The Neer Classification for Proximal Humerus Fractures

Proximal humerus fractures are the third most common fracture type in individuals older than 65 years, after distal radius and proximal femur fractures [8]. In 1970, Charles Neer described his four-segment classification system [18]. 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 [5, 12, 18]. 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 [18]. 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 [18] . 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 [7]. 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 [18]. It has now been more than four decades since Charles Neer first introduced his classification system, and it has endured with relatively minor modifications. Neer noted that when the classification was first published in the Journal of Bone and Joint Surgery, the editor Dr. Thornton Brown insisted that he provide defined criteria for determining if a fragment was displaced [18, 20]. In response, Neer set 45 angulation and 1-cm separation as the thresholds for displacement. Ironically, these criteria have become the most recognizable and quotable features of the classification system. Neer acknowledged that these were somewhat arbitrary but embraced the editor’s viewpoint that definitions were necessary for universal application. Aside from changes in the nomenclature of categories, the only other major modification was the addition of the valgus impacted four-part fracture category in 2002 [20]. Each author certifies that he or she, or a member of their immediate family, has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request.