Advanced Shoulder Arthroscopy

CHAPTER 21 Advanced Shoulder Arthroscopy

Laurent Lafosse, MD, Manuel Haag, MD, Tom Van Isacker, MD, Ludwig Anné, MD

EVOLUTION OF SHOULDER ARTHROSCOPY

As shoulder arthroscopists, we begin our practice with limited procedures, confined to the safe area of the shoulder. As our knowledge and skills evolve, we will explore beyond the borders, farther than what has ever been taught.

There is an analogy between this evolution of the shoulder arthroscopist and a kitten’s evolution. In the beginning, its biotope is a little basket. Very fast, it starts to explore the kitchen. Once it goes outside the kitchen, the house and then the garden becomes its territory. What is essential for the cat is to feel confident by knowing the limits and the dangers of its territory.

Shoulder arthroscopy started by exploring and dealing with shoulder pathologies in the glenohumeral space.¹ The limits of the glenohumeral joint are the glenoid, the humeral head, the capsule and the musculotendinous structures. It contains the cartilage, the glenohumeral ligaments, the labrum, and the tendon of the long head of the biceps. The first reconstructive procedure was the arthroscopic treatment of anterior shoulder instability.²

The second step of arthroscopic shoulder surgery extended into the subacromial space, with the treatment of impingement by arthroscopic acromioplasty.³ Because superior cuff tears create a communication between the subacromial and glenohumeral space, arthroscopic rotator cuff repair started with dealing with supraspinatus tendon tears.⁴ Further development led to the arthroscopic repair of large superior tears and later to the exploration and repair of the posterior (infraspinatus and teres minor tendon) and the anterior (subscapularis tendon) rotator cuff.

The limits of arthroscopy are extending to unexplored territories, including the muscles and their innervation.

Advanced arthroscopy uses complex techniques of exploration, dissection, release, and fixation to address most shoulder disorders. Advanced surgery demands a perfect knowledge of shoulder anatomy whether managed arthroscopically or in a open procedure.

An important advantage of arthroscopy is the enhanced view, which allows the surgeon to deal with details. The danger of this potential of focusing is becoming preoccupied with a small place and neglecting to keep an overview. A global view from different angles helps to create a three-dimensional (3D) perspective of the shoulder, facilitating complex procedures. An analogy between the shoulder and a house can help to preserve this 3D global view during the surgery.

THE SHOULDER AS A HOUSE

The house has a first floor, a second floor, and a basement.

The glenohumeral joint is at the first floor, limited by the rotator cuff. The ceiling is the supraspinatus tendon, the anterior wall is the subscapularis tendon, and the posterior wall is the infraspinatus and teres minor tendon. The rotator cuff interval, including the superior glenohumeral ligament and the coracohumeral ligament, closes the junction between the supraspinatus and subscapularis tendon. Inside the glenohumeral joint, the biceps comes from the glenoid and leaves this room through the ceiling as a chimney at the level of the bicipital groove.

Medially, the coracoid process is a key landmark with the attachment of two musculotendinous structures: the pectoralis minor and the conjoint tendon. These structures allow defining the infracoracoid and supracoracoid spaces. The infracoracoid space is the second room on the first floor anterior and medial to the glenohumeral joint. It contains laterally the presubscapular bursa and more medially the plexus including the axillary nerve and the subscapularis nerves. The important medial border of the presubscapular bursa is at the level of the medial border of the coracoid process. The ceiling of this infracoracoid space is the coracoid process and the pectoralis minor tendon. The conjoint tendon is the anterior wall and the subscapularis tendon is the posterior wall.

Posterior to the infraspinatus and teres minor, there is a last room at the level of the ground floor between the rotator cuff and deltoid muscle. This posterior subdeltoid space is like a staircase up to the subacromial space at the second floor and down to the basement, where it contains the terminal branches of the axillary nerve.

