Beijing Jishuitan Hospital Classification of Humeral Lateral Condyle Fractures

Beijing Jishuitan Hospital classifies fractures into 4 types based on pathological changes.
Type I:	Non-displaced fracture type. The periosteum is not torn, and an X-ray shows a fracture line at the metaphysis.
Type II:	Lateral displacement type. Fragments shift laterally, anteriorly, or posteriorly. Mild displacement shows slight widening at the fracture site, with partial tearing of the periosteum; severe displacement leads to complete tearing, and after reduction, fragments may become unstable, with the risk of redisplacement during fixation.
Type III:	Rotational displacement type. Fragments shift laterally, anteriorly, or posteriorly while also rotating. Due to complete rupture of the local fascia and periosteum, and the pull of the forearm extensors, the fragments can rotate externally along the longitudinal axis by 90° to 180°. Rotation may also occur to varying degrees along the transverse axis. No changes occur in the humeroulnar joint.
Type IV:	Fracture-dislocation type. Fragments may shift laterally or rotate, while the elbow joint can dislocate laterally, ulnarly, or posteriorly. The joint capsule and collateral ligaments are torn, and soft tissue injuries around the elbow are severe. This type of fracture is not uncommon. Hardacre reported 46 cases of displaced fractures, with 9 cases complicated by elbow dislocation, approximately 20%. Due to the severity of soft tissue injury around the elbow, treatment is more challenging than for the other three types, and prognosis is worse. Therefore, Beijing Jishuitan Hospital refers to this type of fracture as a fracture-dislocation type to draw attention to it.

Explanation

This is a common type of elbow fracture in children, essentially representing lateral condyle epiphyseal separation. Its incidence is second only to supracondylar humeral fractures. It often results from indirect compound external forces, typically when a child falls and lands on an outstretched hand, with the forearm pronated and the elbow slightly flexed. Most of the external force transmits along the radius to the radial head, impacting the humeral lateral condyle, leading to the fracture. Concurrent factors such as elbow valgus stress and extensor pull contribute to the fracture, with the fracture line extending from the upper part of the lateral condyle diagonally downwards and inward toward the lateral aspect of the trochlea. Fragments often include pieces from the radial metaphysis, the humeral capitellum epiphysis, and the lateral trochlear section, with varying fracture types resulting from the direction of external forces, forearm rotation, and adduction pull.