Abstract
The basics of diagnostic arthroscopy involve knowing where to place portals, understanding the external and internal anatomy of the shoulder, and having an organized approach to reviewing the structures of the shoulder. The essential initial portal is the posterior portal, which establishes visualization of the joint and allows for placement of the remaining portals. The glenohumeral joint is first examined systematically from the posterior portal, and may then be examined from the anterior portals to ensure that all pathology is noted. The subacromial space is examined next using the already established posterior and anterior portals with the addition of a lateral portal. Being familiar with the normal anatomy and normal variants is essential for identifying abnormal pathology.
Keywords
posterior portal, anterior portal, lateral portal, subacromial arthroscopy, glenohumeral arthroscopy, diagnostic arthroscopy
Only with an understanding of normal glenohumeral joint and subacromial space anatomy can the surgeon appreciate which structures are damaged.
Diagnostic Glenohumeral Arthroscopy
Portal placement is critical, so it is important to take sufficient time to mark the portal sites precisely. Draw the bone outlines of the acromion, the distal clavicle, and the coracoid with a surgical skin marker. Be careful not to draw the most superficial bone landmarks, but rather draw their inferior surfaces (which takes into account bone thickness), because portal entry points are referenced from these surfaces ( Figs. 3.1 and 3.2 ).
Although trocar entry into the glenohumeral joint is simple and almost intuitive for an expert, surgeons new to arthroscopy may find joint entrance difficult. The standard advice to “start in the soft spot and aim for the coracoid” is only slightly helpful. Actual joint entry requires precision, and even small deviations of 3 to 5 mm from the desired portal location make the operation more difficult. An additional complication is that portals vary from patient to patient because they are related to the patient’s position on the operating table as well as his or her size, rotundity, and kyphosis. The ideal portal location changes throughout the operation as soft tissue swelling increases and alters the local anatomy. Portal placement is also affected by the underlying diagnosis. For instance, posterior portal placement for an acromioclavicular joint resection differs from that for a superior labrum anterior to posterior (SLAP) lesion repair. There are no absolute rules, but there are a number of guidelines that are helpful.
The most reliable landmarks are bone. Anteriorly, outline the coracoid process, the acromioclavicular joint, and the anterior acromion. Laterally, identify the lateral acromial border, and posteriorly, outline the posterior acromion. The most important landmark is the posterolateral corner of the acromion, which can be palpated even in large patients ( Fig. 3.3 ). Even with these initial landmarks outlined, be prepared to use them only as a guide.
Posterior Portals
Traditionally, surgeons describe the location of the posterior portal as being in the “soft spot” approximately 2 cm inferior and 2 cm medial to the posterolateral acromial edge. Although this location is adequate for glenohumeral joint arthroscopy, it is not optimal for subacromial space operations. If you make the incision in the traditional soft spot, you will enter the joint parallel to the glenohumeral joint line and slightly superior to the glenoid equator. This site allows you to enter and adequately visualize the glenohumeral joint, but you will be at a disadvantage if you try to use the same incision to enter the subacromial space. Once you insert the cannula into the subacromial space, the soft-spot portal directs the cannula superiorly and medially, and causes two problems. First, because the arthroscopic view is now directed medially, the lateral insertion of the rotator cuff is more difficult to visualize. Second, the superior angle of the arthroscope makes it difficult to “look down” on the rotator cuff tendons and appreciate the geometry of rotator cuff lesions. One solution to this problem is a second posterior portal; another solution is to alter the posterior portal’s location ( Fig. 3.4 ).
As noted, the exact location of the posterior portal varies with the clinical diagnosis. For rotator cuff repairs and subacromial decompressions, we make the posterior incision for the portal in a more superior and lateral position, approximately 1 cm inferior and 1 cm medial to the posterolateral acromion, or virtually at the acromial corner. The more superior and lateral location minimizes the aforementioned difficulties. The superior entry allows the cannula to enter the subacromial space immediately beneath the acromion, parallel to its undersurface . This maximizes the distance between the arthroscope and the rotator cuff, allowing a better appreciation of rotator cuff lesions. The superior position (parallel to and immediately inferior to the acromion) also facilitates acromioplasty because the surgeon is afforded a better view of the acromial shape. The more lateral position (immediately medial to the lateral acromion) places the arthroscope in line with the rotator cuff tendon insertion. The glenohumeral joint can be easily viewed with this more lateral portal with simple medial translation of the arthroscope cannula after entry through the skin. For operations restricted to the glenohumeral joint, such as a Bankart or SLAP repair, the joint can be entered with the more traditional medially placed portal, but we still prefer the more lateral portal placement for nearly all of our procedures (see Fig. 3.4 ).
