Reliability of pinch strength testing in elderly subjects with unilateral thumb carpometacarpal osteoarthritis

[Purpose] The aim of this study was to examine the test-retest reliability of pinch strength testing in elderly subjects with thumb CMC OA. [Subjects and Methods] A total of 27 patients with unilateral right-thumb CMC OA (mean ± SD age: 81.3 ± 4.7 years) were recruited. Each patient performed three pain-free maximal isometric contractions on each hand on two occasions, one week apart. Three different measurements were taken: tip, tripod, and key pinch strength. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), and 95% limits of agreement (LOA) calculations were performed. [Results] Test-retest reliability of measurements of tip, tripod, and key pinch strength was excellent for the affected side (ICC=0.93, 0.96, and 0.99) and the contralateral thumb (ICC=0.91, 0.92, and 0.94). [Conclusions] The present results indicate that maximum pinch strength can be measured reliably using the Pinch Gauge Dynamometer, in patients with thumb CMC OA, which enables its use in research and in the clinic to determine the effect of interventions on improving pinch strength.