ACPOC - The Association of Children's Prosthetic-Orthotic Clinics Founded in 1978

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Alternatives For Partial Hand Management


Prosthetic recommendation for partial hand amputation can be characterized by a number dichotomous of factors. Although the residual limb presents with extremely sensate areas and good joint proprioception, it must often be covered for prosthetic wear causing many to reject the prosthesis. Relatively few components exist that are adapted for partial hand application even though among upper extremity amputees there are comparatively large number of partial hands. A number of biomechanic work sources exist at the finger, wrist, and elbow, to drive the prosthesis, but it is difficult utilize them easily. Balancing these factors and adapting control alternatives from orthotics, can contribute to a more optimum and functional prosthetic outcome.

Partial hand amputation accounts for a majority of upper limb amputations. According to Dillingham who surveyed the amputee records in the US from 1988-1996, amputation of the finger(s) represents the largest patient group of 74% of all upper extremity amputations and 13,586 annually1. The amputation of the thumb was second at 16% or 3,002 annually, through the hand amputation was 1% or 259 annually1. The total number of upper extremity amputations was 166,076 or 18,453 annually accounting for 16% of the total number of amputations1. Trauma accounted for 90% of finger amputations, 82% of thumb amputations, and 42% of Hand amputations. Dysvascular causes were the highest through the hand with 53%1.

Challenges of partial hand prosthetic fitting can be considerable and contribute to a higher clinical rejection rate.2 The most obvious factor is the accommodation of a longer limb length. Componentry adapted from more proximal levels can be utilized, but often special components must be created or borrowed from upper extremity orthotic designs. Although more external power components are becoming available, simple body powered solutions are often utilized. The loss of grasp strength and security has psychological effect on the patient overall.2 Interface design must also be considered with control. Distal end sensitivity must be protected while maximizing the exposure of the tactile areas. All these functional needs are tempered by cosmetic requirements. Other than maxiofacial prostheses, partial hand or finger devices are left fairly exposed. Patients that hide their hands in their pocket remove the residual limb from bimanualar activities rendering, as Beasley notes, "as functionally disabled as a forequarter (scapulothoracic) amputee."2

There are also a number of functional advantages that the partial hand presents. Taking advantage of these factors can increase prosthetic acceptance, but often demand design alternatives. The partial hand presents distal suspension options, utilized by orthotic devices, across the dorsal mid-hand, radial-ulnar styloids, or mid-forearm.3 Greater tactile sensation is a crucial advantage when grasping objects. It can be enhanced by opening the palmar area, leaving remnant fingers exposed, or even uncovering the dorsum of the hand. Since so much of the sensate homunculus is dedicated to the fingers, hand, and especially thumb, proprioception of the hand is quite high. The joint positions of the fingers, thumb, and wrist can be quite fine. These fine motor joints can be utilized to increase overall dexterity with finger driven, wrist driven, or even elbow driven devices.

Any of partial hand alternatives must be considered by the degree to which they satisfy the prosthetic goals: 1) Protection, 2) Bimanual Activity, 3) Body Image, 4) Minimizing Harnessing, 5) Maximize Suspension & Gripping Security, 6) Number of Grip Patterns.4 5 These functional goals are often balanced and compromised by the need for cosmetic appearance.

The major gripping patterns remain: Palmar, Tip, Spherical, Lateral, Hook, Cylindrical. Each of these can be evaluated with respect to the partial hand. The ability to switch gripping patterns is a primary function of the mobility and stability of the thumb CMC.3 The orthotic upper extremity goals are: Creation of the thumb webspace, maintaining the palmar arch, and providing thumb opposition.3 Not all prehension patterns retain a neutral gripping presentation. The palmar or 3-jaw chuck gripping pattern is the most often used and versatile of the grip patterns.

