1 Principles top
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.
Proper reduction of the major proximal humerus fragments is essential. In particular, the impacted humeral head must be elevated sufficiently, so that the tuberosities can be placed underneath it.
Tension band sutures in addition to plate and screws
Sutures placed through the insertions of each rotator cuff tendon increase stability, and should be used as well as the plate and screws, particularly for more comminuted and/or osteoporotic fractures. With osteoporotic bone, the tendon insertion is often stronger than the bone itself, so that sutures placed through the insertional fibers of the tendon may hold better than screws or sutures placed through bone.
These additional sutures are typically the last step of fixation.
Angular stable versus standard plates
This section describes proximal humeral fracture fixation with an angular stable plate (A). Sometimes, these implants are not available. Standard plates provide an alternative option, for example the modified cloverleaf plate (B). Presently, the specific indications, advantages, and disadvantages of angular stable and standard plates are being clarified. There is some evidence that angular stable plate provide better outcomes. In addition to type and technique of fixation, the quality of reduction, the soft-tissue handling, and the characteristics of the injury and patient significantly influence the results. There is no evidence that the use of angular stable plates will overcome these other factors.
2 Reduction and temporary fixation 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.
Temporarily fix the tuberosities with K-wires placed outside the intended plate location, as illustrated in this case for a 4-part fracture.
3 Plate position topenlarge
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)
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
4 Plate fixation topenlarge
Positioning wires (for plate location)
To ensure appropriate plate position, somewhat obscured by a small incision, it helps to place temporary K-wires that can be used for radiographically controlled guidance.
Insert 2 positioning K-wires, one at the lateral border the bicipital groove and the other at the tip of the greater tuberosity. (These positioning wires can be used for provisional tuberosity fixation.)
The anterior positioning K-wire sets the location for the anterior edge of the plate, 2-4 mm lateral to the bicipital groove.
The proximal positioning K-wire determines the proximal edge of the plate, 5-8 mm distal to the tip of the greater tuberosity.
Identify the axillary nerve by palpating on the undersurface of the deltoid muscle. This helps protect it during plate insertion.
Insert the plate, assembled on an aiming device, under the deltoid muscle, and slide it distally under the deltoid and along the humerus. Always keep the plate in contact with bone.
Pearl: suturing the deltoid muscle To prevent extending the deltoid muscle split and increasing risk of axillary nerve injury, place a suture at the distal end of the split.
Attach plate to humerus
Position the plate in the planned and marked location on the proximal humerus. Fix it temporarily to the bone with K-wires. Proximally, two wires are placed through specific holes in the aiming device. Distally, use a percutaneously placed K-wire sleeve.
Confirm correct plate position with x-ray.
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.
It may be necessary to remove one or more of the K-wires to make room for screws. Place first screws that are unobstructed and help stabilize the fracture.
Use percutaneous drilling and screw insertion sleeves to fix the plate to the humerus.
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.
Remember the plate lies deep to the axillary nerve. Screws should not be place through the danger zone where the nerve may be injured.
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 screws into humeral shaft
Insert two to three screws into the humeral shaft, below the danger zone, with aiming device and appropriate, percutaneously placed screw insertion sleeves.
Tension band sutures in addition to plate and screws
Supplementary rotator cuff tendon sutures provide additional stability. Varying the arm position helps to place them through such a small incision. The sutures should be inserted close to the bony insertion sites of subscapularis, supraspinatus, and infraspinatus tendons. They are tied to the plate to resist muscle forces and improve plate anchorage.
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.