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We investigated recovery of precision grasping of small objects between the index finger and thumb of the impaired hand without forced use after surgically placed lesions to the hand/arm areas of M1 and M1 + lateral premotor cortex in two monkeys. The unilateral lesions were contralateral to the monkey's preferred hand, which was established in prelesion testing as the hand used most often to acquire raisins in a foraging board (FB) task in which the monkey was free to use either hand to acquire treats. The lesions initially produced a clear paresis of the contralesional hand and use of only the ipsilesional hand to acquire raisins in the FB task. However, beginning about 3 weeks after the lesion both monkeys spontaneously began using the impaired contralesional hand in the FB task and increased use of that hand over the next few tests. Moreover, the monkeys clearly used precision grasp to acquire the raisins in a similar manner to prelesion performances, although grasp durations were longer. Although the monkeys used the contralesional hand more often than the ipsilesional hand in some postlesion testing sessions, they did not recover to use the hand as often as in prelesion testing when the preferred hand was used almost exclusively. These findings suggest that recovery of fine hand/digit motor function after localized damage to the lateral frontal motor areas in rhesus monkeys does not require forced use of the impaired hand.

Purpose: The A2 and A4 pulleys have been shown to be important in finger flexor tendon function. Other authors have suggested either reconstruction or venting of portions of these pulleys in an attempt to preserve finger function in certain clinical situations. This study examines the effects of partial incision of these pulleys on finger flexion kinematics and biomechanics., Methods: The index and ring fingers of 16 cadaveric hands were studied. The flexor digitorum profundus tendon was isolated and attached to a computer driven servo-motor. Micro-potentiometers measured flexion angles of the metacarpophalangeal, proximal inter-phalangeal and distal inter-phalangeal joints. Joint inertial torques were calculated making use of this experimental kinematic data., Results: Proximal 50 % incisions of either the A2 or the A4 pulleys resulted in a statistically significant decrease in overall finger motion. This effect was greatest in the proximal inter-phalangeal joint, with a decrease in joint motion, as well as an earlier time to initiation of motion. These changes in finger motion were more pronounced with A2 pulley incision than they were with A4 pulley incision, but the changes were statistically significant in either case. No significant changes in joint inertial torques were shown., Conclusions: Our data provides evidence to the importance of the proximal portions of the A2 and A4 pulleys, and may support partial distal incision of these pulleys in certain clinical situations.

Over the past two decades, results from neurophysiological studies in animal models and neuroimaging studies in human populations have converged along a common thread. Neuroplasticity in the remaining, intact tissue accompanies functional recovery after brain injury. Now, virtually every new therapeutic approach in postinjury rehabilitation relies on the fundamental principles of neuroplasticity for theoretical validity. In this chapter, the basic tenets of plasticity are outlined, and the neural substrates in the cerebral cortex that may subserve recovered functions are reviewed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Purpose: The purpose of this study was to quantify the changes in the arc of digital flexion before and after metacarpophalangeal (MCP) silicone arthroplasty with a 30 degrees preflexed design., Methods: Index, middle, and ring fingers of 4 fresh-frozen cadaver hands were used. Each hand was attached (palmar side up) to a custom test apparatus. The tendon was drawn by a small winch-type servomotor. Micropotentiometers that were attached to the centers of rotation of the MCP, distal interphalangeal, and proximal interphalangeal joints measured angular displacement before and after MCP arthroplasty as a function of tendon excursion. The data were analyzed comparing the angle of flexion initiation and the angular displacement as a function of tendon excursion before and after joint arthroplasty., Results: There were no statistical differences in the angles of the MCP joints at rest, the order of initiation of joint flexion, and the overall degree of flexion between the unoperated fingers and the fingers that had surgery. There was, however, a trend toward delay in flexion initiation, an increase in the MCP angle at rest, and a decrease in torque after implant arthroplasty., Conclusions: The decrease in initiation of flexion of the MCP joint, although not statistically significant, probably was related to the 30 degrees of preflexion built into the implant. We also noted a trend of decreased flexion at the MCP joint and increased flexion at the proximal interphalangeal and distal interphalangeal joints. This trend may be advantageous in the reconstruction of hands that initially have an MCP joint flexion deformity., Type of Study/level of Evidence: to come.