It can approximate the tip and cylindrical gripping patterns exhibiting fine and broad gripping surfaces. Typically the 2nd and 3rd digit finger are in motion to a posted thumb with and adduction and extension stop slightly flexed with the wrist in neutral position. Tip grasping is also referred as precision grip again with the thumb posted, but only interacting with the index finger. The wrist is held neutral or with a slight radial deviation. The spherical grasp is broad adaptive grip where all the fingers are providing grip, but it is difficult to emulate prosthetically. The thumb is abducted and flexed to the center of the grip envelope providing diagonal opposition with the wrist in slight ulnar deviation. The lateral grip or key pinch pattern is often the most requested grip pattern after plamar gripping for the ability to forcefully flex the thumb against the index finger. This pattern is very similar to the grip provided by a hook type terminal device. This requires the ability of the thumb CMC to move in a more extended and adducted position with the wrist in a neutral position. Cylindrial grasp is also referred to as the power grasp with an ulnar deviation and a neutral 30 wrist extension.

It is the active manipulation of the thumb that sets the cylindrical grasp apart from the passive hook type grip. Hook type grip uses the fingers to passively hold objects usually higher loads the tax the abilities of suspension technique.

The predominant prosthetic recommendation remains passive devices due to their cosmetic quality, ease of fitting, and functional value. Silicone replacement fingers and custom gloves can be created from detailed molds.6 17 These simple devices are limited in function to passive posts and cannot provide active gripping. They often cover the residual limb entirely and limit tactile sensation.

Body powered solutions for the finger only prosthesis are limited to the finger drive variety and the polycentric finger prosthesis. The finger driven device is linked to the opposing finger with a spring-loaded link that can drive the 2nd and 3rd finger post or thumb post together. While effective in utilizing a distal worksource, the moving parts are somewhat bulky and decrease the gripping surface. The poly-centric finger prosthesis clips onto proximal remnant motion and uses a polycentric linkage to drive the DIP and PIP joints into flexion. Each finger may be independently controlled in a life like motion. (7) The difficulty is finding a cover that can move with and stretch dorsally with the device. For a more functional solution, a hook may be mounted in the palmar section and may be affixed to a distal cuff previously referred to as a "Handy-Hook". A lateral cable mounting operates the terminal device with a GH flexion and biscapular abduction similar to transradial designs.9 The disadvantage is that this design covers the entire palmar surface and cable control must be extended the entire arm length. The Robin-Aids hand had fingers that gripped through the PIP joint rather than the MC joint. This represented the only off-the-shelf device that could be retrofitted to the individual needs of the partial hand amputee.9 Wrist driven devices may be a simple wrist hinge attached as a gauntlet or and encapsulating the partial hand distally. Opposition is provided as the limb remnant closes the distal fingers against a passive thumb post. This can be a functional thumb post or it can be incorporated in a more cosmetic form using a cosmetic glove.13 Other wrist driven devices can be created that utilize a parallelogram linkage and wrist tenodesis to close distal fingers. An external device using Rancho, TIRR, or IRM would be too bulky, but the palmar mounted RIC wrist driven device can be used to close the finger portion.3

Meeks and Leblanc described an elbow driven device that can open a terminal device with elbow extension. Using this control method with a biceps cuff, the harnessing and suspension can be minimized to supracondylar involvement.8

Externally powered devices are greatly limited by the expense of development for partial hand use. Primarily shortened versions of standard externally powered hands transcarpal designs can be attached to the socket frame. This eliminates the wrist and incorporates the control electronics in the hand itself. Picken spoke about placing the batteries in the 4th and 5th finger.10 Putzi incorporated the external components by placing the components at a 45 relative to the limb remnant and providing a wrist hinge.11 12 Uellendahl incorporated electrodes and electronics in an all-silicone construction that can have simple push-on suspension or zipper construction.13 This employs custom silicone techniques, foil wrap batteries, and miniaturized electronics into a flexible glove construction. All these design employ standard MP motor driven devices which, though strong, are relatively bulky. One externally driven component places the drive motor in the proximal phalangeal section driving MP and PIP motion.15 Weir created special low-profile electronics and motor drives for partial hand utilizing the thenar and hypothernar prominences for myo sites.16 Another commercially available hand drives the finger only with the linkage to the thumb. This can be anchored, thumb removed, and fingers driven on the dorsal aspect of the hand.17

