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Vol. 36 No. 3, July 1999

Abstract - Knee kinetics during functional electrical stimulation induced cycling in subjects with spinal cord injury: A preliminary study

John C. Franco, MD, MS; Karen L. Perell, PhD; Robert J. Gregor, PhD; A.M. Erika Scremin, MD

Department of Orthopedics, University of New Mexico, Albuquerque, NM; Physical Medicine & Rehabilitation Department, VA Greater Los Angeles Healthcare System--West Los Angeles Healthcare Center, Los Angeles, CA; Department of Medicine, Division of Physical Medicine and Rehabilitation, University of California Los Angeles, Los Angeles, CA; Department of Physical Therapy, Mount St. Mary's College, Los Angeles, CA; Department of Health and Performance Sciences, Georgia Institute of Technology, Atlanta, GA

Abstract--The purpose of this preliminary study was to describe pedal effectiveness parameters and knee-joint reaction forces generated by subjects with chronic spinal cord injury (SCI) during functional electrical stimulation (FES)-induced bicycling. Three male subjects (age 33--36 years old), who were post-traumatic SCI (ASIA-modified level A, level T4-C5) and enrolled in an FES rehabilitation program, signed informed consent forms and participated in this study. Kinematic data and pedal forces during bicycling were collected and effective force, knee-joint reaction forces, knee generalized muscle moments, and knee-joint power and work were calculated. There were three critical findings of this study: 1) pedaling effectiveness was severely compromised in this subject population as indicated by a lack of overall positive crank work; 2) knee-joint kinetics were similar in magnitude to data reported for unimpaired individuals pedaling at higher rates and workloads, suggesting excessive knee-joint loading for subjects with SCI; and 3) shear reaction forces and muscle moments were opposite in direction to data reported for unimpaired individuals, revealing an energetically unfavorable knee stabilizing mechanism. The critical findings of this study suggest that knee-joint kinetics may be large enough to produce a fracture in the compromised lower limbs of individuals with SCI.

Key words: bicycling, biomechanics, joint reaction forces, kinetics, knee joint, osteopenia, spinal cord injured

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