Posterior Approach to Humerus

What it exposes. The posterior approach to the humerus is the workhorse exposure for mid-distal humeral shaft fracture fixation. It gives direct visualisation of the radial nerve in its spiral-groove course and extensile access to the distal two-thirds of the shaft — from the deltoid insertion down to the olecranon. It is the approach of choice whenever the radial nerve must be explored, and for fractures needing long-segment or dual-column distal fixation where anterolateral access is inadequate. Why posterior. The posterior approach is favoured for mid-distal shaft fractures because it puts the surgeon directly on the radial nerve in the groove (rather than having to mobilise it across an anterior field) and exploits the broad, flat posterior cortex that seats a long plate well. The trade-off is patient positioning (lateral decubitus or prone) and the absence of a true internervous plane — both manageable with careful technique. It is particularly valuable for the ~12% of shaft fractures complicated by radial nerve palsy (Shao 2005), where inspection at ORIF distinguishes nerve laceration from contusion/traction. Indications Absolute

• Humeral shaft fracture with radial nerve palsy (~12% prevalence, Shao 2005) — allows direct nerve exploration (explore immediately if secondary palsy after manipulation; expectantly if primary palsy with no recovery by 3-4 months).
• Humeral shaft fracture with vascular injury (proximal brachial artery control).
• Open humeral shaft fracture (debridement and stabilisation).
• Pathological fracture (tumour excision and reconstruction).
• Failed nonoperative management (progressive deformity, neurovascular compromise, nonunion). Relative
• Mid-distal humeral shaft fractures (posterior preferred over anterolateral for the distal third).
• Long-segment / comminuted fractures needing a long plate.
• Bilateral shaft fractures (functional bracing impossible) and polytrauma (early stabilisation to mobilise).
• Floating elbow (ipsilateral forearm fracture — humeral stabilisation needed for elbow stability).
• Patient factors: obesity, non-compliance, inability to tolerate prolonged bracing. Contraindications
• Absolute: active infection at the surgical site, inadequate soft-tissue cover (reconstruct first), medical instability for anaesthesia.
• Relative: acceptable alignment manageable nonoperatively (functional bracing succeeds in 70-90% of shaft fractures); minimal displacement (less than 20 degrees angulation, less than 3cm shortening); severe osteoporosis (intramedullary nailing may be preferred); severe soft-tissue injury (staged reconstruction). Position & landmarks. Lateral decubitus is preferred — the affected arm is superior and free-draped so it can be manipulated and fluoroscoped, gravity assists triceps retraction, and conversion to anterolateral is easy. Use an axillary roll under the dependent axilla, pad all bony prominences, and position the elbow flexed 90 degrees with the shoulder forward-flexed 20-30 degrees. Prone is an alternative (excellent posterior access, good for proximal extension) but makes fluoroscopy harder and adds physiological stress; supine with the arm across the chest is generally not recommended. Palpable landmarks: the posterior acromion (proximal), the olecranon tip (distal), the lateral epicondyle (the radial nerve crosses the posterior humerus a mean 14.2cm above it, Gerwin 1996), and the palpable posterior humeral border that guides the skin incision. Posterior vs anterolateral — how to choose

Work down through the layers in the lateral decubitus position: a midline posterior incision, a triceps split between the long and lateral heads, then identification and protection of the radial nerve in the spiral groove before any fracture work. The exposure is built around one principle — find the nerve proximal to the fracture first and never lose sight of it.

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Structures at risk, by layer

The radial nerve in detail — anatomy, epidemiology and protection

Complications and their management

Postoperative course. Phase 1 (weeks 0-2): wound healing, pain control, pendulums and passive/active-assisted elbow ROM, optional posterior splint for comfort only. Phase 2 (weeks 2-6): active ROM, gentle stretching, light ADLs, no lifting greater than 5 lbs; week-6 radiographs for early callus. Phase 3 (weeks 6-12): strengthening (theraband, light dumbbells) once bridging callus and no fracture-site pain; return to non-manual work week 6-8. Phase 4 (week 12+): unrestricted activity once 4/4 cortices bridged, full ROM and 80%+ contralateral strength. Extensions

Closure. Reattach/realign the triceps split with interrupted absorbable sutures, close the fascia loosely, close the subcutaneous layer and skin, and apply a compressive dressing with an optional posterior long-arm splint for comfort.

• Humeral shaft ORIF — the principal operation; mid-distal shaft fractures (especially the distal third) plating with a 4.5mm LC-DCP/LCP.
• Radial nerve exploration and repair — the approach that puts the surgeon directly on the nerve in the spiral groove (primary palsy with no recovery, secondary palsy after manipulation, open fracture, vascular injury).
• Humeral shaft nonunion revision — atrophic nonunions revised with a longer compression plate, bone graft and BMP-2; hypertrophic nonunions with compression or conversion to an intramedullary nail.
• Pathological humeral shaft fracture — tumour excision and reconstruction.
• Distal humerus fractures (via distal extension) — triceps V-Y lengthening or olecranon osteotomy for metaphyseal and intra-articular extension; dual-column plating via the combined posterior + lateral exposure.