Extract
Using the experience gained from taking care of World War II veterans with
amputations, Ernest Burgess taught us that amputation surgery is
reconstructive surgery. It is the first step in the rehabilitation process for
patients with an amputation and should be thought of in this way. An
amputation is often a more appropriate option than limb salvage, irrespective
of the underlying cause. The decision-making and selection of the amputation
level must be based on realistic expectations with regard to functional
outcome and must be adapted to both the disease process being treated and the
unique needs of the patient. Sometimes the amputation is done as a life-saving
procedure in a patient who is not expected to walk, but more often it is done
for a patient who should be able to return to a full active life. This lecture
addresses amputations done to return the patient to full activity. Our
purposes are to assist the reader in (1) establishing reasonable goals when
confronted with the question of limb salvage versus amputation, (2)
understanding the roles of the soft-tissue envelope and osseous platform in
the creation of a residual limb, (3) understanding the method of
weight-bearing within a prosthetic socket, and (4) determining whether a bone
bridge is a positive addition to a transtibial amputation.
Using the experience gained from taking care of World War II veterans with
amputations, Ernest Burgess taught us that amputation surgery is
reconstructive surgery. It is the first step in the rehabilitation process for
patients with an amputation and should be thought of in this way. An
amputation is often a more appropriate option than limb salvage, irrespective
of the underlying cause. The decision-making and selection of the amputation
level must be based on realistic expectations with regard to functional
outcome and must be adapted to both the disease process being treated and the
unique needs of the patient. Sometimes the amputation is done as a life-saving
procedure in a patient who is not expected to walk, but more often it is done
for a patient who should be able to return to a full active life. This lecture
addresses amputations done to return the patient to full activity. Our
purposes are to assist the reader in (1) establishing reasonable goals when
confronted with the question of limb salvage versus amputation, (2)
understanding the roles of the soft-tissue envelope and osseous platform in
the creation of a residual limb, (3) understanding the method of
weight-bearing within a prosthetic socket, and (4) determining whether a bone
bridge is a positive addition to a transtibial amputation.
The Lower Extremity Assessment Project (LEAP) has provided objective
outcome data on patients with mutilating limb
injuries1. Five
hundred and sixty-nine consecutive patients with mutilating limb injuries
treated at eight academic trauma centers provided objective observational
outcome data relative to limb salvage and amputation. One hundred and
forty-nine underwent lower-extremity amputation during the course of their
care. This ongoing study is providing a realistic understanding of the
less-than-favorable results associated with both limb salvage and amputation.
Much of what has been learned from LEAP can be applied to the care of patients
with a non-traumatic amputation.
A reasonable functional goal should be established before an extremity
amputation is performed. The goals for a young individual who is going to
reenter the workforce after a traumatic amputation are very different from
those for an elderly debilitated patient with diabetes who has a limited life
expectancy. Before surgery is performed, four issues need to be addressed, in
order to create a needs assessment:
If the limb is salvaged, will the functional outcome be better than it
would be after an amputation and fitting of a prosthetic limb? This question
needs to be addressed regardless of whether the patient has a mutilating limb
injury, a diabetic foot infection, a tumor, or a congenital anomaly.What is a realistic expectation following treatment? The realistic expected
functional outcome is the average functional outcome for patients with the
same comorbidities and level of amputation; it is not the best possible
outcome.What is the cost of care? This cost goes beyond resource consumption. Can
the patient and his or her family afford the multiple operations and the time
off from work necessary to accomplish limb salvage, or are they best served by
amputation and fitting of a prosthetic limb?What are the risks? Limb-salvage surgery for any diagnosis is riskier than
an amputation. When a patient has had an infection in an ischemic limb, the
risk of recurrent infection and sepsis is far lower when the limb is removed
than when it is retained.
If the limb is salvaged, will the functional outcome be better than it
would be after an amputation and fitting of a prosthetic limb? This question
needs to be addressed regardless of whether the patient has a mutilating limb
injury, a diabetic foot infection, a tumor, or a congenital anomaly.
