Description
Primary Radial nerve injury
Injury mechanism
Fall: most common mechanism
High energy: MVA, fall from height
Iatrogenic: surgical treatment of humerus/humeral ORIF
Compression/contusion
Secondary nerve injury (after reduction or manipulation of humeral shaft fracture)
Nerve may become incarcerated in the fracture after a reduction
Incidence
9‐12% of fractures of the humerus (about 1 in 10)
Elkhom et al, JBJS, 2006
Shao et al, JBJSB, 2005
Fracture patterns
More common fracture patterns:
Spiral (OTA A1)
Transverse (OTA A3)
Open fractures
Comminuted patterns less common (OTA C1,2,3)
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Fractures from the middle to the distal third of humerus most common for causing
radial nerve palsy. Transverse and spiral fractures the most common types associated
with nerve injury. (Shao et al, JBJSB, 2005)
High incidence of nerve entrapment or transection following open humeral fractures
9/14, Foster et al, JHS 1993
6/11, Ring et al, JHS 2004
Nerve trauma
Neuropraxia v. axonomesis
Stretch or shear injury to the nerve: Most common
Nerve entrapment in the fracture
Rarely complete neruotomesis
Can occur from sharp bone ends lacerating nerve (high energy, open fracture)
The Anatomy
Radial nerve in contact with the humerus
Mid‐humerus, spiral groove
Junction of middle third and distal third (pierces lateral intermuscular septum)
Radial nerve most at risk in these locations
Carlan et al, JHS, 2007
Surface anatomy:
Radial nerve palpable along lateral border of the humerus
Radial nerve at level of the lateral epicondyle to form posterior interosseous nerve
Radial nerve innervates the brachioradialis muscle, 2cm proximal to lateral epicondyle
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Nerve Injury and Recovery Assessment
Diagnosis
Clinical
Motor assessment
Brachioradialis and ECRL are the first muscles to recover, extensor
indicis proprius is the last
Sensory assessment
Recovery of the superficial radial nerve sensation often delayed
Advancing Tinel’s sign
Imaging
Ultrasound
Can detect entrapment or radial nerve transection
Electrophysiology studies
EMGs findings indicative of nerve injury
Fibrillation potentials
Insertional activity
Positive sharp waves, turns, polyphasic signals
Reduced recruitment
Timing of recovery
Reinnervation occurs at 1mm/day with one month delay
Recovery would be expected ~ 4 mo. from injury, under “ideal” circumstances
Non‐surgical Treatment
Monitoring for recovery of the radial nerve
Radial nerve palsy splinting, 8 hours per day to prevent contracture
Stretching exercises of the wrist and digits, daily
Electrical stimulation of extensor musculature of forearm.
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Surgical Treatment
Recommended at 6 months if no clinical or EMG evidence of recovery
Neurolysis if nerve/neuroma is intact and conducts
Resection of damaged/non‐conducting nerve segment/sural nerve graft reconstruction
Primary repair: desirable, usually not feasible
Tendon transfers
- Pronator teres to extensor carpi radialis brevis
- Flexor carpi radialis to extensor digitorum communis to index, long, ring and small
- Palmaris longus tendon to rerouted extensor pollicis longus.
Outcomes
Retrospective data demonstrates that radial nerve recovery occurs in 70% of cases, treated nonoperatively.
Shao et al (JBJSB, 2005) showed no significant difference in final results when comparing nonoperative
management with early exploration
No prospective studies available to compare results of tendon transfers v. radial nerve
reconstruction
Literature does not definitively support exploration over non‐operative management for a
secondary radial nerve palsy.