Elizabeth Matzkin and Craig R. Bottoni
DEFINITION
The shoulder is a spheroidal multiaxial joint stabilized not only by its bony anatomy but also by the surrounding muscles and capsular structures.
Arthroscopy is the process of visualization and examination of a joint using a fiberoptic instrument. All shoulder surgeons must be proficient in diagnostic arthroscopy of the shoulder.
ANATOMY
The glenohumeral joint consists of the glenoid fossa of the scapula that articulates with the head of the humerus.
The labrum is a “bumper” of fibrocartilaginous tissue around the rim of the glenoid that acts to deepen and enlarge the glenoid fossa and increase glenohumeral stability. The biceps tendon is anchored at the superior labrum and acts as a humeral head depressor and also aids in glenohumeral stability.
The static stabilizers of the shoulder include the joint capsule and the glenohumeral ligaments—superior, middle, and inferior glenohumeral ligaments. These will be discussed in greater detail in subsequent chapters.
The dynamic stabilizers of the shoulder are the rotator cuff muscles—supraspinatus, infraspinatus, subscapularis, and teres minor.
The scapular stabilizers—rhomboids, levator scapulae, trapezius, and serratus anterior—also contribute to dynamic stability of the shoulder.
PATHOGENESIS
Shoulder injuries can occur secondary to trauma, microtrauma, or overuse injuries and can be activity and agedependent.
Most patients under age 40 will have symptoms typical of overuse or instability, whereas patients over age 40 present more commonly with rotator cuff, impingement, inflammatory, or degenerative joint disease types of symptoms.
NATURAL HISTORY
Shoulder injuries can be painful and lead to shoulder dysfunction.
Recurrent shoulder instability decreases with age.2
The frequency of rotator cuff tears increases with age.1
If shoulder pathology is left unaddressed, pain, motion loss, degenerative changes, loss of function, and inability to participate in sports or work can occur.
PATIENT HISTORY AND PHYSICAL FINDINGS
The most important part of the physical examination consists of taking an accurate history from the patient.
Was it a traumatic, nontraumatic, or overuse injury?
When and how did the injury occur?
Is the patient's complaint of pain, loss of motion, weakness, or inability to perform sports, activities of daily living, or work?
Is there pain at rest, only with activity, or while sleeping?
Are there any neurologic symptoms?
Basic physical examination methods are summarized below. More specific examinations for different diagnoses will be described in other chapters in this section.
Observation of patient with shoulder pain from the front, back, and side
Identify any muscle atrophy and asymmetry of muscles, shoulder height, or scapular position.
Palpation of different parts of shoulder—sternoclavicular joint, acromioclavicular joint, greater tuberosity and rotator cuff, glenohumeral joint, biceps tendon, trapezium—to localize any areas of point tenderness, which may aid in differential diagnosis.
Passive and active range of motion—forward flexion, abduction, adduction, internal and external rotation
Loss of range of motion may indicate adhesive capsulitis, rotator cuff pathology (tendinitis or rotator cuff tear), or degenerative changes.
Resistive testing of deltoid, supraspinatus, infraspinatus, and subscapularis
Weakness of any muscles may indicate nerve injury, torn muscle or tendon, or weakness secondary to pain.
Rotator cuff and scapular stabilizers: Look for atrophy, scapular winging, weakness with strength testing, and painful range of motion.
Provocative tests for rotator cuff tear include drop arm sign and liftoff or belly press for subscapularis.
Impingement tests include the Neer and Hawkins tests.
Labrum: Catching, clicking, popping may indicate a labral tear; check for instability with provocative tests (load shift, apprehension test or crank test, relocation, O'Brien's).
Multidirectional instability: Look for increased laxity inferiorly and in one other direction.
The sulcus sign demonstrates inferior laxity.
Check for the ability to voluntarily subluxate or dislocate the humeral head.
Acromioclavicular joint: localized tenderness over the acromioclavicular joint and pain with cross-chest adduction and O'Brien's testing
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs are used to assess different aspects of the shoulder joint.
Basic radiographs should consist of anteroposterior, axillary, and outlet views.
Special views may be obtained depending on shoulder pathology and will be discussed in subsequent chapters.
Magnetic resonance imaging (MRI) and MRI arthrograms are also commonly obtained to aid in diagnosis because they are highly sensitive and specific in diagnosing many shoulder injuries.
DIFFERENTIAL DIAGNOSIS
Impingement (internal or external)
Rotator cuff tear
Adhesive capsulitis
Acromioclavicular joint injury or arthritis
Labral tear
Instability
Biceps tendon pathology
Degenerative arthritis
Scapulothoracic dysfunction
Cervical or neurologic
Infection
NONOPERATIVE MANAGEMENT
Nonoperative management for many different diagnoses may first consist of rest, nonsteroidal anti-inflammatories, physical therapy, and diagnostic and therapeutic injections.
