Validation of Ankle Strength Measurements by Means of a Hand-Held Dynamometer in Adult Healthy Subjects

Journal of Sensors, Jul 2017

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 recommended 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.

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Validation of Ankle Strength Measurements by Means of a Hand-Held Dynamometer in Adult Healthy Subjects

Validation of Ankle Strength Measurements by Means of a Hand-Held Dynamometer in Adult Healthy Subjects Andrea Ancillao,1 Eduardo Palermo,1 and Stefano Rossi2 1Department of Mechanical and Aerospace Engineering, “Sapienza” University of Rome, Via Eudossiana 18, 00184 Roma, Italy 2Department of Economics and Management-Industrial Engineering (DEIM), University of Tuscia, Via del Paradiso 47, 01100 Viterbo, Italy Correspondence should be addressed to Stefano Rossi; [email protected] Received 16 March 2017; Revised 13 June 2017; Accepted 28 June 2017; Published 27 July 2017 Academic Editor: Guiyun Tian Copyright © 2017 Andrea Ancillao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract 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 recommended 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. 1. Introduction Measurement of the maximum force that a subject can exert during a volitional contraction is a basic clinical procedure often conducted in clinical and rehabilitation frameworks. It is also referred to as strength assessment [1]. Specifically, this technique enables an easy indirect estimation of joint moment, providing basic information about the healthiness of tendons, ligaments, and joint stability [2]. Furthermore, strength evaluation enables the diagnosis of weakness as a consequence of muscular diseases and allows the quantitative assessment of functional recovery in rehabilitation programs [3–8]. As of today, a widespread and commercially available method to measure muscle strength involves the use of the isokinetic dynamometer [9–12]. This methodology showed a high interrater and intrarater reliability and reproducibility in the measurement of joint forces and torques, on subjects of a wide age range, on both lower and upper limb [5, 9, 13, 14]. However, the isokinetic dynamometer is inherently expensive, cumbersome, and not portable and requires a long patient preparation time. In clinical environments, simpler and faster methods are often preferred to reduce both patient’s discomfort and the examination time. Thus, the most adopted methodology to assess strength involves the Hand-Held Dynamometer (HHD), a low-cost, portable, and easy-to-use device. It consists of a small and portable single-axis dynamometer that can be held in hand by a clinician and applied on some defined landmarks, while asking the patient to exert a force against it [9, 14]. Despite its advantages, reports on HHD reproducibility and repeatability were controversial [15–18]. Principal causes of low reliability of HHD based method have been identified in poor operators’ training and wrong patient’s positioning [7]. In fact, HHD based method relies on operator’s strength and training to contrast the force exerted by the patient, avoiding misplacements [19]. HHD strength measurements can be performed according to two methods [19]: (i) the “make test,” in which the examiner holds the dynamometer stable while the subject exerts a maximal force against it, and (ii) the “break test,” in which the examiner overcomes the maximum force exerted by the subject, producing a small limb movement in the opposite direction of patient’s force. Both methods were proved reliable and repeatable only if the examiner had enough force to contrast the force exerted by the patient [19]. Other studies provided similar results, by showing that strength measurements performed through HHD are operator-dependent and the “break test” requires a larger force exerted by the examiner [20, 21]. The influence of the operator was tested by Kim et al. [9] by comparing three setups: (i) with the HHD fixed to the dist (...truncated)


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Andrea Ancillao, Eduardo Palermo, Stefano Rossi. Validation of Ankle Strength Measurements by Means of a Hand-Held Dynamometer in Adult Healthy Subjects, Journal of Sensors, 2017, 2017, DOI: 10.1155/2017/5426031