People with loss of limbs at partial levels of the hand or fingers, due to a traumatic amputation or due to congenital deficiency, represent the largest population of patients within the scope of those reported with the absence of the upper limb.
Despite its prevalence, the alternatives for prosthetic management at these levels of distal amputation have historically been limited. However, in recent years, new prosthetic options have been developed to address this gap. These have appeared within traditional prosthetic care models and may, over time, be complemented by the evolution of less traditional “disruptive technology” models of open source “software” programs and 3D printing. While not exhaustive, this article provides an overview of the growing range of prosthetic options available for partial finger and hand levels.
Opposition / Static Buffers
A long-standing option that remains a viable treatment consideration in cases where a simple, robust and performance construction is desired is the static opposing stop. While a modest anatomical appearance could be achieved with these applications, the main focus is on function rather than aesthetics. Due to the wide range of presentations of amputations at these distal levels, there is a wide variety of this concept of static opposing stops. They are all based on the premise of tapping the residual hand or finger portion against a fixed prosthetic element to mimic a gripping action or provide a stable opposing surface. In a related approach, the M-Thumb model, more recently developed by the company Partial Hands Solutions, as a static thumb option, which is already available on the market, allows the user to passively position the thumb in flexion, extension and rotation. to adapt it to different grip needs.
Another well-established treatment option that continues to offer good applications in the management of some hands with partial amputations and partial finger deficiencies is silicone restoration. In contrast to the robust construction associated with the opposing stops, the primary focus of the silicone restoration is aesthetics rather than vigorous performance. Colour matching of silicone concerning residual limb skin is difficult in itself and requires careful communication with the manufacturer. While the resemblance can be very similar, it is rarely exact with the physiological skin tones that will change throughout the day and year according to several user-specific variables. The malleable nature of silicone can offer the added benefit of a degree of cushioning to the distal sensitive areas of the residual fingers and hand.
Bio-Mechanical Prosthetic Finger
For finger amputations at or near the IFD joint, the Bio-Mechanical Prosthetic Finger (BPF) from Naked Prosthetics (formerly RCM Enterprise) presents an option that works with body movement or energy and allows the user to regulate the flexion and extension movement of the DIP joint through their own movements at the proximal interphalangeal joint (PIP). The connection system, invented by Colin Macduff to cope with his own finger amputation, links the physiological flexion motion of the PIP joint with the flexion motion of the prosthetic PIP. Similarly, the extension of the prosthetic DIP is produced and controlled by the extension of the physiological DIP. Therefore In contrast to the static opposing stop and silicone restorations, the user can actively control the movement and position of the prosthesis. Additionally, the BPF’s construction frame provides a protective covering around the residual finger that protects the often highly sensitive finger from environmental impacts and pressures.
Developed by Matthew Mikosz, CP / L, an upper limb prosthesis specialist, for finger amputations at or near the IFP joint, Partial Hand Solutions Partial Finger-M, offers prosthetic control of IFP joint movements, with movements or body energy. As with BPF prosthetic fingers, prosthetic flexion is coupled with the movement of the joint more proximal to the segment such as anatomical flexion at the metacarpophalangeal (MCF) joint that creates prosthetic flexion at the PIP joint.
Prosthetic finger pieces are available in three different sizes and are mounted in custom prosthetic sockets, which are often made of silicone for the benefits this material offers, in particular the ability to cushion and protect the segments of the residual finger while ensuring an optimal fit.
Distal cable anchoring is best accomplished through a silicone liner that rests on the back of the hand but surrounds the wrist distally. This provides a comfortable and secure attachment point without unduly restricting the movement of the remaining hand and wrist.
A closely related prosthetic option is Partial Hand Solutions’ complete M-Finger model, designed for the management of the absence of fingers at or near the level of the MCF joint. In the full M-Finger system, the prosthetic joint occurs in both the MCF and IFP joints. As with the Partial Finger-M system, the flexion of these joints is created by the tension of the Spectra cable and with the extension created by the internal springs. In the Finger-M system, the cable excursion is created by flexion of the wrist as the cable runs from the base of the Finger-M, through the back of the hand, and anchors proximally to the joint of the wrist.
The Cyborg Beast
Developed by Jorge Zúñiga, Ph.D., and his research team at Creighton University, the Cyborg Beast is described as a “joint action” hand that requires sufficient “wrist movement and strength to function properly.” It can be printed and assembled by interested persons with access to a 3D printer. In contrast to the approaches outlined above with custom-made sockets and different-sized fingers in stock (available from stock), the Cyborg Beast is tailor-made for individual patients through sizing of part specifications. individual before printing. This can be done according to the age of the child or through the anatomical measurement of the individual. Individual parts are printed and assembled according to freely accessible instructions controlling it. In contrast to the static opposing stop and silicone restorations, the user can actively control the movement and position of the prosthesis. Additionally, the BPF’s construction frame provides a protective covering around the residual finger that protects the often highly sensitive finger from environmental impacts and pressures.