Glenohumeral Instability

Orthopedic surgeons have a fundamental desire to find a simple solution to glenohumeral instability, leading to various operative approaches. Despite the fact that Bankart and Perthes had independently described anterior labral pathology in the 1900s, surgeons in the mid-1900s observed that abduction and external rotation resulted in glenohumeral joint dislocation. Consequently, several operations were popularized to eliminate dislocation by limiting the offending motion—external rotation. These procedures such as the Magnuson-Stack and Putti-Platt succeeded in controlling the dislocation, but some patients were unhappy with the loss of shoulder movement and function; others continued to have instability. Furthermore, many of these patients developed premature osteoarthritis due to overtightening. Subsequently, the Bankart lesion came to be regarded as the essential lesion, so labrum repair predominated. Labrum repair operations were successful in some but not all patients, and the underlying rationale—that lesions of the labrum were the sole cause of instability—could not explain dislocations that occurred without such lesions. Further, as DePalma observed, many patients had degeneration of the labrum that appeared to be an aging phenomenon, yet few of these patients developed glenohumeral joint instability. Subsequently, patients with recurrent anterior dislocations without labrum detachment were treated with an anterior capsular tightening procedure. Again, many patients benefited, but others continued to suffer shoulder dislocation or subluxation. With the understanding that some shoulders are unstable in multiple directions (with or without labrum lesions), interest shifted to global capsular tightening. The capsular shift as described by Neer offered a solution to this challenging condition.

More recently, the desire to control glenohumeral instability while retaining function for overhead sports has motivated the search for new techniques involving arthroscopy. The advantages of arthroscopic stabilization include smaller skin incisions, more complete glenohumeral joint inspection, ability to treat all intraarticular lesions, access to all areas of the glenohumeral joint for repair, less soft tissue dissection, preservation of subscapularis integrity, and maximal preservation of external rotation. Arthroscopy enables surgeons to inspect the entire glenohumeral joint and observe lesions in the unstable shoulder. Concurrently, clinical and basic science investigations have increased our understanding of the pathophysiology of glenohumeral instability. We now have the background, knowledge, and technical skill to more effectively address glenohumeral instability. We also have a better understanding of when arthroscopic procedures are indicated and when open procedures may be more effective.

Literature Review

Because current treatments are directly linked to the past, the intellectual history of arthroscopic shoulder stabilization is summarized. Early arthroscopic repairs used a staple to advance the Bankart lesion superiorly and medially , and were associated with failure rates up to 30%. Owing to potential complications from staples within the glenohumeral joint, other surgeons used a transglenoid suture repair of the Bankart lesion. Early publications reported initial success rates up to 100%, but these results deteriorated with longer follow-up. The two essential elements of these techniques are passage of sutures through the avulsed labrum and then passage through drill holes in the scapular neck. The sutures are tied posteriorly over soft tissue or bone.

Later research and outcomes documented two flaws with these approaches: the medial location of the repaired labrum and failure to address capsular laxity. Neviaser first identified the anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion in shoulders with anterior-inferior glenohumeral instability. The detached labrum-ligament complex healed medially on the scapular neck, which allowed excessive humeral translation. It was apparent that the staple and transglenoid suture techniques described earlier repaired the labrum medially but created an ALPSA lesion. Savoie examined shoulders that had dislocated following arthroscopic stabilization and found that the labrum had been repaired 5 mm medial to the glenoid rim. He was the first to point out that the attachment site of the repaired ligaments was critical. Savoie subsequently modified his technique by moving the entry position of the anchor from the medial scapular neck to the glenoid articular surface and reported improved results with the new technique.

Other implants and techniques were tested, including the use of rivets and tacks to repair the labrum. These all had some higher level of complications and failure rates that were not acceptable. Ultimately, the use of suture anchors enabled repair of the detached labrum directly to the glenoid rim. Wolf pioneered this approach for arthroscopic instability repairs. Improved outcomes occurred as surgeons learned to position the glenoid labrum more appropriately on the glenoid rim. Harryman and associates introduced the term concavity-compression to explain the important role of the labrum in glenohumeral instability. However, further investigation raised two questions: Was the Bankart lesion the only labrum lesion responsible for anterior-inferior instability? Could any labrum lesion or combination of labrum lesions produce glenohumeral instability alone, without the presence of any other lesion?

