Neer classification of proximal humeral fractures
The Neer classification of proximal humeral fractures is probably the most frequently used system along with the AO classification of proximal humeral fractures. The terminology and factors which influence the classification are essential for the utility of radiological reports of proximal humeral fractures.
The two main components of the classification are the number of fracture parts and the displacement .
The Neer system divides the proximal humerus into four parts and considers not the fracture line, but the displacement as being significant in terms of classification. The four parts are the humeral head, the greater tuberosity, the lesser tuberosity and the humeral shaft. Displacement is on a per-part basis. A fracture part is considered displaced if angulation exceeds 45 degrees, or if the fracture is displaced by more than 1 cm .
The simplest displaced fracture which is possible is a two-part fracture, however, a minimally displaced fracture, even one that includes multiple fracture lines, merely constitutes a type I, one-part fracture.
The Neer classification has been variably adapted by multiple authors. The classification consists of four major groupings, based on the number of displaced parts. Neer added a fifth group more recently.
- fracture lines involve 1-4 parts
- none of the parts are displaced (i.e <1 cm and <45 degrees)
These non-displaced or minimally displaced fractures account for ~70-80% of all proximal humeral fractures and are almost always treated conservatively .
- fracture lines involve 2-4 parts
- one part is displaced (i.e >1 cm or >45 degrees)
Four possible types of two-part fractures exist (one for each part):
- frequently seen in the setting of anterior shoulder dislocation
- a lower threshold of displacement (>5 mm) has been proposed
These fractures account for approximately 20% of proximal humeral fractures .
- fracture lines involve 3-4 parts
- two parts are displaced (i.e >1 cm or >45 degrees)
Two three-part fracture patterns are encountered :
- most common three part pattern
These fractures account for approximately 5% of proximal humeral fractures .
- fracture lines involve more than 4 parts
- three parts are displaced (i.e., >1 cm or >45 degrees) with respect to the 4
These fractures are uncommon (<1% of proximal humeral fractures) .
This pattern has poor non-operative results, and as the articular surface is no longer attached to any parts of the humerus which are attached to soft tissues. This pattern has a high incidence of osteonecrosis .
These fractures require operative management.
Valgus impacted four-part fracture
This type of four part fracture is considered its own category and has a different prognosis than typical four part fractures .