Arthroscopic stabilization of anterior shoulder instability

Current Concepts

Arthroscopic Stabilization of Anterior Shoulder Instability: A Review of the Literature Drew A. Stein, M.D., Laith Jazrawi, M.D., and Arthur R. Bartolozzi, M.D.

Abstract: The treatment of anterior glenohumeral instability has been a topic of debate in the recent literature. Current surgical management of shoulder instability has included a variety of open and arthroscopic procedures. Open techniques for anterior reconstruction have been quite successful in preventing recurrent dislocations and continue to be the gold standard of care. In an attempt to address some of the disadvantages associated with open procedures, arthroscopic stabilization procedures have been developed. Arthroscopic capsuloligamentous repair presumably has clear advantages including better cosmesis, decreased perioperative morbidity, and a possible decrease in the loss of external rotation. Advances in arthroscopic instrumentation and improved arthroscopic techniques have increased the popularity of arthroscopic stabilization. The art of diagnosing the anatomic pathology associated with instability and proper patient selection continues to evolve. Most previous reports of arthroscopic stabilization have included small numbers of patients, variable patient pathology, and a variety of surgical techniques, making comparisons between stabilization procedures difficult. Arthroscopy can be valuable in both the confirmation of the degree and severity of the instability and to correct the pathoanatomy responsible for the instability. Key Words: Shoulder instability—Stabilization—Review.

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nterior shoulder instability is commonly encountered by orthopaedic surgeons and arthroscopic procedures have become popular in treating this condition. Arthroscopic surgery has changed the way surgeons think about and treat shoulder instability. A thorough understanding of the pathology associated with this problem is necessary to begin treatment planning. Knowledge of the evolution of arthroscopic stabilization procedures and deciphering the literature allow the surgeon to understand the technical reasons

From the Orthopaedic Institute of Sports Medicine, New Brunswick, New Jersey (D.A.S.); New York University Medical Center– Hospital for Joint Diseases, New York, New York (L.J.); and Pennsylvania Hospital, Philadelphia, Pennsylvania (A.R.B.), U.S.A. Address correspondence and reprint requests to Drew A. Stein, M.D., 304 Chelsea Manor, Park Ridge, NJ 07656, U.S.A. E-mail: [email protected] © 2002 by the Arthroscopy Association of North America 0749-8063/02/1808-3320$35.00/0 doi:10.1053/jars.2002.36148

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for early failures. Treating anterior shoulder instability requires an accurate diagnosis, a detailed operative plan, appropriate arthroscopic equipment, experience with advanced arthroscopic procedures, and individualized rehabilitation programs. ANATOMY Static and dynamic stabilizers of the shoulder create the intricate balance of stability required of the glenohumeral joint. Static stabilizers included the labrum, capsule, glenohumeral ligaments, and rotator interval. Dynamic stabilizers include the rotator cuff and scapular stabilizing muscles. Injury to any of these structures can cause imbalance and may lead to shoulder instability. The labrum is a fibrocartilaginous structure attached to the glenoid rim. It functions to increase the anteroposterior and superoinferior depth of the glenoid.1 Labral resection will reduce resistance to translation by 20%.2 It also functions to increase the surface

Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 8 (October), 2002: pp 912–924

STABILIZATION OF ANTERIOR SHOULDER INSTABILITY contact area for the humeral head, as well as providing an attachment site for the glenohumeral ligaments. The superior aspect of the labrum inserts directly into the biceps tendon distal to the insertion on the supraglenoid tubercle. The supraglenoid tubercle is medial to the margin of the glenoid and therefore there is a synovial recess between the biceps and labrum. Pagnani et al.3 performed a cadaveric study documenting no significant effect on glenohumeral translation with isolated lesions of the superior labrum; however, if the biceps attachment was destabilized then significant translation was noted. Detrisac and Johnson4 classified 2 types of labral attachments to the glenoid. The first type is attached to the glenoid around the periphery through a fibrocartilaginous transition zone. This creates mobility along the central border similar to a meniscus in the knee. The second type is a secure attachment both peripherally and centrally. This distinction is important when evaluating the labral attachment site to determine if labral pathology needs to be corrected. The rotator interval (RI), between the leading edge of the supraspinatus and the superior edge of the subscapularis, has been implicated in glenohumeral instability. In a magnetic resonance imaging study 28 of 37 fetuses were found to have complete absence of the RI, which suggests the defect is congenital. Maximal opening of the RI was seen in internal rotation and downward traction of a hyperextended arm during ultrasonography.5 Closure of a large defect in the RI has been shown to decrease inferior instability. There may be an inverse relationship between the size of the RI and the superior glenohumeral ligament (SGHL) contributing to the instability.6 CLASSIFICATION Numerous classifications for shoulder instability have been described and are obtained from a detailed history, physical examination, and radiographic studies. Shoulder instability can be described by direction (anterior, posterior, inferior, or multidirectional). Degree of instability is described by dislocation, subluxation, or microinstability. The number of times a person has instability is the frequency and is important for determining likelihood of recurrence. The causes of the initial instability as well as the provocative maneuvers that cause subsequent episodes are crucial when classifying unstable shoulders and planning treatment. The chronology should also be determined as acute, chronic, or acute on chronic. Traditional teaching of the eponyms TUBS and

