SPORTS MEDICINE  ·  SURGERY OF THE KNEE  ·  SURGERY OF THE SHOULDER  

Shoulder Arthroscopy Print

Arthroscopy of the shoulder has become a very common procedure. It was first described by Burman in the 1930's, but has only become a useful tool in the past 10-15 years. In that time, innovations in camera designs and fiber optics, as well as the development of specialized tools have moved shoulder arthroscopy from a diagnostic procedure to a treatment modality. Despite the large number of arthroscopies performed each year, shoulder arthroscopy can be challenging to an inexperienced surgeon.

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Figure 1

Shoulder Arthroscopy, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 2

Figure 2

Instruments

The primary instrument for arthroscopic surgery is the fiber optic arthroscope. (Fig. 1). Arthroscopes come in a variety of diameters and lens angles, but the most common scope used in arthroscopy of the shoulder is the 4 mm, 30 degree scope. It consists of a lens encircled by fiber optic fibrils that provide light for visualization. A television camera allows visualization on a television monitor so all members of the surgical team can view the procedure .

To maintain distention in the joint for visualization and limit bleeding, fluid is pumped into the joint under pressure. This is usually accomplished by a computerized pump that precisely monitors the flow rate and intra-articular pressure..

Another essential instrument is the motorized shaver consisting of a rotating blade encased within a smooth sheath. The shaver is connected to suction which draws fluid and tissue into the rotating blade allowing tissue to be removed from the joint.

A variety of other instruments including tiny scissors, biting forceps, burrs for resecting bone and electrocautery for hemostasis are used for specific cases (Fig.2).

 

Patient Positioning

There are two distinct ways to position the patient during arthroscopic surgery of the shoulder. The first is the lateral decubitus position in which the patient is lying on his or her side with the affected limb up (Figure 3). The position is held with an inflatable bean bag that wraps around the patient, stabilizing even an anesthetized patient. The arm is then connected to a traction apparatus that applies 10 to 15 pounds of traction to distract the joint. The torso is then rolled back 15-30 degrees to orient the glenoid surface parallel to the floor. The arm is then abducted 70 degrees and forward flexed 15 degrees to improve visualization.

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 4

Figure 4

The second option is the beach chair position (Fig. 4). In this position, the patient is sitting upright with the back of the bed flexed 70-80 degrees. The arm is allowed to hang freely at the side. No traction apparatus is required. The patient is positioned so that the affected shoulder hangs off the side of the bed allowing full access to both the anterior and posterior aspects.

Each position has both advantages and disadvantages. The lateral decubitus position, due to the arm position and traction applied, offers better visualization of the sub-acromial space. Also, the arm is fixed in space, avoiding the need for an assistant to hold the arm. However, this position requires conversion to the beach chair position should the shoulder need to be opened. Also, complications can occur from the traction apparatus, although these cases are rare.

The beach chair position is more comfortable to the awake patient and allows full ROM of the arm in the OR (sometimes requiring an assistant). Also, it avoids the need to re-position the patient if the arthroscopic procedure is converted to an open procedure. With no traction applied, complications caused by excessive traction can be avoided, however, this is often at the expense of visualization.

Portal Placement

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 5

Figure 5

Arthroscopic surgery is performed through small incisions known as portals. These incisions are usually one centimeter or less in length, so placement of the portal is critical. The standard portals for shoulder arthroscopy are the posterior, anterior and lateral portals. The accessory portals include the accessory anterior and superior portals.

The posterior portal is the primary portal used for visualization (Figure 5). It is usually established first and allows visualization of most of the anterior, superior and inferior structures of the joint. It is placed 3 cm distal and 1 cm medial to the postero-lateral tip of the acromion. It is placed in the "soft-spot" of the shoulder formed by the interval between the infraspinatus muscle and the teres minor muscle.

Therefore, this portal should traverse skin, subcutaneous tissue, posterior deltoid and joint capsule. Structures at risk with this portal include the posterior humeral circumflex artery, the axillary nerve and the scapular circumflex artery.

