Radial nerve

RADIAL NERVE ANATOMY
AND
RADIAL NERVE INJURIES
BY:DR.AMIT KUMAR CHOUDHARY
DEPT OF PLASTIC SURGERY, RIMS, IMPHAL

• The radial nerve (C5, 6, 7,
8, T1) is the
continuation/terminal
branch of the posterior
cord of brachial plexus
ANATOMY

IN THE AXILLA
RN lies anterior to
subscapularis, teres
major and LD
RN leaves the
axilla via the
triangular
space
Motor supply:
long head of
Triceps
Sensory supply:
Posterior
cutaneous nerve
of arm

IN THE ARM
Lies in the spiral
groove(posterior),
accompanied
profunda brachii
artery
• Motor supply:
BR, ECRL,
Brachialis(Shared)
Motor: Triceps,
Anconeus
Sensory: posterior
cutaneous nr. of forearm
lower lateral cutaneous
nr. of arm
Re-enters anterior
compartment by
piercing Lateral
Intermuscular
Septum

IN THE ELBOW
Anterior to lateral
epicondyle, RN
divides into its
terminal branches
Superficial radial
sensory nerve
Posterior Interosseous
Nerve (PIN) and

IN THE FOREAEM
-Posterior Interosseous nerve reaches the back of
the forearm by passing round lateral aspect of the
radius between the two heads of supinator
-As it emerges from supinator posteriorly,The
nerve at first lies between the superficial and deep
extensor muscles
-At the distal border of extensor pollicis brevis, it
passes deep to extensor pollicis longus and,
diminished to a fine thread, descends on the
interosseous membrane to the dorsum of the
carpus- supply carpal ligaments and articulationsextensor indicis

MOTOR
SUPPLY
• PIN
-ECRB
-Supinator
-ECU
-EDC
-APL
-EPL
-EPB
-EI
• RADIAL
-Triceps
-Anconeus
-Brachioradialis
-ECRL

THUMB EXTENSION
1. ABDUCTOR POLLICIS LONGUS
Seen and felt at radial aspect of anatomical snuff box when thumb and wrist
are abducted against resistance at carpometacarpal joint
2. EXTENSOR POLLICIS LONGUS
Palpated at ulnar border of anatomical snuff box when thumb is extended at
inter-phalyngeal against resistance
3. EXTENSOR POLLICIS BREVIS
Felt at radial border of anatomical snuff box, lying medial to the tendon of APL
when the metacarpophalyngeal joint of thumb is extended against resistance

FINGER EXTENSION
1. EXTENSOR DIGITORUM
Tendons readily felt usually seen, when the fingers are extended against
resistance and forearm pronated
2. EXTENSOR DIGITI MINIMI
Extending the little finger while holding the remainig fingers flexed at
metacarpo-phalyngeal joint
3. EXTENSOR INDICIS
Extending the index finger while holding the remaining fingers flexed at
metacarpo-phalyngeal joint

WRIST EXTENSION
1. Extensor carpi radialis longus
Can be palpated when the wrist is extended and abducted against resistance
when forearm pronated
2. Extensor carpi radialis brevis
Can be palpated when the wrist is extended and abducted against resistance
when forearm pronated
3. Extensor carpi ulnaris
Can be palpated when the wrist is extended and adducted against resistance
when forearm pronated at the lateral groove that over lies the posterior
subcutaneous border of ulna

• TRICEPS
Fibres palpated during elbow extension against resistance
• BRACHIORADIALIS
Seen and felt when semi-pronated forearm is flexed against resistance
• SUPINATOR
Too deep to be palpated and independent testing is difficult
Supination produced after making biceps inactive( Supination with full elbow
extension)

RADIAL NERVE INJURIES
• AETIOLOGY
-Associated with fracture humerus
-Gunshot injuries
-Injuries with sharp objects
-Iatrogenic
others
-Compression neuropathies

CLASSIFICATION
TRADITIONAL METHOD- Not accurate
-HIGH(above elbow)
-VERY HIGH(involving triceps)
-LOW(below elbow)
WHAT IS IMPORTANT TO BE CLASSIFIED
Complete radial nerve palsy vs Posterior Interoessous nerve palsy

PHYSICAL EXAMINATION OF NERVE INJURY
-The Tinel sign
-Wound Inspection- Tidy/Untidy/Closed traction injury
-Neurologic examination - 1. Assessment of all muscles distal to injury
2. Sensory examination of affected and
surrounding dermatomes
-Neurophysiological Investigations: Electrodiagnosis

NONOPERATIVE MANAGEMENT
• The most important aspects of nonoperative management of a patient
with radial nerve palsy are
1. Maintenance of full passive range of motion in all joints of the wrist and
hand and
2. Prevention of contractures, including contracture of the thumb–index
web
• Many types of splints have been described
Disturbed balance of the wrist can result in loss of fiber length
of the flexor muscles, making it more difficult to achieve normal
balance after the final nerve recovery or operation