The subacromial space is on the second floor. The supraspinatus tendon and the coracohumeral ligament are the floor now. The acromion, the clavicle, and the deltoid muscle together form the roof. The roof contains the subacromial bursa. The bursa is a little room inside this subacromial space, stuck to a part of the rotator cuff under the acromion, the deltoid muscle, and the coracoacromial ligament. Medially from the subacromial space at the second floor is the supracoracoid space under the clavicle. It contains the coracoclavicular ligaments and the suprascapular nerve. The coracoacromial ligament is the wall between the supracoracoid space and the subacromial space.

Last, at the level of the basement, is the quadrilateral space under the glenohumeral joint. The quadrilateral space communicates anteriorly with the most inferior part of the infracoracoid space and posteriorly with the inferior part of the posterior subdeltoid space. It contains the axillary nerve, which follows the anterior part of the subscapularis tendon, travels posteriorly underneath the subscapularis muscle in the quadrilateral space, and ends inside the deltoid and the teres major muscle. The inferior limits of the quadrilateral space and therefore the floor of the basement are the teres major and the latissimus dorsi tendons.

THE ARTHROSCOPIC PORTALS

Since the beginning of shoulder arthroscopy, many portals have been described. Some are routinely used and others provide more specific access. We name the different portals in a standardized way (Fig. 21-1). Five portals, named A to E, surround the acromion.

FIGURE 21-1 Arthroscopic portals from A to K.

A is the common posterior routine glenohumeral joint access and C is a lateral access to the subacromial space located at the level of the midacromion, two digits away from its lateral border. E is the classic anterior access to the joint through the rotator cuff interval between the upper border of the subscapularis and the anterior border of the coracohumeral ligament, adjacent to the coracoacromial ligament lateral to the coracoid process. The portals B and D are located respectively at the posterior and the anterior corners of the acromion. The B portal is used for posterior access to the rotator cuff and the posterior Bankart repair. The D portal is sometimes referred to as the suprabicipital portal because of its common use in biceps tenodesis. It is also used in rotator cuff repair when additional access is necessary for tendon or suture manipulation. In the Bankart repair, the D portal serves as a very good visualization portal for the anterior glenoid rim and scapular neck as in double-row labral fixation procedures (see later). In the presence of an intact rotator cuff, this portal is placed with close attention to the long head of the biceps tendon and the supraspinatus tendon through the coracohumeral ligament.

The F portal is inferior to the E portal but still lateral to the conjoint tendon. At the supraspinatus fossa, medial to the Neviaser (N) portal, is the G portal just above the suprascapular notch and about 7 cm medially from the lateral border of the acromion.

More anteriorly, the H (high) portal is above the middle of the coracoid process, just anterior to the clavicle at the level of the union between the horizontal and the vertical part of the coracoid process. The I (inferior) portal is the most medial and inferior access to the shoulder. It is located medial to the anterior axillary fold on the chest, just lateral to the lateral border of the plexus. It is used for arthroscopic Latarjet procedure. The J portal is anterolateral at the level of the inferior third of the subscapularis. It enters tangentially over the humerus parallel to the subscapularis tendon and provides a view of the entire muscle and the surrounding neurologic structures.

Posteriorly the K portal is the posterolateral inferior portal, located lateral and inferior to the B portal. To avoid the anterior branch of the axillary nerve, it is placed lateral to the posterior border of the deltoid muscle and not lower than 6 cm from the acromion. This portal provides access to the axillary pouch for the repair of inferior humeral avulsion of the glenohumeral ligament (HAGL lesion), interposition arthroplasty, latissimus dorsi transfer, or simply removing loose bodies.

Except for the primary visualization portal, which is either the A or the C portal, all portals are established with an outside-in technique.

SHOULDER PATHOLOGY BY AREA

The concept of the shoulder as a house helps the surgeon to create a 3D perspective of the shoulder. The classic strategy for addressing disorders in the shoulder is to think by pathology, but it is also possible to think topographically. We divide this house into three distinct anatomic areas: the posterosuperior, the anterior, and the inferior areas. The safe zone, meaning a nerve-free zone, is laterally from the glenoid in the anterior and posterosuperior area (Fig. 21-2).

