Suction Sock Suspension for Above-Knee Prostheses
Charles J. Dietzen, M.D.
Jerald Harshberger, C.P.
Rama D. Pidikiti, M.D.
Introduction
Presently, there are essentially three
forms of prosthetic suspension utilized with
above-knee (AK) amputation proximal to
the femoral condyles: suction, silesian belt
and hip joint with pelvic band. Suction may
be used in combination with one of the other
methods. (1)
Advantages of suction suspension include:
greater freedom of movement, increased use
of the remaining muscles, decreased pistoning, increased comfort due to elimination of
belts and straps and better cosmesis. The
classic suction socket is contraindicated in
patients who have volume changes, poor balance, decreased manual dexterity and/or
other systemic diseases that preclude the exertion needed to don the prosthesis, i.e.,
heart or lung disease (1). Therefore, the geriatric patient often is not a suitable candidate for this suspension system.
The silesian belt has the advantages of
comfort with positive suspension, control of
rotation and aid in adduction of the prosthesis. It is often used in combination with suction socket and can be hidden under clothing
better than the hip joint with pelvic band.
However, it is more cumbersome than the
suction socket, allows for less prosthetic control and is less cosmetic than the suction
socket (1). Because of the belt's placement,
it is contraindicated in pregnancy and in patients who have had by-pass surgery or shunt
placement in the remaining lower extremity
(2).
The hip joint with pelvic band is useful for
geriatric and obese patients because it gives
positive suspension and better control of the
prosthesis. The lever arm also helps absorb
the lateral forces involved with short stumps
(1). The drawbacks are the increased weight
and cumbersome nature of the prosthesis
that can lead to its decreased use.
Technique
In 1985, Ossurr Kristinsson described the
ICEROSS, or Icelandic Roll-On Suction
Socket, system. At that time, the second author began to experiment with silicone socks
for suspension. As a result of the success of
the Durr-Fillauer 3-S Suction Socket System
introduced in 1988, he continued development of this idea for suspension of AK prostheses.
A silicone sock is fabricated using silicone
gel and two or three nylon stockinettes laminated over an AK suction-type socket mold.
A durable cloth strap with Velcro at the terminal end is laminated into the central portion of the distal end of the sock. This strap is
pulled through the distal end of the socket
and secured to the external surface of the
prosthesis with a Velcro hook and pile system to aid in retention of the prosthesis (Figure 1)
.
Another retention device utilized is a simple wooden wedge. Triangular wedges,
7 cm in length and 4 cm in width opposite the
apex, are laminated into the silicone sock
medially and laterally, parallel to one another at the approximate middle of the sock.
The wedges then protrude through matching
windows in the socket wall to provide suspension (Figure 2
and Figure 3
). This mode of suspension is especially advantageous for geriatric patients due to the ease of donning and
doffing. As the patient pushes the sock-covered stump into the socket, the wedges
shape aid in alignment and lock into place
for retention. The patient simply pushes in
on the wedges to release the suspension and
allow removal of the prosthesis.
Application
The true incidence of lower extremity amputation in the U.S. is not known. It is estimated that 30,000-110,000 lower extremity
amputations are performed per year (3,4,5).
Thirty-three thousand AK amputations were
performed in acute care, nonfederal hospitals in 1984, according to the U.S. Department of Health and Human Services (5). The
ratio of below-knee (BK) amputations to
AK amputations was reported as 10:7 in one
reference (4) and 1:1 in another (5). Seventy-five percent of acquired lower extremity
amputations are caused by disease states.
Diabetes and peripheral vascular disease account for the majority, especially in the patient population of 60 years and older (5). It
has also been stated that 85 percent of AK
amputations are secondary to vascular disease (1).
