Arthroscopic Treatment of the Disabled Throwing Shoulder

Matthew T. Boes, James A. Thiel and Craig D. Morgan

Part 1 Arthroscopic Treatment of Internal Impingement

The term internal impingement was initially used by Walch ¹ to describe contact of the undersurface of the rotator cuff with the posterior superior labrum in the abducted and externally rotated position. Jobe² described progressive internal impingement caused by repetitive stretching of anterior capsular structures as the primary cause of shoulder pain in overhead athletes. Our treatment of disability in the throwing shoulder is predicated on the inciting lesion being an acquired contracture of the posteroinferior capsule.³ The posteroinferior capsular contracture alters the biomechanics of the joint and leads to a progressive pathologic cascade observed in the disabled throwing shoulder.

Because of repetitive overuse, throwers are susceptible to the development of posterior shoulder muscle fatigue and weakness, including fatigue and weakness of the scapular stabilizers and rotator cuff. Posterior muscle weakness leads to failure to counteract the deceleration force of the arm during the follow-through phase of throwing. In the healthy throwing shoulder, a glenohumeral distraction force of up to 1.5 times body weight is generated during the deceleration phase of the throwing motion. This distraction force is counteracted by violent contraction of the posterior shoulder musculature at ball release, which protects the glenohumeral joint from abnormal forces and prevents development of pathologic changes in response to these forces. In the presence of posterior muscle weakness, as seen initially in the disabled thrower, the distraction force becomes focused on the area of the posterior inferior glenohumeral ligament (PIGHL) complex because of the position of the arm in forward flexion and adduction during the follow-through phase of throwing. Fibroblastic thickening and contracture of the PIGHL zone occur as a response to this distraction stress (Fig. 11-1A and B). PIGHL contracture causes a shift of the glenohumeral contact point posteriorly and superiorly in the abducted and externally rotated position⁴ (Fig. 11-1C). This shift allows clearance of the greater tuberosity over the posterosuperior glenoid rim, enabling hyperexternal rotation (unlike normal internal impingement). In addition, the posterosuperior shift causes a relaxation of the anterior capsular structures, which manifests as anterior pseudolaxity and allows even further hyperexternal rotation around the new glenohumeral rotation point (Fig. 11-1D).

Figure 11-1 A, Diagram showing location of posterior inferior capsular contracture in the area of the posterior inferior glenohumeral ligament (PIGHL) complex. B, Arthroscopic image from the posterior portal with the camera directed inferior to view posterior inferior capsular contracture. C, Diagram showing biomechanical effect of posterior inferior capsular contracture. In the abduction and external rotation (ABER) position, the glenohumeral (GH) contact point is shifted posterosuperiorly, causing tension on the biceps anchor. D, Diagram showing relative anterior laxity as a result of the posterosuperior shift of the glenohumeral contact point. IGHL, Inferior glenohumeral ligament; MGHL, middle glenohumeral ligament; SGHL, superior glenohumeral ligament.

High-level throwing athletes need to achieve extreme external rotation (ER) of the humerus in the late cocking phase to maximize the throwing arc to generate maximal velocity at ball release. This maneuver creates an abnormal and posteriorly directed force vector on the superior labrum through the long head of the biceps tendon as well as torsion at the biceps anchor. With repetitive stress in the hyperexternally rotated position, the labrum fails and “peels back” from the glenoid rim medially along the posterior superior scapular neck. Failure of rotator cuff fibers in this position can occur through abrasion but also, more important, from twisting and shear failure, which is most pronounced on the articular side of the cuff tendons. Tension failure may ultimately occur in the anterior capsule, causing anterior instability that in our view is a tertiary event and has been erroneously identified as the primary lesion in the disabled thrower.

The collection of symptoms observed in the disabled throwing shoulder has been termed the dead arm syndrome. Essentially, the athlete is unable to throw with premorbid velocity and control because of pain and subjective discomfort in the shoulder. Five pathologic components contribute to symptoms in the dead arm syndrome:

1. Posterior muscle weakness, demonstrated by scapular asymmetry

2. PIGHL contracture, the inciting lesion—manifests as a glenohumeral internal rotation deficit (GIRD) in the throwing shoulder versus the nonthrowing shoulder

3. Superior labral anterior-posterior (SLAP) tear, type II—typically the anterior and posterior or posterior subtype (the “thrower’s SLAP”)⁵

4. Rotator cuff failure—generally partial undersurface and occasionally full-thickness tearing in the posterosuperior cuff

5. Anterior instability (anterior capsular attenuation or capsulolabral injury)—in approximately 10% of cases

Patients start internal rotation “sleeper stretches” preoperatively for assessment of the extent of PIGHL contracture (Fig. 11-4). In general, 90% of patients with severe GIRD (more than 25 degrees) are able to decrease their internal rotation deficit to less than 20 degrees with 10 to 14 days of focused stretching. The remaining 10% are stretch “nonresponders” and are generally older athletes with long-standing GIRD and substantial thickening of the posteroinferior capsule. In these patients a posteroinferior capsulotomy is indicated to increase internal rotation at the time of surgery.