FIGURE 21-2 The three shoulder areas and the safe zone. Top, The numbers 1, 5, and 7 indicate clock positions. Bottom, The curved yellow line indicates axillary nerve.

Three lines originating in the center of the glenoid and directed to the base of the coracoid and the inferior borders of the subscapularis and teres minor, respectively, together with the central axis going through the glenoid center, describe three planes. The three planes separate the three areas within the 3D shoulder. The plane through the coracoid base separates the anterior from the posterosuperior area, the plane through the inferior border of the subscapularis separates the anterior from the inferior area, and the plane through the inferior border of the teres minor separates the posterosuperior area from the inferior area.

Area by area, we describe the anatomy in a simple way, as it is seen during arthroscopy. We describe advanced surgical procedures to deal with a selection of underlying lesions of different pathologies.

Anterior Shoulder Area

The oblique plane of the coracoid base and the oblique plane of the inferior border of the subscapularis muscle span the space of the anterior shoulder area. Regarding the glenoid, this area spans from the 1-o’clock to the 5-o’clock position (see Fig. 21-2). Everything outside—meaning lateral to the glenoid—is considered a safe zone in terms of nerves.

Starting at the center, the anterior glenoid is followed by the anterior capsulolabral complex and the subscapularis tendon. Only the superior third of the subscapularis, being the largest and most powerful muscle of the rotator cuff,⁵ is visible from the intra-articular position. Its origin broadly covers most of the anterior scapula, and it inserts on a large footprint area that practically covers the entire lesser tuberosity. More medially is the coracoid process, with the attachment of four structures: the conjoint tendon, the coracoacromial ligament, the coracoclavicular ligament, and the pectoralis minor tendon. Medial to the coracoid process, the plexus and its vascular components rest on the subscapularis muscle. Under the subscapularis, the axillary nerve travels through the quadrilateral space in the inferior area. More lateral is the long head of the biceps in its bicipital groove, leading down to the humeral attachment of the pectoralis major.

All these structures are important for shoulder function and can be involved in shoulder pathologies or used for reconstructive surgery. The access to this area allows us to treat lesions at the glenoid or the lesser tuberosity, coracoid fractures, anterior rotator cuff tears, and more complex reconstructions.

In the anterior shoulder, placement of the arthroscope through an adequate anterolateral D portal allows simultaneous access to the intra- and extra-articular anterior shoulder (Fig. 21-3). This is only possible by opening the rotator cuff interval between the coracohumeral ligament and the subscapularis tendon. This concept is very important to note. It allows superior orientation not only for placing sequential portals safely but also for locating the neurovascular structures to shuttle between the intra- and extra-articular spaces.

FIGURE 21-3 Combined intra- and extra-articular view through the anterolateral D portal.

Cartilage Lesions (Interposition Capsuloplasty)

Compared to lesions of bone or labrum, idiopathic or secondary glenoid cartilage lesions associated with shoulder instability or trauma are difficult situations to treat. Due to the higher demand and longer life expectancy, this is of even more concern for the younger patients. Up to now there is no ideal solution.

Biological resurfacing of the glenoid and humeral hemiarthroplasty as an open surgical treatment for osteoarthritis in younger and active patients have been performed with acceptable results.⁶^–⁸ At present, arthroscopic treatment of cartilage lesions of the glenoid with labral lesions is limited to reconstructions by covering the cartilage defect as much as possible by the labrum. In some institutions, GraftJacket is used to cover the glenoid cartilage defect arthroscopically, but no long follow-up is available regarding the outcome of this artificial component.⁹

Encouragement by capsular interposition with hemiarthroplasty forged the arthroscopic interposition capsuloplasty. The technique is based on the concept of a capsular flap. It is a unique concept of resurfacing that addresses cartilage lesions selectively on the glenoid side. This seems a logical evolution, because the humeral side is not always the cause of pain and malfunction. We define the indication for this procedure to be younger patients with severe cartilage defects (Fig. 21-4) of the glenoid with or without involvement of the humeral side. The procedure is restricted to patients with only minor osteophytic changes.

