Bony Anatomy
- The bony anatomy of the proximal humerus consists of the shaft, the head, and the greater and lesser tuberosities, which are separated by the bicipital groove (Fig. 6-1).
- The articular surface of the head and the greater tuberosity are separated by a sulcus, where the insertions of the infraspinatus and supraspinatus tendons begin (Fig. 6-2).
- The proximal humerus articulates with the glenoid and is partially covered by the acromion. The acromion overlies the posterior portion of the humeral head, and a significant portion of the humeral head is anterior to the acromion.
- The head is retroverted from the shaft, generally around 30 degrees.
- The humeral shaft has a posterior bow.
- The medullary canal of the humerus tapers and ends several centimeters proximal to the olecranon fossa.
- The proximal humerus articulates with the glenoid and is partially covered by the acromion. The acromion overlies the posterior portion of the humeral head, and a significant portion of the humeral head is anterior to the acromion.
Figure 6-1 The bony anatomy of the shoulder shows the head is anterior to the acromion, and the bicipital groove separates the greater and lesser tuberosities.
Figure 6-2 MRI of the shoulder shows the relevant soft tissue anatomy. Note how the supraspinatus tendon inserts in the sulcus at edge of articular surface.
Radiographic Anatomy
AP View Humerus
- The AP view is obtained with the arm in neutral rotation. There is a tendency to get internally rotated views, with the forearm on the abdomen, and often the arm needs to be held for proper positioning (Fig. 6-3).
- AP of the entire arm is helpful in determining deformity as well as fracture pattern (Fig. 6-4).
- Postoperative x-rays are easier to obtain, with an intact limb.
Figure 6-3 Injury AP film. Note how internally rotated it is.
Figure 6-4 Postoperative AP view is in neutral rotation, and makes it easier to see the bony landmarks.
Lateral View Humerus
- Lateral view of the entire humerus can be difficult to obtain in case of fracture.
- Lateral of the proximal humerus can be obtained with axillary lateral of the shoulder or as a transscapular Y view.
- Caudal portion best obtained as cross-table lateral with arm held in neutral (Fig. 6-5).
- Postoperatively, a single view can be obtained.
Figure 6-5 The lateral view can be obtained by fully internally rotating the arm, or cross table.
AP View Shoulder
- Intraoperatively, the C-arm is used to get a true AP of the proximal humerus (Fig. 6-6).
- A proper AP shows the sulcus between the lateral head and greater tuberosity at its deepest profile.
- Note that the starting point is medial to the sulcus and anterior to the acromion.
Figure 6-6 A neutral AP view, with the sulcus seen at the edge of the joint, will guide placement of the guidewire for nail entry hole placement.
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