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Background: Few prospective studies have investigated the biomechanical risk factors of anterior cruciate ligament (ACL) injury. Purpose: To investigate the relationship between biomechanical characteristics of vertical drop jump (VDJ) performance and the risk of ACL injury in young female basketball and floorball players. Study Design: Cohort study; Level of evidence, 3. Methods: At baseline, a total of 171 female basketball and floorball players (age range, 12-21 years) participated in a VDJ test using 3-dimensional motion analysis. The following biomechanical variables were analyzed: (1) knee valgus angle at initial contact (IC), (2) peak knee abduction moment, (3) knee flexion angle at IC, (4) peak knee flexion angle, (5) peak vertical ground-reaction force (vGRF), and (6) medial knee displacement. All new ACL injuries, as well as match and training exposure, were then recorded for 1 to 3 years. Cox regression models were used to calculate hazard ratios (HRs) and 95% CIs. Results: Fifteen new ACL injuries occurred during the study period (0.2 injuries/1000 player-hours). Of the 6 factors considered, lower peak knee flexion angle (HR for each 10° increase in knee flexion angle, 0.55; 95% CI, 0.34-0.88) and higher peak vGRF (HR for each 100-N increase in vGRF, 1.26; 95% CI, 1.09-1.45) were the only factors associated with increased risk of ACL injury. A receiver operating characteristic (ROC) curve analysis showed an area under the curve of 0.6 for peak knee flexion and 0.7 for vGRF, indicating a failed-to-fair combined sensitivity and specificity of the test. Conclusions: Stiff landings, with less knee flexion and greater vGRF, in a VDJ test were associated with increased risk of ACL injury among young female basketball and floorball players. However, although 2 factors (decreased peak knee flexion and increased vGRF) had significant associations with ACL injury risk, the ROC curve analyses revealed that these variables cannot be used for screening of athletes.

Background Little epidemiological information exists on overuse injuries in elite road cyclists. Anecdotal reports indicate anterior knee pain and lower back pain may be common problems. Purpose This study was conducted to register overuse injuries among professional road cyclists with special focus on anterior knee and lower back pain. Study Design Descriptive epidemiology study. Methods We attended training camps of 7 professional teams and interviewed 109 of 116 cyclists (94%) on overuse injuries they had experienced in the previous 12 months. Injuries that required attention from medical personnel or involved time loss from cycling were registered. Additional information on anterior knee pain and lower back pain was collected using specific questionnaires. Results A total of 94 injuries were registered; 45% were in the lower back and 23% in the knee. Twenty-three time-loss injuries were registered—57% in the knee, 22% in the lower back, and 13% in the lower leg. Fifty-eight percent of all cyclists had experienced lower back pain in the previous 12 months, and 41% of all cyclists had sought medical attention for it. Thirty-six percent had experienced anterior knee pain and 19% had sought medical attention for it. Few cyclists had missed competitions because of pain in the lower back (6%) or anterior knee (9%). Conclusion Lower back pain and anterior knee pain were the most prevalent overuse injuries, with knee injuries most likely to cause time loss and lower back pain causing the highest rates of functional impairment and medical attention. Clinical Relevance Future efforts to prevent overuse injuries in competitive cyclists should focus on lower back pain and anterior knee pain.