FIGURE 21-4 Global glenoid erosion. Inset, External view.

In shoulder instability, the cartilage lesion is caused by trauma from dislocation or is a consequence of chronic wear in persistent instability. In our experience, cartilage erosion associated with anterior or posterior instability is mostly limited to the anterior or the posterior cartilage area, whereas in idiopathic arthritis, the cartilage degeneration often starts inferiorly before becoming a global glenoid erosion. The capsular harvesting site for the interposition capsuloplasty is managed according to the area of the glenoid cartilage defect. The capsulolabral tissue is detached from both the glenoid (Fig. 21-5) and the humeral side (Fig. 21-6). The aim is always to apply the capsulolabral flap on an abraded bony surface, leaving it partially attached to the surrounding connective tissue. This has two major advantages: The biological graft only needs to be attached to the glenoid defect, and its vascularization is preserved.

FIGURE 21-5 Capsulolabral detachment at the glenoid side. Inset, External view.

FIGURE 21-6 Capsular axillary detachment at the humeral side. Inset, External view.

The prepared flap is shifted into the defect and fixed, preferably with resorbable suture anchors, in the medial border of the lesion, covering the whole lesion. In practice, the inferior capsule allows coverage of more than the inferior half of the glenoid. Anterior or posterior localized lesions are managed by harvesting the anterior or posterior capsule respectively.

When the cartilage is missing at the inferior half of the glenoid, the flap needs to be prepared with utmost caution due to the anatomic close relationship of the inferior capsule and the axillary nerve with its branches.

When the cartilage is missing over the entire glenoid (see Fig. 21-4), the entire glenoid is abraded (Fig. 21-7) and the anterior, posterior, and inferior capsule is used (Fig. 21-8) and fixed with three anchors placed along a vertical line in the middle of the glenoid. The anchor sutures are applied in a side-to-side lasso-loop fashion (Figs. 21-9 and 21-10). This allows a strong fixation of the three flaps one to another and to the glenoid surface. This procedure is performed with a superior view through the D portal (Fig. 21-11) and with instrumentation through the A and E portals (Fig. 21-12). Preoperative and postoperative radiographic views are shown in Figure 21-13.

FIGURE 21-7 Abraded glenoid surface. Inset, External view.

FIGURE 21-8 Prepared capsulolabral flap. Inset, External view.

FIGURE 21-9 Side-to-side lasso-loop suturing. Inset, External view.

FIGURE 21-10 Remaining defect after second anchor. Inset, External view.

FIGURE 21-11 Final view from D portal. Inset, External view.

FIGURE 21-12 Final view from A portal. Inset, External view.

FIGURE 21-13 A, Preoperative x-ray. B, Postoperative x-ray.

Capsulolabral Double Row Fixation (Cassiopeia)

The common anterior dislocation is an anteroinferior dislocation with detachment at the glenoid side of the mid glenohumeral ligament and at least the anterior band of the inferior glenohumeral ligament. It is very important to recognize that the created lesion is not restricted to a labrum tear of the glenoid rim. The entire anterior and anteroinferior capsulolabral unit, which form the anterior wall as a passive restraint, are detached and displaced inferiorly. This increases the instability by creating a way for the humeral head to exit underneath the subscapularis musculotendinous unit.

It is very descriptive to consider the detached labrum in analogy to a tire that needs to be put back to its wheel rim. The continuity of the tire’s rubber ring may be intact or broken. Detrisac has described different tear patterns of the labrum as a fibrous ring in detail.

Once the capsulolabral continuity of the ring itself is broken, as in a radial rupture, the situation is much more complicated and unstable. In our opinion, in these cases of structural damage within the capsulolabral complex, a very strong fixation is necessary.

Most arthroscopic techniques address and repair only the labral aspect, employing a single-row technique. The technique in terms of anchor placement and reduction of the labrum—more on the cartilage, on the rim, or further medial—differs from surgeon to surgeon. The amount of capsulolabral tissue taken and shifted with the sutures varies.

