Use of Subcutaneous Silk Scaffolds to Modulate the Interface Between Skin and Percutaneous Osseointegrated Prostheses for Traumatic Limb Amputations
Abstract
This work aims to improve the interface between skin and the prosthetics directly attached to the amputee’s bone stump using silk scaffold to provide the patients with increased mobility and function, while reducing potential infection at the interface site and loosening of the implant from the bone stump. The proposed work addresses the following focus area: Skin-Implant Interface, Identification of best practices to address infection at the skin-implant interface for osseointegrated prosthetic limbs. Amputees have been “wearing” their prosthetics over their amputation stump since the Civil War. While allowing amputees to move about, this approach is fraught with problems and limitations such as excessive pressure on the skin of the stump, resulting in open sores, infection, pain, and poor sense of feeling that limit their ability to move and function and make their bones weaker. Further complicating this problem is the relative youth and high activity level of the Wounded Warriors, making them bad candidates for traditional prosthetics. To date, we have over 1,600 combat-related amputations in Service members from the Global War on Terror, who bear the brunt of the mismatch between the available technology and their life style. Given the devastating physical and psychological impacts of limb loss, in addition to disfigurement and decreased functionality that reduce independence and reinforce negative psychological effects, we believe we can offer a solution to help these young men and women, who have made a significant sacrifice for their nation. Other groups have pioneered this field and have made significant effort to develop prosthetic implants directly attached to the bone stump. The major limitation to date has been the loosening of the implant at the bone site and infection, where the implant leaves the body. The combined toll of these limitations has slowed down the pace of progress in the field. We believe that, by using two technological advances, we can overcome these limitations and offer a prosthetic implant that will not loosen where it attaches to the bone and will not get infected where it leaves the body. We propose to use a special type of thread, called a BITG thread, that will allow us to “screw” the implant directly into the bone canal. The advantage of this thread type is that is it designed to withstand loads from all directions and allow for ingrowth of bone. This is in contrast to existing designs that are designed primarily for loading in one direction only. Given how complicated our motions are, we tend to load our bones in many directions, even in simple motion activities. Additionally, we plan on using an engineered silk interface component to provide a reliable junction between the hard implant metal and the soft skin. The mismatch between these two materials in previous designs has caused this junction to get damaged and prone to infections. The engineered silk allows for the skin to “grow” onto it and become one on one end of the interface and then create an engineered seal with the implant metal on the other end. The engineered silk is highly inert, so it does not elicit a negative response from the skin and can be engineered to provide a gradual change of stiffness from the soft skin to the hard implant metal to avoid damage. Based on our group’s expertise and our previous work, we have a high degree of confidence in this approach. Our goal is to test and optimize our proposed approach in rats and cadaveric specimens over the next 2 years. At that point, we will establish a start-up, raise funds and test the optimized design in a modified large animal model designed specifically for such implants by a group from the University of Utah, followed by a first-in-human clinical trial with amputees. Upon successful implementation of the system in the pig model, we will approach the FDA to request approval through the Breakthrough Devices Program, using the 510(k) stra
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 10, 2021
- Source ID
- W81XWH2010841
Entities
People
- Ara Nazarian
Organizations
- Beth Israel Deaconess Medical Center
- United States Army