What is the difference in management between high and low energy radial nerve lesions and midshaft humeral fractures?

Management Differences Between High and Low Energy Radial Nerve Lesions with Midshaft Humeral Fractures

For low-energy closed humeral shaft fractures with radial nerve palsy, expectant management with observation for 16-18 weeks is recommended, as spontaneous recovery occurs in the vast majority of cases; however, high-energy fractures warrant early surgical exploration within the first 2 weeks due to significantly higher rates of nerve transection and poor prognosis for spontaneous recovery. 1, 2

Low-Energy Fractures: Conservative Approach

Low-energy mechanisms (falls from standing height, simple trauma) demonstrate uniformly excellent outcomes with conservative management. 1

• All patients with low-energy trauma and radial nerve palsy show complete nerve recovery without surgical intervention 1
• Initial signs of nerve recovery appear within a mean of 3.2 weeks (range: 1-8 weeks) 1
• Full recovery occurs by an average of 14 weeks post-injury 1
• At exploration when performed, nerves are found intact or simply entrapped between fracture fragments, never transected 1
• Fracture healing time averages 10.4 weeks 1

Expectant management protocol for low-energy injuries:

• Observe for 16-18 weeks before considering surgical exploration 3
• Monitor for signs of nerve recovery (return of wrist extension, finger extension, thumb extension) 3
• If no recovery by 16 weeks, proceed to surgical exploration 3
• Spontaneous recovery rate is 52% within 12 weeks (range: 7-14 weeks) when exploration is not performed 3

High-Energy Fractures: Early Exploration Strategy

High-energy mechanisms (motor vehicle accidents, falls from height, crush injuries) require early surgical exploration within the first 2 weeks due to high rates of severe nerve injury. 2

Rationale for Early Exploration

• Eight of 13 patients (62%) with high-energy trauma have severely damaged nerves that fail to recover despite microsurgical reconstruction 1
• Nerve transection or severe contusion (neurotmesis) must be expected in high-energy injuries 1
• When exploration is performed early in high-energy injuries, 88.9% of nerves recover completely 4
• Without early exploration in high-energy injuries, only 55.6% of nerves recover 4
• Initial signs of recovery are delayed to a mean of 12 weeks (range: 3-23 weeks) in high-energy injuries 1
• Full recovery, when it occurs, takes an average of 26 weeks 1
• Fracture healing time is significantly prolonged at 18.7 weeks compared to low-energy fractures 1

Specific Indications for Immediate Exploration

Perform immediate radial nerve exploration in the following scenarios regardless of energy level: 3

• Open fractures of the humeral shaft 2, 3
• Irreducible fractures or unacceptable reduction 3
• Associated vascular injuries 3
• Radial nerve palsy developing after closed reduction or manipulation 3
• Intractable neurogenic pain 3

Fracture Pattern Considerations

Spiral fractures with wedge fragments warrant particular attention for early exploration: 5

• Spiral fractures represent 58.3% of cases requiring exploration 5
• Nerve compression between fracture fragments occurs in 29.1% of cases, predominantly with spiral fractures (6 of 7 cases) 5
• Nerve transection can occur with spiral fractures 5
• Early exploration in spiral and comminuted fractures allows early identification of neural injury 5

Surgical Timing and Technique

For high-energy injuries, perform exploration within 4-5 days of injury during fracture fixation: 5, 2

• Average time to exploration in successful series is 4.8 days (range: 1-20 days) 5
• Combine fracture fixation with nerve exploration in a single procedure 1
• Perform microsurgical nerve reconstruction if nerve transection is identified 1
• Nerve recovery rate with early exploration is 95.8% overall 5

Prognostic Counseling

Energy of trauma is the primary prognostic factor for nerve recovery: 1

• Low-energy injuries: Inform patients of excellent prognosis with 100% recovery expected 1
• High-energy injuries: Counsel patients about poor prognosis, with 62% risk of permanent nerve damage requiring tendon transfers 1
• High-energy injuries with intact nerves at exploration still recover, but over a prolonged 26-week timeframe 1

Critical Pitfalls to Avoid

• Do not perform routine early exploration for low-energy closed fractures - this exposes patients to unnecessary surgical risk when spontaneous recovery is expected 1, 2
• Do not delay exploration beyond 2 weeks in high-energy injuries - this misses the window for optimal nerve repair 2
• Do not assume all spiral fractures are low-energy - spiral fractures with wedge fragments often involve nerve entrapment requiring exploration 5
• Do not wait for electrophysiological studies before exploration in high-energy injuries - these are only useful after 12 weeks if no recovery occurs 5