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AMBRI is less descriptive, and many patients fall somewhere between these two groups. TUBS stands for traumatic instability, unidirectional, Bankart lesion, treated with surgery. AMBRI stands for atraumatic instability, multidirectional, bilateral, treatment is initially rehabilitation, and if nonoperative treatment fails then surgical treatment is an inferior capsular shift. The art of history taking, physical examination, and diagnostic arthroscopy has dramatically improved to place patients somewhere in the middle of these categories and most patients should not be boxed into one of these classifications. Kvitne and Jobe7 described a classification of instability in the throwing athlete. This system classified patients into 4 groups. Group I are patients with pure impingement and no instability. Group II is primary instability due to chronic microtrauma or secondary impingement. Group III are patients with generalized ligamentous laxity and group IV are patients with pure instability and no impingement. NATURAL HISTORY Rowe and Zarins8 described a phenomenon called “dead arm syndrome” consisting of sharp or paralyzing pain when the shoulder is moved forcibly into the provocative positions of abduction and external rotation. This was seen in repetitive overhead athletes. Sixty shoulders were divided into 2 groups. Group 1 perceived the sensation of instability in at risk positions and group 2 had no sensation of instability. Both groups had similar pathology at arthroscopy. This demonstrated that a percentage of patients with instability based on pathology will not be able to verbalize their sensation of instability. Rowe9 studied 324 shoulders after dislocation with a follow-up of 10 years. Ninety-four percent of shoulders in patients younger than 20 years had recurrence, whereas, 14% of shoulders in patients older than 40 years had recurrence. Those patients without immobilization had a 70% recurrence rate that decreased to 26% to 46% when immobilized for 1 to 3 weeks. Hovelius et al.10 reported on 247 primary anterior dislocations with a 10-year follow-up in a prospective study; 62% of shoulders in patients younger than 29 years had recurrence necessitating operative intervention and those older than 30 years had a 9% risk for recurrence. Clearly, younger patients with primary anterior dislocations have a higher rate of recurrence. Patients with 2 or more dislocations during the first 2 to 5 years of a 10-year prospective study had a 78% chance of having another episode of instability. Re-

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FIGURE 2. FIGURE 1. Sublabral hole with thickened MGHL. (Reprinted with permission.12)

current instability places patients at risk for multiple episodes of instability in the future.10 Burkhead and Rockwood11 performed a study evaluating the usefulness of rehabilitation after shoulder dislocations. Forty shoulders after traumatic or atraumatic subluxation had rehabilitation of the deltoid, rotator cuff, and scapular stabilizers. Sixteen percent of the 74 shoulders with traumatic etiology had excellent or good results, and 80% of the 66 patients with atraumatic etiology had excellent or good results. This report signified the importance of defining the cause of the patient’s symptoms to formulate a treatment regimen.

NORMAL VARIANTS Buford and Synder12 reviewed 200 shoulder arthroscopy videotapes for variations of normal anatomy; 12% displayed a sublabral hole and 75% of these had a thickened middle glenohumeral ligament (MGHL) (Fig 1). The labrum may be loosely attached superiorly creating a sublabral hole that may be mistaken for a Bankart lesion. If this is found above the transverse equator of the glenoid it should not be considered a pathologic lesion. Nine percent of the total population had a thickened MGHL; 1.5% had a Buford complex, which is distinguished by a thickened MGHL that originates directly from the superior labrum at the base of the biceps tendon (Fig 2). There is a bare area, and no anterosuperior labral tissue associated with this normal variant. This variant should not be mistaken for a labral tear, which may be associated with glenohumeral instability.

Buford complex. (Reprinted with permission.12)

PATHOLOGIC LESIONS The Bankart lesion was originally described as the “essential lesion” to shoulder instability. The Bankart lesion occurs when the anteroinferior labrum with the attached inferior glenohumeral ligament (IGHL) complex is detached from the glenoid rim13 (Fig 3). Biomechanical evaluation of Bankart lesions in cadaveric shoulders has shown small amounts of inferior translation after recreating the Bankart lesion. Bankart lesions do not appear to be solely responsible for anterior glenohumeral translation.14 Neviaser15 described the anterior labral periosteal sleeve avulsion (ALPSA) (Fig 4). The IGHL complex, labrum, and periosteum are stripped and displaced medially and inferiorly on the scapula neck. Unlike with the Bankart lesion, the periosteum remains intact. This lesion is scarred onto the scapular neck; however, Naviaser noted continued instability in these patients. He concluded that the position of the IGHL complex on the articular margin was crucial to preventing instability. The etiology of these differing lesions is likely secondary to the variability in capsular attachment to the labrum. There are 3 different types of attachments described in the literature. Type I is when the capsule inserts directly into the labrum, type II is

FIGURE 3.