SURGICAL MANAGEMENT
A patient who has failed to respond to nonoperative management and continues to have symptoms consistent with his or her diagnosis is a candidate for shoulder arthroscopy.
Preoperative Planning
Patient history and imaging studies are reviewed.
The surgeon should have a good understanding of what pathology to expect at the time of arthroscopy to ensure that all appropriate equipment and instruments are available.
Patient positioning aids (arm holders, weights, beanbag, axillary roll)
Arthroscopic pumps or irrigation system
Video monitor, 30- and 70-degree arthroscopes
Arthroscopic cannulas
Shavers, burrs, suture anchors, arthroscopic instruments (probe, grasper, scissor, basket)
An examination under anesthesia is performed to assess range of motion and stability.
Positioning
Shoulder arthroscopy may be performed with the patient in either a beach-chair position or the lateral decubitus position (FIG 1).
The beach-chair position requires a specially designed operating table attachment that ensures that the surgeon has adequate exposure to the patient's posterior shoulder and the patient's head is well supported.
The advantage of this position is that the shoulder can be freely manipulated throughout the procedure.
Commercially available arm holders can also be used to allow glenohumeral distraction and positioning without the need for an assistant.
When using the lateral decubitus position (FIG 1B), the patient must be properly padded and the body supported with a beanbag, axillary roll, and pillows.
The operative extremity is placed in a commercially available arm holder in approximately 70 degrees of abduction and 15 to 20 degrees of forward flexion, with 10 pounds of weight for traction. This allows for distraction of the glenohumeral joint and offers excellent visualization.
FIG 1 • A. Patient in beach-chair position with standard draping for right shoulder arthroscopy. B. Patient in right lateral decubitus position with shoulder distraction apparatus to abduct and distract the left upper extremity.
Approach
The operating room should be set up to allow the surgeon easy access to the entire shoulder and permit optimal visualization of the video monitors and arthroscopic equipment.
The typical operating room setup is shown in FIG 2.
The entire shoulder, arm, forearm, and hand and the exposed portion of the patient's hemithorax should be sterilely prepared after isolation with a clear U-drape. This will aid in keeping the patient dry in case fluid leaks under the surgical drapes.
FIG 2 • Operating room setup to allow optimal visualization of monitor and arthroscopic equipment.
TECHNIQUES
SETUP AND PORTAL PLACEMENT
Once the patient is prepared and draped, the bony surface anatomy should be outlined with a surgical marking pen. This includes the clavicle, borders of the acromion (anteriorly, posteriorly, and laterally), the spine of the scapula, the acromioclavicular joint, and the coracoid (TECH FIG 1).
TECH FIG 1 • Right shoulder with preoperative markings identifying the acromion, clavicle, and expected portal sites.
All expected portal sites should next be marked. For a basic diagnostic arthroscopy these should include a posterior, anterior, and if necessary lateral portal. Accessory portal locations required for specific procedures will be discussed in subsequent chapters.
Posterior portal: 2 to 3 cm inferior and 1 cm medial to the posterolateral border of the acromion. It is usually located in the “soft spot” of the posterior shoulder that can be palpated between the posterior rotator cuff muscles (infraspinatus and teres minor).
Anterior portal: This portal is marked just lateral to the tip of the coracoid process and inferior to the anterolateral acromial border. Care must be taken to ensure that all anterior portals are lateral to the coracoid to avoid damage to the neurovascular structures located medial to the coracoid.
Lateral portal: This portal is marked 3 to 5 cm lateral to the lateral margin of the acromial border. The location of this portal may change based on the intraarticular anatomy.
Before starting the arthroscopic procedure, the surgeon ensures that all arthroscopic equipment (arthroscope, monitor, pump) is properly functioning.
INSERTION OF THE ARTHROSCOPE
The posterior portal is created first.
A 5-mm skin incision is made using a number 11 scalpel.
All shoulder arthroscopy incisions should penetrate only the skin and no deeper to avoid injury to neurovascular structures and possible damage to articular surfaces.
The arthroscope sheath and blunt obturator are then inserted into the glenohumeral joint (TECH FIG 2).
The trocar should be directed toward the coracoid. One hand can be used to stabilize the shoulder and the index finger used to palpate the coracoid tip.
The obturator should be directed just medial to the humeral head and into the space between the head and glenoid. There should be a “pop” once the capsule is penetrated and the cannula is within the glenohumeral joint.
Some surgeons prefer first to inject saline with a spinal needle into the glenohumeral joint. This expands the joint and allows a bigger target as well as, with fluid return, confirms that the arthroscope is in the proper place.
The irrigation system and pump is turned on and the humeral head, glenoid, and biceps tendon are identified for quick orientation.
A brief inspection of the glenohumeral joint can be performed to determine whether modification of the subsequent portals may be required.