Attention was then returned to the shoulder capsule. Capsular stretch or elongation, with or without a Bankart lesion, was determined to be a primary pathology in instability. Tibone emphasized that the rate of capsular stretch is an important variable because the speed of the injury may determine where the capsular ligament is damaged. In a laboratory study, Bigliani demonstrated that faster strain rates result in ligament injury, whereas slower strain rates result in a higher percentage of failures at the ligament insertion site. Bigliani also studied the tensile properties of the shoulder capsule in patients with acute dislocation and found that some degree of capsular damage was usually present, even with a Bankart lesion. Baker arthroscopically inspected the shoulders of 45 patients within 10 days of acute dislocation and found that the capsule had been stretched or torn in all patients with or without an associated Bankart lesion. Based on these findings and subsequent studies, the capsule became a primary focus for repair and tensioning.

Leaping ahead a few years, it was noted that perhaps the most subjective and difficult pathology to address in instability is capsular tensioning. The orthopedic community, therefore, greeted thermal treatment with great interest. However, clinical application outpaced basic scientific investigation. We soon learned that thermal treatment was associated with the devastating complications of capsular necrosis, capsular rupture, and chondrolysis. The use of thermal capsulorrhaphy has largely been abandoned.

Other structures have been implicated in playing roles in shoulder instability. Rodosky described the role of the biceps-labrum complex in anterior-inferior instability. Detachments of the superior labrum—tear of the superior labrum from anterior to posterior (SLAP lesion)—performed in the laboratory allowed increased anterior humeral head translation. Speer also used a cadaver model to determine that although a Bankart lesion allows increased humeral head translation, it alone does not result in humeral head dislocation. Subsequently, several studies have been equivocal on the role of the superior labrum and biceps complex in glenohumeral stability.

Most descriptions of arthroscopic technique initially omitted treatment of the rotator interval. This area of the glenohumeral joint capsule is the soft tissue between the superior border of the subscapularis tendon and the anterior edge of the supraspinatus tendon, and includes the superior glenohumeral ligament and a portion of the coracohumeral ligament. Subsequently, Neer and Rowe described the role of the rotator interval in open repair of shoulder instability. Rowe and Zarins inspected the superior aspect of the rotator cuff and found that 20 of 37 patients undergoing operation had a large opening in the capsule between the supraspinatus and subscapularis. Harryman's laboratory studies advanced our understanding of the rotator interval. He found that opening the rotator interval increased inferior-posterior translation. Based on these studies and observations, the rotator interval became an issue that was often addressed for both anterior and posterior instability. However, with more recent biomechanical and clinical studies, the role of the rotator interval has been called into question as a primary contributor to instability, and interest in aggressively addressing it surgically has diminished once again.

Initially, arthroscopic stabilization techniques were reported to have higher failure rates than open techniques. These were due to technical factors detailed in several studies, such as medial repair of the anterior labrum and failure to recognize and address bone loss on the humeral and glenoid sides. There are several concepts to keep in mind in order to approach and effectively address glenohumeral instability arthroscopically:

1.
Glenohumeral instability occurs in several directions.
2.
These directions are classified as anterior, posterior, bidirectional (anterior-inferior or posterior-inferior), and multidirectional (inferior, anterior, and posterior).
3.
The classification of direction is somewhat arbitrary.
4.
The primary direction of instability is determined through a combination of patient history, physical examination, radiographic analysis, examination under anesthesia, and evaluation of the glenohumeral joint at the time of arthroscopic surgery.
5.
Lesions are usually multiple.
6.
Instability in any direction may be the result of various combinations of lesions.
7.
The same combination of lesions may produce instability in different directions in different patients.
8.
Instability correction requires that all lesions be identified and repaired.
9.
It may be necessary to operate on areas of the glenohumeral joint on the side opposite the primary instability to balance the shoulder and prevent iatrogenic instability.
10.
Glenohumeral instability should probably be considered a single entity, defined as symptomatic excessive humeral head translation.
11.
The clinical expression of this translation is variable in each individual.
12.
Humeral head and glenoid bony deficits may necessitate open procedures or more advanced reconstructive techniques and may not respond to simply primary repair of soft tissue pathology.