Task specific devices may also be created from existing componentry or functional devices. An infant wrist uses the same terminal device thread size as an adult, so it may be laminated in as a low profile attachment.9 A flexible gauntlet can also be used with a detachable wrist that can switch a variety of tools for specific tasks. This does not require active prehension, but does limit the functional tasks.18

Partial hand amputation, as in other aspects of upper extremity prosthetics, continues to be a challenge because the need to fashion individual solutions. Perhaps with continued development prosthetic usage will increase among this sizeable group of possible users. Although passive cosmetic restorations continue to have functional value, alternative prostheses that present body and external power control options can increase active grip control.

The Fillauer Companies, Inc., Chattanooga, Tennessee

References:

  1. Dillingham, T., MacKenzie, E., Limb Amputation and limb deficiency: epidemiology and recent trends in the United States, Southern Medical Journal, 2002.
  2. Michael, J., Buckner, H., Options for Finger Prosthesis, JPO, 1994, Vol. 6, No. 1, pp. 10-19.
  3. Orthotic Upper Extremity Manual, Northwestern University Prosthetic-Orthotic Center, Chicago, Illinois, 2007.
  4. Lake, C., Partial Hand Amputation: Prosthetic Management, Chapter 14, Atlas of Amputation and Limb Deficiencies, 3rd Edition, 2004, Smith, D., Michael, J., ed., American Academy of Orthopedic Surgeons, Rosemont, Illinois.
  5. Michael, J., Prosthetic and Orthotic Management, Chapter 7B, Atlas of Limb Prosthetics, 2 nd Edition, 1992, Bowker, J., Michael, J.,ed., American Academy of Orthopedic Surgeons, Rosemont, Illinois, pp 217-240.
  6. Living Skin, Aesthetic Concerns, Inc., Middletown, New York, www.livingskin.com, 2008.
  7. Didrick Medical, Naples, Florida, www.didrickmedical.com, 2008.
  8. Meeks, D., Le Blanc, M., Evaluation of a New Design: Body-Powered, Upper-Extremity Prosthesis Without Shoulder Harness, JPO, 1989 , Vol. 1, No. 1, pp. 45-49.
  9. Hosmer-Dorrance Corporation, Campbell, California, www.hosmer.com, 2008.
  10. Picken, B., Myoelectric Prosthesis for Partial Hand Amputee, ACPOC, ICIP, Vol. 1, No. 2, 1986.
  11. Putzi, R., Myoelectric Partial Hand Prosthesis, JPO, Vol. 4, No. 2, pp. 103-108, 1992.
  12. Otto Bock, USA, Minneapolis, Minnesota, www.ottobockus.com, 2008.
  13. Wedderburn, Z., Caldwell, R., A Wrist-Powered Prosthesis for the Partial Hand ACPOC, ICIP, 1986, Vol. 21, No. 3, pp. 42.
  14. Uellendahl, J., Mandacina, S., Custom Silicone Sockets for Myoelectric Prostheses, JPO, 2006, Vol. 18, No. 2, pp. 35-40.
  15. Touch Bionics, Edinburgh, Scotland, www.touchbionics.com, 2008.
  16. Weir, R., Externally Powered Partial Hand Prosthesis, Northwestern University Prosthetics Research Laboratory and Rehabilitation Engineering Research Program. Veterans Administration Merit Proposal A3028R, 2003.
  17. Centri Myo Hand, Centri, ab., Stockholm, Sweden, www.centri.se, 2008.
  18. N-abler III, Texas Assistive Devices, Brazoria, Texas www.n-abler.org, 2008.
  19. Bryant, M., Donahue, J., A Prosthesis to Restore Opposition in Children with Congenital Absence of the Hand, ACPOC, ICIB 1979 Vol 17, No. 6 , pp. 510.
  20. Wagner, L., Bagley, A., Reasons for Prosthetic Rejection by Children with Unilateral Congenital Transverse Forearm Total Deficiency, JPO, 2007, Vol. 19, No. 2, pp. 51-54.