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Section 2: Upper Limb
Figure 2
can be an option if the forces are transmitted
through a component other than the anchors
attaching the silicone to its frame. Photograph
of a patient using a prosthesis with an adjustable suspensio n system. The pos terior aspect of
the frame has a window to allow for donning.
The posterior side was chosen because the anterior aspect is important for loading.
For heavy-duty use, silicone
components such as electrodes, batteries, switches, and charge ports can
be embedded into the silicone. In areas where greater elasticity is desired,
such as the olecranon in a patient with
a transradial amputation, the silicone
can be made thinner or with a lower
shore to allow increased stretching with
elbow flexion.
Clinical Considerations
The high adhesion of HCR silicone
to the skin renders it an ideal interface material. Because there is little
shift in the socket relative to the skin,
problems associated with shear forces and compromised suspensions are
reduced. To don a silicone socket, a
pull sock can be used or a lubricant
liberally applied to the patient’s skin.
A lubricant that is especially slippery,
such as Cal-Stat Plus Antiseptic Handrub with Enhanced Emollients (Steris
Figure 3
silicone as the interface. The components are set up and attached to simulate the nal product.
Healthcare), is preferred in this type of
application. Importantly, lubricants or
lotions with added fragrances should
be avoided because they can cause
skin irritation and rashes. If irritation
occurs, the silicone interface can be
sanitized by placing it in boiling water.
Regular cleaning of HCR silicone can
be accomplished with soap and water
or isopropyl alcohol.
Normal HCR silicone interface construction allows for medium-duty use;
however, if heavy-duty use is desired,
special modifications can be performed
to ensure that forces are applied to a
Photograph of a check socket tting with unpigmented high consistency rubber
Primary Socket and
Suspension Approaches
Limb Protectors
In some instances, a silicone interface
serves solely as a limb protector. The
patient may choose to wear such an interface to protect a limb that is either
especially sensitive or insensate. The pa
tient may wear the silicone interface for
special activities or use it for improved
comfort during sleep. Using a check
socket as a limb protector is a good
use of a device that otherwise might be
discarded when the definitive socket is
fabricated and delivered (Figure 4).
more rigid external frame rather than
the silicone itself (Figure 2). Maximizing the surface contact area between the
silicone and the frame can be accomplished by gluing the two together.
For most prostheses, a check socket
is fitted first (Figure 3). After the desired
volume, range of motion, suspension,
and functionality are achieved within
the design, a definitive prosthesis is
made. In contrast to some commonly
used socket materials, it is very difficult
to adjust the volume of a silicone socket,
and it is best indicated for volumetrically
stable limbs.
Fingertip Amputations
Many patients who play musical instruments desire an extension of the amputated digit to resume playing. Providing
an extension made of silicone has proven
useful for patients who play instruments
such as the guitar and piano. Typically,
a flexion angle of approximately 45° has
been found to be desirable in allowing
the finger to apply pressure to the strings
or keys. A length similar to the anatomic
finger is created for the extension, and
suspension is provided by suction
(Figure 5).
-
Atlas of Amputations and Limb Deciencies, Fourth Edition © 2016 American Academy of Orthopaedic Surgeons
322
Chapter 26: Silicone Interface Options in Upper Limb Prostheses
Figure 4
fabricated for a patient with an insensate upper limb who works as a chef. It provides protection as well as a textured posterior surface
to provide a gripping surface for manipulating
objects.
Photograph of a limb protector
Partial Finger and Partial
Hand Prostheses
HCR silicone has been used for various custom and use-specific prostheses
(for example, allowing a drummer to
hold a drumstick [Figure 6] or a carpenter to hold a hammer [Figure 7]).
In addition, body-powered prostheses
using M-fingers and partial M-fingers
use HCR silicone in the contact areas
with the skin (Figure 8). Silicone also
has been used routinely for externally
powered finger prostheses because it
protects the often scarred residual limb
and can be trimmed away at the wrist
to allow for range of motion (Figure 9).
In such applications, a forearm section
can be fabricated to house the batteries; the switch; and the electrodes, with
channels in the silicone going to the
motors. Zippers in the forearm section
can be used to provide access to a pouch
housing the components and can open
to make it easier to don and doff the
prosthesis (Figur e 10).
Thumbs and Opposition Posts
The thumb is the most important finger because it represents 40% of hand
Figure 5
extension that is helpful in playing the guitar.
