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Prosthetic fingers, molded from rigid polyurethane and then overmolded with a TPU elastomer, are helping returning soldiers regain the use of digits lost in war. Leading the injection molding effort on the project is Vanguard Plastics.

Matt Defosse

August 19, 2010

2 Min Read
Firms join forces on prosthetic fingers for veterans of Iraq and Afghanistan

Prosthetic fingers, molded from rigid polyurethane and then overmolded with a TPU elastomer, are helping returning soldiers regain the use of digits lost in war. Leading the injection molding effort on the project is Vanguard Plastics.

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Vanguard and RTP teamed to work on the development of M-Finger.

Matthew Mikosz, president of Partial Hand Solutions (Southington, CT), built the prototype for the 'M-Fingers' device with material development assistance from custom compounder RTP Company (Winona, MN). The M Fingers are designed to feel and operate as naturally as possible for the recipient. "While there were a number of prosthetic hand designs on the market, no functional mechanical fingers had yet been developed," explained Mikosz. Mikosz, an experienced prosthetics specialist, came up with the idea after working with many veterans of the wars in Iraq and Afghanistan. With Vanguard, he found a company stocked with veterans who were eager to be involved in such a project.

The M-Finger design relies on two materials supplied by RTP: its RTP 2300 Series glass-filled rigid thermoplastic polyurethane is molded to form the inner structure of the fingers and multi-position thumb. These are then over molded with an RTP 1200 Series thermoplastic polyurethane elastomer. The elastomer provides each finger with dexterity to independently conform to whatever it grasps, while the rigid PUR provides strength and dimensional stability.

The mechanical fingers are actuated by wrist flexions. The overmolding does not include the fingernails of the fingers, giving the recipient the ability to pick up small objects such as coins. "The M-Finger design is truly amazing and the feedback has been very positive," added Chris Budnick, general manager of Vanguard Plastics (Southington, CT) and one of the employees there who served in the military. Each finger independently conforms to the shape of the object it is grasping.

M-Fingers are marketed in a variety of lengths and colors and can be customized to meet the specific needs of the patient. Budnick says has company has four molds for the devices, and is able to mix-and-match inserts for molding of complete hands, individual fingers or any combination and size. M-Finger costs less than half as much as many mechanical prosthetic hands or fingers, yet offers much more functionality than a hook or other simple prosthetic.  

M-Fingers are distributed by Liberating Technologies (Holliston, MA), a manufacturer and distributor of prosthetic devices, especially arms and hands. —Matt Defosse

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