To our knowledge, no present arthroscopic technique restores the insertion in an anatomic fashion. More specifically, the capsulolabral unit is generally only fixed to a narrow line. In contrast, open Bankart procedures do fix the unit not only on the glenoid rim but also to the medial scapular neck. This difference might even explain the reports of a relatively higher failure rate with arthroscopic single-row techniques.¹⁰

We use a double-row fixation technique with two transglenoidal suture points on the scapular neck and three anchor fixations on the glenoid rim. The fixation points create a W-shaped pattern, resembling the Cassiopeia constellation (Fig. 21-14). This way, the capsulolabral complex is fixed to a large surface on the anterior glenoid rim and the anterior scapular neck, restoring the physiologic insertion.

FIGURE 21-14 Cassiopeia W configuration.

With this technique, we are able to combine an intra- and extra-articular procedure. A medial extracapsular fixation, being the hypothesized advantage of open repair, is managed arthroscopically and combined with a lateral anchor fixation to the glenoid rim. It allows the inferiorly displaced anterior bundle of the inferior glenohumeral ligament to be shifted back superiorly and permits a strong fixation of the entire anteroinferior capsulolabral complex.

This technique even permits the surgeon to adequately address open ring lesions of the labrum where the self-restoring forces of the capsulolabral complex are completely reduced and a stronger fixation is therefore demanded. The double-row technique permits a solid reconstruction of the biomechanically more important inferior part of the ruptured capsulolabral complex.

Technically, the anterior access of the medial row is difficult due to the anteversion of the glenoid and the neurovascular structures and conjoint tendon blocking a perpendicular approach. We therefore use a retrograde technique. The medial row fixation consists of a suture shuttled through two trans-scapular bone tunnels and through the medial capsule. The tunnels are created from posterior to anterior with a dedicated target device (Fig. 21-15) in order to control the position of the tunnel. The instrumentation further allows protection of the suprascapular nerve posteriorly by the cannulated system (Figs. 21-16 and 21-17). Anteriorly, the capsule can be lifted off the anterior scapula neck, allowing complete visual control as the guidewires exit the bone. In correct application, there is no danger to the brachial plexus and its accompanying vessels. The two ends of a braided suture are shuttled retrograde through the bone tunnels (Fig. 21-18). In the next step, they are passed through the capsule far inferiorly and medially (Fig. 21-19). Only after the labrum is reinserted with the lateral row at the glenoid rim using suture anchors (Fig. 21-20) are the medial row sutures tightened.

FIGURE 21-15 Cassiopeia device.

FIGURE 21-16 Positioning of the Cassiopeia device, 1. Inset, External view.

FIGURE 21-17 Positioning of the Cassiopeia device, 2. Inset, External view.

FIGURE 21-18 Retrograde transglenoidal suture passing. Inset, External view.

FIGURE 21-19 Transcapsular passing of medial suture. Inset, External view.

FIGURE 21-20 Lasso-loop suturing for lateral row.

The entire procedure is visualized through a suprabicipital D portal. This allows visual access to the anterior and posterior glenoid, the scapular neck, and the space between the subscapularis muscle and the capsulolabral complex for management of the medial sutures.

The aim of restoration of the original capsulolabral footprint with the Cassiopeia double-row technique is a more anatomic and stronger fixation of the capsulolabral complex. A decrease of recurrence rates of instability is hypothesized.

Bony Fractures of the Glenoid Rim

Fractures of the glenoid rim are mainly caused by two mechanisms. During a shoulder dislocation, the humeral head applies a tensile force on the capsulolabral complex, potentially resulting in a mostly rather small bony avulsion lesion. Depending on the direction of forces during a trauma, larger fractures of the glenoid rim might occur by a more medial directed force. Because these are articular fractures, anatomic reconstruction is, in our opinion, the primary goal.

