Lateral Condyle of the Humerus - Composition

1. Capitulum (Capitellum)

• The rounded, hemispherical articular surface on the anterolateral aspect of the distal humerus
• Articulates with the head of the radius (radiohumeral joint)
• Faces anteriorly and inferiorly
• Separated from the trochlea by a shallow groove (capitulo-trochlear sulcus)

2. Lateral Part of the Trochlea (Lateral Trochlear Ridge)

• The trochlea extends medially, but its lateral ridge/wall is part of the lateral condyle
• This is clinically important: in Milch Type I lateral condyle fractures, the lateral trochlear ridge remains with the main humeral shaft; in Milch Type II, it goes with the fractured fragment

3. Lateral Epicondyle

• The non-articular bony prominence just proximal to the capitulum
• Site of attachment for the common extensor origin (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris)
• Also gives attachment to the lateral (radial) collateral ligament

4. Radial Fossa

• A small depression on the anterior surface of the lateral condyle just above the capitulum
• Accommodates the anterior rim of the radial head during full elbow flexion

Summary Table

Anatomy Image (3D CT reconstruction)

Clinical Notes

• Lateral condyle fracture is the 2nd most common pediatric elbow fracture (17%), after supracondylar fractures, most common between ages 4-6 years
• Fractures typically involve both the articular (capitulum + lateral trochlear ridge) and non-articular (epicondyle) portions
• Mechanism: fall on outstretched hand causing valgus stress, or avulsion
• Complication of missed/malunited lateral condyle fracture: cubitus valgus deformity, which can cause tardy ulnar nerve palsy (the nerve gets stretched around the medial elbow over time)