Wrist flexion-extension

Fig. 3 shows the results of the revised ECS during wrist flexion/extension at 60bpm when kurtosis is removed. It can be seen clearly the classifier is able to select the correct output, which in this case is STATEl (SI), labeled (a) and (b), where from the output ME, the range is between 0 until 0.3. Even though there are glitches during the classification result in one contraction, the average of the values produces the correct output state. 

The analysis of accuracy (Fig. 4) of the four-system has shown that from the speeds of contraction perspective, during wrist flexion/extension, the classifier was able to select STATEl (SI) and STATE2 (S2) accordingly but not at STATE3 (S3) which is when the contraction is performed at the speed of 120bpm. 

Fig. 4 The accuracy (in %) of the ECS during 1. wrist exion/extension at 60bpm (SLOW) - top, 2. Wrist flexion/extension at 90bpm (MEDIUM) -middle and 3. Co-contraction at 60bpm - bottom, for the revised four-state system...

Wrist joint (combined with carpal joints) Bend palm upwards Move hand away from trunk to the side of radius Flexion (extension") Adduction or radial deviation (adduction or ulnar deviation") ... 

Forearm and hand posture. Extreme elbow flexion or extension, extreme forearm pronation or supination, and extreme wrist flexion or extension should be avoided. The hand should be in line with the forearm (no ulnar/radial deviation of the wrist). 

The estimated values for the maximum acceptable forces for female wrist flexion (power grip) me shown in Table 26. Similarily, the estimated maximum acceptable forces were developed for wrist flexion (pinch grip, see Table 27) and wrist extension (power grip, see Table 28). The torques were converted into forces by dividing by 0.081 m for the power grip and 0.123m for the pinch grip. Snook et al. (1995) note that the estimated values of the maximum acceptable wrist torque do not apply to any other tasks and wrist positions than those that were used in the study. 

Can the tool be used without wrist flexion or extension ... 

FIGURE 49.27 The nonlinear relation between the contact area and the load at the proximal wrist joint. The contact area was normalized as a percentage of the available joint surface. The load of 11, 23, 46, and 92 lbs was applied at the position of neutral pronation/supination, neutral radioulnar deviation, and neutral flexion/extension. (From Viegas S.F., Patterson R.M., Peterson P.D., Roefs J., Tencer A., and Choi S. 1989. /. Hand Surg. 14A 458. With... 

Wrist motion (+) Pronation ( —) Supination (+) Flexion ( -) Extension ( —) Radial deviation ... 

Youm Y, McMurty R.Y, Flatt A.E. et al. 1978. Kinematics of the wrist an experimental study of radioulnar deviation and flexion/extension. /. Bone Joint Surg 60A 423. 

The primary sources of control for body-powered devices are biomechanical in nature. Movement, or force, from a body joint or multiple joints is used to change position, or develop a force/ pressure that can be transduced by a harness and Bowden cable and/or mechanical switches. Typically, inputs such as chin and head force/movement, glenohumeral flexion/extension or abduction/ adduction, biscapular and scapular abduction, shoulder elevation and depression, chest expansion, and elbow or wrist movements are used. However, direct force/motion from muscle(s) has also been used by way of surgical procedures such as muscle tunnel cinepiasty (Sauerbruch, 1916) and the Krukenberg cinepiasty (Krukenberg, 1917). 

Kinematic models are also used in designs of smart hand and hand prostheses in order to track independently the motion in each degree of freedom. For example, fingers as a part of serial kinematic chain are composed of revolute joints. Different motions are considered, such as abduction/adduction and flexion/extension, together with pronation/ supination of the wrist and fingers for the better manipulation and grasping motion of the hand [31-33]. Most of actual motion-tracking models represent the joint as a spherical joint. 

The wrist joint consists of fifteen bones, each with multiple articulations. A good example is the capitate bone, which articulates with the second, third, and fourth metacarpals and with the lunate, scaphoid, trapezoid, and hamate bones (Fig. 83-1). The wrist acts as a functional unit, exhibiting flexion, extension, adduction (ulnar deviation), abduction (radial deviation), and circumduction. 

The wrist moves in two planes. In the sagittal plane, it flexes to approximately 85 degrees and extends to approximately 45 degrees. Flexion and extension appear to occur around more than one axis. In the coronal plane, the wrist moves into abduction (radial deviation) and adduction (ulnar deviation). Abduction is approximately 15 degrees and adduction 45 degrees. Pronation and supination occur at the radioulnar joint and, combined with flexion, extension, abduction, and adduction, permit circumduction so that the hand can lie in any plane. 

The wrist should be put through the ranges of flexion, extension, ulnar deviation, and radial deviation. Ulnar deviation should be greater than radial. These should be performed both passively and actively. 

Wrist flexion and extension strength should be tested with the hand made into a fist. 

The complexity of joint motion at the wrist makes it difficult to calculate the instant center of motion. However, the trajectories of the hand during radioulnar deviation and flexion/extension, when they occur in a fixed plane, are circular, and the rotation in each plane takes place about a fixed axis. These axes are located within the head of the capitate and are not altered by the position of the hand in the plane of rotation (Youm et al., 1978). During radioulnar deviation, the instant center of rotation lies at a point in the capitate situated distal to the proximal end of this bone by a distance equivalent to approximately one-quarter of its total length (Figure 49.28). During flexion/extension, the instant center is close to the... 

The SEMG signals were sampled at 1,500 Hz using a Noraxon 2400T in conjunction with Noraxon Myoresearch XP Master Edition (version 1.06) software. The participants were asked to do movements that related to these particular muscles which were wrist flexion, wrist extension and cocontraction. All the movements were done at different speeds 60 beep per minute (bpm), 90 bpm, 120 bpm and maximum speed. The speed was controlled by using a... 

Fig. 3 The result of the classification system for wrist flexion and wrist extension at 60bpm for the revised four states system...

The EMG signals that were used in the evaluation were recorded from ten normal subjects with seven upper-limb movements and eight muscle positions. The seven upper-limb movements including wrist flexion (wf), wrist extension (we), hand close (he), hand open (ho), forearm pronation (fp), and forearm supination (fs) are shown in Fig. 1 and the eight muscle positions are located on the right arm, as shown in Fig. 2. These data sets were acquired by the Carleton University in Canada [10], A duo-trode Ag-AgCl surface electrode (Myotronics, 6140) was used and an... 

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