Treatment options depend on the size, the location, and the state of the fragment. The crucial criterion for the size is the possibility of screw fixation or not. If the fragment size allows screw fixation, it is a large fragment. In some cases, however, the state of the fragment—if it is comminuted or structurally weak—is the limiting factor disqualifying even larger bone fragments from screw fixation. Another important aspect is the age of the fracture. In terms of the biological healing potential, a short history is favorable for reconstruction. A longer history correlates with an inferior healing response and might be associated with bone loss due to resorption.

Sufficient methods have been developed for treating small fractures. Dealing with them is an integrated part in suture anchor refixation of the labrum.¹¹ In cases of recent fracture, the refixation of the capsulolabral bone unit is performed. In old fractures, resection of the fragment is favored, despite possible risk of chronic instability due to the loss of glenoid support. In a more functional glenoid defect and in a high-demand patient, we consider the arthroscopic Latarjet procedure (see later) for bone reconstruction.

Large anterior or inferior fractures have up to now been a surgical challenge, whereas posterior or superior fractures can be more easily approached directly (anterograde) because no important structures block access to them. Unfortunately most glenoid fractures occur anterior or inferior, or both.

Open surgical treatment through a direct anterior approach requires detachment of the subscapularis. For sufficient arthroscopic access, the axillary nerve and artery are at risk.¹² The anterograde transaxillary mini-invasive approach is therefore known to be associated with neurovascular complications.¹³ A direct arthroscopic approach is further hindered by the coracoid and the conjoint tendon, which course even farther laterally as they descend (Fig. 21-21). Medial to those structures lies the brachial plexus. This prevents the arthroscopist from directly accessing the anterior or inferior glenoid through the interval or subscapularis in a perpendicular fashion as needed for screw fixation.

FIGURE 21-21 Anatomy for anterior access.

We have, concurrently with others,¹⁴ developed for larger fractures of the glenoid rim (Fig. 21-22) a transglenoid technique. In contrast to other groups, we use a retrograde approach, avoiding the difficulties encountered with an anterior approach and avoiding neurovascular complications. Ours is an arthroscopic approach for screw fixation based on the Cassiopeia technique¹⁵ (see earlier). Furthermore, it mediates a perpendicular approach to the fracture surface. This allows a congruent reduction of the often triangular fragment to the glenoid.

FIGURE 21-22 Depressed glenoid rim fracture. Inset, External view.

Visualization for this technique is performed through the suprabicipital D portal. For temporary fixation, guidewires are brought in a retrograde fashion through the scapular neck, perforating the fragment through the posterior A portal. During this step, the fragment needs to be reduced and stabilized with a tissue grasper passed through the E portal. We use a cannulated screw system for final fixation. Complementary fixation is achieved by soft tissue attachment through suture anchors. This technique does not permit compression of the fracture, but it offers a safe reduction and a solid scaffold (Fig. 21-23).

FIGURE 21-23 Reduced glenoid fracture. Inset, External view.

Anterior HAGL Lesions

Traumatic anterior instability can be caused by capsulolabral lesions at the glenoid side and more rarely by capsular avulsion at the humeral side. This is the anterior HAGL lesion deep to the subscapularis tendon. It includes the middle glenohumeral ligament and the anterior band of the inferior glenohumeral ligament. If it is an isolated lesion of the middle glenohumeral ligament, then it is more likely associated with a painful unstable shoulder than with a real dislocation. Incidence of anterior humeral avulsions of the glenohumeral ligament is probably underestimated.

Arthroscopically, anterior HAGL lesions are located at the lesser tuberosity deep and just medial to the subscapularis insertion and continue to the anatomic neck (Figs. 21-24 and 21-25). A high index of suspicion for an underlying anterior HAGL lesion should be present in all cases with a contradiction between a history of post-traumatic recurrent dislocations and no or limited capsulolabral lesions at the glenoid side. Open surgical repair through an anterior approach requires detachment of the subscapularis tendon.^16,¹⁷ Only a few reports exist on arthroscopic HAGL repair.^18,¹⁹

FIGURE 21-24 Posterior view of anterior humeral avulsion of the glenohumeral ligament (HAGL lesion). Inset, External view.

