Elbow Anastomosis

Introduction

Introduction to the Elbow Anastomosis

The elbow anastomosis is a rich network of arteries around the elbow joint that provides collateral circulation, ensuring blood flow to the forearm and hand even when the brachial artery is obstructed at or below the elbow. It connects branches of the brachial artery (superior ulnar collateral, inferior ulnar collateral, radial collateral, and middle collateral) with recurrent branches of the radial and ulnar arteries (radial recurrent, interosseous recurrent, anterior and posterior ulnar recurrent). This anastomosis is clinically important in cases of brachial artery injury (e.g., supracondylar fracture) or ligation, as it can maintain distal perfusion.

Study

Arterial Contributors to the Elbow Anastomosis

A. From the brachial artery (proximal to the elbow): 1. Radial collateral artery: Arises from profunda brachii (deep brachial artery). Descends anterior to lateral epicondyle, anastomoses with radial recurrent artery. 2. Middle collateral artery: Also from profunda brachii. Descends posteriorly, anastomoses with interosseous recurrent artery. 3. Superior ulnar collateral artery: Arises from brachial artery in mid-arm. Runs with ulnar nerve, passes behind medial epicondyle, anastomoses with posterior ulnar recurrent artery. 4. Inferior ulnar collateral artery: Arises from brachial artery ~2-3 cm above elbow. Passes anterior to medial epicondyle, anastomoses with anterior ulnar recurrent artery. B. From the radial and ulnar arteries (distal to the elbow): 1. Radial recurrent artery: From radial artery just after its origin. Ascends anterior to lateral epicondyle, anastomoses with radial collateral. 2. Anterior ulnar recurrent artery: From ulnar artery. Ascends anterior to medial epicondyle, anastomoses with inferior ulnar collateral. 3. Posterior ulnar recurrent artery: From ulnar artery. Ascends posterior to medial epicondyle, anastomoses with superior ulnar collateral. 4. Interosseous recurrent artery: From posterior interosseous artery (branch of common interosseous). Ascends posteriorly to anastomose with middle collateral.

Functional Anatomy & Collateral Circulation

The elbow anastomosis forms a periarticular network that can bypass an obstruction of the brachial artery at any level. For example, if the brachial artery is occluded just above the elbow, blood can flow from the profunda brachii (via radial and middle collaterals) to radial recurrent and interosseous recurrent, then retrograde into the radial and ulnar arteries. Similarly, the ulnar collateral anastomoses provide a medial bypass. This network is also important in maintaining flow during elbow hyperextension or flexion, as the brachial artery may be compressed. The anastomosis is richest around the medial and lateral epicondyles and the olecranon fossa.

Clinical Relevance

- Supracondylar humeral fracture: Can lacerate or compress the brachial artery; the elbow anastomosis may preserve distal pulses if intact, but often is disrupted by the fracture. - Brachial artery aneurysm or embolism: Collateral flow via anastomosis can prevent hand ischemia. - Surgical ligation: Historically, the brachial artery was ligated for aneurysms; the anastomosis allowed limb survival. - Arteriovenous fistula for dialysis: The anastomosis may supply collateral flow if the fistula causes distal steal. - Radial artery harvest (for CABG): The hand still receives flow via ulnar artery and the anastomosis through the palmar arches; the elbow anastomosis is not directly relevant, but the concept of collaterals is similar. - Elbow dislocation: Can stretch or tear the anastomotic vessels, but bleeding is usually self-limited.

Summary

Key Takeaways – Elbow Anastomosis

Four collateral arteries from brachial/profunda brachii: radial collateral, middle collateral, superior ulnar collateral, inferior ulnar collateral. Four recurrent arteries from radial/ulnar: radial recurrent, interosseous recurrent, anterior ulnar recurrent, posterior ulnar recurrent. Function: Collateral circulation around elbow, bypassing brachial artery occlusion. Clinical relevance: Supracondylar fractures, brachial artery injury, limb salvage.