Bankart lesion. (Reprinted with permission.15)

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FIGURE 4. Anterior periosteal labral sleeve avulsion. (Reprinted with permission.15)

defined as the capsule inserting into the base of the labrum, and type III is when the capsule attaches directly to the anterior glenoid.16 Capsular injury to the glenohumeral ligaments can occur after instability events. There may be isolated lesions of the MGHL as well as the IGHL. Savoie et al.17 reported on 33 patients with isolated avulsions of the MGHL. The capsule also permanently elongates before avulsion of the labrum from the glenoid. Patients with chronic instability can elongate the inferior glenohumeral ligament with each subsequent episode of instability.18 This must be evaluated at the time of surgery when formulating an operative plan to address all possible factors causing instability. The humeral avulsion of the glenohumeral ligament (HAGL) lesion described by Wolf et al.19 and the bony HAGL (BHAGL) lesion described by Oberlander et al.20 are other sources of shoulder instability. The incidence of HAGL lesions after a traumatic dislocation was reported at 39%.21 In open procedures, these lesions can be confused with iatrogenic injury to the capsule with dissection inferior to the subscapularis. These lesions need to be defined and identified as sources of instability to clearly dictate a treatment plan and with appropriate repair may restore stability. Snyder et al.22 classified the superior labral anteriorposterior (SLAP) lesion into 4 types. Biomechanical cadaveric studies on SLAP lesions and glenohumeral translation have been performed. Lesions that destabilize the biceps insertion resulted in a 6-mm increase in anterior translation when the arm was in neutral rotation.3 Maffet et al.23 further classified these lesions into 7 types (Table 1). They found 43% of patients with SLAP lesions to have increased humeral head translation on examination under anesthesia. Jobe et al.24 described an association between undersurface rotator cuff tears and instability. Once a rotator cuff tear is noted, a careful examination of the

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labrum and glenohumeral ligaments is necessary to formulate a diagnosis. Bone lesions may be either on the humeral side or the glenoid side after a shoulder dislocation. Burkart described bony Bankart lesions, compression Bankart lesions, and Hill-Sachs lesions. Bony deficiencies were defined as a glenoid with an “inverted pear” shape (inferior glenoid that is narrower than the superior glenoid on arthroscopic visualization) and an engaging Hill-Sachs lesion that engages in abduction and external rotation. Burkhart et al.25 reported that 14 of 21 shoulders that had recurrent dislocations following repair had a large osseous Bankart lesion or a large Hill-Sachs lesion. Burkhart et al.26 performed 194 arthroscopic Bankart repairs and noted a 4% recurrence if there was no bony deficiency, in contrast to a 67% recurrence if there was a bony deficiency. Humeral head allografts have been used to fill large Hill-Sachs lesions with greater than 25% of the articular surface. Defects in the anteroinferior glenoid can be treated with coracoid or iliac crest autograft. PATHOPHYSIOLOGY The pathophysiology of anterior instability can be divided into subluxation or dislocation, functional instability, and microinstability, or pseudoimpingement. After a traumatic dislocation, Hintermann et al.27 found 87% of patients with anterior labral lesions, 79% with ventral capsular deficiency, 55% with glenohumeral ligament insufficiency, 14% with rotator cuff tears, and 7% with SLAP lesions. Further evidence of multipathologic etiology includes a biomechanical study recreating Bankart lesions and measuring glenohumeral translation. The greatest amount of translation measured was 4 mm occurring in the inferior direction at 45° of elevation. The Bankart lesion is not solely responsible for the amount of translation necessary to subluxate or dislocate the glenohumeral joint.14 Functional instability was described by Pappas et al.28 for labral lesions that cause clicking, catching, or locking secondary to interposed fragments between articular cartilage. Microinstability or pseudoimpingement was described by Kvitne and Jobe.7 Repetitive overhead stresses progressively damage the shoulder stabilizers and exceed the rate of tissue repair. After continued damage, the static restraints fail and the dynamic restraints compensate. When the dynamic stabilizers can no longer compensate, mild glenohumeral subluxation occurs. The humeral head subluxates and contacts the coracoacromial arch leading to

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D. A. STEIN ET AL. TABLE 1. SLAP Classification

Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Type 7

Fraying of the anterosuperior labrum Superior labrum-biceps complex detachment from glenoid rim Bucket-handle tear of the labrum with an intact biceps anchor Bucket-handle tear of the labrum with detachment of the biceps complex Bankart lesion continues superiorly and includes separation of the biceps complex Unstable flap tear of the labrum with an unstable biceps complex insertion Labrum-biceps complex separation extending beneath the middle glenohumeral ligament

