PARTIAL HAND AND FUNCTIONAL PROSTHESES
Janet G. Marshall, CPO, Shriners Hospital for Children, Tampa, FL
Congenital partial hands or partial hands acquired at a young age have historically been problematic in terms of patient acceptance of prosthetic wear. These individuals have naturally developed the sound side as dominant with use of the affected side as assistive. Even though the use of a partial hand is limited in grasp, other compensations of function have been adapted to make its general use acceptable with no need or desire for a prosthesis. However, if a prosthesis is prescribed for a partial hand, it is more likely to be rejected than any other upper extremity prosthesis. 1 (Wedderburm)
Rejection is usually due to certain several factors. The sense of touch is compromised when covered by the prosthesis. The natural function already present often outweighs the relatively limited function achieved by the prosthesis. The added length for componentry along with the necessity of a harness can produce a non-acceptable cosmetic appearance. However, there are occasions when a partial hand amputee has demands that require a task specific prosthesis to be designed for use. Also, there is a time, commonly the teenage years, when selfimage is a paramount and a cosmetic hand is requested. Limited function with this would be a bonus.
This paper will discuss three partial hand amputees, two of which are congenital and one traumatic. All three patients desired functional prostheses, but without harnessing. The custom design and fabrication methods will be detailed that achieved satisfactory results for this group.
A fifteen year old male from Bolivia had a traumatic amputations at the age of four that removed all digits of his left hand. The residuum had adequate wrist motion and strength, but the partially present metacarpals within a soft palmar surface resulted in compromised leverage. He first came to our facility at the age of nine with a passive hand. He had not ADL limitations. He was fit with a body powered prosthesis, figure eight harness, and hand of which he demonstrated good use. After this initial visit, he returned again at the ages of ten and twelve to have new prostheses made which wore sometimes for school and hobbies. At his last visit, he rejected the latter, but wanted a cosmetic hand with function. Wedderburn's article, "A Wrist Powered Prothesis for the Partial Hand" prompted the design of a new tenodesis type prehension prosthesis.
An impression cast of the patient's residual limb and forearm was taken with the wrist in an extended position. An additional impression of a left hand of similar size to the patient's was also made in a three jaw chuck prehension position. Both plaster casts, after minor modifications, were pulled with surlyn. This created a durable and lightweight definitve material for the prosthesis. An aluminum single axis hinge was positioned to match the anatomical axis at the radial styloid and the thumb post remained static extending from the forearm. The inner socket for the residual palm was encapsulated with the surlyn fingers that were in a functional prehension pattern opposing the static thumb. When donned, the patient could flex and extend his wrist to grasp and release small objects. A pelite pad inserted on the dorsum of his hand enabled a more secure leverage. This surlyn hand was then covered with a cosmetic glove that was cut strategically for ease of motion. The patient wore a cotton stockinette underneath for comfort. He was pleased with the appearance, but was slightly disappointed in the limited function achieved.
A seventeen year old male from Guatemala has congenital aphalangia of his left hand leaving s shortened thumb and small remnants of his other digits. His range of motion and strength allowed opposition for grasp, but the limited lengths were inhibitive of certain tasks. He was offered surgical lengthening on his first visit at fifteen years of age or a functional prosthesis, but rejected both options. Upon the return, he requested a prosthesis that was task specific for weight lifting. He also desired a cosmetic glove that was functional if possible.
An impression was taken of the patient's residual hand and forearm holding a barbell in lifting position. A plastizote mitt-shaped form was glued onto the modified plaster mold and copolymer plastic was pulled over it. While the vacuum was on and the plastic was still malleable, a barbell was again positioned for grasp. For finishing, a leather surface was applied on the palm for added grip and friction.
For the cosmetic prosthesis, a passive hand was modified to fit over the residual hand. The dorsal surface of this was left intact with the congruent side to the residuum removed. A thimble extension of surlyn fit over the existing thumb of the patient for added length for opposition to the passive fingers. When donned, using a stockinette for con-fort, the patient was able to demonstrated functional opposition with adequate strenth to grasp small objects. He was extremely pleased with the outcome of both prostheses.
The final patient was a twelve year old male with a congenital aphalangia of his left hand leaving a full thumb, a partial palm, and small remnants of the other digits. He also was capable of opposition, but the length factor limited the grasp. He had rejected surgical phalangeal transfers of the toes and had never desired a prosthesis before. He presented with a request for a prosthesis that would enable him to perform fine motor skills for school science projects. A mitt fabricated in the same manner as the previous patient was created. The palmer surface was covered in a relatively thick layer of plastazote to grip small objects. The wrist was left free without a forearm extension. Again this patient was very pleased with his newly found dexterity.
This paper reflects the unique challenges presented by partial hand amputees both congenital and traumatic from a very young age. Solutions must be customized to the function and cosmetic appearance desired so that acceptance of the prosthesis is achieved. The requirements of ingenuity on the part of the prosthetist in order to create this is rewarded by the genuine appreciation and satisfaction from the patient.
- Wedderburn, Caldwell, Sanderson, Olive; "A Wrist-powered Prosthesis for the Partial Hand", JACPOC; Vol. 21, 1986.
- Bender, "Prostheses for Partial Hand Amputation", Prosthetics and Orthotics International, 1978, 2, 8-11. Bowker, Michael, ATLAS OF LIMB PROSTHETICS, 2nd Edition, Mosby, 1992.
- Leow, Pereira, Kour, Pho, "Aesthetic Life-like finger and Hand Prostheses: Prosthetic Prescription and Factors Influencing Choices", Annals Academy of Medicine, 1997.
- Putzi, "Myoelectric Partial-Hand Prosthesis", JPO, Vol. 4, No. 2, 1992.
- Shim, Lee, Lee, Park, Moon; "Wrist-Driven Prehension Prosthesis for Amputee Patients with Disarticulation of the Thumb and Index Finger'; Arch Phys.Med.Rehab, vol. 79, 1998.