title: Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health.
abstract: BACKGROUND
  Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI).
  
  
  RESULTS
  The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9).
  
  
  CONCLUSIONS
  All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans.
authors.forename: Colleen L
authors.initials: CL
authors.lastname: McHenry
authors.forename: Jason
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Physical Therapy & Rehabilitation Science, Carver College of Medicine, University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, USA. richard-shields@uiowa.edu.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Shields
mesh_terms: D006801:Humans; D012038:Regeneration; D013314:Stress, Mechanical; D014732:Vibration