The document summarizes techniques for peripheral nerve repair. It describes nerve anatomy, types of nerve injuries including stretching, compression and laceration injuries. It discusses the process of nerve degeneration and regeneration after injury. Surgical techniques for nerve repair including epineurial and perineurial neurorrhaphy are outlined. Primary and secondary nerve repair indications and techniques are also covered.

1. Peripheral Nerve Repair
Techniques
MMED Orthopedics
PGY-1 Class Presentation
R.Tulsie

2. Anatomy
• The axon with its Schwann cell and myelin sheath is
surrounded by a veil of delicate fibrous tissue called the
endoneurium.
• Endoneurium contains collagen fibers, fibroblasts,
capillaries, and a few mast cells and macrophages.
• Collagen fibers are permeable and concentrated in a zone
beneath the perineurium and around nerve fibers and
blood vessels.
• Fascicle are clusters of sheathed axons which are
surrounded by a denser layer of perineurium.
• The entire group of fascicles with their surrounding
perineurium is encased as a mixed spinal or peripheral
nerve in a denser epineurium.
Epineurium
Perineurium
Endoneurium

3. • The epineurium represents
between 30% and 75% of
the cross-sectional area of
a nerve.
• contains adipocytes,
fibroblasts, connective
tissue fibers, mast cells,
small blood and lymph
vessels, and small nerve
fibers innervating the
vessels.

4. Types of Nerve Injury
• Stretching injury
• 8% elongation will diminish nerve's microcirculation
• 15% elongation will disrupt axons
• Compression/crush Injury
• fibers are deformed > local ischemia and endoneurial edema > nerve
dysfunction
• Laceration or Sharp Injury
• continuity of nerve disrupted, ends retract and nerve stops producing
neurotransmitters
NB: sharp transections have a better prognosis than crush injuries

5. Nerve Degeneration and Repair
• Any part of a neuron detached from its nucleus degenerates and is
destroyed by phagocytosis.
• The time required for degeneration varies between sensory and
motor segments and is related to the size and myelinization of the
fiber.
Time (DAYS) Histological Changes
1-3 Distal nerve shrinks and fragments with
fluid loss
At day 7 Macrophages are present, Schwann cell
mitosis begins
15 -30 Complete clearance of distal fragments;
Axonal Budding occurs
Recovery is apparent at 4-6 weeks

6. • existing Schwann cells proliferate and line endoneurial basement membrane
• proximal budding (occurs after 1 month) leads to sprouting axons that migrate at 1mm/day to connect to the distal
tube

7. Etiology of Nerve Injury
• Peripheral nerves can be injured by metabolic or collagen diseases;
malignancies; endogenous or exogenous toxins; or thermal, chemical,
or mechanical trauma
• Mechanical Causes
• GSW
• Sharp Injury – Lacerations or iatrogenic
• Fractures - displaced osseous fragments, by stretching, or by manipulation
• infection, scar, callus, or vascular complications (hematoma, ischemia, or
aneurysm)
• Crush Injuries – nerve contusion to complete ischemia

8. Common Nerves Injured
Nerve Associated Injury Percentage
Radial Nerve Humeral Fractures 14% humeral shaft #; D/3
Humerus -50%, M/3 -33%
Ulnar Nerve Medial Humeral Epicondylar # - callus formation 30% of Upper Limb injuries with
nerve involvement
Median Nerve -dislocation of the elbow
- carpal tunnel after injury of the wrist or distal
forearm.
15% of upper Limb Injuries with
nerve involvement
Axillary Nerve Shoulder Dislocations 5% of shoulder dislocations

9. Seddon Classification of Nerve Injury
Seddon Classification Nerve Injury Recovery
Neurapraxia nerve contusion or stretch leading
to reversible conduction
block without Wallerian
degeneration
Complete recovery in days to
weeks
Axonotmesis significant injury with breakdown
of the axon and distal Wallerian
degeneration
Spontaneous regeneration with
good functional recovery
Neurotmesis severe injury with complete
anatomic severance of the nerve or
extensive avulsing or crushing
injury
• Spontaneous recovery less
likely
• no recovery unless surgical
repair performed
• neuroma formation at proximal
nerve end may lead to chronic
pain

11. Clinical Examination
• Pain is often so severe that patient cooperation is limited at best.
• Sensation along the nerve distribution
• Assessment of Power to muscles innervated
• The Tinel sign is elicited by gentle percussion by a finger or percussion
hammer along the course of an injured nerve. A transient tingling
sensation should be felt by the patient in the distribution of the
injured nerve. Distal to Proximal along nerve route

12. Diagnosis
• Nerve Conduction Studies
• Sweat Test - The presence of sweating within
the autonomous zone of an injured peripheral
nerve reassures the examiner to a degree,
suggesting that complete interruption of the
nerve has not occurred.
• Skin resistance Test – absence of sweating on
skin decreases electrical current conduction
and can suggest autonomic disruption
• MRI – visualize early nerve injury