Figure 7
such as a hammer.
Figure 8
prepreg carbon frame.
Photograph of a silicone nger
Photograph of a partial hand prosthesis designed for grasping tools with handles,
Photograph of a partial M-nger prosthesis, with a silicone suction socket with a
function and provides opposition to the
remaining fingers.4 In addition to its
traditional use in aesthetic prostheses,
silicone is used in opposition posts and
in conjunction with simple mechanical
thumbs (Figures 11 and 12).
Figure 6
thesis that allows a drummer to hold a drum
stick. The prosthesis grasps the stick yet allows
exibility for percussion.
Photograph of a custom pros-
Wrist Disarticulation
Silicone prostheses for wrist disarticulation have the advantages of providing suction suspension and allowing
retention of residual pronation and
supination.5 Because the silicone brim
© 2016 American Academy of Orthopaedic Surgeons Atlas of Amputations and Limb Deciencies, Fourth Edition
323
Section 2: Upper Limb
Figure 9
The wrist area is exposed to allow free range of motion.
Figure 11
of silicone for the oppositional post for a missing rst digit.
is flexible, it does not impinge on the
epicondyles, and range of motion can be
maximized (Figure 13). If the residual
limb is bulbous, an air expulsion valve
with a carbon frame can be added at the
distal end to make donning and doffing
easier. Another option for a bulbous distal end is to create an air space between
the inner silicone socket and external
frame to allow the silicone to expand as
the styloids pass through. Alternatively,
a zipper can be added to simplify donning and doffing if suction suspension
of the prosthesis is not required.
Photograph of an e xternally powered nger prosthesis with a silicone check socket.
Photograph showing the use
Figure 12
prosthesis for use by a patient with a missing
thumb but in whom digits 2 to 5 are present. A
zipper was added to make it easier to don and
do the prosthesis.
Transradial Sockets
HCR silicone has been successfully integrated into passive, body-powered,
and externally powered transradial
socket designs (Figure 14). Compared
with more rigid socket materials, the
enhanced comfort provided by silicone
is especially important for individuals
with an amputation at the transradial
level. The use of silicone is compatible
with traditional supracondylar socket
designs, but the softer properties of silicone may alleviate the discomfort commonly experienced in the epicondylar
Photograph of an M-thumb
Figure 10
battery-powered nger prosthesis with embedded batteries, myoelectrodes, an on/o
switch, a charge port, and channels for wires.
A zipper in the forearm section allows for ease
in donning and dong the prosthesis, and embedded anchors in the silicone hand shell are
used to screw to the frame. A space is present
where the inta ct fth digit ex its the silicone. The
silicone is pigmented to match the patient’s
skin tone.
Photograph of a denitive,
area because the epicondyles are no
longer compressed as they pass between rigid socket materials. In addition, the elastic properties of silicone
permit increased range of motion at
the antecubital fold and olecranon. At
the antecubital fold, the rigid forearm
shell can be trimmed distal to the fold to
permit stretching the silicone and allow
for tissue expansion (Figure 15, A). At
the olecranon, this elastic accommodation can be facilitated by either creating
space between the silicone and the rigid
forearm shell or by creating a window
over the olecranon as described by Sauter et al6 (Figure 15, B).
Transradial Socket With
Integrated Humeral Sleeve
The use of silicone has created a new
transradial socket design in which the
interface can extend proximally into an
integrated humeral sleeve (Figure 16).
Although all lengths of transradial
sockets have been fitted successfully,
this can be especially useful on a very
short residual limb where suspension is
either difficult or very restrictive. The
silicone of the sleeve itself is fabricated
to be thinner than that of the socket to
Atlas of Amputations and Limb Deciencies, Fourth Edition © 2016 American Academy of Orthopaedic Surgeons
324
Chapter 26: Silicone Interface Options in Upper Limb Prostheses
allow greater elbow range of motion,
and the sleeve can be rolled down for
donning. To don, the patient can spray
the outside of the sleeve with alcohol to
make it easier to reflect over the socket,
push his or her lubricated limb into the
socket, and roll the sleeve up onto the
humeral section of the arm.
Transhumeral Prostheses
As with other levels of amputation,
silicone sockets can be custom fabricated for a passive, a body-powered,
or an electric transhumeral prosthesis.
