1 Principles top
A3 fractures are displaced, non-impacted surgical neck fractures. Some are comminuted. Only the non-comminuted fractures are suitable for closed screw fixation. Because these fractures have little intrinsic stability, screws alone should be used with caution. Plate or nail fixation may be more stable.
After reduction, alignment should be correct in both sagittal and coronal planes. Rotational alignment must also be correct.
Risk of axillary nerve injury
The main structure at risk is the axillary nerve. The axillary nerve should be protected by avoiding incisions within the region of this nerve. It lies approximately 6 cm below the lateral edge of the acromion. Avoid placing wire or screws through a 2 cm wide zone beginning 5 cm below the acromion.
2 Reduction and preliminary fixation topenlarge
Since the fracture is not exposed, the surgeon should be skilled at closed reduction maneuvers.
Traction applied to the limb helps to realign the proximal fragment as well as the distal.
Threaded pins or K-wires may be inserted into the proximal and distal fragments and used as joy sticks for fracture reduction. However, this technique may be less effective in osteoporotic bone.
The reduction of the humeral head is temporarily secured using 2 to 3 K-wires. The optimal position of the K-wires depends on the fracture morphology.
Confirm the reduction by image intensification in two planes.
Attention should be paid on the correct alignment of the proximal humerus in all planes. Particularly varus malposition has to be corrected. The medial “calcar” region should be well opposed.
3 Fixation topenlarge
We illustrate the use of 3.5 mm cannulated screws. A larger diameter screw may be preferred for larger bone fragments, particularly in the surgical neck region. Since interfragmentary compression is desired, use a lag screw technique, with partially threaded screws inserted so screw threads do not cross the fracture line.
Guide wire insertion
At least two screws should be inserted to fix the fracture. Therefore, insert guide wires at the foreseen cannulated screw positions. Make stab incisions and use blunt dissections to spread the muscles. Check the position of the guide wires by image intensification.
Note: axillary nerve
Beware the axillary nerve and the bicipital tendon.
Cannulated screw insertion
Insert partially threaded cannulated screws of correct length over the guide wires. The screw must not perforate the articular cartilage. Use washers only in osteoporotic bone.
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.
After confirming reduction and fixation, remove any guide and K-wires. Close wounds as needed.