A person- does data entry; wishes
to continue working
Able to do so with the dynamic finger
and thumb extension splint
An insurance salesperson who is
more concerned about appearance
Be content with a small, inconspicuous
volar cock-up wrist splint

EARLY TRANSFERS (INTERNAL SPLINT)
• Greatest functional loss after radial nerve injury is weakness of power
grip as a result of loss of wrist extension
• Burkhalter, strong advocate of early palliative tendon (PT)-to-ECRB
transfer
• This eliminates the need for an external splint and significantly
improves power grip and hand function- Splintage
• He suggested that the transfer be done at the same time as radial
nerve repair or as soon as possible thereafter- Helper
• The tendon juncture is done end-to-side so that the ECRB remains in
continuity and can function in its own right as a wrist extensor should
successful reinnervation occur- Substitute

OPERATIVE TREATMENT
1. Nerve Repair
2. Nerve Repair/Grafting Vs Tendon
Transfers
3. Principles Of Tendon Transfers
4. Timing Of Tendon Transfers
5. Requirements
6. Historical Review
7. Tendon Transfer Techniques

NERVE REPAIR
- Nerve Resection and Neurolysis
- Nerve Grafting
(Other Methods
Vascularized Nerve Graft
Freeze-Thawed Muscle Graft
Entubulation)
- Homo-grafts
- Nerve Transfer

Reasons to not proceed with repair of a transected nerve:
1. The general condition of the patient
2. The attributes and skills of the operating team and the availability of
specialized equipment
3. Uncertainty about the viability or state of the nerve trunks
Eg: In injuries torn by a saw or a bullet
4. The risk for local or systemic sepsis
5. When the condition of the nerve is such that function will more surely and
more rapidly be restored by musculotendinous transfer

NERVE REPAIR/GRAFTING VS TENDON TRANSFERS
First decision to make -attempt belated repair of nerve or restore lost
function with tendon transfers
The time since injury is a critical factor, but late repair of the radial nerve
can produce reasonably good results at least in part because
1. the nerve is almost entirely motor and
2. the paralyzed muscles are often reasonably close to
the site of injury.

PRINCIPLES OF TENDON TRANSFERS

1. Prevention and Correction of Contracture

-Far easier prevented than corrected
-No Tendon transfer can move a stiff
joint
-Impossible for a joint to have more
action postoperatively than it had
preoperatively

2. Tissue Equilibrium

-implies that
1.soft tissue induration has resolved
2.wounds have matured
3.joints are supple
4.scars are as soft as they are likely
to become
-Performing tendon transfers, or any
elective operation, before tissue
equilibrium has been reached is to
invite disaster

3. Adequate Strength

3. Adequate Strength - Work capacity of a muscle is
related to its volume
- Relative strengths (and
excursions) of the donor muscle,
as well whose function they will
replace, should be as well
matched as possible
- Transfer to replace inevitably
weakens donar, typically by one
grade on the rather imprecise
Medical Research Council (MRC)

4. Amplitude of Motion

-Surgeon must have an appreciation
of the amplitude of tendon excursion
for each muscle
Wrist flexors and extensors-
33 mm
Finger extensors and (EPL) -50
mm Finger flexors -
70 mm
- Thus, a wrist flexor cannot be
expected to restore full range of
active motion by a finger extensor

5. Straight Line of Pull

-The transfer must run in a straight
line from its own origin to the
insertion of the tendon it is to drive
-If a tendon transfer does not,
-1. increased force needs to be
expended to overcome friction with
surrounding soft tissues and
-2. transfer will try to migrate so
that it does run in a straight line.

6. One Tendon- One Function

- If a muscle is inserted into two
tendons having separate functions,
force and amplitude will dissipated
and less effective
- At the very least if it is done,
extrusion of the two should be the
same

7. Synergism

7. Synergism
-Synergy of activity of the donor and
“recipient” muscles and/or tendons is
generally considered advantageous
should be selected if at all possible
- Eg:Wrist extension usually occurs
with finger flexion, and both sets of
muscles are activated concurrently
by the brain when gripping

7. Synergism
8. Expendable Donor

7. Synergism
8. Expendable Donor
-Transfer of a musculotendinous unit
must not result in unacceptable loss
of function. Eg-One should not
transfer both the ECRL and ECRB to
restore new functions because active
wrist extension would be lost

TIMING OF TENDON TRANSFRES
• Early transfers to restore wrist, finger, and thumb extension when there
was a poor prognosis for the radial nerve injury and its repair.
• Ignoring the nerve and proceeding directly to the tendon transfers if
there was a nerve defect of more than 4 cm, a large wound or extensive
scarring, or skin loss over the nerve
• However, if a good repair of the nerve is achieved, most would wait several
months (at least 5 or 6 after injury in the middle third of the upper arm) to
allow nerve regeneration to occur
• Would only proceed to tendon transfers if it was clear that inadequate muscle
reinnervation had occurred by both clinical and electrodiagnostic
criteria

