Soft Tissue Tension Sensor

Focusstart, Llc, Minneapolis MN

Investigators

Abstract

Abstract Patients' need for orthopeadic joint surgeries, such a total knee replacement surgery (TKA, >700,000/year) is growing at rates > 8% per year. Failure to balance soft tissues such as ligaments (that normally stabilize the body joints) can cause the surgical joint repair to fail prematurely (e.g., almost 30% of revision knee surgeries were linked to instability). Therefore, balanced soft tissue is considered critical for post-operative success. In TKA surgeries, a difference between loads on opposing sides of a knee (femoral tibial inter-compartmental load differences) > 20 pounds was associated with worse postoperative function (Gustke et al, 2014) such as limited range of motion, pain, or implant loosening. Experienced TKA surgeons have been unable to detect significant inter-compartmental load differences as large as 27 to 51.7 lbs, which suggests a demand for a quantitative tool to detect such load differences (Elmallah, 2016). It is anticipated that a much greater number of less specialized surgeons will be performing joint surgeries by the year 2030, because the supply of orthopaedic surgeons will likely not meet demand due to growth of the aging patient population. Therefore, the demand for tools that assist orthopaedic surgeons of all experience levels may potentially improve prosthesis lifetime and enable greater standardization of routine procedures. Current commercial products are limited to the knee, expensive, not adaptable to multiple ligament sizes with varying levels of accessibility, traumatic to the target tissues, or they report overall loads but not tension of individual tissues. FocusStart has fabricated a simple, non-destructive, inexpensive handheld device to reliably and accurately quantify soft tissue tension during orthopedic surgeries. Our previous work has established accuracy of our sensor for individual ligaments; the next step in commercialization is to associate sensor output with resulting mechanical alignment. This Fast Track proposal outlines the development of a modular, standalone handheld soft tissue tension sensor. Phase I of the proposal will correlate ligament tension values to applied loads that experimentally-induce varus and valgus knee imbalances in human cadaver knees. Phase II Aim 1 will develop a library of clinically relevant ligament tension values from normal and abnormal knees under varying amounts of experimentally induced knee imbalance. Phase II Aim 2 of this proposal will package the sensor system into a single physical device, and qualify it for human use. The business plan is to develop and commercialize a tissue tension sensor initially for license to orthopaedic manufacturers for TKA surgeries.