Neer made a significant revision to the Allman classification scheme. Group II (distal clavicle) fractures were further divided into 3 types, based on the location of the clavicle fracture in relation to the coracoclavicular ligaments. The reason for this modification was that distal clavicle fractures behave differently depending on the exact location of the injury. The designations are as follows (see Clinical Presentation and Workup) [14] :
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Type I fractures: Minimally displaced and occur lateral to an intact coracoclavicular ligament complex; these fractures may be treated nonoperatively and symptomatically (see the image below)
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Type II fractures: Occur when the medial fragment is separated from the coracoclavicular ligament complex; the medial fragment is displaced cephalad by the pull of the sternocleidomastoid muscle, and the distal fragment is displaced caudally by the weight of the upper extremity, with the intact coracoclavicular ligament complex; the resulting deformity leads to marked displacement of the fracture ends, predisposing this fracture type to a higher prevalence (up to 30%) of nonunion
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Type III injuries: Minimally displaced or nondisplaced and extend into the acromioclavicular (AC) joint; as with type I fractures, these injuries can be treated symptomatically; the development of late AC degenerative changes can be treated with distal clavicular excision
Type I fracture of the distal clavicle (group II). The intact ligaments hold the fragments in place.
A type II distal clavicle fracture. In type IIA, both conoid and trapezoid ligaments are on the distal segment, while the proximal segment, without ligamentous attachments, is displaced.
A type IIB fracture of the distal clavicle. The conoid ligament is ruptured, while the trapezoid ligament remains attached to the distal segment. The proximal fragment is displaced.
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A posterior view demonstrating a closed clavicle fracture tenting the skin (arrow), which can potentially lead to an open fracture.
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Comparison of both clavicles, with the left tenting the skin (wide arrow).
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Close-up view of clavicle tenting the skin (arrow).
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Comminuted fracture in a hockey player. Note the medial fragment tenting the skin.
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Additional view of fracture displacement and comminution in a hockey player. The sternocleidomastoid is the deforming force of the medial fragment.
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Radiographs after open reduction and internal fixation of a comminuted fracture in a hockey player.
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Anteroposterior view of middle third clavicle fracture illustrating a relatively typical fracture pattern.
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Anteroposterior view of distal clavicle fracture, type II, showing wide displacement.
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The displacing forces on a midshaft clavicle fracture.
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The displacing forces on a distal clavicle fracture.
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Type I fracture of the distal clavicle (group II). The intact ligaments hold the fragments in place.
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A type II distal clavicle fracture. In type IIA, both conoid and trapezoid ligaments are on the distal segment, while the proximal segment, without ligamentous attachments, is displaced.
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A type IIB fracture of the distal clavicle. The conoid ligament is ruptured, while the trapezoid ligament remains attached to the distal segment. The proximal fragment is displaced.
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Anatomy of the clavicle indicating potential fracture sites.
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Nondisplaced middle clavicle fracture.
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Displaced fracture of middle clavicle.
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Displaced middle clavicle fracture.
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Clavicle fracture with rib fractures. Remember to look for associated injuries.