Only about one-fourth of the geriatric amputee population are functional prosthetic
users, with perhaps another fourth becoming
functional users secondary to refinements
(1). Across all age groups, two-thirds of BK
amputees are functional ambulators with
prostheses while only 20 percent of AK amputees will walk. The number of functional
ambulators drops to one in 15 in the geriatric
AK amputee population (3). There would
appear to be a large population of geriatric
patients that could benefit from this improved device. Given the prevalence of peripheral vascular disease and diabetes in this
population, many amputees have had bypass grafts or shunts placed in the remaining
lower extremity, thus precluding the use of
currently available appliances. In addition,
patients with heart and lung disease, causing
decreased exertional ability, would benefit
by an improved appliance.
Evaluation of Technique
We are presently testing several prototypes and are submitting a grant proposal
through the VA Medical Center in Birmingham, Alabama, for long-term evaluation.
Fourteen silicone sleeves have been fabricated for seven different AK amputees. Four of
the amputees lost their limbs secondary to
vascular insufficiency, and the other three
were traumatic amputees. Two of the four
elderly gentlemen who lost their legs from
poor circulation have low activity levels, and
two are fairly active. The three traumatic
amputees remain very active.
No significant problems have been encountered with donning, even in patients
with compromised heart and/or lung function. There have been no reports of slippage,
regardless of temperature or perspiration. In
fact, some of the patients reported decreased
perspiration with the new suspension sock.
Two patients who had used other suspension
means, one a hip joint and the other a thoracic elastic belt, commented that the suction suspension was more comfortable and
allowed increased activity.
The one disadvantage encountered thus
far involves significant volume fluctuation of
the stump, as evidenced by the number of
sleeves (fourteen) fabricated for seven AK
amputees. The movement of the limb in
swing phase with this suspension apparently
causes "milking" of the distal soft tissues.
This results in stump shrinkage which may
easily be remedied by the addition of a sock;
however, if the volume reduction is great, it
may necessitate the fabrication of a new,
smaller silicone sock. It is, therefore, recommended that volume reduction be maximized before the silicone sock is fabricated.
No additional maintenance, beyond that
needed for other AK prostheses, has been
required. The patients have required minimal instruction on proper alignment of the
prosthesis for donning. The usual gait training is the only other instruction necessary.
Conclusion
The AK suction sock suspension appears
to provide a very functional, durable means
of suspending an AK prosthesis with the advantages of suction, while negating the need
for good manual dexterity and increased exertion. This should be of benefit to the geriatric population in particular. The lack of a
strap or belt would benefit pregnant women
and persons with AK amputations who have
undergone by-pass surgery or shunt placement of the remaining lower extremity.
Acknowledgements
The authors would like to thank Mrs. Betty
Barrett for her efforts in producing this manuscript.
Charles J. Dietzen, M.D., is a third year resident, Department of Rehabilitation Medicine,
University of Alabama at Birmingham, Birmingham, Alabama 35294.
Jerald Harshberger, C.P., is president and
owner of Harshberger Prosthetics, 903 21st Street
South, Birmingham, Alabama 35205. Phone
number (205) 328-5347.
Rama D. Pidikiti, M.D., is Chief of Rehabilitation Medicine Service, VA Medical Center, Birmingham, Alabama 35233, and assistant professor, Department of Rehabilitation Medicine,
University of Alabama at Birmingham, Birmingham, Alabama 35294. Phone number (205) 9334390.
References:
- Mooney M, Quigley J. Above-knee amputations. Atlas of Limb Prosthetics, Surgical and
Prosthetic Principles. American Academy of Orthopaedic Surgeons: CV Mosby Company,
1981:378-401.
- Ayyappa E. Prosthetic prescription principles. Material submitted for masters' thesis and
publication, 1988-89.
- Dodson T. Assessment of healing potential.
Lecture material delivered at the VA seminar,
Management of the lower extremity amputee: a
team approach to preservation and augmentation
of function, September 12-15, 1988.
- Friedmann L. Rehabilitation of the amputee. Rehabilitation Medicine. Goodgold J, ed.
1988:601.
- Leonard Jr, I, Meier III, R. Prosthetics. Rehabilitation Medicine: Principles and Practice.
DeLisa J, ed. 1988:330-331.
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