Orthopedic surgeons use patient history, physical examination, radiographic analysis, and operative findings to diagnose the clinical expression of glenohumeral instability. Unidirectional instabilities are well appreciated and are generally categorized as anterior or posterior. On physical examination, patients with multidirectional instability have symptoms of pain and apprehension when the shoulder is stressed in anterior, posterior, and inferior directions. Neer's pioneering concepts were twofold: glenohumeral instability can occur in multiple directions, and correction of all three symptomatic directions is necessary. However, there is a group of patients who are symptomatic in only two directions. There is little in the literature concerning bidirectional glenohumeral instability—that is, inferior instability with either an anterior or a posterior component—which is a separate entity from multidirectional instability and unidirectional anterior or posterior instability. Neer discussed instability in two directions in his paper on multidirectional instability. Altchek described his results with operation for multidirectional instability of the anterior and inferior types. Pollock and Bigliani specifically used the term bidirectional in their paper on recurrent posterior shoulder instability. In a search for a unifying approach to the many forms of glenohumeral instability, Pollock and Bigliani's analysis may be most helpful. In their article on anterior-inferior shoulder instability, they discussed the complexities of instability classification and stressed the need to address all components of glenohumeral laxity to balance the shoulder. They were the first to report that an area of asymptomatic laxity must be treated to correct symptomatic instability in another direction, whereas previous articles had focused on correcting the laxity in the direction of the instability.

The clinical expression of glenohumeral joint laxity is termed instability . The direction or directions of instability are, to a large degree, the result of laxity in various areas of the glenohumeral capsule and insertion tears of the labrum. Other factors undoubtedly play a role. Some of these factors require nonoperative treatment (muscular strengthening and neuromuscular conditioning), and others require modification of the surgical technique, such as when anterior glenoid bone loss dictates an operation such as the Latarjet procedure. Successful arthroscopic treatment requires that the surgeon identify the direction and degree of clinical instability preoperatively, identify the areas responsible for excessive translation arthroscopically, and then correct all necessary areas of the glenohumeral joint. A prime example of this approach is a patient with recurrent posterior glenohumeral subluxation. This patient likely has excessive laxity in the posterior-inferior capsule, but correction of that area alone may not necessarily control excessive humeral head translation. Even though the patient is not symptomatic in the direction of the rotator interval or the anterior-inferior glenohumeral ligament, tightening of one or both these areas may be needed.

There are many similarities between arthroscopic rotator cuff repair and arthroscopic glenohumeral reconstruction, but there are also important fundamental differences. Arthroscopic rotator cuff repair has certain advantages over the traditional open approach, as described in Chapter 12 . Fundamentally, however, the primary goal of both the arthroscopic and the open procedure is identical: to reattach the torn edge of the rotator cuff tendon to its normal point of anatomic insertion. Operations within the glenohumeral joint are technically less demanding than those within the tight confines of the subacromial space, but arthroscopic glenohumeral reconstruction is not a simple operation. Although the glenohumeral joint is better visualized and the surgeon has more space to manipulate instruments than within the subacromial space, the less demanding technical aspects of the procedure are offset by a greater deficit in knowledge. For example, there are no objective standards by which to judge ligament or capsular tension, so the surgeon can only estimate the amount of tightening needed. The most critical part of the procedure is the one that lacks objective guidelines.

