Design and Validation of Implantable Passive Mechanisms for Orthopedic Surgery
Abstract
The suture has been central to surgery for 30,000 years. It requires only a thread and a needle, and its function of securely attaching tissues while healing is simple. However, when used in reconstructive orthopedic surgery, the suture is mostly limited to repairing tendons to transmit movement and forces directly between the muscle and tendon. Specifically, the suture couples the movement of the muscle and tendon(s) to replicate prior function and cannot preferentially enhance, scale, or distribute a muscle s force and movement across the tendon(s). These two properties of the suture limit both post-surgery functional outcomes and surgical choices for trauma patients. The long-term goal of this work is to advance orthopedic surgery by designing implantable, miniature, passive mechanisms, such as insertable rods and tendon networks, for enhancing the functional attachment of muscle to tendon(s) and bone in place of using the direct suture for the same purpose. Specifically, inspired by the use of such passive mechanisms in the design of robotic grippers, we seek to design and use similar passive mechanisms to "re-engineer" the transmission of forces and movement within the human body. A fundamental ingredient in this work is to design these implants so that the mechanism may be surgically constructed in situ by using the existing biological tendons as much as possible. When used in place of the direct suture to attach muscle and tendon(s), the implanted mechanism will enable superior and customizable manipulation and locomotion capability using the patient s natural musculature without external power or control input. As a first step to achieving the long-term goal, this 3-year Neuromusculoskeletal Injuries Research Award proposal will design, fabricate, and validate a biocompatible implantable rod that enables the surgical construction of a "differential mechanism" in situ using existing biological tendons in the tendon-transfer surgery for high median-ulnar nerve trauma. High median-ulnar nerve trauma disables the finger flexor muscles and thus precludes the grasping of objects. The current surgery seeks to restore hand grasping capability by transferring all four deep flexor tendons to a wrist muscle. However, this surgery uses sutures to make the attachment between the muscle and the tendons, and this results in coupled finger movement and poor grasping capability. The proposed work seeks to replace the suture used in the surgery with a "differential" mechanism constructed using an implanted insertable rod that can route the forces and movements from one muscle to multiple tendons while allowing variable movement in each finger. Specifically, the mechanism will enable the fingers to naturally conform to objects of various shapes and require less force from the muscle during grasping tasks, thus improving hand function. The implants designed will be validated through biomechanical simulations and human cadaver arms and live animals. Expected Timeframe: The expected timeframe for a patient-related outcome is 2022-2023. This includes 3 years of the research proposed here (2016-2019) and 4 years to translate the technology for clinical use and conduct clinical trials (2019-2023). Military and Public Benefit: Upper-extremity injuries are the most common war injury impacting Soldiers in the U.S. military. Reconstructive orthopedic surgeries, such as tendon transfers, have been extensively utilized to help wounded military personnel and civilians regain hand function for a variety of conditions such as spinal, nerve, or muscle trauma, stroke, and paralysis. Statistics show that about 20,000 hand tendon-transfer surgeries are performed annually in the United States alone. In addition to addressing the drawbacks in current tendon-transfer surgery, the proposed technology is also applicable to joint-replacement surgeries (over one million per year in the United States) and in the area of regenerative
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610794
Entities
People
- Ravi Balasubramanian
Organizations
- Oregon State University
- United States Army