The anterior portal is the work-horse of the shoulder. Most of the instruments used within the gleno-humeral space are passed through this portal. It can be established with either and inside-out or outside-in technique. With the inside-out technique, the arthroscope in the posterior portal locates the precise position where the anterior portal should be and a rod is passed through the arthroscpopic cannula to exit the anterior shoulder.

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic sports medicine, figure 6

Figure 6

A cannula is then passed retrograde over the rod, and the portal is established. The outside-in technique locates the precise placement be passing a needle through the anterior shoulder and visualizing where it enters the joint (Figure 6).

When an acceptable position is found, an incision is made and the portal established. The portal should be placed lateral to the coracoid, roughly between the coracoid and the anterior acromion. The structure at risk with this portal is the musculocutaneous nerve.

The lateral portal is used in the sub-acromial space for decompression and visualization. It is located just lateral to the lateral edge of the acromion at its anterior aspect. The structure at risk is the axillary nerve.

The superior portal is seldom used but can prove invaluable is select cases. It is placed in the superior "soft-spot" bordered by the posterior edge of the clavicle, medial edge of the acromion and the anterior edge of the scapular spine.

When used in the gleno-humeral joint, the portal passes through the supraspinatus muscle which prevents its routine use. The structures at risk are the suprascapular nerve and artery.

 

Arthroscopic Anatomy

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic  sports medicine, figure 7

During arthroscopic surgery of the shoulder, two general areas of the shoulder are examined, the glenohumeral joint and the sub-acromial space above the rotator cuff. Within each general area, specific anatomic structures are visualized.

The first area examined is the glenohumeral joint. Within this space are several structures that must be viewed. These include the socket or glenoid(G), the ball or humeral head(HH), biceps tendon (B) Fig. 8A, labrum (L) (Figure 11), subscapularis tendon(SS), superior glenohumeral ligament(SGHL), middle glenohumeral ligament(MGHL), inferior glenohumeral ligament complex(IGHLC) and the undersurface of the rotator cuff (Fig. 8B).

 

 

shoulder-anthropathy-dr-allen-f-anderson-nashville-orthopaedic-surgery-sports-medicine-figure-7a-3-lettered shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 7b
Figure 8A Biceps Tendon Figure 10 Rotator  Cuff

 

Within the sub-acromial space, one should see the undersurface of the acromion, the distal end of the clavical, the undersurface of the acromiocalvicular joint, the sub-acromial bursa and the superior surface of the rotator cuff (Figure 9).

Specific Anatomic Structures

The biceps tendon (B) attaches to the superior portion of the glenoid (G) and serves as one of two points of origin for the powerful biceps muscle (Figure 7). It is the primary structure used for orientation during arthroscopic surgery. It angles inferiorly 10-15 degrees from the horizontal to exit through the interval between the subscapularis (SS) and the supraspinatus, (Fig. 10-12) the rotator interval. The tendon is intimately associated with the superior labrum and should be smooth in appearance throughout its course.

 

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shoulder-anthropathy-dr-allen-f-anderson-nashville-orthopaedic-surgery-sports-medicine-figure-9-lettered
Figure 9 Figure 10   Labrum

 

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Figure 11

 

The humeral head (HH) and glenoid (G) are the articulating surfaces of the shoulder joint and should be smooth throughout. Approximately 1/3 of the humeral head can be visualized at any given time through the arthroscope. The humeral head articulates with the glenoid which is pear-shaped and approximately ¼ the size of the humeral head. Thinning and fibrillation of the cartilage at the inferior portion is normal after the second decade of life.

Interspersed between these surfaces is a ring of tissue (glenoid labrum) that increases the stability of the joint by increasing the congruity between the surfaces. The labrum is 3-4 mm in thickness and is intimately associated with the inferior gleno-humeral ligament complex inferiorly and the superior gleno-humeral ligament and biceps tendon superiorly. The inferior portion should be firmly attached to the glenoid. It should be smooth throughout, although fraying is normal later in life (Figure 8B).

The superior gleno-humeral ligament (SGHL) is the smallest of the three ligaments and runs from the base of the coracoid and superior labrum to the anatomic neck of the humerus. It prevents inferior instability with the arm in the adducted position. The ligament is often poorly visualized due to its location behind the biceps and its small size.

