Tendon transfer surgeries to restore hand function after cervical spinal cord injury are not always as successful as expected. This study will attempt to develop better biomechanical models for predicting the outcome of the brachioradialis-to-flexor-pollicis-longus (Br-FPL) tendon transfer, a procedure that restores lateral pinch following tetraplegia. The PIs hypothesize that the effectiveness of the transferred Br is impaired because of post-operative muscle adaptations and weakness of elbow and wrist extensors. The goal of this study is to characterize the structural and functional changes that take place in transferred muscle, and to more accurately model the impairments associated with the surgically altered tetraplegic limb.
Aim 1 will define the maximum potential of the Br-FPL transfer to produce lateral pinch force. A nominal model of the transfer will characterize the clinical ideal, in which the transferred muscle has normal strength and can be maximally activated for its new function. Previous work suggests that this model will substantially overestimate actual pinch forces measured in subjects who have had transfers.
Aim 2 will determine the extent to which pre-operative weakness limits force production. Personalized simulations of Br-FPL tendon transfers will be developed for 8-10 surgical candidates based on preoperative assessments of Br cross-sectional area, obtained by medical imaging, and elbow and wrist extension strength. These models should predict pinch force better than the nominal model.
Aim 3 will identify post-operative changes to muscle and fiber architecture. The transferred Br will be reimaged and a novel electrophysiological technique will be applied. It is expected that the transferred muscle will have reduced cross-sectional area and lack distal bands of muscle fibers, and that models incorporating these differences will lead to even better predictions of actual outcomes.
Aim 4 will test the ability to fully activate the transferred Br during lateral pinch. EMG during maximum voluntary effort for pinch is expected to be less than EMG during maximum resisted elbow flexion (Br's original function), in part due to lack of wrist and elbow extension strength needed for joint stabilization. This work will identify and characterize factors responsible for disappointing surgical results, and this better understanding will lead to better treatment decisions.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD046774-02
Application #
6919889
Study Section
Special Emphasis Panel (ZHD1-RRG-K (11))
Program Officer
Quatrano, Louis A
Project Start
2004-07-15
Project End
2009-04-30
Budget Start
2005-05-01
Budget End
2006-04-30
Support Year
2
Fiscal Year
2005
Total Cost
$272,128
Indirect Cost
Name
Palo Alto Institute for Research & Edu, Inc.
Department
Type
DUNS #
624218814
City
Palo Alto
State
CA
Country
United States
Zip Code
94304
Seth, Ajay; Hicks, Jennifer L; Uchida, Thomas K et al. (2018) OpenSim: Simulating musculoskeletal dynamics and neuromuscular control to study human and animal movement. PLoS Comput Biol 14:e1006223
Buffi, James H; Sancho Bru, JoaquĆ­n Luis; Crisco, Joseph J et al. (2014) Evaluation of hand motion capture protocol using static computed tomography images: application to an instrumented glove. J Biomech Eng 136:124501
Nichols, Jennifer A; Bednar, Michael S; Murray, Wendy M (2013) Orientations of wrist axes of rotation influence torque required to hold the hand against gravity: a simulation study of the nonimpaired and surgically salvaged wrist. J Biomech 46:192-6
Buffi, James H; Crisco, Joseph J; Murray, Wendy M (2013) A method for defining carpometacarpal joint kinematics from three-dimensional rotations of the metacarpal bones captured in vivo using computed tomography. J Biomech 46:2104-8
Wohlman, Sarah J; Murray, Wendy M (2013) Bridging the gap between cadaveric and in vivo experiments: a biomechanical model evaluating thumb-tip endpoint forces. J Biomech 46:1014-20
Goehler, Craig M; Murray, Wendy M (2012) Computational Development of Jacobian Matrices for Complex Spatial Manipulators. Adv Eng Softw 47:160-163
Mogk, Jeremy P M; Johanson, M Elise; Hentz, Vincent R et al. (2011) A simulation analysis of the combined effects of muscle strength and surgical tensioning on lateral pinch force following brachioradialis to flexor pollicis longus transfer. J Biomech 44:669-75
Lateva, Zoia C; McGill, Kevin C; Johanson, M Elise (2010) The innervation and organization of motor units in a series-fibered human muscle: the brachioradialis. J Appl Physiol 108:1530-41
Goehler, Craig M; Murray, Wendy M (2010) The sensitivity of endpoint forces produced by the extrinsic muscles of the thumb to posture. J Biomech 43:1553-9
Holzbaur, Katherine R S; Delp, Scott L; Gold, Garry E et al. (2007) Moment-generating capacity of upper limb muscles in healthy adults. J Biomech 40:2442-9

Showing the most recent 10 out of 12 publications