The entry point for a bent nail may go through the bony attachment of the rotator cuff. This bony defect in the footprint cannot be reconstructed later.

The entry point for a straight nail lies under the rotator cuff so the nail is inserted through the rotator cuff. This requires an incision, which should be made in the line of the tendon fibers which can then be closed effectively by a side to side suture.

Due to the bone density in osteopenic bone straight nails provide a better fixation in the proximal humerus in the region of their entry point. Bent nails run through the greater tuberosity which has a lower bone density compared to the superior humeral head.

In proximal humeral fractures which consist of a fracture of the greater tuberosity the trajectory of bent nails often passes through the fracture line between the greater tuberosity and the humeral head whereas straight nails penetrate the humeral head medial to the fracture line.

Straight nails run more medial in the axis of the medullary cavity. Therefore, it is possible to perform a direct fixation of the lesser tuberosity through the nail.

A precise entry point of the humeral nail is crucial. For straight nails, the correct entry point is in line with the axis of the humeral shaft. An incorrect entry site results in malreduction of the metaphyseal fracture.

It might be difficult or even not possible to access the correct entry point if the humeral head is displaced severely into a varus position. Therefore, it is strongly recommended to expose the entry point by manipulating the humeral head. K-wire “joy-sticks” (as illustrated) or sutures through the rotator cuff insertions can be used to achieve this.

If the entry point has been chosen correctly, insertion of the nail will help reduce the fracture.

The main structure at risk is the axillary nerve. The axillary nerve should be protected by limiting the incision to less than 5 cm distal to the acromial edge, by palpating the nerve, and by avoiding maneuvers that stretch the nerve during reduction and fixation.

In addition, any suspicious screw trajectory should be made to the bone with blunt dissection and checked with finger palpation if necessary.

Remember the course of the nerve when placing the screws depending on the chosen nail and/or position of the nail itself.

Sutures placed through the rotator cuff tendons and the bolts increase stability, and should be used as well as the nail and screws, particularly for more comminuted and/or osteoporotic fractures. With osteoporotic bone, the tendon insertion is often stronger than the bone itself, so that sutures placed through the insertional fibers of the tendon may hold better than screws or sutures placed through bone.

These additional sutures are typically the last step of fixation.

AO teaching video: Proximal humerus – 3-part fracture – Reconstruction using the MultiLoc Proximal Humeral Nail
 

This procedure is normally performed with the patient in a beach chair position.

An anterolateral incision is recommended for nailing of proximal humeral fractures. The need for additional access depends upon fracture type. Small separate stab incisions may be used for these fractures.

Before opening the humeral entry point reduce the humeral head. A “joy-stick” technique, as illustrated, is helpful.

Alternatively, or in addition one can use stay sutures through the tendon of the rotator cuff to manipulate the humeral head.

The nail insertion site lies on the axis of the humeral shaft. It is located intraarticularly posterior to the tendon of the long head of the biceps within the cartilage. It is typically near the highest point of the humeral head. It is slightly anterior to the center of the greater tuberosity. A supraspinatus split is necessary.

Incise the supraspinatus tendon for approximately 3 cm over the foreseen entrance point posterior to the long head of the biceps. Retract the edges of the supraspinatus tendon with the help of stay sutures.

Insert a K-wire through the correct entry point and confirm proper placement by image intensification.

A cannulated drill bit is recommended for opening the proximal humerus. This drill bit should be inserted over the previously placed guide wire. It should be advanced into the proximal medullary canal.

Alternatively, an awl may be used to open the humerus.

The humeral nail is mounted on an insertion handle. The nail must be rotated correctly relative to the insertion handle.

Insert the nail with slightly rotating movements down to the metaphyseal fracture line. Pass the fracture zone under image intensification and make sure that the nail enters the distal fragment properly.

Make sure the proximal end of the nail is placed beneath the bony surface of the humeral head.

No protrusion of the nail may be tolerated. Confirm with appropriately oriented C-arm images that the nail is below the bone.

A K-wire placed through an aiming device may help to adjust the appropriate insertion depth.

In order to lock the nail in the correct trajectory, mount the aiming arm and swivel it approximately 25° anteriorly in order to follow the retroverted axis of the humeral head. (Due to the physiological retrotorsion of the humeral head, the axis of the humeral head is directed approximately 25° posteriorly to the condylar plane of the distal humerus.)

To obtain a true AP view of the proximal humerus, the forearm has to be rotated approximately 25° externally relative to the sagittal plane.

The trocar for the planned screw fixation is placed through the aiming device, if necessary through a separate skin incision. Perform blunt dissection down to the bone so that the trocar may be placed without interposition of soft tissue.

Check once more the correct retrotorsion.

Drill with the calibrated drill bit carefully just to the level of the subchondral bone. The final position of the drill bit can be checked with the image intensifier. The screw length can be determined from the measurements of the drill bit.

If necessary, a conical drill bit may be used to countersink the lateral cortex.

Attach the screw to the screw driver and insert the screw.

In some systems, as the one shown in this illustration, a screw-in-screw fixation is possible (see below). If so and if also intended, the plane of the handle of the screw driver should be horizontal and the arrow should point posteriorly once the final position of the screw is reached.

Using an additional trocar, K-wires can help to achieve more stability temporarily.