The elasticity of HCR silicone sockets
is especially beneficial for elbow disarticulations and transhumeral level amputations when partial or full suction
suspension is used. The elasticity allows
the socket to be made slightly undersized, requiring the material to stretch
during donning. This helps maintain
contact between the silicone and skin
as the user moves the prosthesis during
activities. A donning sleeve can be used
for pulling the residual limb into the
socket, and a distal one-way air valve
can be added in the silicone interface.
In such instances, a reinforcing prepreg carbon frame is required to create
a stable platform for securing the twopiece valve. Because the carbon frame
is bonded to the silicone socket over its
entire surface, it also prevents the flexible silicone around the distal end from
inverting because of distraction forces
created by the weight of the prosthesis
does not bulge under clothing7 (Figures
18, C and 19).
(Fi g ure 17).
Suspension of an HCR silicone transhumeral prosthesis can be achieved
through a pin system, a harness, or
suction (Fig ure 18). The flexibility and
comfort provided around the shoulder
area make silicone a choice material for
transhumeral prostheses. With a Sauter
integrated shoulder saddle modification,
the silicone stays in contact with the individual’s skin as he or she moves, and it
Figure 13
lation. The prosthesis allows elb ow range of motion in exte nsion and exion. Neithe r pronation (A)
nor supination (B) is limited by the material.
Clinical photographs of a patient with a silicone prosthesis after a wrist disarticu-
Shoulder Disarticulations
When applied to a shoulder disarticulation prosthesis, HCR silicone provides
a comfortable interface next to the patient’s skin and reduces edge pressure
from the frame.
6,8
The silicone extends
slightly beyond the trim lines of the
frame and makes moving and bending
more comfortable. A thoracic pad made
of silicone can be added to the harness
Figure 14
prosthesis (B), and total silicone myoelectric system (C).
Clinical photographs of patients tted with silicone sockets after transradial amputations. A passive prosthesis (A), body-powered
© 2016 American Academy of Orthopaedic Surgeons Atlas of Amputations and Limb Deciencies, Fourth Edition
325
Section 2: Upper Limb
Figure 15
silicone to stretch as the limb changes shape relative to the joint position.
Figure 16
tient with a transradial socket with an integrated humeral sleeve that provides additional
suspension and security.
A and B, Photographs of prostheses with areas of silicone exposed from the frame in areas where elasticity is desired. This allows the
Photograph of a tr anshumeral silicone so cket with a suction val ve that is suppor ted
Clinical photograph of a pa-
Figure 17
by a carbon frame.
Figure 18
Atlas of Amputations and Limb Deciencies, Fourth Edition © 2016 American Academy of Orthopaedic Surgeons
326
Photographs of transhumeral silicone sockets suspended via a pin (A), a harness (B), and suction (C).
Chapter 26: Silicone Interface Options in Upper Limb Prostheses
Figure 19
tient with a pros thesis with a silicone socket a nd
a silicone shoulder saddle. The use of silicone
is especially advantageous for this patient because of severe scarring. Silicone gel is embedded in the saddle at the clavicle.
Clinical photograph of a pa-
to make a more comfortable and hygienic option compared to a cloth webbing
or elastic strap (Figure 20). Some patients prefer the silicone thoracic pad because it organizes the straps and makes
donning easier.
Summary
The use of HCR silicone can facilitate
prosthetic sockets in being more comfortable, having better range of motion,
and improving suspension and functionality. These interfaces are beneficial
to the skin because of good adhesion,
biocompatibility, and resistance to bacterial and fungal growth. The elastic
properties of HCR silicone, as well as
its allowance for varied thicknesses and
ability to have various components embedded with the interface, permit HCR
socket designs to address many of the
challenges encountered when fitting an
upper limb amputee or a patient with
an upper limb deficiency.
References
1. Dodson R, Jowid B: e custom silicone interface: Clinical applications
and observations. Proceedings of the
2008 MyoElectric Controls/Powered
Prosthetics Symposium. Available
Figure 20
icone thoracic pad. The pads are comfortable and hygienic and help to organize the straps (B).
at: http://dukespace.lib.duke.edu/
dspace/bitstream/handle/10161/2766/
Dodson%202008.pdf?sequence=3.
Accessed September 26, 2014.
2. Charles H: Silicone rubber for medical applications. Medical Device and
Diagnostic Industry. Available at:
http://www.mddionline.com/article/
silicone-rubber-medical-device-applications. Accessed September 26,
2014.
