Attach plate to humeral shaft
Attach the plate to the humeral shaft with a bicortical small fragment 3.5 mm screw inserted through the elongated hole.
Pearl 1: fine tuning of plate position
If the first screw is inserted only loosely in the center of the elongated hole, fine-tuning of the plate position is still possible. With the plate in proper position, tighten this screw securely.
Correct plate position
The correct plate position is:
about 5-8 mm distal to the top of the greater tuberosity
aligned properly along the axis of the humeral shaft
slightly posterior to the bicipital grove (2-4 mm)
Confirmation of correct plate position
The correct plate position can be checked by palpation of its relationship to the bony structures and also confirmed by image intensification.
To confirm a correct axial plate position insert a K-wire through the proximal hole of the insertion guide. The K-wire should rest on the top of the humeral head.
Pitfall 1: plate too close to the bicipital groove
The bicipital tendon and the ascending branch of the anterior humeral circumflex artery are at risk if the plate is positioned too close to the bicipital groove. (The illustration shows the plate in correct position, posterior to the bicipital groove).
Pitfall 2: plate too proximal
A plate positioned too proximal carries two risks:
- The plate can impinge the acromion
- The most proximal screws might penetrate or fail to securely engage the humeral head
Pearl 2: preliminary plate fixation with K-wires
For x-ray confirmation of plate position, one can fix the plate preliminarily to the bone with several 1.4 mm K-wires inserted through the small plate holes, before placing any screws.
Pearl 3: insert K-wires through appropriate guiding sleeves.
Fix plate to the humeral head
Use an appropriate sleeve to drill holes for the humeral head screws. Do not drill through the subchondral bone and into the shoulder joint.
Avoiding intraarticular screw placement
Screws that penetrate the humeral head may significantly damage the glenoid cartilage. Primary penetration occurs when the screws are initially placed. Secondary penetration is the result of subsequent fracture collapse. Drilling into the joint increases the risk of screws becoming intraarticular.
Two drilling techniques help to avoid drilling into the joint.
Pearl 1: “Woodpecker”-drilling technique (as illustrated)
In the woodpecker-drilling technique, advance the drill bit only for a short distance, then pull the drill back before advancing again. Keep repeating this procedure until subchondral bone contact can be felt. Take great care to avoid penetration of the humeral head.
Pearl 2: Drilling near cortex only
Particular in osteoporotic bone, one can drill only through the near cortex. Push the depth gauge through the remaining bone until subchondral resistance is felt.
Determine screw length
The intact subchondral bone should be felt with a depth gauge or blunt pin to ensure that the screw stays within the humeral head. The integrity of the subchondral bone can be confirmed by palpation or the sound of the instrument tapping against it. Typically, choose a screw slightly shorter than the measured length.
Insert a locking-head screw through the screw sleeve into the humeral head. The sleeve aims the screw correctly. Particularly in osteoporotic bone, a screw may not follow the hole that has been drilled.
Number of screws and location
Place a sufficient number of screws (often 5) into the humeral head. The optimal number and location of screws has not been determined. Bone quality and fracture morphology should be considered. In osteoporotic bone a higher number of screws may be required.
It is strongly recommended to use “calcar screws” in all varus displaced fractures, especially, if there is medial comminution. Their purchase in the inferomedial humeral head adds mechanical stability.
Lesser tuberosity fixation
If the lesser tuberosity is involved, lag screw fixation might be considered. This technique may be superfluous when appropriate tension band sutures are placed through the rotator cuff insertions. Another option is one or more absorbable polymer pins.
If in doubt, once the sutures are secure, check the stability of the lesser tuberosity clinically by rotating the arm. If there is any micro movement visible or palpable consider additional fixation, which is typically placed after the rest of the fixation.
Insert additional screws into the humeral shaft
Insert one or two additional bicortical screws into the humeral shaft.
K-wires placed during the procedure may now be removed. In some cases, preservation of head fracture stability may require use of separate lag screws, absorbable polymer pins, or even buried K-wires.