an impingement process. The undersurface of the rotator cuff will impinge on the posterosuperior glenoid rim. Morgan et al.29 further defined the pathologic process as a tightening of the posterior structures including the capsule and the posterior band of the IGHL. This creates a glenohumeral acquired internal rotation deficit that is compensated for by a posterior superior shift of the humeral head around a new center of rotation. This in turn causes an anterior pseudolaxity. Increased forces occur at the posterior superior biceps labral complex and a posterior SLAP lesion occurs. This is known as the “peel-back” effect. The anterior pseudolaxity is corrected with repair of the labrum. Predictable undersurface rotator cuff tears occur at the point of contact with the posterior-superior glenoid. EXAMINATION UNDER ANESTHESIA A meticulous examination under anesthesia (EUA) must be performed before shoulder arthroscopy. Passive range of motion (PROM) in forward elevation, external rotation, and internal rotation with the arm at the side and at 90° of abduction is initially recorded. The examination should be performed either supine or in the beach-chair position with both arms available for comparison. With the arm abducted 90° and in neutral rotation, an anterior and posterior force is applied. Axial pressure is critical during this maneuver. The method of the examination involves tactile sensation of the humeral head translating over the glenoid surface. Externally rotate the arm 90° and reassess anterior excursion. Internally rotate the arm and assess posterior translation. The weight of the arm will internally rotate the arm for this maneuver. A sulcus sign can be tested in adduction, external rotation, and in abduction to 45° that will tighten the

inferior capsule. Persistent sulcus signs during external rotation and in the abducted position are abnormal and indicate an incompetent RI. Cofield et al.30 reported on 55 shoulders with a clinical diagnosis of shoulder instability. The findings at EUA were compared with findings observed arthroscopically or at open procedure. Pathologic evidence of instability was found in 25 of 55 patients. All 25 had an abnormal EUA. The 30 shoulders without anatomic pathology had 2 abnormal EUAs. These results show a sensitivity of 100% and a specificity of 93%. Cofield classified the amount of translocation of the humeral head on the glenoid in 5 directions (anterior, anteroinferior, posterior, posteroinferior, and sulcus) and in 3 different rotations (neutral, external, and internal rotations) (Table 2). Harryman et al.31 found that the humeral head may translate as much as 2 cm in either direction in a patient without instability. ARTHROSCOPIC TREATMENT OF ACUTE INITIAL DISLOCATION The natural history of traumatic anterior dislocations in young patients has been reported to have high recurrence rates. Arciero et al.32 at the United States Military Academy at West Point conducted a prospective study on nonoperative versus arthroscopic Bankart repair after acute, initial dislocations. Thirty-six patients were included in the report with an average age of 20 years and a follow-up of 32 months. Fifteen patients were randomized into the nonoperative group consisting of 1 month of immobilization followed by rehabilitation; 80% of them developed recurrent instability. Twenty-one patients were in the operative group that had a transglenoid suture repair of the Bankart lesion; 14% of them developed recurrent instability. Arthroscopic Bankart repair reduced the recurrence rate in young athletes after a primary acute shoulder dislocation. DeBerardino et al.,33 also at West Point, reported on a similar study with an average follow-up of 37 months. Forty-nine shoulders were treated with arthroscopic stabilization with a bioabsorbable tissue tack after acute, initial dislocation; 43 shoulders reTABLE 2. Cofield’s Classification Grade 1 Grade 2

No translation Mild translation, however unable to progress to rim of glenoid Grade 3 Moderate translation or progression to rim of glenoid Grade 4 Dislocated glenohumeral joint

STABILIZATION OF ANTERIOR SHOULDER INSTABILITY mained stable. Recurrence of instability was associated with bilateral instability, 2⫹ sulcus sign, or poor capsulolabral tissue. Mohtadi et al.34 performed a prospective randomized clinical trial reporting similar recurrence rates of 15.9% in the surgical group and 47% in the rehabilitation group. Boszotta et al.35 reported on 72 patients after a 66-month follow-up and had 6.9% develop instability; 85% resumed sporting activity to their preinjury level. All patients with recurrence had associated capsuloligamentous injuries combined with a Bankart lesion. Arthroscopic stabilization for acute, primary traumatic anterior shoulder instability associated with a Bankart lesion has been shown to significantly reduce the rate of recurrence. ARTHROSCOPIC STABILIZATION VERSUS OPEN STABILIZATION Recently comparisons between open procedures and arthroscopic procedures have been reported in the literature. Green et al.36 reported that arthroscopic stabilization procedures decreased operating room time, blood loss, narcotic use, hospital stay, time lost from work, and complications when compared with open procedures. Comparison studies have reported rates of recurrence between 13% and 70% in the arthroscopic group and 0% and 30% in the open group.37-39 Although initial results from the arthroscopic procedures indicated significantly higher rates of recurrence, improvements in patient selection and operative technique have steadily decreased recurrence rates to match that of open procedures. A prospective study on transglenoid suture repair versus open stabilization had a 6% recurrence rate in the open group and a 17% recurrence in the arthroscopic group over 36 to 40 months.40 Cole et al.41 reported a prospective study on arthroscopic stabilization with bioabsorbable tacks versus open repair in which patients initially had an EUA and diagnostic arthroscopy. Based on the findings at arthroscopy, patients were placed in the arthroscopic group or the open group. Recurrence rates were 24% for the arthroscopic group and 18% for the open group. This study concluded that both groups yielded similar results if the procedure was selected on the basis of the pathology found at the time of EUA and diagnostic arthroscopy. Karlsson et al.42 prospectively evaluated open versus arthroscopic repair in patients with recurrent dislocations. Arthroscopic repair with the Suretac (Acufex Microsurgical, Mansfield, MA) device was