What is a realistic expectation following treatment? The realistic expected
functional outcome is the average functional outcome for patients with the
same comorbidities and level of amputation; it is not the best possible
outcome.
What is the cost of care? This cost goes beyond resource consumption. Can
the patient and his or her family afford the multiple operations and the time
off from work necessary to accomplish limb salvage, or are they best served by
amputation and fitting of a prosthetic limb?
What are the risks? Limb-salvage surgery for any diagnosis is riskier than
an amputation. When a patient has had an infection in an ischemic limb, the
risk of recurrent infection and sepsis is far lower when the limb is removed
than when it is retained.
Once these issues have been addressed, the patient and the surgical team
generally have sufficient data to support the decision-making process.
When performing an amputation as a reconstructive effort after trauma,
infection, tumor, or vascular insufficiency, one should strive to create:
Optimal residual limb length without osseous prominences.Reasonable function in the joint proximal to the level of the amputation to
enhance prosthetic function.A durable soft-tissue envelope. Although new prosthetic technology allows
compensation for a suboptimal soft-tissue envelope, it is well accepted that
amputees fare better with a durable soft-tissue envelope and fare worse when
the skin is adherent to bone or there is a split-thickness skin graft in areas
of high pressure or
shear2,3.
Therefore, muscles should be secured to bone to prevent retraction. When
possible, full-thickness myocutaneous flaps should be used, with muscle
cushioning in areas of high pressure and shear (Figs.
1-A and 1-B,
1-C and 1-D).
Optimal residual limb length without osseous prominences.
Reasonable function in the joint proximal to the level of the amputation to
enhance prosthetic function.
A durable soft-tissue envelope. Although new prosthetic technology allows
compensation for a suboptimal soft-tissue envelope, it is well accepted that
amputees fare better with a durable soft-tissue envelope and fare worse when
the skin is adherent to bone or there is a split-thickness skin graft in areas
of high pressure or
shear2,3.
Therefore, muscles should be secured to bone to prevent retraction. When
possible, full-thickness myocutaneous flaps should be used, with muscle
cushioning in areas of high pressure and shear (Figs.
1-A and 1-B,
1-C and 1-D).
The more distal the level of lower-extremity amputation, the better the
walking independence and functional outcome, unless the quality of the
residual limb creates so much discomfort that it negates the potential
benefits of limb-length retention. Therefore, the amputation should be done at
the most distal level that will result in a functional residual limb. Efforts
to create a functional residual limb should take into account the method of
weight-bearing (load transfer) and the tissues available to create a
soft-tissue envelope.
The best residual limb cannot duplicate the unique weight-bearing
properties of a normal foot. The foot has multiple bones and articulations
that function as a shock absorber at heel strike, a stable platform during
stance phase, and a "starting block" for stability at push-off.
The multiple bones and joints allow positioning of the durable plantar
soft-tissue envelope in an optimal orientation for accepting load. An amputee
has, in place of a foot, a residual limb that must tolerate weight-bearing
(load transfer) with the socket of a prosthesis.
When the amputation is through a joint (disarticulation), the load transfer
can be accomplished directly; i.e., there is end-bearing. When the amputation
is done through the bone (transosseous), the load transfer must be
accomplished indirectly by the entire residual limb, through a total-contact
socket of the prosthesis, as weight-bearing on the end of the residual limb is
too painful. Disarticulation allows dissipation of the load over a large
surface area of less stiff metaphyseal bone. With a well-constructed
soft-tissue envelope to cushion the residual osseous platform, the
direct-transfer prosthetic socket need only suspend the prosthesis. This
differs from transosseous amputation at the transtibial or transfemoral level,
where the surface area of the end of the bone is small and the diaphyseal bone
is less resilient. The end of the bone must be "unweighted" by
dissipating the load over the entire surface of the residual limb. This
indirect load transfer requires a durable and mobile soft-tissue envelope that
can tolerate the shearing forces associated with weight-bearing. The socket
fit becomes crucial. When a patient loses weight the residual limb tends to
bottom out, and painful end-bearing or tissue breakdown develops. Patients who
gain weight are not able to fit the limb into the prosthesis. The choice of
disarticulation or transosseous amputation must be individualized for each
patient.