The middle gleno-humeral ligament (MGHL) runs from the superior and middle glenoid, scapular neck to the anterior neck of the humerus. It courses across the posterior surface of the subscapularis to which it is often adherent. This ligament functions to prevent anterior instability in the 45 degree abducted arm.

The inferior gleno-humeral ligament complex (IGHLC) is divided into anterior and posterior bands, with an axillary pouch between. This is the most important stabilizer of the shoulder functioning to prevent anterior instability in the 90 degree abducted arm.

The subscapularis (SS)tendon makes up the anterior portion of the rotator cuff muscles. This is a large tendon, only the most superior of which can be viewed from within the joint. It should be smooth throughout its course.

The undersurface of the rotator cuff (RC) is a common site of partial rotator cuff tears. This confluence of tissue represents the insertion of the supraspinatus, infraspinatus and teres minor muscles which can be viewed at the insertion onto the humeral head.

Specific Clinical Problems

Instability is often caused by detachment of the inferior gleno-humeral ligament complex from the inferior glenoid (Bankart lesion). This is often accompanied by stretching of the remaining fibers, leading to laxity in the shoulder. The detached ligament can be repaired arthroscopically.

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 10
Figure 12

Rotator cuff tears usually occur in the tendinous insertion on the lateral aspect of the humeral head (Figure 9). These can also be treated through the arthroscope. The torn tendon can be repaired arthroscopically using bioabsorbable anchors or through a small, "mini-open" procedure.

Bicep Tendonosis

The bicep tendon runs through a groove in the humeral head and and attaches to top of the socket (glenoid). Problems with this pully system may cause shoulder pain. The tendon may become worn (Figure 13A & B) or slip partially or all the way out of the groove in the humerus. In these circumstances the tendon is released from the humerus and reattached to the humerus (biceps tendonosis).

 

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 11A shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 11B

Figure 13A

 Arthroscopic view of moderate biceps tendonosis

Figure 13B

Arthroscopic view of severe tendinosis

 

Slap Lesions

The labrum is the fibrous tissue which surrounds the shoulder socket (glenoid). The acronym, SLAP, refers to a tear of the superior labrum from anterior to posterior. When viewing the glenoid, a SLAP tear occurs between the 10 and 2 o’clock positions. The superior labrum serves as an anchor for the biceps tendon to the glenoid and a SLAP tear always includes the area of the biceps tendon anchor complex. A review of the arthroscopic appearance of these lesions results in a classification into four basic types of SLAP tears.

A type I SLAP lesion has a degenerative appearance in the superior labrum. Figure 14A shows a type I SLAP lesion. Fig. 14B show the appearance after arthroscopic debridement.

 

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 12A shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 12B
Figure 14A Figure 14B

 

A type II SLAP lesion may have a degenerative appearance similar to a type I SLAP lesion (Fig. 13A), however, in type II lesions, the superior labrum is also detached from its insertion on the superior glenoid, along with the biceps tendon, it arches away from the underlying glenoid neck. Figure 13B demonstrates repair of this type II SLAP tear.

 

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 13A shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 13B
Figure 15A Figure 15B

 

In a type III SLAP lesion, the superior labrum has a bucket handle tear analogous to that seen in the meniscus of the knee. The biceps tendon attachment is intact. (Fig 16A). Fig. 16B demonstrates the appearance after debridement.

 

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 14A shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 14B
Figure 16A Figure 16B

 

The type IV SLAP lesion, a bucket handle tear of the superior labrum extends as a split tear of variable degrees into the biceps tendon. The biceps tendon is displaced with a labral flap into the joint (Fig. 15A). Figure 15B shows the appearance after debridement of the SLAP tear.

 

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 15A shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 15B
Figure 17A Figure 17B

 

Symptoms

The two most common complaints in patients with SLAP lesions are pain with overhead activities, and mechanical symptoms of catching, locking, popping, or grinding. Frequently the pain is impossible to differentiate from impingement-type pain. Other complaints include pain when lying on the shoulder, decreased ROM, pain with activities of daily living and loss of strength.

