Digitized photographs and schematic illustrations of the apparatus used for simulating the stance phase of gait in fresh cadaver extremities. Click for 300DPI version.
Tel: 814-865-1972
Fax: 814-863-4755
Email: nas9@psu.edu
Website: www.kinesiology.psu.edu/research
Dr. Sharkey's research focuses on musculoskeletal physiology and tissue-level biomechanics, including functional aspects of normal, pathologic, and reconstructed skeletal tissues. Particular emphasis has been placed on developing laboratory protocols and techniques that facilitate the biomechanical study of normal, pathologic, and reconstructed bones and joints using cadaver material. These unique models attempt to load bones and joints in environments that accurately reproduce those experienced by the tissue in vivo. To do this, both physiologic muscle forces and externally applied loads are incorporated. The inability to simulate muscleaction has been a major problem in biomechanical studies employing cadaver material due to difficulties in coupling force-producing devices to fresh tendon. Dr. Sharkey's laboratory has developed 4 reliable method of attachment that can consistently and repetitively transmit forces comparable to forces produced by muscle in life. These devices, in conjunction with computer controlled stepper motors, servos, and electric linear actuators, have been used to simulate motion and loading in the hand, elbow, shoulder, hip, knee, and foot.
Over the last several years attention has been focused on issues related to foot function and pathology. Several recent publications describe the internal loading environment of the foot as a function of externally measurable loading parameters. Studies examining the temporal and spatial distributions of strain in bone, metatarsal stress fracture, the mechanical consequences of muscle and soft tissue dysfunction, tendo-Achilles lengthening, tendon transfer surgeries, and trauma about the ankle are ongoing. Funding agencies include the Whitaker Foundation, the American Orthopaedic Foot and Ankle Society, the Orthopaedic Trauma Association, and NASA,
Dr. Sharkey's laboratories are located in the Center for Locomotion Studies at the University Park Campus and are well equipped for researching the internal biomechanical behavior of musculoskeletal tissues. Operational models include a Dynamic Gait Simulator that reproduces normal gait in cadaver extremities (Figure). State-of-the-art instrumentation is available for accurate measurement of tissue-level force, displacement, and strain. Other resources include external force platforms, plantar pressure measurement systems, a new MTS Bionics servo-hydraulic testing machine, and a complete machine shop.
Goodwin, K.J., Sharkey, N.A.: Material properties of interstitial lamellae reflect local strain environments. Journal of Orthopaedic Research 20:600-606, 2002.
Michelson, J., Hamel, A.J., Buczek, F.L., Sharkey, N.A.: Kinematic behavior
of the ankle following malleolar fracture and repair in a high fidelity
cadaver model. Journal of Bone and Joint Surgery 84-A:2029-2037, 2002.
Peterman, M.M.; Hamel, A.J.; Cavanagh, P.R.; Piazza, S. J., and Sharkey, N.A.:
In vitro modeling of human tibial strains during exercise in micro-gravity.
Journal of Biomechanics 34(5): 693-698, 2001.
Donahue, S.W., Sharkey, N.A., Modanlou, K.A., Sequeira, L.N., Martin, R.B.:
Bone strain and microcracks at stress fracture sites in human metatarsals.
Bone 27(6):827-33, 2000.
Donahue, S.W. and Sharkey, N.A.: Strains in the metatarsals during the stance phase of gait: implications for stress fractures. Journal of Bone and Joint Surgery 81-A(9):1236-1244, 1999.
Sharkey, N.A., Hamel, A.J.: A dynamic cadaver model of the stance phase of
gait: performance characteristics and kinetic validation. Clinical Biomechanics
13:420-433, 1998.