Posterolateral Approach to the Elbow

Posterolateral Approach to the Elbow (also known as Kocher approach) is used to expose the elbow joint and specially the proximal radioulnar joint.

Kocher approach indications include the following:

1. Management of pathologies of the radial head: Open reduction and internal fixation of the radial head, radial head replacement and radial head excision.
2. Lateral collateral ligament (LCL) reconstruction or repair.
3. Management of coronoid fractures (limited access).

Position of the Patient

In Kocher approach, the patient is positioned either in Supine position with the upper extremity supported on a hand table or on patient’s trunk, or in Lateral decubitus with the arm supported over a bolster. The forearm is pronated in both positions.

Landmarks and Incision

Landmarks:

• Lateral humeral epicondyle.
• Radial head: 2.5 cm distal to lateral epicondyle, head (or crepitus in fractured) is palpable with pronation/supination.
• Olecranon.

Incision:

Make a 5cm longitudinal or gently curved incision based off the lateral epicondyle and extending distally over the radial head approximately. Incision angle can be varied based on need to address associated pathology.

Internervous plane

The Internervous plane of Posterolateral Approach to the elbow (Kocher approach) lies between:

1. Aanconeus muscle: it’s innervated by the radial nerve.
2. Extensor carpi ulnaris muscle (ECU): it’s innervated by the posterior interosseous nerve.

Superficial dissection

Incise deep fascia in line with incision. Identify plane between Extensor carpi ulnaris muscle (ECU) and anconeus muscle distally.

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Deep dissection

Maintain arm in pronation to move posterior interosseous nerve away from field of operation. Split proximal fibers of supinator muscle, staying on the posterior cortex of the radius away from posterior interosseous nerve.

If Lateral collateral ligament is intact, stay 1 cm anterior to crista supinator to avoid damage. In cases of elbow dislocation, Lateral collateral ligament frequently is not intact.

Incise capsule longitudinally, avoid dissecting distally or anteriorly (risk of posterior interosseous nerve injury). Maintain dissection in mid radiocapitallar plane to avoid damaging the Lateral collateral ligament.

Approach Extension

Kocher approach can be extended proximally and distally as following:

Proximal Extension:

Extend superficial dissection by dissecting down onto lateral supracondylar ridge. You should Avoid origin of Lateral collateral ligament unless operation directed at its repair/reconstruction.

Distal Extension:

Posterolateral Approach to the Elbow (Kocher approach) should not be extended distally as this places the posterior interosseous nerve at risk.

Dangers

Structures at risk during Posterolateral Approach to the Elbow (Kocher approach) include:

1. Posterior Interosseous nerve: It’s not in danger as long as dissection remains proximal to annular ligament. Release supinator along posterior radius border beyond annular ligament with forearm in full pronation. Retractors placed blindly anteromedially or with excessive retraction may lead to nerve injury.
2. Radial nerve: It’s not in danger as long as elbow joint is entered laterally and not anteriorly.

References & More

• Surgical Exposures in Orthopaedics book – 4th Edition
• Campbel’s Operative Orthopaedics book 12th
• Orthobullets
• Barnes LF, Lombardi J, Gardner TR, Strauch RJ, Rosenwasser MP. Comparison of Exposure in the Kaplan Versus the Kocher Approach in the Treatment of Radial Head Fractures. Hand (N Y). 2019 Mar;14(2):253-258. doi: 10.1177/1558944717745662. Epub 2018 Jan 22. PMID: 29357701; PMCID: PMC6436133.