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 fragmentation. Their purchase in the inferomedial humeral head adds mechanical stability.
Insert additional screws into the humeral shaft
Insert one or two additional bicortical screws into the humeral shaft.
Supplementary rotator cuff tendon sutures
Secure the tendons of the rotator cuff (subscapularis, supraspinatus, infraspinatus) with additional tension band sutures through the small holes in the plate.
Pitfall: inadequate reduction
A common mistake is inadequate reduction. Residual varus malalignment often results in further (secondary) displacement with varus malunion or fixation failure and possible nonunion.
This illustration shows the completed osteosynthesis for a medially fragmentary fracture using calcar screws.
Final check of osteosynthesis
Using image intensification, carefully check for correct reduction and fixation (including proper implant position and length) at various arm positions. Ensure that screw tips are not intraarticular.
Also obtain an axial view.
In the beach chair position, the C-arm must be directed appropriately for orthogonal views.