Co-Principal Investigators: Wendy M. Murray, PhD and V. Rodney Hentz, MD Co-Investigators: Felix E. Zajac, PhD; M. Elise Johanson, MS, PT; Joseph D. Towles, PhD; and Niels Smaby, PhD Objective: This project aims to establish specific, objective procedural guidelines for determining the length at which donor muscles in tendon transfer surgeries should be set to best restore function. The brachioradialis is often used as a donor muscle for tendon transfers that restore wrist and hand function after tetraplegia. Restored function often depends on elbow position, wrist position, and thumb posture after brachioradialis transfers. There is evidence that intra-operative surgical tensioning is the critical factor that determines in what joint postures the transferred muscle is strongest. We hypothesize that the functional outcomes can be improved by optimizing surgical tensioning. Research Plan: We completed biomechanical computer simulations of two common brachioradialis transfers, quantified current surgical techniques using a laser diffraction device to measure muscle sarcomere lengths intra-operatively, and implemented innovative, scientific-based tools to test hand impairment and function before and after brachioradialis transfers. Work Accomplished: The major initiative of this grant period was to determine the relationship between surgical tensioning and post-operative hand impairment and function. As a result of our multi-faceted approach, we assembled a cohesive set of results from computer simulations, intra-operative studies, and post-operative assessments that demonstrated the potential of surgical attachment length to predictably alter the functional outcomes of tendon transfers. The work accomplished this grant period positioned us appropriately to design a multi-center clinical study that will provide the first direct evidence that the surgeon’s choice of surgical attachment length has a known effect on post-operative outcome. The proposal for the multi-center study received a fundable score, and we are currently coordinating human subjects approvals at six sites to facilitate initiation of that project. The current project will remain open until the multicenter study begins. Expected Outcome: This project combined intraoperative data describing surgical technique with theoretical computer simulations and post-operative assessments of hand function to provide evidence that suggests different choices of surgical attachment length for brachioradialis tendon transfers may alter outcomes in a quantifiable way. This study produced several clinically testable hypotheses, which will be fully demonstrated when the intraoperative data are paired with post-operative assessments in the same patients, which is the objective of the funded multi-center study. This work will educate surgeons on the consequences of different surgical techniques. Understanding the relationship between surgical technique and post-operative muscle function will provide surgeons more control of clinical outcomes. Publications Johanson ME, Smaby N, Hentz VR, and Murray WM. Reduced activation in transferred brachioradialis muscles to restore lateral pinch in tetraplegia. J Hand Surg. 2006, 31:747- 53, 2006. Murray WM, Hentz VR, Fridén J, Lieber RL. The significance of surgical attachment length for hand and wrist function following brachioradialis tendon transfer. J Bone Jt Surg. 2006, 88:2009-2016. Johanson ME and Radtka SA. Amplitude threshold criteria improve surface electrode specificity during walking and functional movements. Gait and Posture. 2006, 24:429- 34. Abstracts Johanson ME, Murray WM, Smaby N, Hentz VR. Effect of elbow strength on lateral pinch function following tendon transfer in spinal cord injury. Platform presentation Combined Sections Meeting of APTA in San Diego, CA, Feb 2006. Johanson ME, Murray WM, Smaby N, Hentz VR. Relationship between muscle activation and pinch strength after tendon transfer in spinal cord injury Journal of Neurologic Physical Therapy Vol, 30 no, 4 p. 205, 2006. Johanson ME, Loomis V, Broberg M, Houghtaling J, Chang J, Hentz VR. Comparison of surgical interventions for thumb carpometacarpal joint arthritis using thumb-tip force and pinch stability measurements. Poster presentation at the American Society for Surgery of the Hand, Washington DC, September 6-9, 2006. Funding Source: Department of Veterans Affairs - Merit Review
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