Linemen are at high risk for knee cartilage injuries and osteoarthritis. High-intensity movements from squatting positions (eg, 3-point stance) may produce high joint loads, increasing the risk for cartilage damage. We hypothesized that knee moments and joint reaction forces during lineman-specific activities would be greater than during walking or jogging. Data were collected using standard motion analysis techniques. Fifteen NCAA linemen (mean ± SD: height = 1.86 ± 0.07 m, mass = 121.45 ± 12.78 kg) walked, jogged, and performed 3 unloaded lineman-specific blocking movements from a 3-point stance. External 3-dimensional knee moments and joint reaction forces were calculated using inverse dynamics equations. MANOVA with subsequent univariate ANOVA and post hoc Tukey comparisons were used to determine differences in peak kinetic variables and the flexion angles at which they occurred. All peak moments and joint reaction forces were significantly higher during jogging than during all blocking drills (all P < .001). Peak moments occurred at average knee flexion angles > 70° during blocking versus < 44° in walking or jogging. The magnitude of moments and joint reaction forces when initiating movement from a 3-point stance do not appear to increase risk for cartilage damage, but the high flexion angles at which they occur may increase risk on the posterior femoral condyles.
Rebecca L. Lambach is currently with the Musculoskeletal Research Laboratory, VA Palo Alto Health Care System, Palo Alto, CA; and the Department of Mechanical and Aerospace Engineering, Ohio State University, Columbus, OH. Jay W. Young is with the Department of Biomedical Engineering, Ohio State University, Columbus, OH. David C. Flanigan is with the Sports Health and Performance Institute and the Department of Orthopaedics, both at Ohio State University, Columbus, OH. Robert A. Siston and Ajit M.W. Chaudhari are with the Department of Mechanical and Aerospace Engineering, the Department of Biomedical Engineering, the Department of Orthopaedics, and the School of Health & Rehabilitation Sciences, Ohio State University, Columbus, OH.