FIGURE 21-25 Anterolateral view of anterior humeral avulsion of the glenohumeral ligament (HAGL lesion). Inset, External view.

Knowledge of the arthroscopic anatomy of the anterior shoulder permits an all-arthroscopic reconstruction of the anterior glenohumeral ligaments to the lesser tuberosity and anatomic neck. We routinely inspect the anterior humeral insertion in all shoulder arthroscopies.

The repair is visualized through the posterior A and the anterolateral D portal above the subscapularis tendon by opening the rotator cuff interval and partially resecting the coracohumeral ligament. A single-row suture anchor repair through the anterior E portal is applied (Figs. 21-26 to 21-29). To enhance the exposure, the arm can be brought into slight internal rotation. Possible difficulties encountered with arthroscopic treatment are due to the narrow space at the humeral insertion, poor tissue quality, or retraction. If the given circumstances do not allow a sufficient anatomic reconstruction, an arthroscopic Latarjet procedure (see later) is proposed as a nonanatomic alternative stabilization procedure to prevent failure or stiffness.

FIGURE 21-26 Repair of anterior humeral avulsion of the glenohumeral ligament (HAGL lesion) I. Inset, External view.

FIGURE 21-27 Repair of anterior humeral avulsion of the glenohumeral ligament (HAGL lesion) II. Inset, External view.

FIGURE 21-28 Anterolateral view of anterior humeral avulsion of the glenohumeral ligament (HAGL lesion) after repair. Inset, External view.

FIGURE 21-29 Posterior view of anterior humeral avulsion of the glenohumeral ligament (HAGL lesion) after repair. Inset, External view.

Subscapularis Pathologies

Recognition and treatment of lesions of the subscapularis tendon are more recent in comparison with the other rotator cuff tendons. We know now that the impact of subscapularis tears is very important. It is not only the single internal rotator and anterior constraint of the rotator cuff, but also in diameter and strength it is the most important muscle of the rotator cuff. Failure of its function can therefore insufficiently be compensated and is associated with anterior instability and deterioration of the shoulder function.

Ruptures of the subscapularis tendon most commonly occur from superior to inferior and from deep to superficial. Superolaterally, the tendon takes part in the complex anatomy of the long head of the biceps tendon pulley system. Superior subscapularis lesions associated with anterior pulley rupture can lead to a very painful instability of the long head of the biceps tendon. Sometimes the biceps luxates into the subscapularis tendon, causing a cleavage. Due to their close relationship, retraction of the subscapularis causes tension and shearing forces to the brachial plexus and especially the axillary nerve.

Until now, the open subscapularis repair has been the standard approach and the most widely applied technique for large or retracted tears. An intra-articular arthroscopic approach for reconstruction has recently been popularized but is limited to rather small and nonretracted tears.

So to manage all subscapularis tears arthroscopically, we developed an extra-articular approach. As a function of the stage of the rupture, gradual steps are necessary to obtain a repair. We propose a classification system of rupture stages, and we base the surgical steps needed for repair on these stages (Table 21-1).²⁰ Type I tears are localized to the superior third of the subscapularis tendon and are partial tears of the deep fibers at the insertion onto the lesser tuberosity. These tears never display tendon retraction because the superficial fibers of the subscapularis remain intact. Type II tears are complete ruptures of the superior third of the tendon. Type III tears are complete tears of the superior two thirds of the tendon. The intact inferior one third of the tendon still limits the degree of retraction. Type IV tears are complete tears of the entire subscapularis tendon from its insertion, combined with retraction of the tendon edge to the level of the glenoid rim without anterior subluxation of the humeral head. Type V tears are complete tears of the subscapularis tendon with retraction and an eccentric humeral head, anteriorly subluxated, with possible impingement on the coracoid process.

