Determination of entry point
The nail insertion site lies on the axis of the humeral shaft. It is located at the bone-cartilage junction of the humeral head. It is not more lateral on the greater tuberosity. Therefore, a supraspinatus split is necessary.
It is slightly anterior to the center of the greater tuberosity.
Be aware, that the correct entry point depends on the type and design of nail used.
Note: For simplicity, the following illustrations are shown without sutures inserted at the margins of the supraspinatus split.
Insert a K-wire through the correct entry point and confirm proper placement by image intensification.
Open the humerus
The nail entry track passes through or close to the tuberosity fracture plane. Take care not to displace the tuberosity fracture during passage of awl or drill. Ensure that sufficient bone is removed to allow the nail to pass through the reduced fracture. Confirm this at the end of nailing.
A cannulated awl is recommended for opening the proximal humerus. This awl can be inserted over the previously placed guide wire. It should be advanced into the proximal medullary canal.
Pitfall: hidden entry point
If the humeral head is abducted or externally rotated, the entry point is under the acromion. This is typical with varus malaligned fractures.
One has to reduce the humeral head before opening the humeral entry point. A joy-stick technique, as illustrated, is helpful. Alternatively, sutures though the rotor cuff can be used in order to manipulate the humeral head.