The circle concept is helpful to understand some of the factors involved in glenohumeral joint instability ( Fig. 4.1 ). Think of the circle in the figure as a sagittal view of the right shoulder, with the arrow representing the direction of anterior-inferior translation. The most common form of shoulder instability occurs in the anterior-inferior direction, and our initial understanding was that the lesion was in the anterior-inferior portion of the shoulder. Depending on the surgeon's country of origin, this lesion is termed the Bankart , Broca , or Perthes lesion . The search for this “essential” lesion dominated research for 50 years, and other surgeons presented their clinical and laboratory work questioning this idea. DePalma thought this explanation was inadequate because he had identified unstable shoulders without any labrum abnormality, as well as shoulders with labrum abnormalities that were stable. Nonetheless, the Bankart lesion became the focus of operative repair. This thinking persisted with few challenges until Neer and Foster's article on multidirectional instability emphasized the importance of an inferior capsular lesion. Rowe and Zarins also described operative correction of a shoulder with anterior-inferior instability in which no Bankart lesion was found. Further investigation identified the importance of the inferior-posterior capsule and ligaments as additional static stabilizers, as well as the importance of the rotator cuff muscles as dynamic stabilizers. The role of the superior labrum in anterior-inferior instability was described by Snyder and Rodosky. Harryman reminded us of the role the rotator interval plays in glenohumeral joint motion and translation. Morgan, Burkhart, and Jobes pioneered our thinking on the influence of glenohumeral joint translation (if any) on internal impingement. Obviously, as we learn more about the glenohumeral joint structures in both normal and pathologic shoulders, surgical decision-making becomes more complex.

FIGURE 4.1, The circle concept of instability. AIGHL , Anterior-inferior glenohumeral ligament; PIGHL , posterior-inferior glenohumeral ligament; SLAP , superior labrum from anterior to posterior.

Diagnosis

Patient History

Shoulder instability can be classified in many ways including chronicity, degree, direction, and traumatic onset. We document whether the instability is a chronic or acute event (<6 weeks) and further classify it as recurrent dislocation, recurrent subluxation after a single dislocation, or recurrent subluxation without prior dislocation. We record whether the patient developed instability after a traumatic event of a magnitude sufficient to damage the glenohumeral ligaments (traumatic or atraumatic). A traumatic cause is supported by an injury with the arm forcefully abducted, externally rotated, and extended; sudden sharp pain; the need for manipulative reduction; and residual aching in the shoulder for several weeks. Atraumatic instability is characterized by an insidious onset or following minor trauma and is associated with mild pain and a spontaneous reduction. All patients are questioned about arm position or activity that reproduces their symptoms.

Additionally, the sports participation, if any, of each patient is recorded. Sports can be classified according to the method described by Allain. Type 1 sports are nonimpact and consist of breaststroke swimming, rowing, running, or sailing. Type 2 sports are high impact and include bicycle riding, snow skiing, soccer, and water skiing. Type 3 sports require overhead use of the arm with hitting movements, such as crawl-stroke swimming, golf, tennis, throwing, and weight lifting. Type 4 sports involve overhead hitting movements and sudden stops such as basketball, football, handball, ice hockey, judo, karate, kayaking, lacrosse, polo, rodeo, volleyball, wind surfing, and wrestling. Shoulder dominance is also recorded.

Physical Examination

Active ranges of motion including forward flexion, abduction, external rotation in abduction, and behind-the-back internal rotation are recorded. Passive elevation and external rotation (with the arm adducted), as well as external rotation and internal rotation with the arm abducted 90 degrees, are measured. Internal rotation at 90 degrees of abduction in the coronal as well as the scapular plane is also recorded.

Elevation strength is measured using a dynamometer with the arm elevated 90 degrees in the scapular plane and internally rotated, with the result recorded in pounds.

The instability examination is performed on both shoulders. The humeral head is loaded or compressed into the glenoid during all maneuvers. Glenohumeral translation is generally assessed in the anterior, inferior, and posterior directions. An essential element of the instability examination that is not often achieved is patient relaxation; an effective examination is not possible if the patient's muscles are tense. This may occur as a result of pain during the examination or fear that pain will follow a particular maneuver. This examination is performed with the patient seated or supine.

Anterior translation is assessed with an anterior force applied to the shoulder with the arm in 90 degrees of abduction; anterior-inferior translation is tested with the arm in the same position, but the direction of force is changed to anteroinferior ( Fig. 4.2 ). The relocation test is also performed ( Fig. 4.3 ). A particularly useful maneuver is the Rowe test to assess inferior-anterior translation. To perform this examination, have the patient stand and flex the trunk from the hips approximately 30 degrees. Instruct the patient to relax the arms and let them hang from the shoulder toward the floor. In this relaxed position, the shoulders are effectively elevated 30 degrees ( Fig. 4.4 ); the examiner then applies a distraction force. Inferior translation is assessed with an inferior force applied with the shoulder at 0 degrees of abduction (sulcus test). If the translation force is applied in an inferior-posterior direction, the surgeon can gain additional information. Posterior translation is examined with the arm elevated 90 degrees, adducted slightly, and rotated internally approximately 30 degrees. The shoulder is translated in a posterior-inferior direction and the result is recorded. This is repeated for a posterior force. Typically, posterior translation produces minimal complaints, but as the shoulder is extended, the humeral head reduces, and the patient reports pain.

