical ground reaction force and less knee flexion. Contrary to their expectations, they did not find that frontal plane mechanics were related to ACL injury.
The results of this study suggest efforts should be directed at facilitating a less stiff landing to reduce ACL injury risk. However, while associated with ACL injury, these aberrant mechanics could not predict ACL injury with adequate sensitivity and specificity. Orthopedic surgeons, should be aware that no one screening test may reveal ACL injury or re-injury risk. Additionally, these results support counseling patients to avoid stiff landings to minimize ACL injury and perhaps re-injury risk.