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performed in 66 patients and open repair with suture anchors was performed in 53 patients. Recurrence rates after a 32-month follow-up were 15% in the arthroscopic group and 10% in the open group. Both methods produced stable functional shoulders. Recently, Pagnani and Dome43 reported their results for open anterior shoulder stabilization in professional contact athletes. They performed open stabilization with metal suture anchors in 58 players with recurrent instability. There were 2 postoperative subluxations and 90% returned to professional sports for more than 1 year. Interestingly, 49 of the 58 shoulders returned to within 5° of external rotation compared with the opposite side. They concluded that open stabilization in professional football players was superior to arthroscopic techniques. TECHNICAL REASONS FOR IMPROVED ARTHROSCOPIC RESULTS Arthroscopic results have improved to the point of being equivalent to open procedures for several reasons. Previous research has instructed the surgeon to limit the selection criteria for arthroscopic stabilization. Patients with glenoid bone loss, attenuated capsulolabral tissue, engaging Hill Sachs lesions, and HAGL lesions are contraindicated for arthroscopic repair. Surgeons have expanded selection criteria to include patients with recurrent instability events and patients who participate in contact sports. Improved arthroscopic technique including recognition of pathology during diagnostic arthroscopy, glenoid neck preparation, soft-tissue tensioning, and experience of arthroscopic surgeons has advanced this procedure. Evolving arthroscopic instruments and implants has also decreased the technically demanding nature of the procedure. Finally, adjusted rehabilitation of individualized programs based on each patient’s pathology and arthroscopic procedure has improved results. ARTHROSCOPIC STAPLING AND TRANSGLENOID SUTURE TECHNIQUES In 1982, Johnson44 performed the first arthroscopic shoulder stabilization procedure using a capsular stapling technique. This technique was quickly abandoned because of hardware problems and an inability to address capsular laxity. Since Morgan et al.45 first described the transglenoid suture technique for repairing Bankart lesions in 1987, many authors have reported variable results (Fig 5). In 1988, Caspari46 described a technique that al-

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FIGURE 5. Transglenoid technique. (© 1999 Lippincott Williams & Wilkins. Reprinted with permission.78)

lowed the surgeon to advance and adjust tension in the capsuloligamentous structures. Disadvantages included the need to tie the sutures over the posterior fascia, which placed the suprascapular nerve at risk and did not provide secure fixation of the knots. This technique was technically challenging and had variable success rates reported in the literature. However, it did pave the way for the development of advanced implants to avoid posterior fixation. This procedure also began to elucidate poor prognostic factors for arthroscopic stabilization. Risk factors for failure of arthroscopic stabilization include males, age younger than 18 years, collision athletes, bone deficiencies on the glenoid, the absence of a Bankart lesion, an attenuated IGHL complex, RI lesions, and short immobilization periods. SUTURE ANCHORS AND BIODEGRADABLE TACKS The use of suture anchors was initially described by Richmond.47 The technique was modified by Wolf48 and Snyder et al.22 who used absorbable and nonabsorbable sutures, respectively. This technique has the advantage of allowing the capsuloligamentous structures to be shifted superiorly and properly tensioned without the need to penetrate posteriorly. Initially, a standard posterior portal is used for diagnostic arthroscopy. An anterior superior portal is created with an in-side out or outside-in technique between the biceps tendon and superior edge of the subscapu-

laris. This portal is used for mobilization of the capsulolabral complex and for subsequent suture management. A second anterior inferior portal is placed just above the superior edge of the subscapularis to allow for inferior placement of suture anchors on the lower aspect of the glenoid neck. Alternatively, one can use a transubscapularis portal as described by Davidson and Tibone.49 Assessment of the mobility of the capsuloligamentous complex is crucial to determine if the soft tissues have been displaced or are scarred in a medial position on the neck of the glenoid. A combination of probes, rasps, motorized shavers, and periosteal elevators are used to mobilize the soft tissues. Care must be taken not to debride normal tissue needed for the repair. It is recommended to release tissue inferiorly to the 6 o’clock position on the glenoid face for optimal mobilization of tissue. Attention is then turned toward the glenoid preparation. An abrader or rasp is used to gently decorticate the glenoid edge. After the glenoid has been prepared attention is directed toward suture anchor insertion. Each anchor is unique with regard to its pull-out strength, type of suture, retrievability, bioabsorbability, insertion technique, and cost. The anchors are then routinely placed in the 2 o’clock, 3 o’clock, and 5 o’clock positions.50 Anchor placement on the edge of the articular surface is crucial to restoring the depth of the glenoid and the stability of the glenohumeral joint. Care must be taken during placement with regards to the position on the glenoid face and the angle of insertion (Fig 6). Once the anchors are placed, suture management then becomes paramount. Both suture limbs are left exiting the anterior inferior cannula. A soft-tissue penetration device is then used to create a hole in the proper position so as to shift the labroligamentous complex superiorly and medially as needed. A Caspari suture passer (Concept Inc, Largo, FL), suture lasso (Arthrex, Naples, FL), or similar device is used to facilitate suture passage (Fig 7). Once the suture is passed through the tissue, a suture grabber then pulls the limb back out the anterior inferior cannula. Using colored sutures aids with suture management. Arthroscopic knots are then used to securely fix the soft tissue to the glenoid. After all suture anchors are tied, the repair is evaluated from both the posterior and anterior portals (Fig 8). The Suretac device is a cannulated tack molded from polyglyconate. Use of this device avoids the suture management associated with suture anchors (Fig 9). The head and body are molded separately and then attached to each other. Reports of breakage at the junction site have compromised fixation. The device is

