Sanchez, G.N., Sinha, S., Liske, H., Chen, X., Nguyen, V., Delp, S.L., Schnitzer, M.J. In Vivo Imaging of Human Sarcomere Twitch Dynamics in Individual Motor Units. Neuron, vol 88, pp 1109-1120. Download PDF Document
Wireless optogenetics research appears on cover of Nature Methods.
Keenan, K.E., Besier, T.F., Pauly, J.M., Smith, R.L., Delp, S.L., Beaupre, G.S., Gold, G.E.. T1rho dispersion in articular cartilage: relationship to material properties and macromolecular content. Cartilage, 6(2), 113-122
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Gerus, P., Sartori, M., Besier, T.F., Fregly, B.J., Delp, S.L., Banks, S.A., Pandy, M.G., D’Lima, D.D., Lloyd, D.G. Subject-specific knee joint geometry improves predictions of medial tibiofemoral contact forces. Journal of Biomechanics, vol 46, pp 2778-2786. Download PDF Document
Persons with cerebral palsy frequently walk with a crouched, internally rotated gait. Spastic medial hamstrings or adductors are presumed to contribute to excessive hip internal rotation in some patients; however, the capacity of these muscles to produce internal rotation has not been adequately investigated. The purpose of this study was to determine the hip rotation moment arms of the medial hamstrings and adductors in persons with femoral anteversion deformities who walk with a crouched, internally rotated gait. A musculoskeletal model with a “deformable” femur was developed. This model was used, in conjunction with kinematic data obtained from gait analysis, to calculate the muscle moment arms for combinations of joint angles and anteversion deformities exhibited by 21 subjects with cerebral palsy and excessive hip internal rotation. We found that the semimembranosus, semitendinosus, and gracilis muscles in our model had negligible or external rotation moment arms when the hip was internally rotated or the knee was flexed — the body positions assumed by the subjects during walking. When the femur was excessively anteverted, the rotational moment arms of the adductor brevis, adductor longus, pectineus, and proximal compartments of the adductor magnus in our model shifted toward external rotation. These results suggest that neither the medial hamstrings nor the adductors are likely to contribute substantially to excessive internal rotation of the hip and that other causes of internal rotation should be considered when planning treatments for these patients.
Besier, T.F., Pal, S., Draper, C.E., Fredericson, M., Gold, G.E., Delp, S.L., Beaupre, G.S. The role of cartilage stress in patellofemoral pain. Medicine & Science in Sports & Exercise, vol 47, pp 2416-2422. Download PDF Document
Ong, C.F., Hicks, J.L., Delp, S.L. Simulation-Based Design for Wearable Robotic Systems: An Optimization Framework for Enhancing a Standing Long Jump. IEEE Transactions on Biomedical Engineering, in press. Download PDF Document
Wireless optogenetics research appeared in the Stanford Report.
Montgomery, K.L., Yeh, A.J., Ho, J.S., Tsao, V., Iyer, S.M., Grosenick, L., Ferenczi, E.A., Tanabe, Y., Deisseroth, K., Delp, S.L., Poon, A.S.Y. Wirelessly powered, fully internal optogenetics for brain, spinal and peripheral circuits in mice. Nature Methods, vol 12, pp 969-974. Download PDF Document
Ku, J.P., Hicks, J.L., Hastie, T., Leskovec, J., Re, C., Delp, S.L. The mobilize center: an NIH big data to knowledge center to advance human movement research and improve mobility. Journal of the American Medical Informatics Association, vol 22, pp 1120-1125. Download PDF Document