An Innovative Approach for Noninvasive Evaluation of Stability at the Implant-Bone Interface for Transfemoral Osseointegrated Implants
Abstract
Leg amputation is a major injury that disrupts normal life for military members and civilians alike. The higher the amputation of the leg, the more severe the limitation and the harder it is to return to desired activities. Current artificial limbs for leg amputation above the knee are often uncomfortable and poorly controlled, limiting people from returning to full function. Newer techniques to replace lost limbs have great potential to make a person feel more like they have a real limb restored. Surgeons can now insert a titanium rod into the end of the remaining bone and bring it out through the skin of the limb of the person with the amputation, allowing the prosthesis to be directly attached to the skeleton. This provides better control and often a feeling of having your own foot back. The procedure of getting a “bone-anchored” artificial limb prosthesis is termed “osseointegration.” Currently, patients get excellent benefit and improvement from the osseointegration procedure, but there is still a risk and fear of infection and loosening of the metal implant in the bone, which could be disastrous and require another surgery for removal of the implant. Unfortunately, clinicians do not have good ways to monitor or detect this drastic complication until after it is quite severe and obvious. Some studies have looked at doing repeated X-rays or other imaging to try to detect early loosening, but this exposes a person to extra radiation (which may increase later risks of cancer) or requires costly and time-intensive imaging tests that are often only available in major hospital or research centers. Our project will develop a new device that can record information about the healing of the bone-implant interface by applying a simple probe to the end of the implant (outside the leg, where the prosthesis normally attaches) and tapping/vibrating it for a few seconds. The equipment developed for this test is small, portable, and uses a handheld probe and a laptop. It could be utilized by a clinician at routine follow-up and does not require major time or expense. Monitoring the results of this vibration test over time would show the pattern of healing of the bone and implant and allow detection of early failure or loosening of the implant. This information would then allow clinicians to provide early directed treatment or to alter the rehabilitation plan (such as slowing down or reducing the load on the leg) to prevent major failure of the implant. It would also allow comparison of rates of healing of different implants to inform rehabilitation protocols and choice of implants. We have already successfully developed a similar device for monitoring very small implants used for bone-anchored hearing aids and craniofacial reconstruction. At the end of the proposed 4-year project, we will have redesigned and developed a new hand piece and analytical model to account for the larger implants used for osseointegrated limb prostheses. We will also collect measurements in 10 patients undergoing osseointegration for above the knee amputation to validate the technique and the measurements obtained and to develop reference range values for the stability coefficient number that will provide the pattern of healing for an individual patient. By the end of the project, we will be able to provide this tool and analysis to other centers to use for studying other patients and implant designs. This project will directly address the FY20 PRORP CTRA Focus Area, “Osseointegration - Identification of best practices,” to address failure of percutaneous osseointegrated prosthetic limbs by providing a validated method to monitor bone integration and to detect early loosening or failure of implants. Right now, there is still uncertainty over which implants are the best for which patients and some hesitancy to undergo the procedure, due the risks of implant failure and the inability to detect bone healing. This study will help milita
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 05, 2021
- Source ID
- W81XWH2110857
Entities
People
- Jacqueline S Hebert
Organizations
- United States Army
- University of Alberta