Lateral Portals
A lateral subacromial portal is not routinely used during diagnostic glenohumeral joint arthroscopy. More commonly, a lateral portal is used during arthroscopic subacromial decompression and rotator cuff repair. This portal will be discussed in more detail in the applicable chapters. Briefly, the portal location is marked with a skin marker 2 to 5 cm distal to the lateral acromial border and at the midway point of the lateral acromial width ( Fig. 3.5 ). This portal is only marked as an approximation as the best way to create it is with an outside-to-in technique. Once the camera has been placed in the subacromial space through the posterior portal, the exact location of the lateral portal is identified with a spinal needle before incising the skin. This allows for the assessment of the caudad/cephalad and the anterior/posterior position of this portal ( Figs. 3.6 and 3.7 )
An anterolateral portal is very helpful for rotator cuff repairs. The initial posterior portal can be considered a posterolateral portal. An equivalent anterolateral portal is made with an outside-to-in technique. This portal is often more distal as it needs to allow for work access to the suprapectoral region to work on biceps pathology, and it provides excellent access for a needle-passing device for supraspinatus and subscapularis repairs ( Figs. 3.8–3.10 ).
Anterior Portals
There are two basic anterior portals: anterior-inferior and anterior-superior ( Fig. 3.11 ). These are used for glenohumeral reconstruction, SLAP repair, and subscapularis repair. Several other anterior portals may be used, but care must be paid to the neurovascular structures as the portals venture more medial past the coracoid and more inferior. The anterior-inferior portal is marked 5 mm lateral to the coracoid tip with the anterior-superior portal at least 1.5 cm lateral and 1 cm superior to the anterior-inferior portal. However, these marks are only approximations as the best way to assess the portal is with an outside-to-in technique to confirm the angle of approach to the target pathology. Sometimes, a high anterior–superior portal that enters over the biceps can be most useful for viewing and as access for superior labral tears (see Fig. 3.11 ). A superior portal also can be helpful for acromioclavicular joint resections ( Fig. 3.12 ). This is in the same area as the more classically described Neviaser portal.
Physical Examination
Because a patient’s pain on physical examination may cause the surgeon to underestimate the range of motion or stability of the shoulder, both shoulders should be examined after the induction of anesthesia. The range of motion in elevation, in external rotation with the arm adducted, and in external and internal rotation with the arm abducted 90 degrees should all be recorded. The shoulder should then be examined for stability by applying anterior, posterior, and inferior force while changing the positions of abduction and rotation ( Figs. 3.13–3.21 ).
Arthroscopic Procedure ( and )
Only incise the skin and avoid plunging the knife into the underlying structures. Superficial skin nerves are susceptible to neuroma formation, and muscle bleeding unnecessarily complicates the procedure. Some surgeons prefer to insufflate the joint with saline prior to the procedure. We prefer to not insufflate the joint with a needle because it allows us to better determine the entry point into the glenohumeral joint using the rigid trocar to palpate the humeral head and the glenoid rim. Only a blunt-tipped trocar is used; never use a sharp trocar.
To begin, insert the cannula and trocar through the skin incision and gently advance them through the deltoid muscle until bone resistance is felt. With your opposite hand pushing the humeral head posteriorly against the trocar tip, you can tell by palpation whether the bone is the glenoid or the humeral head . Alternatively, you can grasp the forearm and rotate the shoulder; if you feel the bone rotate, the trocar tip is resting against the humeral head and you must direct the arthroscope medially to enter the joint. If no rotation is felt, the trocar is touching the glenoid and you must direct it laterally to enter the joint. When the trocar tip is at the joint line, a slight lateral movement allows you to palpate the head, and a slight medial movement results in contact with the glenoid. The posterior joint line is medial to the posterolateral acromion, and the direction of entry is generally oriented toward the tip of the coracoid . Angle the cannula slightly superiorly and advance it into the joint. Usually a distinct “pop” is felt as the trocar enters the glenohumeral joint. It is often helpful to place the arm in a neutral or internal rotation when placing the trocar as this distracts the posterior capsule, increasing the surface area for entry. Remove the trocar, insert the arthroscope through the cannula, and begin the diagnostic inspection. If you have not entered the joint, remove the cannula and trocar to check the bone landmarks drawn on the skin ( Fig. 3.22 ).
