Intraoperative Optimization and Validation of Musculoskeletal Reconstruction

点击翻译按钮获取中文摘要

The long-term goal of this project is to improve the outcome of surgical procedures involving skeletal muscle transfer, whether muscle transposition or transplantation. Under previous support from V.A. Rehab R&D, we characterized the design of muscles involved in tendon transfer surgery and developed high-resolution tools with which to study them. In this proposal, we exploit a relatively rare surgical procedure for brachial plexus injury, in which the gracilis muscle is surgically isolated and then transplanted into the arm to act as an elbow flexor. The key idea is that this surgical procedure allows us, for the first time, to completely characterize a single human skeletal muscle intraoperatively and then to predict and subsequently test its function in vivo. Further, because gracilis is the only muscle acting at the elbow we can explicitly test our model to optimize this and related types of surgery since no other muscles are involved in the elbow flexion movement. Our three aims are (1), to measure gracilis muscle sarcomere length and active and passive mechanical properties intraoperatively during surgical transplantation in 30 patients, (2) to compare predicted and actual function of the transferred gracilis muscle one- and two-years postoperatively, and (3) to develop a practical tool to train surgeons to perform these complex procedures. This proposal consists of three aims. The first two aims are interconnected. Aim 1 presents a sophisticated intraoperative experiment in which gracilis muscles are measured in vivo, in isolation, and then after transplantation into the arm. This aim is based on our previous intraoperative experience with tendon transfer surgery and biomechanical testing of muscle. The novelty of this experiment is that, for the first time, a complete structural and functional data set will be obtained from a single human muscle. In aim 2, using a deterministic model of muscle function (rather than current models which are indeterminate and must be solved by optimization), we will determine whether the typical biomechanical modeling approaches used in the field can accurately predict elbow flexion torque given the most detailed set of tissue-level parameters ever directly collected from a human muscle. If it is, this will be the first explicit validation of such an approach. If it is not, we will be able to identify and isolate the factor(s) that are obstacles to simulation validity. Aim 3 came directly out of our discussions with surgeons at the Mayo Clinic. We have spent a tremendous amount of time training them regarding muscle active and passive mechanical and functional properties as we perform these procedures. However, they encouraged us to create a training tool that would allow other surgeons across the country to be trained using the same concepts but not in the actual operating room. Aim 3 does just that by programming an ergometer to “feel” just like a muscle in the operating room and then to practice “transferring” it based on its known properties. Successful completion of this project will improve our understanding of human skeletal muscle biomechanics, test our ability to model human joint function, and provide concrete surgical guidelines for this brachial plexus surgery and related tendon transfer surgeries.