TECH FIG 2 • Arthroscope insertion. The trocar and arthroscopic cannula are directed toward the coracoid process. It enters the glenohumeral joint just lateral to the posterior glenoid labrum and approximately in the middle of the glenoid from superior to inferior. The surgeon's index finger is on the tip of the coracoid to help direct the trocar into the joint.
ESTABLISHING THE ANTERIOR PORTAL
The anterior portal is next created. Depending on the intra-articular shoulder pathology to be addressed, a modified anterior portal may be needed; this is discussed in other chapters.
For most standard arthroscopic procedures, the anterior portal may be created using either an inside-out or an outside-in technique.
Inside-Out Technique
The arthroscope is placed within the rotator interval just inferior to the biceps tendon and held firmly against the anterior capsule. The camera is then removed while holding the cannula in position.
A switching stick or Wissinger rod (a long metal rod that fits within the arthroscopic sheath) is inserted into the cannula and used to penetrate the anterior capsule and tent the skin.
A small skin incision is made over the end of the switching stick.
A cannula may then be passed over the switching stick and into the glenohumeral joint.
Outside-In Technique
A spinal needle is inserted at the expected site of the anterior portal and into the joint (TECH FIG 3).
Once the needle is visualized and its location deemed adequate, it is removed and a small skin incision is made at the site where the spinal needle was inserted.
A cannula with its obturator is used to penetrate the anterior capsule into the glenohumeral joint under direct arthroscopic visualization.
TECH FIG 3 • Spinal needle inserted in rotator interval to establish correct placement of anterior superior portal. The humeral head (H) and the long head of the biceps tendon (B) are clearly identified.
DIAGNOSTIC ARTHROSCOPY
Arthroscope in the Posterior Portal
Diagnostic arthroscopy of the shoulder begins with the arthroscope in the posterior portal and a probe through the anterior portal. From this position, the following structures should be visualized and probed:
Articular surfaces of the humeral head and glenoid
The cartilage surface is evaluated, noting any chondral damage.
The glenoid cartilage may have a normal “thinnedout” appearance at its center.
Occasionally, the demarcation of the two ossific centers of the glenoid may be identified as a thin line on the chondral surface.
Subscapularis tendon and rotator interval
The integrity of the superior tendinous edge of the subscapularis and its attachment to the lesser tuberosity is evaluated (TECH FIG 4A).
The tissue quality and laxity of the rotator interval (the capsular tissue between the anterior edge of the supraspinatus and the superior edge of the subscapularis) is noted.
Superior and middle glenohumeral ligaments
The superior ligament is evaluated as it crosses between the subscapularis and biceps tendon and the middle ligament as it crosses the subscapularis tendon (TECH FIG 4B).
Variants may include a Buford complex (cord-like middle glenohumeral ligament) or even absence of the ligament altogether.
Superior labrum and biceps tendon
The biceps tendon is evaluated on both sides, using a probe to pull it into the joint to evaluate for hidden synovitis or fraying that exists as it leaves the joint and enters the bicipital groove (TECH FIG 4C).
Rotator cuff
The tendons of the rotator cuff are evaluated with the arthroscope looking superiorly. The rotator cuff tendon attachment to the humeral head should be smooth, without any fraying (TECH FIG 4D).
As the arthroscope is moved posteroinferiorly around the humeral head, the normal “bare spot” on the humeral head is easily identified by the lack of articular cartilage and the presence of nutrient foramen in the bone (TECH FIG 4E).
Inferior capsule and recess
The inferior capsular pouch and the capsular attachment to the humeral head are assessed (TECH FIG 4F).
Occasionally a humeral avulsion of the inferior glenohumeral ligament may occur here with or without a fragment of bone.
TECH FIG 4 • A. Left shoulder in lateral decubitus position with anterior superior and anterior inferior portals established. The biceps tendon (B) is between the two cannulas. The humeral head (H), glenoid (G), and superior edge of the subscapularis (S) are identified. B. Left shoulder in beach-chair position, with subscapularis (S), biceps tendon (B), and middle glenohumeral ligament (M) identified. The anterosuperior labrum is highly variable and in this case presents as a sublabral hole (arrow). C. The long head of the biceps can be pulled into the joint to inspect for synovitis (arrows), as shown in this shoulder. D. The anterior edge of the suprapinatus and the normal rotator cuff insertion are depicted in this image. E. As the arthroscope is swept posteriorly along the rotator cuff, the bare area of the humeral head is identified. This is a normal area devoid of articular cartilage. The transition between the posterior rotator cuff and the inferior capsule is identified (arrow). F. The inferior capsular pouch is seen attaching to the humerus. This is a common area to find loose bodies as they tend to fall to the most dependent aspect of the joint (in the beach-chair position). G. The inferior glenoid labrum can be visualized as the arthroscope is redirected superiorly from the axillary pouch. H,I. The anterior labral attachment is inspected. H. The labrum and capsular attachment are normal. I. There is a disruption in the attachment of the anteroinferior labrum (Bankart lesion). J. The superior labral attachment is probed.
