Anterior Approach to Humeral Shaft (Henry)

The anterior approach to the humeral shaft (also known as the Henry approach or anterolateral approach) provides direct access to the middle and distal 1/3 of the humerus for fracture fixation, nonunion repair, and tumor excision. First described by Henry in 1945, this approach has become the most commonly used surgical corridor for humeral shaft fractures requiring operative fixation.

Historical evolution:

• 1945: Henry described the anterior approach for humeral shaft access
• 1970s-1980s: Functional bracing (Sarmiento) became gold standard for non-operative management
• 1980s-1990s: AO principles established plate fixation techniques (6-8 cortices, compression)
• 2000s-present: Modern locked plating expanded indications (osteoporotic bone, comminution)

Modern applications:

1. Displaced humeral shaft fractures (middle/distal 1/3) - ORIF with plate fixation
2. Humeral nonunion/malunion - revision ORIF with bone grafting
3. Pathological fractures - prophylactic fixation for metastatic lesions
4. Polytrauma - early stabilization in multiply-injured patients

Internervous Plane

The anterior approach utilizes an internervous plane with brachialis muscle splitting:

Primary Interval:

• Between: Biceps muscle (medial, musculocutaneous nerve) and lateral edge of brachialis
• Brachialis splitting: The brachialis muscle has DUAL INNERVATION - medial portion (musculocutaneous nerve) and lateral portion (radial nerve)
• Splitting technique: Split brachialis LONGITUDINALLY in its midline (internervous plane WITHIN the muscle) - separates musculocutaneous-innervated medial fibers from radial-innervated lateral fibers

Critical concept: This is NOT a "pure" internervous plane (like Thompson or Henry radius approaches) because brachialis must be SPLIT to access humerus. However, splitting in the midline respects the dual innervation and minimizes denervation.

Critical Neurovascular Structures

1. RADIAL NERVE (PRIMARY HAZARD):

Anatomic Course:

• Origin: Posterior cord of brachial plexus
• Proximal humerus: Lies posteromedial to humerus (behind brachial artery)
• Spiral groove crossing: Crosses from POSTERIOR to LATERAL surface of humerus at spiral groove (also called radial groove)
• Spiral groove location: Mean 14.2cm proximal to lateral epicondyle (range 10-17cm - Gerwin 1996)
• Distal course: Enters lateral intermuscular septum and descends between brachialis (anterior) and brachioradialis/ECRL (posterior)
• Bifurcation: Divides into PIN (motor) and superficial radial nerve (sensory) at level of lateral epicondyle (2cm proximal)

Surgical Importance:

• Radial nerve is MOST VULNERABLE at spiral groove (adherent to bone via lateral intermuscular septum)
• Holstein-Lewis fracture (distal 1/3 spiral fracture) traps radial nerve in fracture site - HIGHEST iatrogenic injury risk (18% - Ring 1999)
• Radial nerve injury risk: 2-5% for standard mid-shaft fractures, 18% for Holstein-Lewis

Protection Strategy:

• Identify radial nerve at lateral intermuscular septum (palpable as cord crossing spiral groove)
• Subperiosteal dissection ONLY (avoid dissecting around spiral groove - nerve adherent to bone)
• Proximal-to-distal exposure (reduces risk of dissecting into nerve at spiral groove)
• NEVER explore nerve unless pre-operative function was intact and post-operative palsy occurred (iatrogenic injury indication)

2. BRACHIAL ARTERY:

Anatomic Course:

• Location: Lies MEDIAL to biceps muscle throughout arm
• Relationship: Accompanied by median nerve
• Surgical relevance: Usually NOT visualized in anterior approach (lies medial to surgical field)

Protection:

• Retract biceps MEDIALLY (pulls brachial artery and median nerve away from surgical field)
• Avoid dissection medial to biceps

3. MEDIAN NERVE:

Anatomic Course:

• Proximal arm: Lies MEDIAL to brachial artery
• Mid-arm: Crosses ANTERIOR to brachial artery
• Distal arm: Lies LATERAL to brachial artery
• No branches to muscles in proximal arm (first branch: pronator teres at elbow)

Protection:

• Retract biceps and brachial artery MEDIALLY as a unit (median nerve accompanies artery)
• Rarely visualized unless dissection extends to distal humerus

4. MUSCULOCUTANEOUS NERVE:

Anatomic Course:

• Entry into biceps: Enters biceps muscle 6-8cm distal to coracoid process (variable)
• Course: Runs between biceps and brachialis muscles
• Exit: Emerges lateral to biceps tendon as lateral antebrachial cutaneous nerve (LABC) at elbow

Surgical Relevance:

• Usually NOT at risk (lies within biceps muscle, medial to surgical field)
• LABC may be injured with excessive distal dissection

Operative vs Non-Operative Decision-Making

ABSOLUTE INDICATIONS FOR OPERATIVE FIXATION:

1. Open fractures (Gustilo I-III) - require irrigation, debridement, and stabilization
2. Vascular injury requiring repair (brachial artery laceration - 2-3% of humeral shaft fractures)
3. Polytrauma requiring early stabilization (chest trauma, multiple long bone fractures, head injury)
4. Bilateral humeral shaft fractures (functional bracing impossible)
5. Floating elbow (ipsilateral humerus + forearm fractures)
6. Pathological fractures (metastatic disease - prophylactic fixation if >50% cortical destruction)

