Ulna – Approach

Modern Study Review (AI-Generated)

High-Yield Summary

The posterior approach to the ulna is a versatile, extensile technique primarily used for open reduction and internal fixation of ulna shaft fractures and olecranon procedures. It exploits a safe internervous plane between the extensor carpi ulnaris (ECU) and flexor carpi ulnaris (FCU), minimizing neurovascular risk. Despite advances in minimally invasive and percutaneous methods, this approach remains the gold standard for direct visualization and stable fixation of ulna fractures.

Applied Anatomy & Intervals

Internervous Interval

Between the ECU (innervated by the Posterior Interosseous Nerve [PIN]) and the FCU (innervated by the Ulnar Nerve).

Anatomic Landmarks

• Subcutaneous border of the ulna (palpable along the medial forearm).
• Olecranon tip proximally.
• Ulnar nerve palpable proximally near the FCU muscle belly.

Patient Positioning & Setup

Table Type

Standard operating table with arm board.

Patient Position

Supine with the affected forearm placed across the chest for optimal access to the subcutaneous border of the ulna.

Specialized Equipment

• Pneumatic tourniquet on the upper arm for a bloodless field.
• Arm supports or sandbags to stabilize the forearm.
• C-arm fluoroscopy positioned contralaterally for intraoperative imaging.

Surgical Technique (The “Vital Steps”)

Incision & Superficial Dissection

• Longitudinal skin incision centered over the subcutaneous border of the ulna.
• Longitudinal incision of deep fascia to expose the interval between ECU and FCU.

Deep Dissection & Exposure

• Identify and develop the internervous plane between ECU (radial/posterior compartment) and FCU (ulnar/volar compartment).
• Middle third ulna: partial detachment of ECU fibers from bone may be necessary for exposure.
• Olecranon level: carefully retract FCU and anconeus muscles along the dissection plane.
• Incise periosteum longitudinally to expose the ulna shaft.
• Proximal fifth ulna: partial detachment of triceps insertion may be required for adequate exposure.

The “Danger Zone”

Post-Operative Pearl

Encourage early gentle range of motion. Avoid aggressive elbow extension if triceps detachment was performed to protect repair integrity.

Classic Clinical Notes

Ulna – approach

• Position: Supine with forearm across chest & tourniquet
• Incision: Longitudinal over subcutaneous border of ulna
• Internervous plane: ECU (PIN) & FCU (ulnar nerve)
• Dissection:
• Incise deep fascia
• Find interval between ECU & FCU
• Middle 1/3: ECU fibers may need to be divided from bone
• At olecranon: FCU & anconeus run along plane of dissection
• Incise periosteum
• Proximal 1/5 of ulna: insertion of triceps may need to be detached to gain access to bone
• Dangers:
• Ulnar nerve: travels under FCU; should be identified proximally as it emerges between two heads of FCU before stripping FCU from bone
• Ulnar artery: runs on radial side of ulnar nerve

Last Updated on January 25, 2026 by orthonet