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Figure 9.4. Pinch force for lateral and palmar prehension with and without the FreehandĀ® neuroprosthesis. The histogram family on the left represents lateral grasp; palmar grasp is on the right. Force represented in Newtons. There is some increase in force produced post-operatively even with the neuroprosthesis turned off. This is probably related to the increase in tone produced by surgical tightening of the flexor tendons.

Lateral

Palmar

Lateral

Palmar

Figure 9.4. Pinch force for lateral and palmar prehension with and without the FreehandĀ® neuroprosthesis. The histogram family on the left represents lateral grasp; palmar grasp is on the right. Force represented in Newtons. There is some increase in force produced post-operatively even with the neuroprosthesis turned off. This is probably related to the increase in tone produced by surgical tightening of the flexor tendons.

No improvement was seen in manipulation of the lightest objects. An ADL abilities test evaluated whether the neuroprosthesis decreased the amount of assistance required to perform various ADLs. Across all patients and tasks, 50% showed an improvement in independence score, and 78% preferred to use the neuroprosthesis to perform the activities. Through a survey instrument, patients reported overall satisfaction with the performance of the system, indicated that it had a positive impact on their lives, and provided them with less dependence on other adaptive equipment. As of January 2004, there are over 200 patients in the world who have received this device.

Adverse events requiring surgical management included receiver repositioning or replacement, skin openings, electrode breakage, infection requiring electrode removal or system explant and tendon adhesion. The major non-surgical adverse events included swelling or discomfort over the implantable components, skin irritation from external products, irritation from incisions or sutures and skin irritation from splints or casts.

Handmaster

The Handmaster, which is produced by the NESS Corporation in Israel (Jjzerman et al., 1996), is composed of a hinged shell with a spiral splint that stabilizes the wrist. Surface electrodes are built into the shell and stimulate the finger flexors and extensors and the thenar musculature. In addition, the company has recently produced a proximal arm segment

Figure 9.5. The Handmaster System external orthoses, manufactured by NESS Limited. The forearm device incorporates three surface stimulation electrodes into the molded orthosis to provide pinch grip. An additional arm segment and a lower leg segment using the same surface stimulation technology, is also available. The subject controls the device through a controller box, which contains a trigger button to start stimulation and a mode button to choose between pre-programmed patterns of muscle activation.

Figure 9.5. The Handmaster System external orthoses, manufactured by NESS Limited. The forearm device incorporates three surface stimulation electrodes into the molded orthosis to provide pinch grip. An additional arm segment and a lower leg segment using the same surface stimulation technology, is also available. The subject controls the device through a controller box, which contains a trigger button to start stimulation and a mode button to choose between pre-programmed patterns of muscle activation.

and a leg segment using the same technology (Fig. 9.5). A trigger button mounted on a separate control unit allows the user to start the stimulation sequence. A separate mode button allows the user to choose different pre-programmed patterns of muscle activation. The device is designed to be used with C5 and C6 tetraplegic individuals as well as individuals with hemiplegia. The NESS device has been studied clinically in pilot investigations (Weingarden et al., 1998; Alon and McBride, 2003). A case study of seven patients with C5 or C6 tetraplegia has been completed, and three ADL activities that could not be performed without the Handmaster were performed successfully with the neuroprosthesis. In addition, improvements in grip strength, finger motion, and Fugl-Meyer scores were documented. The advantages of the Handmaster are its non-invasiveness, cost, and relative ease of application. Disadvantages include its cosmesis, as external splinting is required and the fact that the device is less customizable than the Freehand system.

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