1 Principles top
A2 fractures are impacted surgical neck fractures without comminution. If the fracture plane is oblique and long enough, they may often be fixed satisfactorily with lag screws after reduction.
Disimpaction is the key to successful reduction of A2 fractures.
After reduction, alignment should be correct in both sagittal and coronal planes. Rotational alignment must also be correct.
2 Reduction and preliminary fixation topenlarge
Since A2 fractures involve an impaction, pure traction alone may not be effective to reduce the fracture.
While longitudinal traction is applied to the limb, insert a periosteal elevator into the fracture gap to disimpact the fracture. The elevator should be inserted from the front and pointed medially and superiorly.
Due to the overlap, the periosteal elevator might not be inserted easily from anterior. If so, insert it into the gap between the fracture fragments. The periosteal elevator might then be used as a lever to disimpact the fragments.
Confirm proper rotational alignment
Correct rotational alignment must be confirmed. This can be done by matching the fracture configurations on both sides of the fracture. This would be useful in the more transverse fracture configuration as shown in the illustration.
Pearl: check retroversion
The bicipital groove might be a good indicator for correct rotation. In case of correct rotation, no gap/angulation is visible at the level of the fracture.
In A2-type fractures the forces by the tendons are normally neutral, therefore, the humeral head is in neutral version. Remember that the humeral head is normally retroverted, facing approximately 25° posteriorly (mean range: 18°-30°) relative to the distal humeral epicondylar axis. This axis is perpendicular to the forearm with the elbow flexed to 90°.
Holding the reduction manually or with a pointed reduction forceps, temporarily secure it with 2 K-wires. Place them outside the foreseen screw position. The illustration shows two such K-wires placed from distal to proximal. Alternatively, they might be inserted from proximal to distal.
Avoid the path of the axillary nerve.
The correct reduction must be confirmed in both AP and lateral views by image intensification.
3 Fixation topenlarge
Cannulated or non-cannulated screws can be used according to the surgeon’s preference. 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. Check the position of the guide wires by image intensification.
Note: beware the axillary nerve and the bicipital tendon.
Cannulated screw insertion
Insert 3.5 mm cannulated screws of correct length over the guide wires. The screw must not perforate the articular cartilage. Use washers only in osteoporotic bone.
Remove any remaining guide and K-wires. Close wounds as needed.
4 Final check of osteosynthesis topenlarge
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.