Creating a Baseline for Dynamic Movement Involving the Carpometacarpal Joint Through Surface Electromyography

Hand osteoarthritis of the carpometacarpal (CMC) joint affects approximately 70 percent of people above the age of 65, inhibiting an individual's capacity to perform daily tasks. Although osteoarthritis (OA) is often considered a degenerative disease of the cartilage, recent research suggests it most likely begins in the surrounding tissues. By studying the muscles that support this joint, we can understand how OA affects these surrounding tissues and develop a rehab protocol to counter these effects. The primary goal of this project is to determine whether surface electromyography (sEMG) can be used to understand the effects of OA on muscle activation. Specifically, this study aims to establish baseline activation levels during various acts of daily living (ADLs) in healthy individuals and compare them to those who are diagnosed with CMC OA. Previous researchers in the CHKE lab utilized a muscle specific approach, where they would place the sEMG sensors on the First Dorsal Interosseous (FDI), the Abductor Pollicis Brevis (APB), the Abductor Pollicis Longus (APL), the Extensor Pollicis Brevis (EPB), and the Flexor Pollicis Brevis (FPB). The layered location of these muscles led to crosstalk making it difficult to pinpoint the activation of individual muscles. Due to this crosstalk , we have pivoted to a muscle zone approach. In an article published in 2018 titled, "Identification of forearm skin zones with similar muscle activation patterns during activities of daily living", the forearm was separated into 7 distinct zones based on anatomical movements of the hands and fingers. Different ADLs resulted in varying degrees of activation across the zones, enabling the researchers to identify relevant muscle groups. We plan to use a similar zonal approach in our study. We hypothesize that the "healthy" baselines for these muscle zones will have lower mean and peak activation level for acts of daily living compared to individuals afflicted with this condition.