Diagnostic Shoulder, Subacrominal Bursectomy, Subacromial Decompression, and Distal Clavicle Excision
- Amputate specimen at mid humerus and disarticulate at the sternoclavicular joint.
- Use the short specimen holder and secure the scapula in the beach chair (upright position).
- 30 Degree 4.5 mm arthroscope
- 5.5 mm full radius resector
- 5.5 mm burr
- Knife with #11 blade
- Marking pen
- Spinal needle
- Two switching sticks
- 5 mm blue cannula
- 30 cc syringe with 18 gauge needle
I) Mark Anatomy
Mark the following anatomy with a marking pen:
- Scapular spine and acromion
- Distal clavicle and acromioclavicular joint
- Coracoid process
II) Mark Portals
Location: At a point 2 cm distal and 2 cm medial to the posterolateral border of the acromion.
Location: At a point 3 fingerbreaths distal to the anterolateral border of the acromion.
Location: At a point about 3 cm distal to the acromioclavicular joint. This portal is usually made under arthroscopic control while viewing from the subacromial space. If it is made during diagnostic arthroscopy of the shoulder, it should be made coplanar with the orientation of the acromioclavicular joint.
MRI of AC Joint
III) Joint Insufflation
Take the 30 cc syringe and insufflate the glenohumeral joint with 30 cc of fluid through the posterior portal. Or you can wait and inflow through the scope after scope placement.
IV) Make the posterior portal and place the scope in the glenohumeral joint
Make a ¼ inch incision at the posterior portal site and direct the arthroscope into the glenohumeral joint. It may help to place a finger on the coracoid process and direct the arthroscope towards this finger.
V) Make an anterior portal under arthroscopic control in the rotator interval
With a spinal needle, locate the rotator interval between the subscapularis tendon and the biceps tendon. Try to make this portal coplanar with the acromioclavicular joint since this portal will later be used for the distal clavicle resection. Place a 5 mm blue cannula in this portal.
VI) Visualize and probe the anterior structures of the glenohumeral joint.
Place a probe into the cannula and visualize and probe the following structures:
- The articular cartilage of the glenoid. Note the central bare spot.
- The articular cartilage of the humerus.
- The superior, middle, and inferior glenohumeral ligaments.
- The anterior band of the glenohumeral ligament.
- The anterior inferior labrum and its capsular attachment (the capsulolabral complex).
- The superior labrum and the biceps attachment.
- The attachment of the rotator cuff to the humerus.
VII) Visualize and probe the posterior structures of the glenohumeral joint.
Place switching sticks into the anterior and posterior cannulas then switch the arthroscope to the anterior portal and the cannula to the posterior portal. Place a probe into the posterior cannula then probe the following structures:
- The posterior insertion of the rotator cuff.
- The posterior superior labrum.
- The posterior band of the inferior glenohumeral ligament.
- The posterior labrum and its attached capsule (capsulolabral complex).
VIII) Perform a subacromial bursectomy and a subacromial decompression in the following manner.
Place the arthroscopic sheath with a blunt obturator into a posterior portal and direct the arthroscope into the subacromial space. It may help to put a finger on the anterior aspect of the subacromial space and direct the sheath towards this finger.
Make ¼ inch incision at the lateral portal site then direct the shaver into the subacromial space. Since cadaveric bursa is often quite thick it may help to direct the shaver towards the tip of the scope until you can feel it. Now you should resect the anterior part of the bursa. Once you are able to adequately see the tip of your shaver, you should direct the shaver in a distal direction. Remember that the bursal insertion is about 2-3 cm distal to the top of the humeral head.
Anatomical structures of the shoulder. Recognize the distal insertion of the subacromial bursa.
Initial view of the subacromial space.
Shaver from lateral portal used to resect anterior and lateral subacromial bursa.
You cannot resect the entire bursa through this portal only. Once an adequate anterior bursal resection has been done, you should switch the arthroscope to the lateral portal and the shaver to the posterior portal and then begin the posterior bursal resection.
View with the arthroscope in the lateral portal. The shaver is in the posterior portal.
At the completion of the resection you should be able to visualize completely the rotator cuff and the acromion.
Once visualization is complete, place the shaver on the burr mode and start doing an acromioplasty using the cutting block technique. The principle of this technique is to use the flat part of the acromion as a block. Lay the shaver against the acromion and then, working in a medial to lateral direction, remove the anterior lip of the acromion. The coracoacromial ligament attaches to the anterior part of the acromium and it should be peeled off subperiosteally. At the end of the procedure, the anterior acromion should be flat, and the there should be no impediment of moving the shaver towards the deltoid. Make sure to remove enough medial acromion in order to visualize the acromioclavicular joint. Additionally, verify that there is not any lateral impingement and, if there is, remove enough lateral acromion in an anterior to posterior direction. If the bone is too hard for the shaver, switch the shaver for a 5.5 mm burr.
Cadaveric photo of scope in lateral portal and the shaver in posterior portal. The shaver is in the correct position to do a cutting block acromioplasty.
Arthroscopic photo of an acromioplasty using the cutting block technique. A medial acromioplasty has to be done in order to expose the distal clavicle.
Tip: It seems that in cadavers it is more difficult working in the subacromial space because of difficulties with visualization. Most of the time, this problem is the lack of inflow. It may be helpful to make an extra posterior portal near the standard posterior portal and add gravity inflow through an extra 5 mm cannula.
IX) Perform a distal clavicle resection in the following manner.
Keep the arthroscope in the lateral portal. Take a spinal needle and verify that the anterior portal is coplanar with the acromioclavicular joint. If it is not, make a new anterior portal.
Place a 5.5 mm full radius resector into the anterior portal and remove enough inferior acromioclavicular joint capsule in order to see the distal clavicle.
Rotate the arthroscope lens such that you are looking in an anterior - posterior direction (up the pike) of the acromioclavicular joint. Now place the shaver in a burr mode and remove 2 mm of medial acromium at the joint level. This act will greatly facilitate visualization of the entire joint.
Now take the shaver and burr evenly about 8 – 10 mm of distal clavicle. Make sure that the superior and posterior parts of the clavicle are being resected since these areas are the most common sites of acromioclavicular joint impingement.
At the end of the procedure, there should be about 10 mm of acromioclavicular joint decompression (about two widths of a 5.5 mm shaver). The superior acromioclavicular ligament should be fully visualized and without boney impingement.
X) Preserve this cadaver for the rotator cuff exercise. Dissection will follow that exercise.