Uniaxial Hand-Held Dynamometer (HHD) is a low-cost device widely adopted in clinical practice to measure muscle force. HHD
measurements depend on operator’s ability and joint movements. The aim of the work is to validate the use of a commercial HHD
in both dorsiflexion and plantarflexion ankle strength measurements quantifying the effects of HHD misplacements and unwanted
foot’s movements on the measurements. We used an optoelectronic system and a multicomponent load cell to quantify the sources
of error in the manual assessment of the ankle strength due to both the operator’s ability to hold still the HHD and the transversal
components of the exerted force that are usually neglected in clinical routine. Results showed that foot’s movements and angular
misplacements of HHD on sagittal and horizontal planes were relevant sources of inaccuracy on the strength assessment. Moreover,
ankle dorsiflexion and plantarflexion force measurements presented an inaccuracy less than 2% and higher than 10%, respectively.
In conclusion, the manual use of a uniaxial HHD is not recommend
ed for the assessment of ankle plantarflexion strength; on
the contrary, it can be allowed asking the operator to pay strong attention to the HHD positioning in ankle dorsiflexion strength
measurements