The standard transtibial prosthetic socket is fabricated with the knee in
approximately 10° of flexion, in order to unload the distal part of the
tibia and optimally distribute the load. Load transfer is accomplished by
distributing the load over the entire surface area of the residual limb, with
a concentration over the anterior-medial and anterior-lateral areas of the
tibial metaphysis.
Mutilating limb injuries frequently disrupt the interosseous membrane,
disengaging the relationship between the tibia and fibula. This loss of
integrity of the interosseous membrane prevents the fibula from participating
in normal load transfer. In other situations, the residual fibula may become
unstable following transtibial amputation because of loss of the integrity of
the interosseous membrane or as a result of loss of the integrity of the
proximal tibiofibular joint even without an obvious traumatic disruption.
Individuals with instability of the residual fibula following transtibial
amputation can have pain due to several causes. When the residual limb is
compressed within the prosthetic socket, the residual fibula may angulate
toward the tibia with prolonged weight-bearing. The result is a conical,
pointed residual limb, which tends to bottom-out during prolonged
weight-bearing. The conical residual limb acts as a wedge, leading to painful
end-bearing and soft-tissue breakdown over the terminal tibia. When the
residual limb is short, or the interosseous membrane has been disrupted, the
residual fibula can be abducted as a result of unopposed action of the biceps
femoris muscle (Fig.
2)4,5.
These alterations of the load-bearing platform become accentuated in younger,
more active amputees, with higher demand, or with prolonged
activities6,7.
During World War I, Ertl proposed the creation of an osteoperiosteal tube,
derived mostly from tibial periosteum, and affixing it to the fibula to create
a stable residual
limb8. Following
World War II, his concept was successfully introduced in the United States by
Loon4,
Deffer9, and
others10.
Arthrodesis, or bone-bridging, of the distal parts of the tibia and fibula has
recently become a controversial topic, with both ardent supporters and strong
detractors. Recent investigations suggest that the technique may provide a
potential benefit for an active amputee by creating a stable platform with an
enhanced surface area for load
transfer5,11,12
(Figs. 3-A and 3-B). Most
supporters suggest that the technique should be reserved for younger, more
active amputees who will benefit from the potentially enhanced functional
residual limb and are more able to tolerate the increased morbidity risk
associated with the additional surgery necessary to obtain the bone
bridge.
The surgery can also be performed as a late reconstruction for active
amputees with residual limb pain that appears to be associated with an
unstable or disengaged residual fibula. These patients may have a conical
end-bearing residual limb, usually with pain at the end of the residual limb
and occasionally with tissue breakdown. Others may have pain along a prominent
or unstable fibula. On examination, the fibula usually can be felt to be
unstable.
The operation involves use of a long posterior myocutaneous flap. For the
average 6-ft (1.8-m)-tall patient, the optimal residual tibial length should
be a minimum of 10 to 12 cm in order to create an adequate weight-bearing
platform, but it should not be longer than 15 to 18 cm. (An excessively long
residual limb requires the prosthetic socket to be put into full extension.
This leads to increased distal pressure, increased end-bearing, and more stump
failures.) The fibula is divided 4 cm distal to the tibia to allow the
creation of the bone bridge. Care is taken to maintain as many muscular
attachments to the distal aspect of the fibula as possible. One centimeter of
the fibula is removed at the level of the distal tibial cut to allow rotation
of the vascularized bone. A notch is made in the lateral cortex of the
residual tibia to accept the rotated fibular segment. Stability can be
obtained by suturing the fibular segment through drill-holes, or with screw
fixation (Fig. 3-B).
The transferred fibular segment used between the distal parts of the fibula
and tibia can be supplemented with a vascularized periosteal sleeve taken from
the tibia, as described by
Ertl8. The
periosteum on the anterior surface of the tibia, which is quite thick, is
raised from the tibia distal to the level of the tibial transection. When the
periosteum is raised, it is important to keep it attached proximally and to
take a thin slice of cortical bone with it. This almost guarantees that the
periosteum obtained has maintained its vascular supply. A 1-in (2.5-cm)
osteotome is used to raise the periosteum and the thin slice of cortical bone.
