What is the treatment for a radial nerve lesion with a midshaft humerus fracture?

Treatment of Radial Nerve Lesion with Midshaft Humerus Fracture

For radial nerve palsy associated with midshaft humerus fractures, initial management should be expectant (observation) with serial clinical examinations, reserving early surgical exploration only for open fractures, fractures requiring open reduction, or evidence of nerve entrapment. 1, 2

Initial Assessment and Decision Algorithm

Determine the timing and mechanism of nerve injury:

• Primary (immediate) radial nerve palsy present at initial presentation indicates injury at time of fracture and typically has excellent prognosis with conservative management 1, 2
• Secondary radial nerve palsy developing after manipulation or during treatment requires immediate surgical exploration 1, 2
• Document baseline motor function: wrist extension, finger extension (MCP joints), thumb extension, and sensory function over first dorsal web space 2

Treatment Strategy Based on Fracture Management

If fracture requires closed reduction and conservative treatment:

• Observe the radial nerve palsy expectantly with serial clinical examinations every 2-4 weeks 1, 2
• Recovery occurs in 86.7-91.9% of cases with conservative management 3, 2
• Most recovery begins within 3-4 months; if no clinical or electrophysiologic evidence of recovery by 3-4 months, consider delayed exploration 3, 1

If fracture requires open reduction and internal fixation (ORIF):

• Perform radial nerve exploration at the time of fracture fixation 1, 2
• This allows direct visualization of nerve integrity and identification of entrapment, laceration, or contusion 4, 2
• If nerve is in continuity without laceration, perform neurolysis and proceed with expectant management postoperatively 3, 1
• If nerve is transected, perform primary repair or interfascicular grafting 3

Specific Indications for Early Surgical Exploration

Immediate exploration is warranted in these scenarios:

• Open fractures with radial nerve palsy 1, 2
• Penetrating trauma mechanism 1
• Secondary nerve palsy (developing after closed reduction or manipulation) 1, 2
• Fractures with undisplaced posterior triangular fragment, which may indicate intramedullary nerve entrapment 4
• Fractures requiring surgical fixation for other indications 1, 2

Surgical Technique Considerations

When exploring the radial nerve:

• Use anterolateral or posterior approach depending on fracture location 1, 2
• The radial nerve is most vulnerable at the junction of middle and distal thirds of humerus where it pierces the lateral intermuscular septum 5, 1
• Avoid closed intramedullary nailing if posterior triangular fragment is present, as this may indicate nerve entrapment in the medullary canal 4
• If nerve is intact, perform interfascicular neurolysis; if transected, perform interfascicular grafting with 91.9% useful functional recovery 3

Timing of Delayed Exploration

If initial expectant management is chosen:

• Monitor for clinical signs of recovery (Tinel's sign progression, return of proximal muscle function) 1
• Obtain baseline electromyography (EMG) and nerve conduction studies at 3-4 weeks post-injury 1
• If no clinical or electrophysiologic evidence of recovery by 3-4 months, proceed with surgical exploration and nerve reconstruction 3, 1
• Delayed exploration beyond 6 months significantly reduces likelihood of functional recovery 3, 1

Adjunctive Management

During the observation period:

• Provide wrist and finger extension splinting to prevent contractures 1
• Initiate early range of motion exercises for shoulder and elbow to prevent stiffness 6
• Consider tendon transfers if no recovery by 6-12 months and nerve reconstruction not feasible 1

Critical Pitfalls to Avoid

• Do not perform closed intramedullary nailing without first excluding nerve entrapment, particularly with undisplaced posterior triangular fragments 4
• Do not delay exploration beyond 6 months if considering nerve reconstruction, as outcomes deteriorate significantly 3, 1
• Do not assume all primary palsies will recover—approximately 8-13% will not recover and require intervention 3, 2
• Do not miss secondary nerve palsies developing after manipulation, which mandate immediate exploration 1, 2