The reliability and validity of the Tekdyne hand dynamometer: Part II.

The purpose of this study was to evaluate the reliability and validity of the Tekdyne hand dynamometer for measuring grip strength as compared with the Jamar dynamometer. Additionally, it was hypothesized that one to six weeks after carpal tunnel release (CTR) grip strength would appear to be greater when tested on a softer tool than when tested on the Jamar dynamometer. The Tekdyne, the standard Jamar instrument (SJ) and a Jamar dynamometer modified with foam padding (MJ) were compared in 48 subjects without upper-extremity abnormality and 30 subjects following open-palm CTR. The Tekdyne and the Jamar hand dynamometers were well correlated in the presence and in the absence of upper-extremity abnormality (r = 0.975 and r = 0.871, respectively). Tekdyne intrasession reliabilities in both the non-surgical group and the surgical group were high (ICC = 0.954, SEM = 0.290 psi and ICC = 0.958, SEM = 0.219 psi). The Tekdyne intersession reliability of the non-surgical group was high (ICC = 0.971, SEM = 0.22 psi). There was no statistically significant difference between the ratios of the non-operated grip strengths across the three measurement devices, suggesting that the softer device did not promote greater force production by the operated hand.