The diagnostic examination of the shoulder is systematic to ensure that no lesions are overlooked. The plan described in Table 3.1 can serve as a guide.
| Anterior View—Arthroscope in Posterior Cannula |
| Biceps-labrum complex |
| Biceps tendon |
| Biceps exit from the joint |
| Articular surface of supraspinatus |
| Superior glenohumeral ligament |
| Rotator interval |
| Subscapularis tendon |
| Subscapularis recess |
| Middle glenohumeral ligament |
| Anterior labrum |
| Anterior-inferior glenohumeral ligament |
| Inferior labrum |
| Inferior capsule |
| Posterior-inferior glenohumeral ligament |
| Posterior labrum |
| Infraspinatus tendon |
| Posterolateral humeral head |
| Posterior View—Arthroscope in Anterior Cannula |
| Posterior glenoid labrum |
| Posterior capsule |
| Posterior rotator cuff (site of internal impingement) |
| Subscapularis recess |
| Middle glenohumeral ligament and its humeral attachment |
| Anterior-inferior glenohumeral ligament and its humeral attachment |
Once you have entered the glenohumeral joint, identify the biceps tendon–labrum complex and rotate the camera to orient the glenoid on the monitor screen. Most surgeons prefer the vertical orientation when using the beach-chair position ( Fig. 3.23 ). This is the orientation that will be used throughout this book.
For a right shoulder, advance the arthroscope into the joint and rotate it so that it is looking at the 1 o’clock position relative to the glenoid surface. Inspect the rotator interval and superior glenohumeral ligament. Apply inferior distraction and observe the tension that develops. Distract the arm with the shoulder externally rotated and internally rotated, and note any difference. Perform this portion of the examination first because when the anterior cannula is introduced, it passes through the rotator interval and alters the local anatomy. The rotator interval may appear normal in subacromial impingement, contracted in patients with shoulder stiffness, and widened or lax in patients with glenohumeral instability ( Figs. 3.24–3.30 ).
There are two basic techniques to establish an anterior portal: inside out or outside in. To establish the anterior portal with the inside-out technique, advance the arthroscope until it is in the middle of the triangular space bordered by the glenoid rim, the superior border of the subscapularis tendon, and the biceps tendon. Press the arthroscope against the rotator interval and hold the cannula in position while you remove the arthroscope from the cannula . Insert a blunt-tipped rod (Wissinger) through the cannula and advance it through the capsule until it tents the skin anteriorly. Maintain pressure on the rod and make a skin incision directly over its tip. Advance the rod anteriorly so that it projects 5 to 10 cm. Slide a second cannula over the rod tip anteriorly and advance this cannula into the joint until you can feel the two cannulas touch each other. Remove the rod and reinsert the arthroscope into the posterior cannula. Adjust the anterior cannula until 15 to 20 mm is visible within the joint. Outflow can remain connected to the arthroscope cannula or it can be moved to the anterior cannula, as desired. I used this technique early in my arthroscopic experience because it enabled me to reliably enter the glenohumeral joint. As I began doing more reconstructive shoulder operations, I discovered some inadequacies with this approach. The inside-out approach allows variability in the precise entry spot for the anterior portal because there is some inevitable manipulation of the arthroscope during the necessary sequence of maneuvers. For glenohumeral joint reconstruction for instability, I need two anterior cannulas, and their positions are critical. If the inferior cannula is too superior, there will not be enough space for the anterior-superior cannula. If the cannulas are too medial or too lateral, the anchor insertion is complicated, and the suture placement is compromised. For these reasons, I now establish the anterior portals with an outside-in approach.
To establish the anterior portal with the outside-in technique, point the arthroscope at the rotator interval and use your index finger to push on the skin of the anterior shoulder lateral and superior to the coracoid process. Observe where your finger indents the anterior capsule, and move that location until the anterior capsule is indented in the middle of the rotator interval. Note this location on the anterior shoulder with a marking pen and then use a spinal needle to enter the joint at this point. The exact position and angle of entry is dictated by the target pathology and the intended number of portals. Once the location is marked, remove the spinal needle, make a small incision, and place the cannula and trocar into the joint. As with the inside-out technique, outflow can remain connected to the arthroscope cannula or it can be moved to the anterior cannula ( Figs. 3.31–3.33 ).
Rotate the arthroscope so that the camera is facing the 7 o’clock position for a right shoulder (light cord is positioned at 1 o’clock) or facing 5 o’clock for a left shoulder. Advance it anteriorly and inspect the subscapularis recess and the superior border of the subscapularis tendon. Rotate the arthroscope to have the camera face the 9 o’clock position for a right shoulder (light cord is positioned at 3 o’clock), advance it anteriorly, and inspect the anterior labrum and the middle glenohumeral ligament ( Fig. 3.34 ). The normal opening of the foramen at the anterior–superior labrum should not be confused with a Bankart lesion. Observe the anterior labrum for signs of glenohumeral instability, such as fraying, tearing, or separation from the glenoid. Insert a probe through the anterior cannula and test the anterior labrum’s attachment to the glenoid. Use the probe to test the tension of the middle glenohumeral ligament. Translate the humeral head anteriorly, inferiorly, and posteriorly, and observe the tension that develops in the ligament. Perform these maneuvers with the arm internally and then externally rotated. The middle glenohumeral ligament has a variable appearance and may be poorly defined, prominent, or cordlike ( Figs. 3.35–3.46 ).