3. Uellendahl J, Mandacina S, Ramdial
S: Custom silicone sockets for myoelectric prostheses. J Prosthet Orthot
2006;18(2):35-40. DOI
4. Ullendahl JE, Uellendahl EN: Use
of HCR silicones for upper-limb
prostheses. Journal of the Proceed-
ings American Academy of Orthotists and Prosthetists, 37th Annual
Meeting and Scientic Symposium,
Orlando, Florida, 2011. Available at:
http://www.oandp.org/publications/
jop/2011/2011-57.pdf. Accessed No-
vember 10, 2014.
5. Engleberg A: Guides to the Evalua-
tion of Permanent Impairment, ed
A, Clinical photograph of a patient with a shoulder disarticulation wearing a sil-
3. Chicago, IL, American Medical
Association, 1988, pp 20-21.
6. Sauter WF, Naumann S, Milner M:
A three-quarter type below-elbow
socket for myoelectric prostheses.
Prosthet Orthot Int 1986;10(2):79-82.
Medline
7. Bush G: Powered upper extremity
programme: Above elbow ttings, in
Rehabilitation Engineering Annual
Report. Ontario, Canada, Hugh Mac-
Millan Rehabilitation Centre, 1990,
pp 35-37.
8. Uellendahl J, Uellendahl E: Use of
high consistency rubber (HCR) silicones for upper extremity prostheses.
Conference Proceedings of the International Society for Prosthetics and
Orthotics World Congress, Leipzig,
Germany, ISPO, Brussels, Belgium,
2010, p 481.
© 2016 American Academy of Orthopaedic Surgeons Atlas of Amputations and Limb Deciencies, Fourth Edition
327
Chapter 27
Targeted Muscle Reinnervation for Prosthetic
Control and Treatment of Neuroma Pain
Gregory A. Dumanian, MD, FACS Jason M. Souza, MD
Abstract
Targeted muscle reinnervation is a surgical procedure that transfers nerve endings to the
motor nerve of a nearby muscle. Aer neurotization, the muscle acts as a biologic amplier of the information still contained within the amputated nerve. e electromyographic
signals provide intuitive control of myoelectric prostheses. In addition, providing a function
for these nerves may be an optimal strategy for the treatment of chronic, local pain caused
by postamputation neuromas.
Keywords: nerve transfer; neuroma; prosthetic control; targeted
muscle reinnervation
Introduction
Refinements in amputation techniques
throughout the 20th century led to great
improvement in the durability and functionality of the residual limb. Strategies
for controlling the prosthesis primarily remained the responsibility of the
prosthetist. However, continuing improvements in the capabilities of myoelectric prosthetic devices have led to
the need for an improved control strategy. In 1995, Kuiken et al1 found that an
amputated rat nerve transferred into a
nearby denervated muscle produced a
transcutaneously detectable electromyographic (EMG) signal corresponding to
the transferred nerve. This finding led
to the use of the targeted muscle reinnervation (TMR) technique in humans.
The use of TMR was reported in 2004 in
a patient with a shoulder disarticulation
and subsequently in patients with transhumeral amputation.
to bridge the gap between prosthetic capability and control. The TMR surgical
Neither of the following authors nor any immediate family member has received anything of value
from or has stock or stock options held in a commercial company or institution related directly or
indirectly to the subject of this chapter: Dr. Dumanian and Dr. Souza.
2-6
TMR was found
procedure effectively salvages and amplifies information contained in motor
nerve endings that had been rendered
functionless by major limb amputation.
The TMR technique is best characterized as a series of nerve transfers
between the amputated brachial nerves
and muscle targets within the resi dual
limb or chest wall. After successful
neurotization, the target muscles produce myoelectric activity that is easily
detected by surface electrodes and can
be harnessed to control the function of
a prosthesis. Importantly, TMR enables
intuitive pairing between a transferred
nerve’s myoelectric signal and prosthetic
functions that correspond to the nerve’s
premorbid function (for example, a median nerve signal for closing the hand).
TMR represents a dramatic improvement over both body-powered and
conventional myoelectric prostheses,
in which control signals are provided
by muscles that are at best indirectly
related to the prosthetic functions they
control. The intuitive pairing provided
by TMR greatly reduces the duration
and difficulty of a patient’s early prosthetic rehabilitation.7 By increasing the
number and variety of available control
signals, TMR offers the potential for simultaneous functionality of prosthetic
hands, wrists, and elbows with multiple
degrees of freedom.
