Abstract
Introduction
Lesions of the upper extremities, and especially of the hands, are the most common form of occupational injury in the agricultural and industrial sectors [1]. When the grip strength and the way of its development are relevant, it would be very useful to be able to rely on an instrumental procedure, in support of the clinical examination, for both clinical and legal purposes.
The possibility of differentiating between healthy subjects and patients affected by disabilities of the upper extremities, using parameters based on force-time curves for handgrip tests, was investigated with the aim to obtain objective and comprehensive outcome, useful to support the clinical evaluation.
Materials and Methods
The reference group consisted of 151 subjects examined for occupational trauma of the upper limbs, all with a dominant right arm, who had suffered an occupational injury. The 74% of the injuries affected the hand. A further 648 healthy people were enrolled as the control group.
Grip strength was measured with an electronic dynamometer. The signals acquired with the dynamometer were subdivided into 5 characteristic phases [2]: first reaction, explosive contraction, isometric contraction, release and relaxation.
The maximum force, the ratio between the maximum force exerted by the two arms and an index related to the explosive muscle power and the ability to maintain maximum voluntary contraction were calculated.
Percentage variations of each parameter, as compared to a threshold value, were taken into account and an overall value (T) was calculated, representing the sum of these variations.
Result and Discussion
This acquisition system was shown to be reliable and easy to use, and the test could be administered simply and fairly rapidly. The findings in the control group were comparable to those reported in the literature [3–4].
A negative value of T invariably identified a subject with a disability. By associating assessment of T with those of the specific indexes, other subjects with a clinical disability were identified.
The use of the parameters we describe makes it possible not only to assess the maximum force of the handgrip but also how it is exerted and maintained, thus providing a more reliable method of differentiating between normal function and impairment and what it is more obtaining an objective and comprehensive outcome, which sensitivity is useful to support clinical evaluation.
The proposed functional tests could offer the clinician a possible diagnostic aid, providing a method that can describe the motor skill on the basis of objective parameters. In view of its good sensitivity (0.99%) and specificity (0.84%), relatively rapid execution and the low cost of the tools, it could be usefully adopted in the clinical setting.
