LTI VariGrip III Features Multi-Device Control

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The latest advance in microprocessor technology for powered upper-limb prosthetic systems is the Programmable VariGrip" III Multi-Device Prosthetic Controller from LTI. This controller operates up to four powered prosthetic devices using a control strategy tailored to the user. The system adapts to the patient, rather than requiring the patient to adapt to the controller, thus reducing training time and increasing functionality. Since it is programmable, the clinician can quickly adjust it through his personal computer.

The VariGrip III is light weight (11 grams) and smallabout half the size of competitive controllersmaking it ideal for adults' and children's prostheses. It can be concealed in the prosthesis and, when combined with built-in batteries, results in improved cosmetic appearance.

Universal Controller

VariGrip III Multi-Device Controller
VariGrip III Multi-Device Controller

The controller is universal and operates devices from any manufacturer, even systems with a mix of components from several manufacturers. This means that prosthetists can choose the best combination of products for users' individual needs.

Traditionally, prosthetic controllers were designed to perform one function. Early microprocessor-based controllers were similar, since they were preprogrammed to perform a specific task. However, they did allow the prosthetist to make adjustments for the individual user.

The new VariGrip III Controller takes this one step further. In addition to the adjustment capabilities, it can be programmed with a variety of control strategies, making it easier for the user to operate the system. These strategies are downloaded by the clinician to the prosthetic system. This allows the prosthetist to try several strategies with the user and to choose the one best suited for the user's particular needs.

Once a strategy is chosen, the controller is fine-tuned through software-adjustable settings, providing significantly more adjustment than previously offered with prosthetic controllers. The result is a control strategy and user-specific adjustments that allow the user to obtain maximum performance and functionality.

Controller Evaluates Patients

Patient Evaluation using MyoAssistant™
Patient Evaluation using MyoAssistant™

The VariGrip III Controller has an additional feature: the ability to evaluate patients to determine which control strategy would be best for them. The patient evaluation tells the prosthetist if the patient has sufficient muscle signal strength and coordination to operate the prosthetic system myoelectrically. If not, the VariGrip III Controller can be reprogrammed to use a different input device. Input device options include myoelectrodes, Touch Pads", switches, or a linear transducer. Again the most suitable input device is chosen to accommodate the user.

The VariGrip III Controller uses proprietary software MyoWizard" and MyoAssistant". MyoWizard provides 16 control strategies, along with a complete description of their features and benefits. To select one, the prosthetist simply highlights the preferred strategy and downloads it to the VariGrip III Controller. If the user is not satisfied with this control strategy, the prosthetist selects a different strategy until the best one if found. Once a suitable strategy has been chosen, MyoAssistant is used to make necessary adjustments to the system. This results in a custom control system that is optimal for the individual user.

Additional control strategies are being developed and will be added in the next release of the software, scheduled for the first quarter of 2003.

Last year, a new HCPCS L-Code was issued for microprocessor-based prosthetic controllers. Code L-6882, "microprocessor control feature, addition to upper-limb prosthetic terminal device," provides additional reimbursement for this new technology.

For more information, contact Liberating Technologies, 800.437.0024 or visit