Figure 11-4 Glenohumeral internal rotation or sleeper stretches. The patient lies on the involved side to minimize scapulothoracic motion. The opposite hand provides steady internal rotation pressure.

Contraindications to the procedure are similar to those for other elective arthroscopic shoulder procedures, such as infection and concomitant medical illness.

Surgical Planning

Before the procedure is begun, it is important to have all anticipated instruments and materials needed for the surgery available and on the surgical field so that the procedure can be performed without unnecessary intraoperative delays (Table 11-1). Efficient performance of the procedure will avoid the dreaded scenario of attempting an arthroscopic repair in the distended, “watermelon” shoulder that can severely compromise the quality of the surgery. This cannot be overemphasized. As a general guideline, the type of repair described here should be accomplished in 20 to 40 minutes, depending on the associated pathologic processes. Superior labral tears in throwers may be associated with rotator cuff and anterior capsulolabral pathology. Treatment of these associated pathologic processes must be anticipated at the time of surgery.

TABLE 11-1

Instrument	Use
Camera
30-Degree lens
Shoulder arthroscopy set (Arthrex)
Arthroscopic rasp	Labral detachment
Arthroscopic elevator
Arthroscopic cannulas
8 mm	Anterior working portal
5 mm	Anterior accessory portal
Motorized shaver	Debridement
Full-radius blade (Stryker)
Motorized bur	Preparation of glenoid rim
Protective hood; SLAP bur (Stryker)
Arthroscopic bovie	Posterior capsulotomy
Long handle, hook tip (Linvatec)
Bio-Suture Tak anchors (Arthrex)	Labral fixation
No. 1 PDS suture	SLAP fixation
	Free suture: capsular plication
SutureLasso passer device (Arthrex)	Suture passage: superior labrum
Right-angled
Birdbeak suture retrievers (Arthrex)	Suture passage
45-Degree	Posterior superior labrum
22-Degree	Anterior superior labrum
Suture-passer set (e.g., Spectrum)	Suture passage
Straight	Longitudinal rotator cuff tear
45-Degree curved hook (left and right)	Capsular plication

PDS, polydioxanone; SLAP, superior labral anterior-posterior.

Surgical Technique

Anesthesia and Positioning

Patients are administered general anesthesia after placement of an intrascalene nerve block, which greatly assists with postoperative pain control.

We perform all arthroscopic repairs with the patient in the lateral decubitus position. Positioning is controlled with a beanbag brought to the level of the axilla. The operative extremity is secured in 30 to 40 degrees of abduction by a pulley device with 10 pounds hung to counterweight the arm. The patient is administered antibiotic prophylaxis for skin flora, and the skin is painted with povidone-iodine (Betadine).

Surgical Landmarks, Incisions, and Portals

Repairs in throwing athletes are performed through the following portals:

• Posterior: viewing portal

• Anterior: main working portal; anchor placement in anterior labrum, knot tying

• Posterolateral (portal of Wilmington): anchor placement and suture passage in posterior labrum (Fig. 11-5)

Figure 11-5 Diagram showing location for posterolateral portal or portal of Wilmington. A spinal needle is used for specific localization.

• Anterosuperior: accessory portal; viewing and suture passage in anterior labrum or capsule (depending on associated pathologic changes)

The posterolateral border of the acromion is marked, and a posterior portal is established approximately 2 cm medial and 2 or 3 cm inferior to the corner of the acromion. The blunt camera trocar is directed through the posterior capsule just above the level of the equator of the humeral head. Both the anterior portal and the portal of Wilmington are established by an outside-in technique with an 18-gauge spinal needle.

Examination

Diagnostic Arthroscopy and Surgical Techniques: Routine diagnostic arthroscopy is performed to ensure that all portions of the joint are inspected and no pathologic lesion is overlooked. In the disabled throwing shoulder, areas requiring particular attention include the following:

• Superior labrum and biceps anchor

• Rotator cuff insertion

• Anterior labrum and capsuloligamentous structures

• Posterior capsule

Evidence of labral injury must be assessed carefully, as findings may be subtle (Box 11-1). An assessment is quickly made of the pathologic areas to be addressed, and a plan is made for the completion of the repair (Box 11-2).

