Proximal Humerus Fracture Background:
A proximal humeral fracture is the third most common fracture type in individuals older than 65 years, after distal radius and proximal femur fractures. In 1970, Charles Neer described his four-segment classification system. He believed the existing classifications were inadequate for research purposes, as they did not differentiate between injuries of varied severity nor did they group like fractures. The classification systems at that time were based on the mechanism of injury or level of the fracture line, but did not consider many surgically important aspects or pathologic features of injury such as tuberosity displacement.
Forty years later, surgeons continue to use Neer’s four-segment fracture classification system for proximal humerus fractures because it is useful in guiding treatment, grouping similar fracture patterns for research purposes, and explaining pathologic features of injury.
Neer’s classification was based on careful analysis of radiographs and surgical findings from 300 proximal humerus fractures he treated at the New York Orthopaedic Hospital-Columbia Presbyterian Medical Center between 1953 and 1967. His classification system was based on an observation made much earlier by Codman, that all proximal humerus fractures were composed of four major segments: the lesser tuberosity, greater tuberosity, articular surface, and humeral shaft. Neer added categories for articular surface fractures and dislocations, as he correctly observed these to be important prognostic factors. He sought to provide a conceptual framework to explain the pathoanatomy of proximal humerus fractures by accounting for displaced bone fragments, rotator cuff attachments, and vascular supply. His secondary aim was to catalogue the most common injury patterns for research purposes. In his original article, he described how characteristic patterns of displacement occur with each fracture type, and he explained how these result from the attached bone segments and the deforming forces generated by the rotator cuff.
How do we classify proximal humerus fractures?
The four-segment classification system defines proximal humerus fractures by the number of displaced segments or parts, with additional categories for articular fractures and dislocations. The potential segments involved are the greater tuberosity, lesser tuberosity, articular surface, and humeral diaphysis. A segment is defined as displaced if there is greater than 1 cm separation or 45° angulations.
No fragments meet the criteria for displacement; a fracture with no fragments considered displaced is defined as a one- part fracture regardless of the actual number of fracture lines or their location.
One segment is displaced, which may be the greater tuberosity, lesser tuberosity, or articular segment at the level of the anatomic neck or surgical neck.
With a three-part fracture, one tuberosity is displaced and the surgical neck fracture is displaced. The remaining tuberosity is attached, which produces a rotational deformity.
All four segments (both tuberosities, the articular surface, and the shaft) meet criteria for displacement. The articular segment typically is laterally displaced and out of contact with the glenoid. This is a severe injury and carries a high risk of avascular necrosis.
Valgus Impacted Four-Part Fractures
Neer added this pattern as a separate category in 2002. In this situation, the head is rotated into a valgus posture and driven down between the tuberosities, which splay out to accommodate the head. Unlike in the classic four-part fracture, the articular surface maintains contact with the glenoid, and is not laterally displaced. This four-part fracture warranted its own category because the prognosis and treatment for this injury are different than those for the classic four-part fracture.
Fracture Dislocations and Articular Surface Injuries
Separate categories were added for dislocations because they represent more severe injuries, and are more likely to have avascular necrosis and heterotopic ossification develop. Similarly, articular surface fractures were placed in a separate category because of their unique treatment considerations. These come in two varieties, head-splitting fractures and impaction fractures.
Treatment Options for Proximal Humerus Fractures
If a proximal humerus fracture is non-displaced and stable, non-operative management could be a viable option. This would consist of sling wear, rest, medication for pain and gentle physical therapy following the healing of the fracture. Typically bone takes anywhere from 8-12 weeks to fully mature. Keeping the arm supported and limiting the amount of stress on the fracture is key.
Sometimes, the fracture is beyond fixation and a reverse total shoulder arthroplasty will be required. This is often indicated if someone has osteoarthritis or a rotator cuff tear, compounded by a proximal humerus fracture. Please follow this link to learn more about a reverse total shoulder arthroplasty to treat a severe proximal humerus fracture.