Investigation of trapeziometacarpal joint configuration and morphometric parameters of the thenar muscles in patients with trapeziometacarpal osteoarthritis

The aim of this study was to demonstrate the descriptive values of the joint configuration and morphometric parameters of the thenar muscles in patients with trapeziometacarpal osteoarthritis (TMC OA) and to demonstrate the association between thenar muscle parameters and osteoarthritis stages and hand dexterity. Sixteen patients (osteoarthritis group) (age average: 53.18±9.11) and 8 healthy subjects (control group) (age average: 50.25±5.75) were included in the study. Pain severity, grip and pinch strength, morphometric parameters of the thenar muscles and joint configuration, functional level and hand dexterity were assessed. There was no difference between control and osteoarthritis groups in regards to joint configuration. Thickness and cross-sectional area of abductor pollicis brevis, opponens pollicis and flexor pollicis brevis muscles in the osteoarthritis group were lower than the control group. There was no difference between two groups in regards to muscle thickness. TMC OA stages were not correlated with cross-sectional area and thickness of the thenar muscles. The osteoarthritis group completed the "turning" component of the Minnesota Hand Function Test on the non-dominant side for a longer time than the control group. There was a negative correlation between the cross-sectional area of the non-dominant side of the first dorsal interosseous muscle and finishing time of the Minnesota Test, whereas there was a positive correlation between muscle thickness of the abductor pollicis brevis and 9 Hole Peg Test. The results of this study showed that cross-sectional area of the abductor pollicis brevis and opponens pollicis muscles, which play important role in dynamic stability of the TMC was decreased, hand dexterity was impaired and associated with the morphometric parameters of the thenar muscles. Studying quantitative changes in thenar muscles is a guide to goal setting for exercise protocols for TMC OA.