1 Introduction top
The lesser tuberosity fracture may result in weakness if it is not fixed. The primary task of the plate is to stabilize the metaphyseal fracture that requires disimpaction to correct significant angulation.
The anterolateral approach is more suited for lesser tuberosity reduction and fixation, though a separate anterior incision may be required.
2 Principles topenlarge
Risk of axillary nerve injury
The main structure at risk is the axillary nerve. The axillary nerve should be protected by limiting the incision to less than 5 cm distal to the acromial edge, by palpating the area to determine the location of the nerve, and by avoiding maneuvers that stretch the nerve during reduction and fixation. Remember the course of the nerve when placing K-wires.
Lesser tuberosity reduction
Proper reduction of the lesser tuberosity is difficult. Its position is hard to visualize with intraoperative image intensification.
Medial displacement of the lesser tuberosity (A) produces an intraarticular anterior step which can compromise internal rotation.
Lateral displacement of the lesser tuberosity (B) obstructs the bicipital groove and may compromise the bicipital tendon. If possible, correct reconstruction of the bicipital groove is desirable to allow sliding of the tendon. An alternative would be tenodesis of the long head of the biceps.
Suture fixation of the lesser tuberosity
Sutures in the subscapularis tendon insertion aid both reduction and fixation of the lesser tuberosity. Once reduced, lesser tuberosity sutures are tied to a similar suture in the infraspinatus tendon for provisional fixation. Ultimately, these sutures contribute significantly to primary stability of the lesser tuberosity.
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 procedure 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.
3 Reduction and preliminary fixation topenlarge
Sequence of repair:
- Reduce and fix the lesser tuberosity to the humeral head (thereby converting the 3-part fracture into a 2-part situation)
- Reduce the proximal humeral fragment to the shaft and fix it.
Place rotator cuff sutures
Subscapularis and supraspinatus tendon
Begin by inserting sutures into the subscapularis tendon (1) and the supraspinatus tendon (2). Place these sutures just superficial to the tendon’s bony insertions. These provide anchors for reduction, and temporary fixation of the greater and lesser tuberosities.
Next, place a suture into the infraspinatus tendon insertion (3). This can be demanding, and may be easier with traction on the previously placed sutures, with properly placed retractors, and/or repositioning the arm.
Use of stay sutures
Anterior traction on the supraspinatus tendon helps expose the greater tuberosity and infraspinatus tendon.
Insert a preliminary traction suture into the visible part of the posterior rotator cuff …
… and pull it anteriorly. This will expose the proper location for a suture in the infraspinatus tendon insertion. Then the initial traction suture is removed.
Pearl: larger needles
A stout sharp needle facilitates placing a suture through the tendon insertion.
Reduction of the lesser tuberosity
Direct reduction of the lesser tuberosity fragment is performed by pulling the sutures or, …
… with instruments (eg, elevator) applied either through the incision (as illustrated) or through a separate stab incision.
Preliminary fix the lesser tuberosity
Tighten and tie the transverse sutures in order to preliminarily fix the lesser tuberosity fragment. Thereby, the 3-part fracture is converted into a 2-part situation.
Reduction of the head fragment
Distal traction, perhaps augmented with increased angulation, will help to reduce the fracture.
Use of an elevator
Sometimes, the incision allows insertion of an elevator to disimpact the humeral head, or to help to correct inclination/torsion and to restore a normal relationship of the medial fracture surface. The proximal fragment should be reduced anatomically to the shaft.
The actual process of reduction is done with image intensifier control.
After the tuberosity and humeral head have been reduced and stabilized with sutures, there may be no need for additional preliminary fixation, but it might be advantageous to use additional K-wires to secure the position of the humeral head relative to the humeral shaft. This is illustrated with 2 retrograde K-wires. Make sure to place them from anterior in order to avoid interference with the foreseen plate position.
If the greater tuberosity is multifragmentary it might become necessary to use additional small K-wires in order to fix separate fragments.
Confirmation of reduction
The correct reduction must be confirmed in both AP and lateral views using image intensifier control.
4 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
5 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 the aiming device with drill sleeves to drill holes for the proximal screws. Make sure not to perforate the humeral head.
Follow the manufacturers technique guide.
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 an appropriate 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.
All four proximal screws should be inserted as previously described.
Remember the plate lies deep to the axillary nerve. Screws should not be place through the danger zone where the nerve may be injured.
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.
The illustration shows the completed osteosynthesis.
Additional fixation of the lesser tuberosity
Lag screw fixation of the lesser tuberosity might be considered.
This may be unnecessary if a secure subscapularis suture has been placed. If in doubt, it is recommended to check the fixation stability of the lesser tuberosity clinically by rotating the arm. If there is any micro movement visible or palpable one should consider insertion of an additional lag screw.
Supplementary tension band sutures
In minimally invasive plate fixation, it is wise to increase stability by adding supplementary tension band sutures to attach the rotator cuff tendons to the plate.