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FIGURE 8. Completed suture anchor repair. (Reprinted with permission.79)

FIGURE 6. Placement of anchor displaying location and angle of instrumentaion.

degraded by hydrolysis and does not require an inflammatory process from the body. Laboratory studies reveal approximately 50% loss of strength at 2 weeks and 100% loss at 4 weeks. Animal studies showed the heads of the tacks to be loose at 6 weeks and broken at 12 weeks.51 Technical pitfalls encountered when using the bio-

FIGURE 7. sion.79)

Suture anchor technique. (Reprinted with permis-

degradable anchors have been studied on cadaver shoulders. Common errors included inadequate abrasion of the glenoid rim, inadequate superior and medial shift of the IGHL, medial placement of the anchor

FIGURE 9. Biodegradable tack technique. (© 1999 Lippincott Williams & Wilkins. Reprinted with permission.78)

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relative to the articular margin, and insufficient capture, compression, and fixation of the capsular tissue. Initial fixation strength of bioabsorbable tacks (100 N) may be less than that of open procedures or with suture repair and, therefore, may require an initial prolonged period of immobilization.52 There are case reports of foreign-body reaction to the Suretac device. These problems have been addressed with the development of newer tacks that have been molded as a single unit, instead of a body and head, which was thought to increase strength. Changes in the biochemical composition of the tacks have been explored to reduce the inflammatory response as well. ADJUNCT PROCEDURES: RI REPAIR, THERMAL SHRINKAGE, TISSUE TUCKS Adjunctive procedures may need to be performed in order to completely correct all pathology associated with the instability. Assessment of the RI and capsular tissue is approached with the EUA and diagnostic arthroscopy. An incompetent RI is diagnosed with a positive sulcus sign in both neutral and external rotation of the arm. Increased capsular laxity is diagnosed by several measures including obvious capsular injury with tears or lacerations, increased capsular volume, or increased external rotation compared with the opposite side. RI tears are often associated with glenohumeral instability, and interval pathology should be evaluated during arthroscopic stabilization. Arthroscopic findings consistent with RI tears are capsular redundancy between the supraspinatus and subscapularis, biceps tendon fraying, superior glenohumeral ligament tear, and the superior border of the subscapularis fraying.53 Arthroscopic closure of the deep layer of the RI capsule (SGHL to MGHL) imbricates the anterosuperior capsule and limits humeral external rotation, elevation, and extension.54 If a surgeon is not comfortable addressing this lesion arthroscopically then an open procedure is indicated. Thermal shrinkage of the capsule addresses capsular stretching that may occur with instability events. This technique has the advantages of not altering inherent anatomy and the procedure is not technically demanding; however, reports of early failure and complications do exist. Electrothermal shrinkage does reduce capsular laxity, but alters the viscoelastic properties placing the tissue at risk for recurrent stretching.55 Risk factors for early failure after thermal shrinkage are patients with previous operations and those with recurrent dislocations.56 There are anec-

dotal cases of axillary nerve injury, adhesive capsulitis, and an attenuated capsular layer after applying thermal energy to the shoulder capsule. Capsular plication or capsular tucks have been performed by surgeons to avoid using thermal energy on capsular tissue. There has been no evidence that this procedure decreases capsular volume equivalent to open procedures; however, it visually decreases redundancy associated with capsular injury or stretching. DISCUSSION Lane et al.57 retrospectively reported on 54 patients who underwent arthroscopic staple capsulorrhaphy with an average follow-up of 39 months. There was a 33% recurrence rate, with 18.5% requiring a subsequent open reconstructive procedure. Fifteen percent developed loose staples as shown on follow-up radiographs. Only 43% of athletes were able to return to their preinjury level of activity. Benedetto et al.58 reported on 31 patients after transglenoid suture repair with a follow-up of 2 years with no recurrences. Grana et al.59 followed-up 27 patients for 36 months with a 44.4% recurrence rate. Failures were attributed to plastic deformation in the capsular tissue after shoulder dislocations. Despite the repair of the Bankart lesion, a component of the instability still existed; 75% of these failures were in high contact athletes. Failures were also associated with immobilization periods of less than 1 week. A group of 59 patients with recurrent anterior dislocations underwent arthroscopic transglenoid suture stabilization and were followed-up for 49 months. Forty-nine percent developed recurrent instability. Failures in this study were associated with a positive sulcus sign, bony lesion on the anterior glenoid on radiographs, and extended ligamentous lesions.60 Bony deficiencies and RI lesions were not addressed surgically and may have accounted for the increased recurrence rates. Green et al.61 performed arthroscopic transglenoid suture fixation on 60 patients with a follow-up of 41 months; 42% experienced recurrent instability. This study classified labral lesions and correlated degeneration or attenuation of the IGHL complex with higher failure rates. Youssef et al.62 reported on 30 patients followed-up for 38 months after an arthroscopic Bankart repair secondary to traumatic anterior shoulder dislocations; 27% experienced recurrence of instability. All failures were male contact athletes under 35 years of age.

