**2. Literature review**

**Figure 1** shows a deformed joint site. The symptoms can only be alleviated by minimally invasive joint cleansing or by the severing of painful nerve fibers. In a last step, there remains in some cases only a partial stiffening of the carpal bones—or the supply of individual finger joints by arthroplasty or prosthetic. In the case of joint cleansing, a needle is inserted into the joint capsule. If the injection is deeply injected into the thumb saddle joint, the palmar-

A novel therapy involves a stabilization by kinesio-taping. In addition to the massage effects, that stimulate the flow of blood and lymph. The elastic adhesive tape supports joint functions. The influence of the tapes on the tensions corrects muscular imbalances so that a balance between the muscle groups can arise again. The stimulation of the proprioceptors in the joints ensures a better sense of movement. By stimulating the receptors, pain in the joint is

In the application of hand-held products, the user is under different stress factors. These stress factors cause in human's strains, depending on individual characteristics and abilities. Stress means the physical characteristics of the work situation, for example, a force transmission on

In most cases monitoring methods are used to determine the hand strain. These monitoring methods are based on the scoring of certain stressful situations. Thereby valid low scores lead to low strain. But in the most monitoring methods the level of detail of the hand is

the hand. Strain, in contrast, refers to the reactions such as hand pain [5].

extending tendon of the flexor carpi radials can be injured [3].

18 Anatomy, Posture, Prevalence, Pain, Treatment and Interventions of Musculoskeletal Disorders

relieved [4].

**1.2. Determination of hand stress**

**Figure 1.** Computed-tomography of a rhizarthrosis.

#### **2.1. Simulation-models to determine the hand stress**

To provide early ergonomic criteria for product design, digital hand models can be used for the simulation of hand stress. Digital hand models are generated by computer representations of the hand and can be simulated using either the multibody systems method (MBS) or the finite element method (FEM). It is also possible to couple the methods of FEM and MBS. In contrast to MBS models, FEM models are deformable and can calculate mechanical stresses such as pressure in certain parts of the body. MBS models consist of rigid non-deformable bodies connected to one another by kinematic joints. Using the MBS method, it is only possible to determine the kinematics of the body and the contact forces. These data are used, for example, as input data for FEM simulation [8]. Often the hand models are simulated as part models because of their complexity. This includes, for example, simulating finger models. For example, [9] developed a combined FEM and MBS finger model of three finger segments with realistic bones, nails and soft tissue. In the dynamic simulation, the stiffness of the grip surface was varied and demonstrated in final results the decrease of the pressure distribution. The work [10] developed a FEM fingertip and simulated the pressure distribution on the fingertip when opening can a tab. The results revealed that over a large contact area pressure, distribution was reduced to the fingertip. With the thumb model the static pressure distribution for use of clip connections are simulated by [11]. These influences such as pressure level, material, geometry and position change of the clips are examined. This influence examination gives design proposals for clips [12]. Other digital hand models focus on realistic simulation. The work [13] presented a hand model for the simulation of non-linear contact deformations, in relation to realistic overlapping of the skin (**Figure 2**).

To measure the hand posture there, exist optical methods and methods in which active sensors are attached to the hand [14]. This chapter deals with sensor gloves with active sensors, since optical methods require a complex experimental setup and capture only the movement and posture of the hand. Active sensors are placed in the design as a sensor glove directly to the hand and do not require complex experimental setup [22]. The sensor gloves are often equipped with fiber optic [23], strain gauges [24] or goniometers [25]. Through the further development of microelectronic sensors, circuits and batteries are designed with smaller size and weight. The data collection, processing and storage are done internally, or the data are transmitted to the computer externally via wireless protocols [26]. **Figure 3** shows new technologies with RFID to measure the time in relation

Analysis for Objective Evaluation the Stress of the Hand http://dx.doi.org/10.5772/intechopen.71474 21

The term "comforting" is an artistic word and has emerged from the composition of comfort and prototyping. Comfortyping is intended to function as a stand-alone simulation program, in which a digital hand model is included in the simulation environment. After importing a hand-held product as well as after selection of influencing variables, they should be calculated on the basis of their design proposals. A similar goal for assessing the ergonomics of the man-machine interface also exists as ergotyping of [27]. In contrast to this, the focus should be placed on the hand-arm system with Comfortyping. For example, it should be possible to deliver spline suggestions to the user, which can then be imported into the CAD system. For Comfortyping is a database with different influencing variables such as grip types, gripping forces as well as hand-type and handle-dependent material properties is required. The

of the motion.

**3. Simulation of hand stress**

**Figure 3.** Example of support-system by http://www.proglove.de (2017).

**3.1. Comfortyping**

**Figure 2.** Example of hand models.

#### **2.2. Support-systems to reduce the hand stress**

In the context of the present work there exist sensor gloves to measure forces when gripping and using products. Some works are focused exclusively on the development of new sensor gloves. The research of [14] shows that the sensor gloves are exploring the relations between forces and other variables such as muscle tension [15], handling and feel [16] and the perceived gripping force [17].

Since 1991 are sensor gloves designed to measure forces in gripping and operation of handheld products. To measure the force distribution on the palm most sensor gloves have piezo (-resistive) sensors such as in Refs. [18, 19] or [20]. Due to the simple programming and low cost compared to capacitive sensors these are preferred. The force sensors are varying in the number and in the position on the hand and in their form. For the investigation of pressure distribution on the palm [21] develops a sensor system of six force sensors based on FSR sensors (FSR—Force Sensing Resistor). These resistive sensors are based on the measurement of the resistance change of semiconductor materials such as silicon. In applying three different shaped handles are pressed on the palm and then calculated from the force-measuring the pressure distribution.

To measure the hand posture there, exist optical methods and methods in which active sensors are attached to the hand [14]. This chapter deals with sensor gloves with active sensors, since optical methods require a complex experimental setup and capture only the movement and posture of the hand. Active sensors are placed in the design as a sensor glove directly to the hand and do not require complex experimental setup [22]. The sensor gloves are often equipped with fiber optic [23], strain gauges [24] or goniometers [25]. Through the further development of microelectronic sensors, circuits and batteries are designed with smaller size and weight. The data collection, processing and storage are done internally, or the data are transmitted to the computer externally via wireless protocols [26]. **Figure 3** shows new technologies with RFID to measure the time in relation of the motion.

**Figure 3.** Example of support-system by http://www.proglove.de (2017).