The periosteal sleeve is sutured over the rotated fibular segment. The
periosteal graft alone has also been used in place of the fibula, but we have
no experience with that technique and do not recommend it.
The anterior aspect of the distal surface of the tibia is beveled, and a
durable full-thickness myocutaneous flap is repaired to the anterior aspect of
the tibia through drill holes or by suturing the posterior gastrocnemius
fascia to the anterior periosteum of the residual tibia and the anterior
compartment fascia.
When the surgery is performed as a late reconstruction or if there is no
distal part of the fibula with which to create the bone bridge, a tricortical
iliac crest bone graft is wedged between the terminal residual tibia and
fibula after the inner surfaces of both have been prepared with a burr
(Figs. 4-A, 4-B, and 4-C).
Postoperative Care
A rigid plaster dressing is applied to protect the residual limb and to
control postoperative swelling. Another option is to use elastic bandages for
a compressive dressing, but these need to be put on carefully so as not to
produce a pressure sore. This is especially important when a patient has a
peripheral neuropathy. Our experience has been that if the patient has pain at
the end of the stump or in the stump shortly after surgery it is due to a
local problem and the dressing needs to be changed, but pain that seems to be
in the distal, amputated part of the limb is the so-called phantom-limb
phenomenon. Phantom sensation is a normal response after an amputation that
usually resolves. Telling the patient before the surgery that they will have
phantom sensations tends to decrease anxiety about this phenomenon.
Weight-bearing with a temporary prosthesis is initiated when the residual
limb appears capable of tolerating weight-bearing. Pain with weight-bearing
lasts longer for patients who have had a bone-bridge reconstruction than it
does for those without a bone bridge. The pain may last for six to nine months
and seems to resolve as the bone bridge heals. It is assumed that the site of
healing between the fibula and tibia remains tender until the bone becomes
solid. The pain should be treated nonoperatively unless there is a sign of
inadequate placement of the graft or sutures. Usually, the patient can be
fitted for a prosthesis, but he or she may not be able to bear full weight
until the tenderness resolves.
Skin Flap for Transtibial (Below-the-Knee) Amputation
Load transfer following transtibial amputation appears to be enhanced when
the residual limb has a large osseous surface area covered with a durable
soft-tissue envelope composed of a well-cushioned mobile muscle mass and
full-thickness skin. This desired result is best achieved through use of a
long posterior myofasciocutaneous flap. Despite the fact that the standard
posterior flap for transtibial amputation is satisfactory for most patients,
retraction of the flap over time can lead to a troublesome pressure point
overlying the anterior aspect of the distal part of the residual tibia. The
standard transtibial amputation technique, popularized by Burgess et al.,
often places the surgical incision directly over that portion of the residual
tibia13. This
raises the potential for adherent scarring of the skin to that part of the
tibia or for inadequate cushioning of this region during weight-bearing. When
the anterior aspect of the distal part of the residual tibia is not
sufficiently padded, there is an increased likelihood of localized discomfort,
blistering, or tissue breakdown associated with the normal pistoning that
occurs between the residual limb and the prosthetic socket during normal
walking. An extended posterior flap appears to prevent these potential
morbidities by providing improved cushioning and comfort even for individuals
who are capable of only limited
activity14. The
encouraging results of this relatively simple modification support the
well-accepted notion that an optimal residual limb should be composed of a
sufficient osseous platform and a durable and cushioned soft-tissue
envelope11.
The extended posterior flap is created by increasing the length of the
standard posterior flap by several centimeters (Figs.