The most common mechanism of injury includes either traction or compression injuries.

Physical Exam:

None of the physical exam techniques have proven very accurate. We, therefore, rely on a high index of suspicion in a patient with shoulder symptoms and physical findings indicative of possible SLAP tear.

Diagnostic Imaging:

Radiographs of the shoulder are routinely obtained as part of the diagnostic workup, but they are not helpful in diagnosing labral tears. MRI is the best diagnostic tool for assessing the labrum and rotator cuff in patients with pain of uncertain origin.

Surgical Technique:

Although MRI may provide useful information for evaluating the superior labrum, the diagnosis of a SLAP tear is generally made during diagnostic arthroscopy. The treatment of type I SLAP tears is debridement of the frayed tissues (Fig. 14B).

Type II

Type II lesions are repaired by means of suture anchors inserted into the glenoid on both sides of the biceps tendon affording secure stability for healing. (Fig. 15B).

Type III

Type III SLAP lesions have an unstable bucket handle fragment that is removed with the arthroscopic shaver (Fig. 16B).

Type IV

Type IV lesions are treated based on the severity of the biceps tendon split. When more than 30% of the biceps tendon is included with a displaced labral tear, then a clinical decision must be made regarding repairing the tendon and labrum or performing a biceps tenodesis. The decision depends upon the age and activity level of the patient and the condition of the remainder of the biceps tendon. In most cases, we prefer to excise the labral fragment along with the attached portion of the biceps tendon (Fig. 17B).

Adhesive Capsulitis (or Frozen Shoulder)

Stiff or frozen shoulder is a relatively common problem in which both active and passive shoulder motion is lost because of soft tissue contracture. Unfortunately, it can pose a considerably frustrating condition for both the patient and the physician. Although reported to be self-limiting, frozen shoulders may take years to "thaw." Even then, patients may be left with residual loss of motion. Adhesive capsulitis is a term for loss of shoulder motion caused by thickening and contracture of the joint capsule, which results in decreased joint volume. Figure 18A shows a normal joint capsule and Fib. 18B shows severe inflammation in adhesive capsulitis.

shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 16A shoulder, anthropathy, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 16B
Figure 18A Figure 18B

The stiff or frozen shoulder is classified into one of four causes: idiopathic frozen shoulder (no apparent cause), diabetic frozen shoulder, post-traumatic stiff shoulder, or post-surgical stiff shoulder. Frozen shoulder is common in patients with diabetes mellitus and is more frequently bilateral and resistant to treatment in these patients. The process of adhesive capsulitis is caused by cells within the lining of the shoulder joint capsule which contract and form scar tissue.

Most patients with frozen shoulder respond to nonsurgical treatment with supervised physical therapy combined with a home program of stretching exercises. If conservative therapy is unsuccessful, manipulation under anesthesia and arthroscopic release offers the advantage of restoring motion without necessity of an open surgical release.

The mainstay of treatment for a stiff or frozen shoulder is conservative and includes non-steroidal anti-inflammatory drugs, physical therapy, intra-articular corticosteroid injections, and alternative modalities. If these methods of treatment fail to restore sufficient comfort, motion and function within a two to three month of period of time, manipulation under anesthesia and arthroscopic release may be considered.

Postoperative Management:

Arthroscopic release of the joint capsule can be performed as an in-patient or out-patient basis. We placed our patients in a continuous passive motion machine to keep the shoulder moving and to minimize muscle spasms. Patients are given analgesics and anti-inflammatories post-operatively. The patients are seen by the physical therapist the next day and are instructed in a home stretching program, emphasizing aggressive range of motion in all directions, to be done at home 5 times per day, in additional to supplemental physical therapy.

Results:

Results of arthroscopic release for adhesive capsulitis has been generally good, although treating this condition remains a challenging problem. Success appears to depend largely on the diagnosis and the degree of stiffness. Diabetic frozen shoulders are the most difficult to manage. They are often the stiffest and are the most frequent to recur.

 
© Allen F. Anderson, M.D. 2017