Surgical Planning for
TMR in the Upper Limb
The TMR procedure was designed to
create control sites for the following four
basic prosthetic functions in a patient
with an upper limb amputation: elbow
flexion, elbow extension, hand opening, and hand closing. If possible, the
surgeon should create additional control sites to allow greater wrist and hand
control as well as the potential benefits
offered by advanced control algorithms.
The number of control sites can be maximized by splitting residual limb muscles into separate segments based on
neurovascular anatomy.
The most important considerations
in planning a TMR procedure are the
length of the amputated nerves and
the availability of the residual limb or
chest wall muscle targets. The amputation level is defined by the presence or
absence of recipient muscle motor entry
points rather than by conventional skeletal levels. All upper limb amputations
can be categorized at three basic levels
(transradial, transhumeral, and shoulder disarticulation), which span the six
commonly described skeletal amputa
tion levels (Figure 1).
-
© 2016 American Academy of Orthopaedic Surgeons Atlas of Amputations and Limb Deciencies, Fourth Edition
329
Section 2: Upper Limb
Figure 1
amputation levels in the upper limb. The TMR level is dictated by the availability of recipient motor
nerve entry points (black dots).
Amputation at the middle to distal
forearm (the transradial level) leaves
remnant forearm muscles with intact
median, ulnar, and radial nerve motor entry points. As a result, intuitive
control of a myoelectric prosthesis is
possible without the need for nerve
transfers. Intrinsic ulnar and median
nerve function is lost at this level, but
can be regained through TMR. However,
the currently available commercial prostheses do not offer the digital dexterity
and fine control mechanisms necessary
to capitalize on the neural information
salvaged through distal ulnar and median nerve transfers. Consequently, the
principal indication for TMR at this
level is to manage symptomatic end
neuromas.
In an amputation between the proximal forearm and the proximal humerus,
the forearm motor points responsible
for native hand and wrist control are
Schematic drawing comparing targeted muscle reinnervation (TMR) and skeletal
responsible for elbow function remain
intact. TMR at this level is called transhumeral even though the elbow joint
may be present and functional. Nerve
transfers at the transhumeral level seek
to restore functions previously controlled by the median, ulnar, and distal
radial–posterior interosseous nerves,
while preserving elbow function provided by the intact musculocutaneous
and proximal radial nerves.
At the shoulder disarticulation level,
the upper arm motor points of the musculocutaneous and radial nerves have
been removed. The proximal humerus
and the shoulder joint may be present,
but the remnant biceps and triceps lack
the potential for reinnervation. The
musculocutaneous, median, radial, and
ulnar nerves all should be transferred.
The pectoralis major, pectoralis minor,
and latissimus dorsi most commonly are
used as nerve transfer recipients.
lost, but the upper arm motor points
Transhumeral TMR
General Considerations
At the transhumeral level, TMR may be
indicated if the patient has unsatisfactory prosthetic function with the use of
a standard, body-powered myoelectric
or hybrid system despite adequate training. The optimal candidate is vibrant, in
good health, and has adequate capacity
for nerve healing. Although there is no
specific age cutoff, younger patients often have more capacity for nerve regeneration. On physical examination, the
amputee has strong biceps and triceps
contractions and has a long residual
limb with supple soft tissue. A patient
with bilateral amputation may benefit
from unilateral TMR surgery to enhance
dexterity, with body-powered prosthesis
use retained for the contralateral limb to
allow robust activity. Patients with an
amputation resulting from an avulsion
mechanism should be screened to rule
out a brachial plexopathy, because proximal damage to potential donor nerves
precludes successful reinnervation.
Brachial plexopathies can be difficult
to diagnose clinically if the forearm and
hand have been amputated. Clinically
detectable pectoralis and latissimus
muscle contractions are useful markers
of brachial plexus function but cannot
entirely rule out the presence of a partial
brachial plexus injury. TMR can be done
only with transected donor nerves that
retain cortical control, and this critical
element is lacking if the patient has a
severe proximal brachial plexopathy.
The presence of a long residual limb
is important for mechanical advantage
and fitting of the prosthesis. Typically,
the level of the donor nerve injury is
relatively distal in a long residual limb.
The nerve, therefore, can be aggressively trimmed back to visualize healthyappearing fascicles before transfer to
the more proximal motor entry point.