As the arthroscope is directed superiorly, the inferior labral attachment can be examined (TECH FIG 4G).
Anterior band of the inferior glenohumeral ligament
This is the primary static stabilizer to anterior glenohumeral translation.
The anteroinferior labrum should be tightly attached to the glenoid (TECH FIG 4H). Detachment in this area is commonly referred to as a Bankart or Perthes lesion (TECH FIG 4I) and will be discussed in greater detail in Chapter SM-2.
Visualization of this ligament is facilitated when the ligaments and capsular tissues are loose and the arthroscope may easily pass into the anterior recess between the humeral head and glenoid. This is known as a “drive-through” sign and may represent multidirectional laxity.
Biceps anchor
The superior labral attachment to the glenoid is probed to evaluate for a superior labral anterior to posterior (SLAP) lesion.3
Typically the superior labrum is well attached to the superior glenoid (TECH FIG 4J).
Normal variants such as a meniscoid superior labrum and variations of the biceps tendon (bifid tendon) are not uncommon. They must be differentiated from pathoanatomy that requires repair.
Arthroscope in the Anterior Portal
The arthroscope is removed while keeping the sheath in the joint posteriorly. It is placed in the anterior cannula to allow evaluation of the posterior joint and to assess the rest of the joint from another viewpoint.
TECH FIG 5 • The arthroscope is now switched to the anterior portal to inspect the posterior labrum and capsule. The transition of the posterior labrum into the superior labrum and biceps attachment (arrows) is smooth.
The posterior labrum should be smooth and tightly attached to the glenoid (TECH FIG 5).
The scope is angled upward to assess posterior capsular attachment to the humeral head. If detached, this represents a reverse humeral avulsion of the glenohumeral ligament.
Subscapularis and biceps tendon
The subscapularis recess and subscapularis attachment to the humeral head can be evaluated.
Loose bodies are occasionally found within the subscapularis recess.
Integrity and stability of the groove and the synovium of the biceps tendon are evaluated.
SUBACROMIAL ARTHROSCOPY (BURSCOSCOPY)
Once the diagnostic glenohumeral arthroscopy is completed, the sheath and obturator are then directed into the subacromial space.
This is done by placing the obturator tip just beneath the posterior acromion and then inserting it parallel to the acromion.
If the arthroscope is inserted properly into the subacromial space anterior to the posterior bursal curtain, then the distended bursal space should allow for visualization of the subacromial structures.3
At the surgeon's preference, a lateral portal may be created at this time.
The inferior aspect of the acromion is evaluated and the coracoacromial ligament is identified.
The lateral and anterior aspects of the acromion are assessed.
The anterior acromial spur is evaluated if present.
The arthoscope is oriented to look downward at the greater tuberosity and attachment of the rotator cuff.
A probe from the anterior or lateral portal is used to assess the rotator cuff integrity. The rotator cuff attachment should be smooth, without fraying or thinning of the tissue.
Internal and external rotation of the arm will allow for visualization of the entire cuff.
The acromioclavicular joint is evaluated. The distal clavicle may be hidden behind thickened tissue. Further evaluation of this joint is discussed in Chapter SM-8.
Once the subacromial space has been evaluated and all pathology has been addressed, the arthroscopic instruments and cannulas can be removed from the shoulder.
The portals can be closed with a simple suture or subcuticular stitch.
Wounds can be dressed and the shoulder placed in a sling for comfort or for rehabilitation purposes, depending on the procedure performed.
POSTOPERATIVE CARE
The patient is placed in a sling for comfort. Allowable range of motion and exercises are tailored to the specific procedure performed and will be discussed in detail in the following chapters.
Cryotherapy (a commercial ice unit) may be used.
OUTCOMES
Shoulder arthroscopy is a safe and effective procedure. It allows for complete visualization of the glenohumeral joint and subacromial space and treatment of identified pathology.
Outcome data for specific procedures performed are discussed in the following chapters.
COMPLICATIONS
Failure to address all pathology with thorough diagnostic examination
Infection
Loss of motion or adhesive capsulitis
REFERENCES
1. Nove-Josserand L, Walch G, Adeleine P, et al. Effect of age on the natural history of the shoulder: a clinical and radiological study in the elderly. Rev Chir Orthop Reparatrice Appar Mot 2005;91:508–514.
2. Rowe CR. Acute and recurrent anterior dislocation of the shoulder. Orthop Clin North Am 1980;11:253–270.
3. Snyder S. Diagnostic arthroscopy. In: Snyder S, ed. Shoulder Arthroscopy, ed 2. Philadelphia: Lippincott Williams & Wilkins, 2003.