Lateral Approach to the Distal Humeral Shaft

What it exposes The lateral approach gives direct access to the

distal third of the humeral diaphysis and the lateral column through a true internervous plane, with the patient supine. It is the workhorse exposure for distal-third humeral shaft plating — including a long bridging plate that the mobilised radial nerve is allowed to cross — and it extends smoothly distally onto the capitellum and lateral column and proximally as the anterolateral (Henry) shaft approach. ### Why this approach is chosen The distal third of the humeral shaft is difficult to reach from the posterior surface because the olecranon and the radial nerve block direct access. The lateral approach uses a true internervous plane and places the patient supine, which is familiar, allows simultaneous access to the abdomen or other injured regions, and gives an excellent view of the anterolateral surface of the distal humerus. It is the natural approach when a plate must sit on the flat lateral or anterolateral cortex of the distal shaft. ### Indications - Distal-third humeral shaft fractures requiring open reduction and internal fixation, where the fracture line is too distal for reliable locked nailing and too proximal for standard distal humeral columns

• Distal humeral fractures with lateral-column involvement when an anterolateral or lateral-column plate is planned
• Non-union and malunion of the distal-lateral humeral shaft
• Bridging-plate fixation of comminuted shaft fractures where the radial nerve must be mobilised and crossed by a long plate
• Debridement for infection or biopsy and resection of tumours of the distal-lateral shaft ### Contraindications - Soft-tissue compromise, blistering or open wounds over the lateral distal arm that demand a different window or staged surgery
• A fracture pattern whose apex of displacement or main fragment lies on the medial column, better served by a posteromedial approach
• Pathology centred posteriorly where a posterior approach gives a more direct route
• Inability to tolerate the supine position or arm positioning (rare) ### Alternative approaches

Position and landmarks Place the patient

supine with the affected arm abducted onto a radiolucent hand table and the shoulder slightly abducted and externally rotated. Pad all pressure points, position the image intensifier from the opposite side so anteroposterior and lateral views of the distal humerus are unobstructed, and confirm the elbow can be freely flexed and extended during the case. Apply a sterile tourniquet high on the arm if the fracture level allows, or plan a bloodless field without a tourniquet. Bony landmarks: the lateral epicondyle (the fixed distal landmark), the lateral supracondylar ridge (the subcutaneous line of the incision, running up to the deltoid tuberosity), and the olecranon tip and radial head to orient the elbow. Soft-tissue landmarks: the brachioradialis belly (the mobile lateral boundary of the distal interval) and the biceps medially, with brachialis lying deep to it; the mobile wad (brachioradialis and extensor carpi radialis longus) defines the distal-lateral limit. Incision planning: a longitudinal incision centred over the lateral supracondylar ridge, directly over the fracture or pathology, typically 10 to 15 cm long, following the lateral intermuscular septum and centred so it can be extended proximally and distally in line with the ridge.

Work down through the layers along the lateral supracondylar ridge, develop the true internervous plane between brachialis and the triceps or brachioradialis, and — the defining step — identify and protect the radial nerve before any bone is exposed.

Bony and muscular anatomy

The distal third of the humeral shaft flares into the two columns that support the trochlea and capitellum. The flat lateral and anterolateral cortex of the distal shaft is the ideal plate-bearing surface, and the lateral supracondylar ridge is subcutaneous, providing a continuous bony guide from the lateral epicondyle proximally to the deltoid tuberosity.

The internervous plane The safe corridor of the approach is a genuine internervous plane:

• Proximally: between brachialis (musculocutaneous nerve) anteriorly and triceps (radial nerve) posteriorly
• Distally: between brachialis (musculocutaneous nerve) anteriorly and brachioradialis (radial nerve) laterally Because brachialis is supplied by the musculocutaneous nerve and the triceps and brachioradialis are supplied by the radial nerve, this is a true internervous plane — unlike the posterior triceps-splitting exposures. ### Neurovascular anatomy and the radial nerve

Structures at risk

Radial nerve injury management - If the nerve is found

transected intra-operatively, primary repair or grafting is performed.

• If a neurapraxia is suspected post-operatively, observe, document and splint the wrist in extension.
• Persistent palsy without recovery warrants electromyography at about three to four weeks and exploration if there is no sign of recovery.

