4-Part, marked displacement, intact articular, valgus malalignment
In these fractures both tuberosities are displaced. The periosteum, especially the medial hinge, is quite often ruptured. The fracture is typically unstable. Due to the displacement and instability an operative treatment is recommended.
This group of 4-part fractures is characterized by a marked displacement of the fragments and disruption of the periosteal sleeve. They are highly unstable. Due to the disrupted periosteal sleeve, especially on the medial side, the blood supply of the humeral head is severely affected. Prognostic factors of an ischemic humeral head are a) a fracture line located in the anatomic neck, b) a ruptured medial soft-tissue hinge, and c) a short posteromedial distal metaphyseal extension beyond the humeral head (less than 8 mm). Although these fractures do not necessarily pass through the articular surface, they are termed “articular fractures”; the articular surface is detached from both tuberosities and/or fractured itself. 4-part fractures according to Codman and Neer separate the proximal humeral epiphysis from both tuberosities and the metaphysis.
X-rays by courtesy of B Ockert, LMU Munich, Germany.