5-A and
5-B). The posterior
myocutaneous flap is created and the osseous cuts are performed in the
traditional manner. The myocutaneous flap is generally created from the
gastrocnemius muscle and overlying skin, with removal of the soleus muscle
belly in all but very thin patients. Care is taken in the handling of the
transected nerves to avoid the development of sensitive, painful neuromas. It
is advised to avoid clamping of the nerves prior to transection in order to
avoid the pain so frequently encountered following crushing injuries. The
nerves should be dissected proximal to the level of the bone transection, with
use of gentle traction with a sponge, and then they are transected with a
fresh scalpel blade. This allows the inevitable terminal neuroma to be
cushioned within bulky muscle. To avoid a bulbous stump, the posterior and
lateral compartment muscles (except the gastrocnemius) should be transected at
the level of the transected tibia. Anterior skin is removed to allow proximal
attachment of the muscle flap and proximal placement of the wound scar. A
myodesis of the posterior muscle flap to the tibia can be performed through
drill holes. The posterior gastrocnemius fascia is secured to the transected
anterior compartment fascia and tibial periosteum with horizontal mattress
sutures (Figs. 6-A and 6-B). A
rigid plaster dressing is applied, and prosthetic fitting is initiated when
the residual limb appears capable of weight-bearing.
Transfemoral amputation is performed less frequently than in the past, but
it is still necessary in some patients with severe vascular disease, a
neoplasm, infection, or trauma in whom reconstruction at a more distal level
is not
feasible15,16.
The energy expenditure for walking, even on a level surface, by an individual
with a transfemoral amputation has been shown to be as much as 65% greater
than that for similar, able-bodied
individuals17,18.
Energy expenditure can be minimized by a properly performed above-the-knee
amputation.
The anatomical alignment of the lower limb has been well defined. The
mechanical axis lies on a line from the center of the femoral head through the
center of the knee to the center of the ankle. In normal two-limbed stance,
this axis measures 3° from the vertical axis and the femoral shaft axis
measures 9° from the vertical
axis19. The femur
is normally oriented in relative adduction, which allows the hip stabilizers
(the gluteus medius and minimus) and abductors (the gluteus medius and the
tensor fasciae latae) to act on it to reduce the lateral motion of the center
of mass of the body, producing an energy-efficient gait
(Fig. 7).
In most individuals who have undergone a transfemoral amputation, the
mechanical and anatomical alignment is altered as a result of disruption of
the adductor magnus insertion at the adductor tubercle and the distal part of
the linea aspera20.
This allows the residual femur to drift into abduction as a result of the
unopposed action of the hip abductors. Many patients who have undergone a
transfemoral amputation encounter difficulties with prosthetic fitting due to
inadequate muscle stabilization at the time of the
amputation21. The
unstable femur disrupts the relationship between the anatomical and mechanical
axes of the limb. The abductor lurch, so common after transfemoral amputation,
is a consequence of the unopposed action of the intact hip abductors. This
dynamic deformity overcomes the capacity of even modern prostheses to
compensate.
Traditional transfemoral amputation is done by suturing the femur flexors
to the extensors—i.e., creating a myoplasty—while ignoring the
adductors that contribute to stability of the residual
femur22. When the
adductors are not anchored to bone, the hip abductors are able to act
unopposed, producing a dynamic flexion-abduction deformity. This deformity
prepositions the femur in an orientation that is not conducive to efficient
walking23,24.
The retracted adductor muscles lead to a poorly cushioning soft-tissue
envelope, further complicating prosthetic
fitting25.
The cross-sectional area of the adductor magnus is three to four times
larger than that of the adductor longus and brevis combined. It has a moment
arm with the best mechanical advantage. Transection of the adductor magnus at
the time of amputation leads to substantial loss of cross-sectional area, a
reduction in the effective moment arm, and loss of up to 70% of the adductor
pull20,25.
This results in overall weakness of the adductor force of the thigh and
subsequent abduction of the residual femur
(Fig. 7). The decrease in
overall limb strength is due to (1) a reduction in muscle mass at the time of
the amputation, (2) inadequate mechanical fixation of the remaining muscles,
and (3) atrophy of the remaining
muscles26,27.
