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. 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.Introduction
Materials and Methods
Clinical follow-up of hip and knee arthroplasty is not related to objective functional parameters while this is one of the main goal of evidence based medicine. Therefore a functional test was defined in order to correlate clinical and biomechanical data. The experimental set-up has been presented [1] as well as the test protocol [2]. Three parameters have been analyzed: reaction time (Tr), flight time (Tf) and maximum force (Fmax). The data refer to 21 subjects with hip joint replacement (HRG) and 22 subjects with knee joint replacement (KRG). Tests, were performed before surgery and after one, three and six months. The results were compared with values obtained from a control group of 402 normal subjects. One months after surgery the performance is lower respect to normal data, both for HRG and KRG. Three months later, there is a partial recover expecially for HRG. At six months follow-up, also the KRG reach better performance. While the performance starting point is higher in the HRG, the percentage recovery is equal in both the groups. During the follow-up also the non operated leg, both for HRG and KRG, shows a progressive changing in its performances, which can increase or decrease, but always it brings at the same level of ability for both legs. The data suggest that there are different performance and time recover related to the replaced joint (hip or knee) while the total amount of recover is not joint related and there are no differences for laterality. Experimental data correlate with clinical observation; therefore the proposed protocoll seems to be usefull for objective evaluation of joint replacement follow-up. The re-equilibration of the kinematic abilities between the limbs, which cannot be detected by clinical observation, requires further investigation and could be related to neurological integration and less algia limitation.