RELATIVE INDICATIONS (Operative vs Non-Operative Decision):

1. Failed closed reduction with unacceptable alignment (>20° varus/valgus, >30° anterior/posterior angulation, >3cm shortening)
2. Radial nerve palsy with fracture manipulation (suggests nerve entrapment - EXPLORE nerve)
3. Progressive displacement on serial X-rays despite functional bracing
4. Segmental fractures (two distinct fracture lines with intercalary fragment - unstable)
5. Patient factors: Obesity (functional brace difficult to fit), non-compliance, bilateral upper limb injuries

NON-OPERATIVE MANAGEMENT (Functional Bracing - STILL FIRST-LINE):

Sarmiento functional bracing remains GOLD STANDARD for closed, isolated humeral shaft fractures with acceptable alignment:

• Union rate: 85-88% (Sarmiento 2000)
• Acceptable alignment: <20° varus/valgus, <30° anterior/posterior angulation, <3cm shortening
• Advantages: No surgery risks, no anesthesia, immediate ROM
• Disadvantages: 12-15% nonunion rate (vs 5-8% with ORIF), prolonged immobilization (8-12 weeks)

Approach Selection

Intraoperative Complications

1. RADIAL NERVE INJURY (2-18%):

Mechanism:

• Holstein-Lewis fractures (distal 1/3 spiral) - nerve trapped in fracture site (18% iatrogenic injury)
• Excessive lateral retraction during fracture reduction
• Subperiosteal dissection AROUND spiral groove (violates nerve on posterior humerus)
• Drill penetration through lateral cortex during screw placement

Prevention:

• Subperiosteal dissection ONLY - do NOT dissect circumferentially around spiral groove
• Proximal-to-distal exposure - encounter nerve predictably
• For Holstein-Lewis fractures - identify nerve at lateral intermuscular septum BEFORE fracture manipulation
• Use drill depth gauge for screw length measurement

Recognition:

• Intraoperative: Loss of wrist/finger extension during case
• Postoperative: Wrist drop, finger/thumb extension weakness (EPL, EDC, EIP), thumb abduction weakness (APL, EPB)
• Preserved function: Sensation over dorsal thumb/index web space, elbow extension (triceps innervated proximal to spiral groove)

Management:

• Immediate post-operative palsy (pre-operative function intact):
  • Urgent re-exploration (within 24-48 hours) - iatrogenic injury suspected
  • Identify nerve at lateral intermuscular septum
  • Neurolysis if nerve in continuity (free from scar, hematoma, or suture entrapment)
  • Nerve repair if laceration (primary end-to-end if tension-free, nerve graft if gap >1cm)
• Pre-operative palsy unchanged post-operatively:
  • Observation for 3-4 months (70% spontaneous recovery - Shao 2005)
  • Serial EMG at 6-8 weeks (signs of reinnervation indicate recovery)
  • Nerve exploration if no recovery by 4-6 months
• Tendon transfers if no recovery by 12 months:
  • PT to ECRB (wrist extension)
  • FCR to EDC (finger extension)
  • PL to EPL (thumb extension)

Outcome:

• Neurolysis (nerve in continuity): 80% recovery
• Nerve repair (laceration): 40-60% recovery
• Spontaneous recovery (observation): 70% (Shao 2005)

Postoperative Complications

1. NONUNION (5-8%):

Risk Factors:

• Inadequate fixation (<6 cortices proximal/distal to fracture)
• Excessive periosteal stripping
• Infection (deep infection 15-20% nonunion risk)
• Smoking (5-10× increased nonunion risk)
• Transverse fracture pattern

Management:

• Hypertrophic nonunion: Revision ORIF with larger plate, compression, NO bone graft needed
• Atrophic nonunion: Revision ORIF with bone grafting (iliac crest autograft), larger plate, consider BMP-2 if high-risk
• Smoking cessation: MANDATORY (10× reduced union rate if continued smoking)

2. INFECTION (2-3%):

Management:

• Superficial infection: Oral antibiotics (flucloxacillin or cephalexin 500mg QDS for 10-14 days)
• Deep infection: I&D + culture-guided IV antibiotics (6 weeks minimum) + hardware retention if fracture healing progressing

3. SHOULDER STIFFNESS (10-15%):

Prevention:

• Early ROM at 2 weeks (pendulum exercises, passive ROM)
• Minimize immobilization duration (coaptation splint for 7-10 days ONLY)

Management:

• Physical therapy: Progressive ROM exercises
• Corticosteroid injection if adhesive capsulitis (triamcinolone 40mg + lidocaine)
• Manipulation under anesthesia (MUA) if stiffness persists beyond 6 months

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2. Gerwin M, Hotchkiss RN, Weiland AJ. Alternative operative exposures of the posterior aspect of the humeral diaphysis with reference to the radial nerve. J Bone Joint Surg Am. 1996;78(11):1690-1695.

3. Shao YC, Harwood P, Grotz MR, Limb D, Giannoudis PV. Radial nerve palsy associated with fractures of the shaft of the humerus: a systematic review. J Bone Joint Surg Br. 2005;87(12):1647-1652.

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8. Rüedi TP, Buckley RE, Moran CG. AO Principles of Fracture Management. 2nd ed. Stuttgart: Thieme; 2007.