Magnetic resonance imaging has demonstrated a 40% to 60% decrease in muscle
bulk after a traumatic transfemoral amputation. Most of the atrophy is in the
adductor and hamstring muscles, whereas the intact hip abductors and flexors
show smaller changes, ranging from 0% to
30%28,29.
As much as 70% atrophy of the adductor magnus has been found. The amount of
atrophy correlates with the length of the residual limb, and this atrophy is
most likely due to loss of the muscle insertion.
Electromyographic studies of residual limbs following transfemoral
amputation have revealed normal muscle phasic activity; however, the active
period of the retained muscles appears to be
prolonged29. The
electrical activity of sectioned muscles varies, depending on whether the
muscles have been reanchored and on the length of the residual femur.
Furthermore, asymmetric gait has been related to residual limb length, and
lateral bending of the trunk has been correlated directly with atrophy of the
hip stabilizing
muscles30.
All of these findings indicate the need to preserve the hip adductors and
hamstrings. Preservation of a functional adductor magnus helps to maintain the
muscle balance between the adductors and abductors by allowing the adductor
magnus to maintain its power and retain the mechanical advantage for
positioning the femur. Preservation is best accomplished with a myodesis. The
patient is positioned supine with a sandbag under the buttocks to avoid
performing the myodesis with the hip in a flexed position and thus producing
an iatrogenic hip flexion contracture. A tourniquet is generally not necessary
for patients with peripheral vascular disease. Depending on the size of the
patient, a standard, or a sterile, tourniquet can be used when the
transfemoral amputation is being performed because of a traumatic injury or a
tumor and normal femoral vessels can be expected.
Equal anterior and posterior flaps should be avoided, as such flaps place
the suture line under the end of the residual limb, making prosthetic fitting
more difficult and adequate muscular padding less likely. A long medial-based
myofasciocutaneous flap is dependent on the vascular supply from the obturator
artery, which generally has less severe vascular disease and is thus preferred
(Figs. 8-A and
8-B)31.
The flap configuration may need to be modified, in order to preserve residual
limb length, when an amputation is done after trauma or because of neoplastic
disease. The tendon of the adductor magnus is detached. The femoral vessels
are identified in Hunter's canal and are ligated. The major nerves should be
dissected 2 to 4 cm proximal to the proposed bone cut, gently retracted, and
sectioned with a new sharp blade. The quadriceps is detached just proximal to
the patella, with retention of some of its tendinous portion. The smaller
muscles, including the sartorius and gracilis and the more posterior group of
hamstrings (biceps femoris, semitendinosus, and semimembranosus) should be
transected 2 to 2.5 cm longer than the proposed bone cut to facilitate the
anchoring of those muscles in bone.
The femur is then transected with an oscillating power saw 12 to 14 cm
proximal to the knee joint to allow sufficient space for the prosthetic knee
joint. Drill-holes are made in the distal end of the femur to anchor the
transected muscles. The adductor magnus is attached to the lateral cortex of
the femur while the femur is held in maximum adduction. This allows
appropriate tensioning of the anchored muscle. The hip is positioned in
extension for reattachment of the quadriceps to the posterior part of the
femur, and the remaining hamstrings are anchored to the posterior area of the
adductor magnus or the
quadriceps32.
Postoperative Care
A soft compression dressing with a "mini-spica" wrap above the
pelvis is used in the early postoperative period. Because the residual limb is
relatively short, it is difficult to maintain a rigid plaster dressing.
Range-of-motion exercises and early walking are encouraged. Preparatory
prosthetic fitting can be initiated as soon as the residual limb appears
capable of accepting the load associated with weight-bearing. This varies with
individual patients and the experience of the rehabilitation team.
In conclusion, an amputation should be considered the first step in the
rehabilitation of a patient for whom reconstruction of a functional limb is
not possible. Care should be taken to create a residual limb that can
optimally interact with a prosthetic socket to create a residual
limb-prosthetic socket relationship capable of substituting for the highly
adaptive end organ of weight-bearing. A well-motivated patient in whom the
amputation is done well and who is taught how to use the prosthesis will be
able to return to most activities.
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