FIGURE 4.2, Dr. Rowe examines a patient for anterior instability.

FIGURE 4.4, Patient position for the Rowe test.

Record the presence or absence of pain and apprehension for each instability maneuver and grade the amount of humeral head translation on the glenoid surface as 0 (stable or trace laxity), 1 (up to 50%), 2 (>50% but not dislocatable), or 3 (dislocatable). The grading of instability is somewhat subjective but appears to be relatively consistent for each examiner. Record the presence of laxity in the contralateral shoulder, elbows, and knees, and the patient's ability to bring the thumb to the forearm. Beighton's signs may be used as a formal grading system for the degree of generalized ligament laxity, but a simple general assessment may be sufficient. Other sources of shoulder pain (rotator cuff lesions, acromioclavicular joint arthritis, thoracic outlet syndrome, brachial plexus lesions, glenohumeral arthritis) may need to be excluded through the patient history, physical examination, and radiographic analysis.

Radiographs

Routine radiographs that we use include anteroposterior glenoid, Bernageau, and supraspinatus outlet views. Most of the time, patients have already had magnetic resonance imaging, with or without arthrography (MRI or MRA). If not, we will obtain one or the other study depending on acuity of the injury and the clinical or radiographic suspicion that surgery may be indicated. In patients with a traumatic dislocation that occurred within days, often the arthrogram is not needed, as the hemarthrosis provides sufficient contrast. Also, depending on the radiographic and MRI findings, a computed tomography (CT) scan may be added with or without reconstructions to assess humeral and glenoid bone loss or if the patient has failed prior surgery to more thoroughly assess the anatomy and hardware placement.

Direct radiographic evidence of glenohumeral instability consists of humeral head dislocation. Indirect radiographic signs of instability include calcification adjacent to the anterior glenoid, a bony Bankart lesion, anterior glenoid bone loss, or a Hill-Sachs lesion. On MRI and CT, additional evidence of instability includes detachment of the glenoid labrum from the glenoid bone, capsular stripping from the glenoid, and ligament insufficiency ( Figs. 4.5–4.15 ).

FIGURE 4.5, Radiographs of anterior-inferior dislocation.

$FIGURE 4.6, Radiograph of glenoid rim fracture.$

FIGURE 4.8, Bony Bankart lesion (circled) , axillary view.

FIGURE 4.9, Superior labrum from anterior to posterior lesion.

FIGURE 4.12, Anterior capsular stripping.

$FIGURE 4.13, Glenoid rim fracture.$

FIGURE 4.14, Posterior humeral glenohumeral ligament tear (arrow) .

FIGURE 4.15, Three-dimensional computed tomographic reconstruction with anterior bone loss.

If the diagnosis is in doubt, an arthroscopic examination and examination under anesthesia are helpful. I observe humeral head movement under direct arthroscopic visualization. The presence of intraarticular lesions may allow the surgeon to diagnose a predominant direction of instability or an unrecognized direction of instability. These lesions are located in the humeral head and glenoid (chondral or osteochondral defects), labrum (fraying or separation from the glenoid), and capsular ligaments (tear or laxity; Fig. 4.16 ).

Nonoperative Treatment

Nonoperative treatment consists of avoidance of painful activities, nonsteroidal antiinflammatory medication for pain if necessary, and a home physical therapy program designed to eliminate contractures and maintain or improve shoulder girdle strength and neuromuscular coordination. The goal is to improve the strength of those muscles responsible for glenohumeral stability. Therefore patients perform resistive exercises of the internal rotators, external rotators, biceps, triceps, and scapular muscles with surgical tubing and light weights (maximum 5 pounds). Patients are instructed in exercises to improve neuromuscular coordination and proprioception. Areas of contracture are identified and corrected with specific stretching. Posterior contracture commonly occurs in patients with traumatic anterior-inferior glenohumeral instability ( Fig. 4.17 ).

