- STUDY DESIGN: Descriptive cross-sectional study. INTRODUCTION: Hand osteoarthritis (OA) is a condition that results in hand pain and disability. It is important to understand how muscle function impairments contribute to impaired dexterity. PURPOSE OF THE STUDY: To compare muscle activation in women with and without hand OA and determine if the activation relates to measures of impairment and disability. METHODS: Electromyography (EMG) was recorded from four muscles of the hand/forearm while subjects threaded (assembly) and unthreaded (disassembly) a small bolt. The groups were compared on the integrated EMG (IEMG) of four muscles using two-way repeated-measures analyses of covariance for the assembly and disassembly tasks. RESULTS: No differences were found in muscle activation between groups when IEMG values were normalized by time (p>0.05). CONCLUSIONS: Patients with OA have some indicators of altered muscle function. It is unclear whether these are adaptive or predisposing changes. When controlling for the time to perform a task, there were no significant IEMG differences between women with hand OA and control subjects. LEVEL OF EVIDENCE: 2b.