STABILIZATION OF ANTERIOR SHOULDER INSTABILITY Caspari et al.63 reported a 4% failure rate with a 2 to 6 year follow-up using the technique to tension the capsuloligamentous structures. Savoie et al.64 reported a prospective study of 163 patients followed-up for 36 to 72 months after a transglenoid suture reconstruction using the Caspari technique. They reported a 9% failure rate. Patients younger than 18 years of age had a 26% failure rate; 97% were considered successful for patients over age 22 years. This clinical study confirmed previous anatomic studies reporting weaker labroligamentous attachments to the glenoid in patients who are in their teenage years.65 In younger patients, although healing occurs, it may be with weaker tissue, which attributed to the increased incidence of recurrence. Warren et al.66 published a retrospective report on the transglenoid technique with one of the longest follow-ups in the literature. They reported on 41 patients followed-up for 5 years; 19% had recurrent instability. Thirty percent of the contact athletes developed instability within 2 years. The absence of a Bankart lesion was associated with a poor outcome. Bacilla et al.67 reported on 40 patients considered high-demand athletes after arthroscopic stabilization with suture anchors. Three patients had recurrent instability, but 91% returned to the same or higher level of athletic activity. These results are equivalent to open procedures in this high-risk group. Implants about the glenohumeral joint can cause complications. Symptomatic intra-articular migration of a suture anchor several weeks after placement with resultant pain and articular cartilage loss on the humeral head has been reported.68 Rockwood et al.69 reported on 3 of 8 patients with articular damage after complications from improper placement of metallic suture anchors. The use of metallic hardware about the glenohumeral joint has been shown to have complications such as loosening, migration, and breakage leading to pain and arthrosis70 (Fig 10). This problem led to the development of biodegradable implants for the shoulder. Warner et al.71 reported on 20 patients treated with arthroscopic Bankart repair using a Suretac implant. The patients were immobilized for 4 weeks after surgery. The authors found a 20% recurrence rate after 32 months. There were no complications associated with the implant. Additional studies with second-look arthroscopy secondary to pain and decreased range of motion were performed an average of 9 weeks after the initial surgery and revealed massive synovitis. Loose fragments of the tack were visualized in the joint. On histologic examination, there was an infil-

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FIGURE 10. Retained metallic hardware in the shoulder. (Reprinted with permission.80)

tration of histiocytes and multinucleated giant cells containing birefringent polymeric particles. All cultures were negative. The most common failure was breakage, which may have caused a foreign-body reaction.72 Warner et al.73 also evaluated 15 patients with a second-look surgery after arthroscopic stabilization using the Suretac anchor. The second-look procedure was performed for recurrent instability or pain an average of 9 months after the index procedure. Biopsies of 2 patients with recurrent instability showed residual polyglyconate polymer debris surrounded by a histiocytic infiltrate with foreign-body giant cells. In the stable shoulders, the Bankart repairs had all either completely healed or partially healed. In the patients with recurrent instability, 43% of the Bankart lesions were not healed and 86% had capsular laxity. Therefore, selection criteria are paramount for a successful outcome when using the Suretac. Patients with unidirectional, traumatic, or anterior instability, with a discrete Bankart lesion, and with well-developed glenohumeral ligaments who do not participate in collision athletics are ideal for an arthroscopic procedure. Additionally, Speer et al.74 concluded that the procedure may be accomplished with a tack in patients who do not need capsular volume reduction. Laurencin et al.75 used strict criteria to perform this procedure. Indications for selection included traumatic, unidirectional anterior instability, presence of a Bankart lesion, thick IGHL, and minimal bony ero-