13. Management of Nerve Injury
Conservative
• observation with sequential EMG
• Indications
• neuropraxia (1st degree)
• axonotmesis (2nd degree)
Surgical Repair
• indications
• neurotmesis (3rd-5th degree)
• early surgical exploration: penetrating trauma, iatrogenic injury, vascular injury,
progressive deficits
NB: gunshot wounds affecting brachial plexus may be observed

14. Indications for Nerve Repair
• Obvious Nerve Injury by Sharp Transection – early exploration and
neurorrhapy can be done immediately
• Avulsion, blasts and abrading Injuries – Initial exploration to
demarcate the proximal and distal nerve ends; can be loosely sutured
to soft tissue to prevent retraction; repair at later date
• Blunt or closed Trauma – initial observation for spontaneous nerve
recovery up to 3-6 weeks; if no clinical or electrical conduction
evidence then exploration.

15. Timing of Nerve Repair
• Delay of neurorrhaphy affects motor recovery more profoundly than
sensory recovery, most likely because of the survival time of
denervated striated muscle.
• 1% of recoverable nerve function is lost for each week of delay after 3
weeks postinjury.
• perform neurorrhaphies in clean, sharp wounds immediately or
during the first 3 to 7 days.
• In the presence of extensive soft-tissue contusion, laceration,
crushing, or contamination a delay of 3 to 6 weeks is preferred.

16. Primary vs Secondary Repair
PRIMARY REPAIR
• Primary repair done in the first 6 to 8 hours or delayed primary repair
done in the first 7 to 18 days is appropriate when the injury is caused
by a sharp object, the wound is clean, and there are no other major
complicating injuries.
• Primary repair should shorten the time of denervation of the end
organs
• minimal dissection because the nerve ends have not retracted and
become imbedded in scar; allowing for improved fascicular Alignment

17. Primary vs Secondary Repair
Indications for Delayed or Secondary repair:
• Nerve division by a blunt instrument that inflicts more tissue damage
than is readily apparent, such as the case with: -
• GSW,
• avulsion injuries
• grossly contaminated injuries
• delay in exploration of a nerve injury is indicated if progressive
regeneration is evidenced by improvement in sensation, motor
power, and electrodiagnostic tests and by progression of the Tinel
sign.

18. Instruments and Materials
• Nerve Stimulator -investigating partially severed nerves and
neuromas in continuity and in locating and preserving nerve
branches.
• magnifying loupes or the operating microscope
• Spring-loaded microscissors
• Pointed or diamond-bladed knife
• Pneumatic tourniquet, suction apparatus, bipolar electrocautery,
Gelfoam and thrombin for hemostatic control

19. Choice of Suture
• The Suture needs to be monofilament on an atraumatic needle to minimize
the trauma to the nerve ends
• Minimal suture size and number of ties reduce scarring by limiting suture-
nerve contact
• 8-0, 9-0, and 10-0 Monofilament Nylon is most appropriate
• The tensile strength, easy handling qualities, and minimal tissue reaction of
nylon makes it the most desirable material for neurorrhaphy.
• Campbell’s authors recommend that most epineurial repairs are best done
with 8-0 or 9-0 nylon. For perineurial or epiperineurial repair, 9-0 or 10-0
monofilament nylon is preferable.

20. Types of Neurorrhaphy
• EPINEURIAL NEURORRHAPHY
• PERINEURIAL (FASCICULAR) NEURORRHAPHY
• Epineural repair is currently the gold standard for repair, as no
prospective studies have indicated that fasicular repair is superior.
• it is probably most indicated in pure sensory or pure motor nerves.

21. Epineurorrhaphy Technique
1. Excise and dissect the nerve ends from surrounding tissue; taking care to conserve
orientation and rotation of nerve ends
2. Make serial cuts about 1 mm apart in the end of the nerve until normal-appearing
fasciculi are exposed
3. The nerve can be transfixed at the epineurium at each end with small straight
needles about 1cm from ends
4. first suture is placed in the posterior or deep surface of the nerve in the epineurium
and leave the suture long to make later rotation of the nerve easier.
5. Place the next three sutures in the remaining three quadrants of the nerve.
6. Inspect for tension free repair with no kinking; remove stay sutures or needle
fixations before wound closure.

23. Perineural (Fascicular) Neurorrhaphy
Technique
1. Excise and dissect the nerve ends from surrounding tissue; taking care to
conserve orientation and rotation of nerve ends
2. Using magnification, Identify corresponding groups of fasciculi in the
proximal and distal nerve stumps.
3. Incise the epineurium longitudinally proximally and distally to expose the
fasciculi; approximate them individually with interrupted 9-0 or 10-0
nylon sutures
4. After the fasciculi have been matched and approximated, close the
epineurium with interrupted nylon sutures OR
5. if the neurorrhaphy is secure and there is no tension on the repair, omit
the epineurial closure to decrease the amount of fibrosis after surgery.

26. References
• Canale, S., Azar, F., Beaty, J. and Campbell, W., 2021. Campbell's
operative orthopaedics. Philadelphia, PA: Elsevier, Inc.
• T. Bates, Peripheral Nerve Injury & Repair, Orthobullets.