Standard of Care: Lower Extremity Amputation
Copyright ©2011 The Brigham and Women’s Hospital, Inc., Department of Rehabilitation Services. All Rights Reserved.
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Ideally the prosthesis should restore function with a minimal amount of energy expenditure
29
.
Oxygen consumption increases approximately 33% for the transtibial amputee, and nearly doubles
for the transfemoral amputee
28
. Due to the increasing cardiopulmonary demands with more
proximal or bilateral amputations, the level of amputation has a direct effect on successful
prosthetic rehabilitation in the older patient
29
.
Prosthetic limb choices have increased dramatically over the past several years
8
, but the basic
components remain the same for all LE prosthetic devices: a foot, pylon, socket, suspension
system and, if appropriate, a knee mechanism.
• Prosthetic Feet: The foot (or terminal device) serves as a shock absorber and provides a
stable weight-bearing surface
28
. A variety of prosthetic feet are currently available, ranging
from the simple SACH foot to the sophisticated energy storing and multiaxis function of
some feet
8
.
• Suspension System: The prosthetic socket may be suspended in a number of ways
including various cuffs and sleeves, which hold to socket onto the residual limb. Suction is
often a feature, which contributes to reliable suspension of the socket. Another type of
popular suspension system involves a pin on the bottom of a liner, which inserts and locks
into a pinhole at the bottom of the socket
28
.
• Sockets and Liners: Sockets are custom made by obtaining a negative impression of the
residual limb in plaster and made of plastic materials such as polyester resin
8
. Sockets for
individuals with a transtibial amputation may be patellar tendon bearing (PTB), which
offers areas of weight-bearing pressure and relief, or total surface bearing (TSB), which
distributes pressure more equally throughout the residual limb
4
. Sockets for individuals
with a transfemoral amputation generally include the quadrilateral socket, named for its’
square appearance in the transverse plane, and ischial-containment socket, which has a
wider anteroposterior (AP) dimension and narrower mediolateral (ML) dimension
4
. Liners
allow for total contact between the residual limb and prosthetic socket, and may be added
or taken off dependent on daily edema changes in the residual limb.
• Prosthetic Knees: Can have a single axis or be poly-centric
8
. Most basic prosthetic knee has
a locking mechanism that is manually applied to provide stability in the stance phase, with
more advanced options including a weight activated brake or a fluid controlled cylinder
8
.
To control limb displacement during swing phase options are available and include friction,
springs, and fluid resistance
8
. Electric controllers for the timing and amount of fluid
resistance (the C-Leg) results in a less effortful and safer gait pattern
8
.
For persons undergoing hip disarticulation or external hemipelvectomy, the skeletal structure and
soft tissue available for prosthetic weight bearing are significantly compromised and result in an
increased incidence of skin breakdown
30
. Lower extremity prosthetics for these patients’ will
include a hip socket and prosthetic hip joint. Prosthetic sockets for external hemipelvectomy
encase the abdominal cavity and provide hard walls that protect and compress the abdominal
viscera so that these areas may accept weight-bearing, and may extend superiorly to the tenth rib to
allow additional vertical loading
4
. The hip disarticulation socket encloses the ischial tuberosity and
gluteal muscles for weight bearing, extends over the ilium to provide suspension, and also encases
the opposite pelvis to assist in mediolateral trunk stability
4
. The prosthetic hip joint in the hip
disarticulation prosthesis is attached to the socket anteriorly, which causes the weight line to fall
posterior to the hip and anterior to the knee, to assist hip and knee extension, and also to allow the