Operative Treatment

Indications

The indications for surgery are not clearly elucidated as patient choice does play a role. The most commonly accepted medical indication for surgery is persistent shoulder pain or recurrent glenohumeral instability that has not responded to a minimum of 3 to 6 months of nonoperative treatment. The second indication is a patient at high risk for recurrence after a primary traumatic dislocation event. Fundamentally, the decision to operate is the patient's, based on appropriate counseling by the surgeon.

When a patient sustains an initial dislocation that occurs with sufficient energy that it can be classified as traumatic, surgical repair is an option. There are several factors that may favor surgical intervention, as they suggest a high risk of recurrence:

1.
Patient age younger than 20 years.
2.
Traumatic dislocation (as opposed to dislocations that occur with minimal force).
3.
The need for a closed reduction (this also supports the diagnosis of a dislocation as opposed to the patient's subjective account).
4.
Involvement of the dominant arm.
5.
High level of current activity.
6.
Desired high level of activity.
7.
Sensation of instability with minimal provocation.
8.
Radiographic findings of a bony Bankart, large Hill-Sachs lesion, or persistent subluxation or dislocation.
9.
CT or MRI findings that suggest moderate soft tissue or bony structural compromise.

We explain the chance of recurrent instability in light of the patient's particular situation and let the patient and family decide on operative or nonoperative care. Our experience correlates with much of the recent literature. Patients who are younger than 20 years and participate in vigorous overhead activities or contact sports have a high rate of recurrent dislocation. However, unless the patient falls into the select subgroup described earlier with factors influencing early repair, the chances of recurrent dislocation are less than 50%, and of those in whom repeat dislocation occurs, only 50% request surgery.

Historians will likely view our past treatment of traumatic shoulder dislocation as suboptimal. Essentially, there is a 25% recurrence rate (much higher in certain patients). Arthroscopic treatment has a 90% to 95% success rate, yet it is not routinely performed. Orthopedic surgeons operate on acute ligament injuries of the knee and ankle but rarely on the shoulder. As our techniques and equipment continue to improve, and as our ability to identify patients at high risk of recurrent symptomatic dislocation increases, patients with acute shoulder dislocation will have greater access to surgical care.

Contraindications

Absolute contraindications to surgery include glenohumeral instability with selective voluntary muscle contractions and questionable emotional stability. Patients who can activate their muscles and demonstrate glenohumeral subluxation or dislocation with the arm by the side seem to have a poor prognosis after operative care. Evaluating a patient's emotional stability is, of course, subjective. Relative contraindications to arthroscopic shoulder stabilization include failed prior instability surgery, poor-quality ligaments, and large bone defects of the glenoid or humeral head. The potential solution in the last case is the Latarjet procedure, discussed later in this chapter.

Most small Hill-Sachs lesions do not affect the arthroscopic surgical result because with restoration of soft tissue tension, the Hill-Sachs lesion does not engage the anterior glenoid. However, when the humeral head defect is large enough, there is insufficient surface area to allow adequate external rotation. If the patient regains external rotation, he or she may experience a sensation of catching and recurrent dislocation as the Hill-Sachs lesion rides over the anterior rim ( Figs. 4.18–4.20 ). Earlier operations dealt with this issue by intentionally restricting external rotation, but such an approach limits function and may lead to asymmetric loading and arthrosis.

FIGURE 4.19, Large Hill-Sachs lesion in external rotation perched on the anterior glenoid.

FIGURE 4.20, Large Hill-Sachs lesion in external rotation anteriorly dislocated.