Extensile options

Distal extension to the capitellum. Continue the incision along the lateral supracondylar ridge onto the capitellum and lateral column by developing the interval between brachioradialis and extensor carpi radialis longus and the capsule, ligating the radial recurrent artery and protecting the posterior interosseous nerve. This exposes the lateral column and capitellum, connecting with the lateral or Kocher approach to the elbow. Proximal extension as the anterolateral (Henry) shaft approach. Continue proximally along the line of the lateral intermuscular septum toward the deltoid tuberosity, maintaining the brachialis and triceps interval. It is limited by the radial nerve, which crosses the field more proximally and must be mobilised, and is useful for longer plating of mid to distal shaft fractures. Combined approaches. For complex distal humeral fractures the lateral approach is frequently combined with a medial or posteromedial approach for the medial column, a posterior approach when both columns and the articular surface need simultaneous visualisation, or arthroscopy for selected capitellar fractures. ### Closure Copious saline irrigation; check for bleeding from the radial recurrent and small muscular branches and achieve meticulous haemostasis. Reapproximate brachialis over the shaft and plate to cover the construct and protect the radial nerve, close the deep fascia loosely to avoid compressing the radial nerve, approximate the subcutaneous layer, and close skin with staples, interrupted or subcuticular sutures. A drain is used selectively; apply a posterior splint or a functional brace for comfort and protection. ### Complications

Post-operative care and outcomes

Immediate: neurovascular check documenting wrist and finger extension (radial nerve function) against the pre-operative baseline, wound and splint check, and elevation for comfort. Mobilisation: early active elbow, wrist and finger motion as pain allows; progressive weight bearing and resistance once radiographic healing permits; functional bracing is an option for shaft fractures. Follow-up: 2 weeks (wound check and suture or staple removal), 6 weeks (radiographs and progress motion), 12 weeks (radiographs and progress weight bearing), and 6 months and 1 year (clinical and radiographic review of union). Good prognostic factors: anatomic reduction with a stable construct, an intact radial nerve confirmed at surgery, comminution amenable to bridging, early controlled motion, and a healthy soft-tissue envelope. Poor prognostic factors: an open or high-energy injury with soft-tissue compromise, marked comminution or bone loss, infection, and non-union requiring revision.

• Distal humerus ORIF — the principal operation done through this exposure, including distal-third shaft and lateral-column plating.
• Long bridging plate for a comminuted distal-third shaft, with the radial nerve mobilised to lie on the plate.
• Lateral-column plating of distal humeral fractures, and the lateral-column component of dual plating for intercondylar injuries.
• Non-union, malunion, debridement and tumour work of the distal-lateral shaft.
• 3.5 mm limited-contact dynamic compression or locking compression plate on the flat anterolateral or lateral cortex.

Guidelines, registries and global practice

The lateral approach to the distal humeral shaft is taught and performed worldwide across examination systems. The principles converge on supine positioning, use of the true internervous plane, mandatory identification of the radial nerve, and application of a plate to the flat anterolateral or lateral cortex. Side-by-side principles (where guidance converges): | Body | Position on distal humeral shaft and lateral-column fixation | |------|--------------------------------------------------------------| | AO Foundation | Anatomic restoration of length, alignment and rotation; bridge comminuted zones to preserve biology; identify and protect the radial nerve during lateral or anterolateral plating | | BOA and BOAST (open and soft-tissue) | Early soft-tissue assessment, photographic documentation, joint orthoplastic care for open injuries, definitive fixation only once soft tissues permit | | AAOS and OTA | Stable fixation with a plate on the anterolateral or lateral cortex when nailing is not appropriate for the distal third; documentation of radial nerve status before and after surgery | Anatomic and population evidence: - The radial nerve pierces the lateral intermuscular septum about 10 cm, classically one hand's breadth, proximal to the lateral epicondyle.

• Cadaveric refinement places the mean crossing of the septum at about 14 cm above the lateral epicondyle, with the nerve first lying on the shaft about 21 cm proximal to it.
• The lateral humeral cortex distal to about 10 cm above the lateral epicondyle is a relative safe zone, but the nerve is always at risk within the distal interval. Global practice variation: in high-resource settings, pre-contoured locking plates and routine fluoroscopy are standard. In resource-limited settings the same biomechanical principles are achieved with standard small-fragment reconstruction or dynamic compression plates, and the hand's-breadth rule guides safe nerve identification when imaging is limited. Consent (globally applicable): discuss radial nerve injury and the possibility of wrist drop, infection, non-union requiring revision, stiffness, and the small chance of needing further surgery.