Definition of the Proximal Humerus
The proximal humerus is anatomically defined as the upper portion of the humerus bone that includes the humeral head, the anatomical and surgical neck, and the greater and lesser tuberosities.
Anatomical Components of the Proximal Humerus
The proximal humerus consists of several key anatomical structures:
- Humeral head: The rounded articular surface that forms part of the glenohumeral joint
- Anatomical neck: The oblique groove immediately adjacent to the articular surface of the humeral head
- Surgical neck: The narrowed portion below the tuberosities, a common fracture site
- Greater tuberosity: The lateral prominence serving as an attachment site for the supraspinatus, infraspinatus, and teres minor muscles
- Lesser tuberosity: The anterior prominence serving as an attachment site for the subscapularis muscle
Clinical Significance
Understanding the proximal humerus anatomy is crucial for proper diagnosis and management of fractures in this region. According to the American College of Radiology guidelines:
- CT is the preferred imaging modality for characterizing complex fracture patterns and humeral neck angulation 1
- 3D volume-rendered CT images help better characterize fracture patterns 1
- Standard radiographs are used for initial diagnosis and fracture pattern identification 1
- MRI is recommended for detecting associated rotator cuff tears 1
Associated Structures
The proximal humerus has important associated soft tissue structures:
- Rotator cuff: Complete tears of at least one rotator cuff tendon can be seen in up to 40% of humeral head fractures 1
- Neurovascular structures: The axillary nerve and posterior humeral circumflex artery pass close to the surgical neck, making them vulnerable during fractures or surgical interventions
Clinical Considerations
When evaluating proximal humerus fractures:
- Preservation of the tuberosities and attached rotator cuff is important for shoulder stability and function 2
- Intraoperative resection of the humeral head fragment and tuberosities is associated with increased risk of complications such as dislocation following reverse shoulder arthroplasty 2
- Early rehabilitation is essential to avoid the harmful effects of immobilization 3
Treatment Implications
The anatomical definition of the proximal humerus directly impacts treatment approaches:
- Characterization of complex fracture patterns using CT scans informs treatment decisions 1
- Significant rotator cuff tears are typically addressed during open reduction and internal fixation of proximal humerus fractures 1
- The specific fracture pattern (particularly involving the surgical neck, tuberosities, and humeral head) determines whether non-operative management, internal fixation, or arthroplasty is most appropriate 4, 5