PURPOSE: The pathophysiology of thumb carpometacarpal (CMC) osteoarthritis (OA) involves complex interactions between the ligaments and muscles supporting the joint. Factors such as muscle volume and strength may be more relevant in early disease. We used ultrasound as a noninvasive method to explore differences in the intrinsic hand muscles of patients with early CMC OA, as determined using physical exam and radiographs, and healthy controls. We also assessed differences in grip strength.METHODS: A convenience sample of postmenopausal women with early CMC OA diagnosed using a physical examination or radiographs was recruited from an orthopedic clinic specializing in hand surgery. Healthy controls who were matched for age and hand dominance were recruited from the same clinic. We used ultrasound to determine the length of the first metacarpal and the muscle thickness of the abductor pollicis brevis, opponens pollicis (OPP), and first dorsal interosseous. Grip strength measurements were taken using a standard Jamar dynamometer and 2 custom-designed tools for cylindrical grasp and pinch strength.RESULTS: Twenty-three subjects were enrolled, with a total of 32 thumbs measured: 15 thumbs with arthritis and 17 healthy thumbs. Multivariable logistic regression models indicated that thumbs with thicker OPP had 0.85 lower odds (95% CI= 0.71-0.97) of early OA, adjusting for hand dominance and the first metacarpal length. Linear regression models indicated no association between early OA and grip strength.CONCLUSIONS: The size of OPP may have a weak association with the diagnosis of early OA.CLINICAL RELEVANCE: This study supports further exploration of the role of OPP in stabilizing the CMC joint, particularly with regard to minimizing joint subluxation. This may be clinically relevant to providers who treat patients with CMC OA early in the course of the disease, when nonsurgical treatment is the most relevant.
View details for DOI 10.1016/j.jhsa.2021.07.021
View details for PubMedID 34509311