REQUIREMENTS IN PATIENTS WITH RADIAL NERVE
PALSY
A patient with an irreparable radial nerve palsy needs to be provided
(1) wrist extension
(2) finger (MP joint) extension
(3) a combination of thumb extension and abduction
“The motors available for transfer for a patient with isolated radial nerve palsy
include all the extrinsic muscles innervated by the median and ulnar nerves’’
Unless patient has a painful neuroma- sensory part of the radial nerve usually
can be ignored

HISTORICAL REVIEW
Sir Robert Jones, 1st Baronet,
KBE, CB, TD, FRCS
Father of Modern Orthopaedics
Sir Robert Jones proposition not universally accepted.
Only part that is accepted and in practise is PT to Wrist
Extensors
Germans were influenced by Perthes, who advocated
tendodesis or arthrodesis but later proved obsolete
Zachary in 1946 illustrated that it is desirable to leave atleast
one wrist flexor intact; PL alone for stabilisation is not enough
Boyes in 1960 reasoned that FCU is more important to
preserve than FCR because normal axis of wrist motion is
from dorso-radial to radio-ulnar

TENDON TRANSFERS
1. FCU Transfer
2. Superficialis Transfer
3. FCR Transfer

FCU TRANSFER
Incision : 3 as shown in Figure
1st incision:
- Longitudinally over the FCU tendon in the distal half
of forearm; Distal end is J shaped to reach PL tendon
-FCU Freed up and Transected proximal to pisiform
2nd Incision:
-2 inches below M. Epicondyle towards Lister’s
3rd Incision:
-Begins volar radial; passes dorsally in the insertion
region of PT; then angles back towards Lister’s
-PT Freed up and Transected

-PT muscle–tendon unit must be freed up
proximally to divide adhesions to improve
subsequent excursion
-The PT muscle and tendon are passed
subcutaneously around the radial border of
the forearm, superficial to the BR and
ECRL, to be inserted into the ECRB just
distal to its musculotendinous junction
1. PT to ECRB

2. FCU TO EDC
-A tendon passer or large Kelly clamp is passed from
dorsal wound (third incision) subcutaneously, and the
tendon of the FCU is pulled
-FCU muscle belly is further trimmed if there is still
excessive muscle overlying the ulnar border of the
forearm
-End-to-side juncture is shown hereThis allows a more
direct line of pull

3. PL TO REROUTED EPL
-The EPL muscle is identified in the dorsal wound;
divided at its musculotendinous junction and
passed across the anatomic snuffbox toward the
palmar aspect of the wrist
-The PL tendon is transected at the wrist, and
muscle–tendon unit is freed up proximally until a
straight line of pull is achieved
The PL tendon is delivered into the dorsal wound
in the region of the snuffbox.

TENSION
• FCU under maximum tensionTension
• Wrist in neutral (0 degrees)
• MP joints in neutral

POST-OP MANAGEMENT
In the operating room, a long arm splint that immobilizes
-Forearm in 15 to 30 degrees of pronation
-Wrist in approximately 45 degrees of extension
-MP joints in slight (10–15 degrees) flexion
-Thumb in maximum extension and abduction
-PIP joints of the fingers are left free
10 to 14 days postop The splint and sutures are removed, long arm cast
applied
4 weeks postop The cast is removed and a short arm splint is applied to hold
wrist, fingers, and thumb

• A planned exercise program
-Begun at week 4
-Good control of function by 3 months
-Maximum recovery by 6 months

POTENTIAL PROBLEMS
1. Excessive Radial Deviation
Removing FCU(the only remaining ulnar deviator)
Contra-indicated in isolated PIN palsy
-Altering the insertion- Centeralisation
-Suturing to ECRB after resecting distal 2 to 3 cms
-Reinserting ECRL in the base of third and fourth metacarpals
2. Absence of PL
-Including EPL into FCU to EDC transfer
-BR after extensive freeing up
-Boye’s Superficialis transfer

SUPERFICIALIS TRANSFER
1. PT to ECRL and ECRB
2. FDS iii to EDC
3. FDS iv to EIP and EPL
4. FCR to APL and EPB
• Important Steps
Muscle bellies of transferred FDS muscles
are passed through interosseous space to
prevent adhesions
• Tension
Wrist : 20 degrees extension
Fingers and Thumb held in a fist
FDS under maximum tension

FCR TRANSFER
1. PT to ECRB
2. FCR to EDC
3. PL to rerouted EPL
• Important Steps:
Divide FCR near its insertion and pass subcutaneously
Divide EDC tendons just proximal to retinaculum and
reposition stumps superficial to retinaculum
• Tension:
• Wrist in neutral (0 degrees)
• MP joints in neutral (0 degrees)
• FCR under maximum tension

Radial nerve

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