Box 11-1 Arthroscopic Findings Consistent with Labral Injury or an Unstable Biceps Anchor

Labral Injury

• Frayed labral edge

• Adjacent capsular irritation

• Disruption of the smooth articular contour of the glenoid rim

Unstable Biceps Anchor

• Superior labral sulcus >5 mm

• Displaceable biceps root

• Positive peel-back test result

• Presence of drive-through sign

Box 11-2 Recommended Sequence for Arthroscopic Repairs in Throwing Shoulders with Multiple Pathologic Sites

1. Anterior inferior capsulolabral disruption (if present)

2. Posterior portion SLAP tear

3. Anterior portion SLAP tear

4. Anterior inferior capsular attenuation (if present)

5. PIGHL contracture (if present)

6. Rotator cuff tear (if present)

PIGHL, Posterior inferior glenohumeral ligament; SLAP, superior labral anterior-posterior.

Provocative Tests

Drive-Through Sign: Before other cannulas or instruments are introduced, an assessment is made of laxity in the joint by testing for the drive-through sign. In a normal shoulder, capsular restraints prevent passage of the arthroscope from posterior to anterior at the midlevel of the humeral head or sweeping of the scope from superior to inferior along the anterior glenoid rim. The drive-through sign may be present in patients with a SLAP tear because of pseudolaxity from the loss of labral continuity around the glenoid rim.⁷

Peel-Back Test: The peel-back test is performed by removing the arm from traction and placing it into the abducted and externally rotated position. With a posterior SLAP lesion, the labrum can be observed to fall medially along the glenoid neck during this maneuver (Fig. 11-6). Anterior SLAP lesions will have a negative result for the peel-back test. After assessment of the biceps anchor, the probe is used to assess the undersurface of the rotator cuff and to estimate depth of partial-thickness tears, to determine the stability of the anterior inferior labrum, and to identify any redundancy in the anterior capsule.⁸

Figure 11-6 Images and corresponding arthroscopic views during dynamic peel-back test. A, The superior labrum is reduced in neutral position. B, When the shoulder is placed in abduction-external rotation, superior labral instability is revealed, with the labrum falling posteriorly and medially along the scapular neck.

Specific Steps

Specific steps are outlined in Box 11-3.

Box 11-3 Surgical Steps

1. Placement of secondary portals

2. Probing of intra-articular structures

3. Intra-articular debridement

4. Preparation of superior labral bone bed

5. Anchor placement, suture passage, and knot tying

6. Dynamic assessment of repair

7. Treatment of associated pathology

1: Placement of Secondary Portals An 8-mm cannula is used as a primary anterior working portal. An 18-gauge spinal needle is used to localize the cannula so that it can accommodate all necessary repairs, including anterosuperior anchor placement in the labrum and tying of posterosuperior anchor sutures. The cannula is readied near the skin surface, the spinal needle is used as a guide to the proper insertion angle, the spinal needle is withdrawn, and the cannula is inserted. An accessory 5-mm anterior portal may be placed, depending on the location of associated pathologic lesions requiring treatment.

2: Probing of Intra-articular Structures A probe is introduced in the anterior cannula for more careful assessment of stability of intra-articular structures. Normally, a sublabral sulcus with healthy-appearing articular cartilage can be seen extending up to 5 mm beneath the labrum. An unstable biceps root can easily be displaced with the probe medially along the glenoid neck ⁸ (Fig. 11-7; see also Box 11-1).

Figure 11-7 Superior labrum and biceps anchor are gently probed to identify evidence of injury or instability.

3: Intra-articular Debridement A full-radius blade motorized shaver is used to gently debride loose and frayed tissue to prevent snagging of tissue with joint motion or potential loose bodies.

4: Preparation of Superior Labral Bone Bed An arthroscopic rasp is used to completely separate any remaining attachments in the injury area. A rasp is used because there is less risk of causing intrasubstance injury in the labrum than with an elevator. On occasion, some tenuous attachments from the labrum may be present medially, but the biceps anchor is still unstable. In these cases we routinely complete the lesion by removing these loose attachments before repair. All loose soft tissue is removed from the repair site carefully with the shaver.

An arthroscopic bur is then used to remove cartilage along the superior glenoid rim to make a bleeding bone bed for labral repair (Fig. 11-8). This step is crucial to allow subsequent healing of the labrum back to the glenoid rim. We prefer a bur with a protective hood that is specifically designed to prevent damage to labral tissue during this step (SLAP bur, Stryker Endoscopy, San Jose, CA). No suction is used while the bur is on to ensure that tissue is not inadvertently sucked into the instrument.