1 Principles top
Impacted minimally displaced proximal humerus fractures, even though they involve the anatomical neck, have a relatively good prognosis. Due to the intact periosteum, they are often quite stable. Improved alignment can often be obtained and stability provided with minimal fixation (eg, screws alone). Reduction with disimpaction may result in fracture instability. Some of these fractures may have questionable stability before reduction. In order to improve stability, an osteosynthesis might be considered.
Valgus impacted 3- and 4-part fractures (C1.1) and slightly displaced comminuted fractures with varus malalignment (C1.2) are particularly suitable for less invasive reduction and fixation. These are the most suitable procedures for patients with good bone quality.
Risk of avascular necrosis
Even minimally displaced anatomic neck fractures (type C) have a significant risk of avascular necrosis (AVN) of the humeral head. This risk is increased with extensive surgical exposure for open reduction and plate fixation.
With the blood supply already at risk, closed reduction and minimal internal fixation through very limited approaches is advisable.
2 Reduction topenlarge
C1.2 fractures produce separate fragments of the proximal humerus: an epiphyseal (humeral head) fragment and one or both tuberosities in addition to the shaft. Reduction involves repositioning the humeral head, and also restoring the tuberosities to their proper location.
The medial periosteum (medial hinge) is not ruptured. Much of the remaining periosteum (especially laterally) may also be intact
As a first step perform a closed reduction taking advantage of the intact soft-tissue sleeve (as with ligamentotaxis). Frequently, the displaced fragments will snap into position with this maneuver.
Valgus forces (abducting at the fracture) can be applied to the lateral aspect of the humeral shaft to correct the varus deformity and facilitate manual reduction.
Periosteal elevator and/or bone hook
If closed reduction is unsuccessful, minimally invasive open reduction can be attempted through a small transdeltoid incision using appropriate instruments.
Periosteal elevators or punches can be used to disimpact and reposition fracture fragments.
If the reduction is not adequate, a similarly inserted bone hook may aid reduction of the tuberosities.
Protect the axillary nerve on the deep surface of the deltoid muscle, 6 cm below the acromion.
In C1.2 fractures, adequate reduction has been achieved if the tuberosities become to lie laterally flush or slightly underneath the elevated humeral head.
Check reduction by image intensification.
3 Preliminary fixation topenlarge
Temporarily fix the fracture with K-wires as illustrated in this case for a 4-part fracture. Place the K-wires so that they do not hinder subsequent screw insertion.
4 Fixation topenlarge
Fixation of the head fragment
Two or more percutaneously inserted screws linking the shaft fragment to the head fragment are inserted first.
Cannulated 3.5 mm lag screws (as illustrated), or non-cannulated small fragment lag screws are used according to the surgeon’s preference.
This illustration shows two screws inserted over guide wires.
Note: Washers may be advisable in poor bone stock. Generally, they are not preferable as they make the screw heads more prominent and may result in shoulder impingement.
Fixation of the tuberosities
Remove K-wires and guide wires from the shaft.
Fixation of the head fragment is followed by insertion of screws in the greater and lesser tuberosity.
Again, in this case, screws are inserted over guide wires.
The illustration shows the completed osteosynthesis.
Check the reduction and the length/position of the screws by image intensification.
5 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.
Also obtain an axial view.
In the beach chair position, the C-arm must be directed appropriately for orthogonal views. Position arm as necessary to confirm that reduction is satisfactory, fixation is stable, and no screw is in the joint.