Contact Force Sensor for Knee
Problem statement
An individual with chronic knee issues must make extensive sacrifices of their time and hard earned money in order to undergo a total knee arthroplasty (TKA). However, this sacrifice does not guarantee that the patient will reap equally as momentous long term postoperative improvements. The success of these knee replacements depends on several technical factors, including: appropriate alignment of components, rotational congruence between the prosthetic proximal tibia and prosthetic femoral condyles, ligamentous soft-tissue balance of the knee joint, and in this case, selecting the correct thickness. [4] Due to advancements in technology, intraoperative sensors allow surgeons to more accurately execute the complicated alignments listed above within the tibiofemoral joint. However, there is still no sensor that can help surgeons obtain, or even understand, a proper soft-tissue balance in the patellofemoral joint. This soft-tissue imbalance within the knee is responsible for 40% of early TKA revisions. [4] While there currently exists a US patent for a force sensor that provides an accurate and quantifiable measurement of force during TKA [5], a study performed by the journal of arthroplasty concluded that the use of the sensor did not result in improved clinical outcomes. [6] However, there is evidence supporting the opposite claim as well. The ambiguity among clinical data and conclusions stems from the lack of in-vitro sensors available, and the debate surrounding the validity of the soft-tissue balance. [6] Soft-tissue is imperative to the stability of the patellofemoral joint. Without a sensor measuring patellar forces, only a portion of the loads are being considered. The joint is reliant on the static and dynamic soft tissue structures, including the joint capsule, the extensor mechanism (quadriceps tendon and patellar tendon), and the medial and lateral ligamentous structures. [7] Ultimately, our goal is to design a sensor that can measure the contact forces on the patellofemoral knee joint to assist a surgeon in balancing the soft tissue, and take the first concrete steps in reducing the 35% of TKA revisions caused by soft-tissue imbalance.
Team members
Nick McCabe – leader
Ellie Zimmer – communicator
Danny Kuehn – accountant
Cece Hartigan – admin
Client
Josh RothUW ME/Ortho