Anterolateral Approach to the Acromioclavicular Joint and Subacromial Space
Anterolateral Approach to the Acromioclavicular Joint and Subacromial Space
The anterolateral approach to the shoulder offers excellent exposure of the acromioclavicular joint and the underlying coracoacromial ligament and supraspinatus tendon. Its uses include the following:
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Repair of the rotator cuff
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Repair or stabilization of the long head of a biceps tendon
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Excision of osteophytes from the acromioclavicular joint
The use of arthroscopic subacromial decompression has reduced the use of this approach in the treatment of impingement syndrome and for some cases of rotator cuff repair.29
The approach, however, remains clinically relevant in large numbers of cases involving extensive degenerative disease of the rotator cuff.30
Position of the Patient
Place the patient in the supine position on the operating table, with a
sandbag under the spine and medial border of the scapula to push the affected side forward (see Fig. 1-4). Elevate the head of the table to 45 degrees. Apply surgical drapes in such a way that the limb can be moved easily during the operation. This allows different structures to be brought into view.
Landmarks and Incision
Landmarks
Coracoid Process. Palpate the coracoid process 1 in from the anterior end of the clavicle just inferior to the deepest point of the clavicular concavity.
Acromion. Palpate the acromion at the shoulder summit.
Incision
Internervous Plane
No internervous plane is available for use. The deltoid muscle is detached at a point well proximal to its nerve supply, which, therefore, is not in danger.
Superficial Surgical Dissection
Deepen the incision through the subcutaneous fat to the deep fascia. Numerous small vessels will be divided. Coagulate these meticulously to ensure adequate visualization of the deeper structures. Incise the deep fascia in the line of the skin incision (Fig. 1-31). Palpate the acromioclavicular joint. If the approach is to be used for a subacromial decompression and access to the rotator cuff is not required, detach the fibers of the deltoid that arise from the acromioclavicular joint and continue this detachment by sharp dissection laterally to expose 1 cm of the anterior aspect of the acromion (Fig. 1-32). Bleeding will be encountered during this dissection as a result of the division of the acromial branch of the coracoacromial artery. This must be coagulated. Do not detach more of the deltoid than is necessary because reattachment is difficult and extensive stripping of the deltoid from the acromion may be associated with poor long-term results of surgery.
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Figure 1-30 Make a transverse incision beginning at the anterolateral corner of the acromion, ending just lateral to the coracoid process. For alternate skin incision, see Figure 1-60.
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Figure 1-31 Incise the deep fascia in the line of the skin incision to reveal the underlying deltoid muscle.
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Figure 1-32 Detach the deltoid from the acromioclavicular joint and 1 cm of the anterior aspect of the acromion.
If the approach is to be used for repairs of the rotator cuff, split the deltoid muscle in the line of its fibers starting at the acromioclavicular joint. The deltoid muscle is multipennate in its middle third and distinct fibrous septi are present. Splitting the muscle may therefore involve some sharp as well as blunt dissection. Extend this split 5 cm down from the acromioclavicular joint (Fig. 1-33). Insert stay sutures in the apex of the split to prevent the muscle from splitting inadvertently further down during retraction and damaging the axillary nerve. Continue the dissection as for subacromial decompression by detaching the fibers of the deltoid that arise from the acromioclavicular joint, and, as before, continue this detachment by sharp dissection laterally to expose 1 cm of the anterior aspect of the acromion. Retract the split edges of the deltoid muscle to reveal the underlying coracoacromial ligament.
Deep Surgical Dissection
Detach the coracoacromial ligament from the acromion, either by sharp
dissection or by removing it with a block of bone from the undersurface of the acromion. Detach the medial end of the coracoacromial ligament just proximal to the coracoid process and excise the ligament. The supraspinatus tendon with its overlying subacromial bursa now is revealed. Rotate the head of the humerus to expose different portions of the rotator cuff (Fig. 1-34). Full external rotation will reveal the long head of the biceps tendon in its groove.
Dang
Nerves
The axillary nerve runs transversely across the deep surface of the deltoid muscle about 5 to 7 cm below the tip of the acromion. There is variability in the position of the nerve with relation to the edge of the acromion. In general term however the longer the humerus is the greater will be the distance from the nerve to the anterior edge of the acromion.31,32
Splitting the deltoid below this level may damage the nerve. Inserting the stay suture in the apex of the deltoid split will prevent this possibility. The nerve can easily be palpated under the under surface of the muscle, if you are in doubt as to its position.
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Figure 1-33 Split the deltoid muscle in the line of its fibers for 5 cm.
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Figure 1-34 Resect the coracoacromial ligament with a block of bone from the undersurface of the acromion to reveal the underlying subacromial bursa and supraspinatus tendon.
Vessels
The acromial branch of the coracoacromial artery that runs immediately under the deltoid muscle will be divided during the superficial surgical dissection. Unless bleeding from this site is controlled, it will be very difficult to identify deeper structures, which may cause inadvertent deviation from the proper surgical plane. Damage to this vessel is also a problem in arthroscopic surgery of this area.
How to Enlarge the Approach
Local Measures
Because reattaching the deltoid to its insertion is so difficult, extensive detachment of this muscle is not recommended, even though it does facilitate the exposure.
Extensile Measures
Because this approach does not operate in an internervous plane, no useful extensions, either proximal or distal, are possible.