In addition, the brachialis muscle
and its motor entry points frequently
are preserved in a long transhumeral
amputation. This muscle can be used
Atlas of Amputations and Limb Deciencies, Fourth Edition © 2016 American Academy of Orthopaedic Surgeons
330
Chapter 27: Targeted Muscle Reinnervation for Prosthetic Control and Treatment of Neuroma Pain
to provide a wrist control signal after
reinnervation by the ulnar nerve. In a
short transhumeral bone amputation,
brachialis muscle sufficient for reinnervation typically is lacking, and it is often challenging to trim and mobilize the
donor nerves without creating undue
tension at the coaptation site. Supple,
soft-tissue coverage is essential because
it is difficult to obtain a wide dissection
if the limb is scarred by skin grafts or
heterotopic ossification.
The preoperative workup is straightforward. Radiographs should be obtained to assess limb length and the
extent of heterotopic ossification. Earlier surgical reports should be obtained.
On physical examination, the level and
location of the median, ulnar, and radial
nerves are determined by evaluating the
Tinel sign relative to the residual bone.
The Tinel sign is identified at or proximal to the level of nerve injury. Thus, a
Tinel sign close to the end of the residual
limb suggests the presence of a relatively
long healthy donor nerve. Native innervation of the remnant biceps and triceps
muscles is confirmed by visualization
and palpation during voluntary muscle
contraction. Additional nerve and vascular studies typically are not required.
However, if the Tinel signs are difficult
to reliably identify and the associated
neuromas are not palpable, confirma
tory MRI or ultrasound evaluation can
be useful to confirm neuroma level and
location.
Surgical Technique
The Tinel sign locations of the me dian,
ulnar, and radial nerves are marked
while the patient is in the preoperative
holding area. The borders of the biceps
and triceps muscles should be clearly
outlined because it can be disorientating to operate on an upper arm in the
absence of forearm and hand landmarks
to delineate true anterior and posterior
surfaces. The transhumeral procedure
is done through an anterior incision
oriented longitudinally along the raphe
Figure 2
targeted muscle reinnervation. The medial antebrachial cutaneous (MABC), median (M), musculocutaneous (MCN), and ulnar (U) nerves are identied before nerve transfer. In this patient, the
distal limb had been shortened, and a long segment of the lateral antebrachial cutaneous (LABC)
nerve also is present. A recipient motor branch to the short head of the biceps (arrow) has been
tagged with a vessel loop.
between the long and short heads of the
biceps brachii muscle. The posterior incision mirrors the anterior incision and
is positioned over the raphe between the
long and lateral heads of the triceps. The
orientation of these incisions is offset
90° from the incisions traditionally used
to create anterior and posterior fishmouth skin flaps. When TMR is done
-
at the time of the initial transhumeral
amputation, the TMR incisions should
maintain their anterior-posterior orientation; they can simply be ex tended
distally to create medial and lateral skin
flaps for distal limb coverage. Thin skin
flaps are elevated on both sides of the
incision, leaving a layer of fat on top
of the deep fascia. A proximally based
adipofascial flap is then elevated to reveal the raphe between the short (medial) and long (lateral) heads of the
biceps brachii. Blunt digital dissection
reveals the musculocutaneous nerve,
which is characterized by its trifurcation into the motor nerve to the long
head of the biceps, the motor nerve to
the short head of the biceps, and the
Photograph showing an anterior exposure in a patient undergoing transhumeral
distal continuation of the nerve as the
brachialis motor branch and lateral antebrachial cutaneous nerve. Dissection
on the medial aspect of the arm is done
to identify the median nerve next to the
brachial artery. The medial antebrachial
cutaneous nerve often can be seen early
in the dissection. This nerve can be distinguished from the median or ulnar
nerves by its smaller caliber and relative
posterior position along the intermuscular septum. A typical anterior exposure
and the median, ulnar, musculocutaneous, and medial antebrachial cutaneous
nerves are shown in Figure 2. Because
the hand is not present, the surgeon cannot stimulate the major mixed nerves
to confirm their identities. Motor axon
frozen section staining is possible but
usually is unnecessary.
The median nerve is shortened until healthy fascicles are observed and
is mobilized to the motor point of the
short head of the biceps. The musculocutaneous nerve motor branch to
the short head of the biceps is divided
approximately 1 cm from its entry into
© 2016 American Academy of Orthopaedic Surgeons Atlas of Amputations and Limb Deciencies, Fourth Edition
331
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