There have been several publications that try to use CT scans or MRIs to predict the amount of glenoid or humeral bone loss or patterns of loss that would predict when an arthroscopic anterior capsulolabral repair is not sufficient to restore stability. It is still not clear that there is a definitive answer, but generally, a glenoid defect of more than 15% to 20% of the diameter of the inferior circle of the glenoid or a Hill-Sachs lesion that involves more than 30% of the humeral head should be approached cautiously with isolated arthroscopic capsulolabral repair. Arthroscopy as a diagnostic tool is effective to evaluate whether the Hill-Sachs lesion is engaging or if the anterior glenoid bone loss or labral loss is too significant to manage the patient with a capsulolabral repair. If the Hill-Sachs lesion is engaging, a remplissage procedure can be considered in conjunction with the capsulolabral repair ( Fig. 4.21 ). Alternative options include arthroscopic or open humeral head allograft placement, rotational osteotomy, or placement of a partial humeral head metal implant.

FIGURE 4.21, Arthroscopic view of Remplissage.

Operative Approach

Operative Rationale

The underlying principle of arthroscopic repair is to identify and repair all lesions that contribute to glenohumeral instability. This involves débridement, repair of ligament and labral tears, capsular tensioning, and if needed, repair of the rotator interval.

The first step to approach a patient with glenohumeral instability is to determine the direction or directions of instability by conducting a thorough history, physical examination, examination under anesthesia, and examination during glenohumeral arthroscopy. All of the structures within the glenohumeral joint are then evaluated to determine which ones need to be addressed. A patient with anterior-inferior instability may require an anterior labral repair, but if capsular stretching has occurred, anterior capsular imbrication may be necessary as well. Another patient with the same direction but a higher degree of translation may need a more aggressive capsular plication, simply based on the history, imaging, and exam under anesthesia ( Fig. 4.22 ; ). A patient with posterior-inferior instability may not be stabilized after posterior labrum and posterior capsule repair, and may require tightening of the inferior capsule and anterior-inferior glenohumeral ligament. A rotator interval repair may be necessary. The decision-making is complex, but it accurately reflects the reality of the clinical situation. Often the decision is made prior to surgery, but surgical findings definitely impact what is addressed and the level of aggressiveness to address different structures.

FIGURE 4.22, Anteroposterior radiographs of static anterior inferior humeral subluxation.

The goals of débridement are to remove sources of mechanical irritation or functional instability. Only minor labrum flap tears (<50% of the labrum thickness) are removed, and every attempt is made to repair the lesions ( Figs. 4.23 and 4.24 ).

FIGURE 4.24, Posterior labral faying after débridement.

The purpose of ligament and labrum reattachment to bone is twofold. First, adequate capsular tension is impossible to achieve unless the labrum and ligament are securely attached to the glenoid. All traumatic tears of the superior, anterior, posterior, and inferior labra are repaired because these lesions contribute to glenohumeral instability. Second, anatomic repair of the ligament and labrum restores cavity-compression to the glenohumeral joint. Lippitt has demonstrated that compression of the humeral head into the glenoid by muscular force is an effective stabilizer to humeral translation, and resection of the labrum decreases stability by 20%.

Reattaching the anterior-inferior ligament–labrum complex to the glenoid may not restore sufficient stability to the glenohumeral joint. Speer demonstrated only a small increase in humeral translation with a simulated Bankart lesion and concluded that capsular stretching or elongation is necessary to produce glenohumeral instability. Therefore, the final portion of the operation is to restore capsular tension.

Capsular elongation can be classified as primary or secondary. Primary elongation refers to permanent deformation of the capsular fibers due to a single traumatic event or multiple episodes of instability. Secondary elongation occurs when there is a tear at the insertion site, thereby decreasing capsular tension. This may occur within the anterior-inferior capsule after a Bankart lesion or as a result of a superior labrum tear. The biceps-labrum complex contributes to anterior-inferior translation, and its detachment results in increased humeral translation. Thus we repair all traumatic superior labrum detachments. Rotator interval and superior glenohumeral ligament tears may also affect glenohumeral stability. We have observed at operation that repair of the rotator interval decreases inferior and posterior translation of the humeral head. If the repair also incorporates the superior portion of the middle glenohumeral ligament, anterior capsular tension is increased. Thus the surgeon can restore capsular tension by two methods: primary capsular elongation requires operation directly on the capsule, and secondary elongation responds to repair of insertion site tears.