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sions on the glenoid. They reported a 10% recurrence rate. Several studies have compared results of suture anchors versus transglenoid fixation. Suture anchors are devices that are implanted with an attached suture that is then used to secure the soft tissue. Kandziora et al.76 retrospectively studied 163 patients with posttraumatic shoulder instability requiring labral fixation. The incidence of recurrence was 32.4% in the transglenoid group and 16.4% in the suture anchor group. There was a correlation between the postoperative dislocation rate and the number of preoperative dislocations and the severity of the labral lesion. The authors reported that the learning curve with the suture anchor group was less dramatic than with the transglenoid technique. The transglenoid group displayed a recurrence rate of 50% when the technique was introduced. This decreased to 11.6% over the next 5 years. The suture anchor technique had a recurrence rate decrease from 22.2% to 10% over a similar time. Kandziora et al. concluded that the suture anchor technique was superior to the transglenoid technique, but was still inferior to the reported results for the open technique, and that arthroscopic stabilization may be indicated in a patient with fewer than 5 preoperative dislocations. Tauro77 prospectively reported on 34 patients treated with an arthroscopic Bankart repair with a 2- to 5-year follow-up. The Bankart repair was combined with an inferior capsular split that advanced the capsule an additional 2 cm in an attempt to restored normal capsular tension. A transglenoid suture technique was used in 5 patients and a suture anchor technique in 29 patients. The transglenoid group had a recurrence rate of 40%, whereas the suture anchor group had a recurrence rate of 6.9%. Tauro summarized that the suture anchor technique was superior to transglenoid and, when combined with a capsular advancement, had an acceptable level of recurrence. SUMMARY The role of arthroscopic procedures in the management of glenohumeral instability continues to evolve and represents an effective alternative for addressing the pathology associated with this condition. Patient selection criteria, operative techniques, and implants all continue to evolve and have resulted in improved rates of success. Arthroscopic procedures benefit patients by avoiding the common morbidities associated with the disruption of the anterior soft tissues including a loss of external rotation associated with open

procedures. Arthroscopic procedures remain technically demanding and require skills to address all of the existing pathology. The arthroscopic surgeon must be prepared to address many conditions beyond the Bankart lesions, including glenoid bone lesions, capsular laxity, RI lesions, and SLAP lesions. In addition to the documentation of recurrence, the success of this procedure must be evaluated within the context of retained ranges of motion, recovery time, proprioceptive control, and the return to prior levels of activity. As further studies are performed, as indications are better defined, and as improved devices are developed, there will undoubtedly be superior results for arthroscopic shoulder stabilizations. REFERENCES 1. Howell SM, Galinat BJ, Renzi AJ, et al. Normal and abnormal mechanics of the glenohumeral joint in the horizontal plane. J Bone Joint Surg Am 1988;70:227-232. 2. Lippitt SB, Vanderhooft JE, Harris SL, et al. Glenohumeral stability from concavity-compression: A quantitative analysis. J Shoulder Elbow Surg 1993;2:27-35. 3. Pagnani MJ, Deng X, Warren RF, et al. Effect of lesions of the superior portion of the glenoid labrum on glenohumeral translation. J Bone Joint Surg Am 1995;77:1003-1009. 4. Detrisac DA, Johnson LL. Arthroscopic shoulder anatomy: Pathology and surgical implications. Thorofare, NJ, Slack, 1986. 5. Cole BJ, Rodeo SA, O’Brien SJ, Altchek D, Lee D, DiCarlo EF, Potter H. The anatomy and histology of the rotator interval capsule of the shoulder. Clin Orthop 2001;390:129-137. 6. Nobuhara K, Ikeda H. Rotator interval lesion. Clin Orthop 1987;223:44-50. 7. Kvitne RS, Jobe FW. The diagnosis and treatment of anterior instability in the throwing athlete. Clin Orthop 1993;291:107123. 8. Rowe CR, Zarins B. Recurrent transient subluxation of the shoulder. J Bone Joint Surg Am 1981;63:863-872. 9. Rowe CR. Prognosis in dislocations of the shoulder. J Bone Joint Surg Am 1956;38:957-977. 10. Hovelius L, Augustini BG, Fredin OH, Johansson O, Norlin R, Thorling J. Primary anterior dislocation of the shoulder in young patients. J Bone Joint Surg Am 1996;78:1677-1684. 11. Burkhead WZ, Rockwood CA. Treatment of instability of the shoulder with an exercise program. J Bone Joint Surg Am 1992;74:890-896. 12. Williams MM, Snyder SJ, Buford D Jr. The Buford complex— The “cord-like” middle glenohumeral ligament and absent anterosuperior labrum complex: A normal anatomic capsulolabral variant. Arthroscopy 1994;10:241-247. 13. Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder joint. Br J Surg 1938;26:23-28. 14. Speer KP, Deng X, Borrero S, et al. Biomechanical evaluation of a simulated Bankart lesion. J Bone Joint Surg Am 1994;76: 1819-1825. 15. Neviaser TJ. The anterior labroligamentous periosteal sleeve avulsion lesion: A cause of anterior instability of the shoulder. Arthroscopy 1993;9:17-21. 16. Moseley HF, Overgaard B. The anterior capsular mechanism in recurrent anterior dislocation of the shoulder. J Bone Joint Surg Br 1962;44:913-927. 17. Savoie FH, Papendik L, Jobe C. Straight anterior instability:

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