Primary capsular elongation can be addressed by three techniques used singly or in combination: (1) advancement of the capsule to the labrum, (2) advancement of the capsule to the glenoid with suture anchors, and (3) capsular imbrication.

The goal of this portion of the procedure is to restore ligament and capsule tension and to eliminate excessive humeral head translation, which we define as greater than 25%. To estimate the percentage of translation, we visually divide the humeral head into four segments and observe how much of the humeral head translates with relation to the glenoid. Any or all of the following areas may require tightening: middle glenohumeral ligament, anterior-inferior glenohumeral ligament, inferior capsule, posterior-inferior glenohumeral ligament, and posterior capsule.

In the past, we have advanced the capsule to the intact labrum if no labral tear exists. However, it has been noted in several studies that it may be beneficial, with more secure fixation and better outcomes, to advance the capsule using suture anchors in the glenoid. Drill holes for the suture anchors are placed through the glenoid articular surface approximately 1 to 2 mm from the peripheral glenoid rim. If the labrum is detached, it is sutured so that it contacts the scapular neck and extends onto the glenoid articular surface. This reestablishes the labrum “bumper” and re-creates an optimal surface for concavity-compression. The amount of tightening is based on both the degree and the direction of translation, using guidelines similar to those described by Warner for open operations. A soft tissue grasper is used to apply traction to the various portions of the capsule while the arm is positioned in different degrees of abduction and external rotation while applying translation forces. Attempts are made to establish tension in different parts of the capsule according to their role in glenohumeral stability. The appropriate tension of the inferior capsule is estimated with the arm in 60 degrees of abduction and 60 degrees of external rotation, the middle glenohumeral ligament with the arm in 30 degrees of abduction and external rotation, and the rotator interval with the arm in 0 degrees of abduction and 30 degrees of external rotation. Because it is difficult to perform the repair with the arm in complete abduction or external rotation, the appropriate amount of tensioning is estimated in this position, but the arm is placed in 20 degrees of abduction and 30 degrees of external rotation to complete the arthroscopic repair.

With the greater visualization afforded by the arthroscope, the surgeon can selectively repair damaged portions of the capsule. This is an advantage over open reconstructions for anterior instability. With the increased selectivity of arthroscopic repair comes the promise of improved patient outcomes, but also a new set of decisions to be made. This is less of a problem with tears of the labrum insertion, because the goal of returning the labrum to its anatomic location is relatively well-understood. More difficult are decisions regarding ligament or capsule tightening; the surgeon has to decide what portions of the capsule should be tightened, how much tightening is necessary, and by which technique tightening should occur.

Intraoperative Decision Making and Indications

Débridement

Minor flap tears of the labrum may be débrided. Palpation with a probe is necessary to determine the presence of minor flap tears, cleavage tears that exist within the labrum substance, and minor separations of the labrum from the glenoid. Loose bodies are removed with grasping instruments ( Figs. 4.25 and 4.26 ).

Labrum Repair

The labrum is normally attached securely to the glenoid bone anteriorly, inferiorly, and posteriorly below the glenoid equator. Any separation in these areas is generally pathologic. The anterior-superior labrum is usually not well attached to the glenoid (sublabral foramen), and separation in this area is considered normal. The superior labrum attachment is variable, and a mobile superior labrum without evidence of trauma is not classified as a SLAP lesion. When the superior labrum separation is a normal variant, the superior glenoid is covered with smooth cartilage, and the labrum shows no evidence of trauma. Signs of traumatic separation include tears within the substance of the superior labrum, cartilage loss with exposed bone at the site of labrum attachment, and an increase in superior labrum separation with abduction and external rotation of the arm. The diagnosis of a superior labral tear can be difficult, and there is much interobserver variation in making the diagnosis. If the superior labrum is repaired, it is repaired anatomically as opposed to repair of the anterior, inferior, or posterior labrum, which are often shifted along with repair.

Capsular Tensioning

The location of the ligament repair site, and therefore the ligament tension, can be estimated by grasping the ligament and placing it at different locations on the glenoid. Typically, 5 to 15 mm of lateral and superior ligament advancement is required. Arm position affects ligament and capsule tension, so the shoulder is typically kept in 20 degrees of abduction and 30 degrees of external rotation during this portion of the operation.

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