TABLE 21-1 Classification of Subscapularis Tendon Tear on the Basis of Preoperative CT and Intraoperative Evaluation

Type	Lesion
I	Partial avulsion of superior one third
II	Complete avulsion of superior one third
III	Complete avulsion of superior two thirds
IV	Complete avulsion of the tendon with head centered and fatty degeneration classified as less than or equal to type III
V	Complete avulsion of the tendon but uncentered head with coracoid impingement and fatty degeneration classified as greater than or equal to type III

An intra-articular approach is generally sufficient for type I and II lesions because they are easily accessible from within the joint and are not associated with major retraction.

In type III lesions, it depends on the reducibility of the tendon retraction if the repair is feasible from within the joint or not. In some cases, an extra-articular release underneath the conjoint tendon and coracoid process is needed for mobilization in addition to the intra-articular release. In this case, we use an extra-articular visualization from either a lateral C or an anterolateral D portal or from both alternately. The D portal and anterior E or F portal (or both) are used for instrumentation. For better visual and manual control of the subscapularis tendon, the coracohumeral ligament is partially detached from the coracoid as far as needed. A traction suture is used to keep the tension on the tendon while it is released. The subscapularis muscle is exposed by careful resection and dissection of the bursa and all fibrous adhesions. If needed, even adhesions to the brachial plexus and axillary nerve can be addressed.

In a type IV rupture (Fig. 21-30) a 360-degree release (Figs. 21-31 to 21-34) is the most crucial step in the repair (Figs. 21-35 and 21-36). Great caution is necessary to preserve not only the subscapular nerves but also all of the brachial plexus with its collateral and terminal branches.

FIGURE 21-30 Subscapularis type IV lesion before release.

FIGURE 21-31 Intra-articular release of subscapularis.

FIGURE 21-32 Release between subscapularis and conjoint tendon.

FIGURE 21-33 Subscapularis release and the axillary nerve.

FIGURE 21-34 Subscapularis after release.

FIGURE 21-35 Subscapularis with traction suture.

FIGURE 21-36 Subscapularis after repair.

We consider type V ruptures not repairable. A partial repair with a pectoralis minor transfer (see later) for augmentation can be performed arthroscopically if a repair is indicated, depending on such other factors as patient’s age or presence and stage of ruptures of other rotator cuff tendons.

Lesser Tuberosity Fracture

Isolated avulsion fractures of the lesser tuberosity (Figs. 21-37 and 21-38) are rare injuries. The underlying trauma mechanism is usually an abduction–external rotation trauma. In elderly and middle-aged patients, it is more likely for the tendon to rupture, but in a younger patient, the high tensile force of the tendon can lead to an avulsion fracture. If the fracture includes the superior third of the lesser tuberosity, it will inevitably affect the stability of the long head of the biceps. This can be due to two reasons: damage of the bony medial wall of the bicipital groove and soft tissue lesions of the reflection pulley system.

FIGURE 21-37 Three-dimensional CT scan outlet view of lesser tuberosity fracture.

FIGURE 21-38 Three-dimensional CT scan anteroposterior view of lesser tuberosity fracture.

As an equivalent to a type IV subscapularis tendon tear, a lesser tuberosity fracture potentially will result in a total insufficiency of the subscapularis muscle and merges with a repair before irreversible retraction. The most common treatment for displaced avulsion fractures of the lesser tuberosity is open reduction and internal fixation using cannulated screws. The arthroscopic technique described in the literature ²¹ uses a posterior intra-articular portal for visualization.

We use an arthroscopic technique with alternating visualization from the posterior intra-articular A portal and subacromial anterolateral D portal. This allows a combined view and intra-articular and extra-articular access to the entire anterior shoulder including the area medial to the coracoid and conjoint tendon. This has marked advantages for the release and mobilization of the subscapular musculotendinous unit and of the surrounding neurovascular structures. The reduction and stabilization can be performed by traction sutures and by suture anchors only. In case of larger fractures, an arthroscopically guided cannulated screw fixation is an attractive effective option. Good reduction and firm fixation can be achieved arthroscopically (Figs. 21-39 and 21-40). If associated biceps instability is present, the arthroscopic osteosynthesis is always performed in conjunction with biceps tenodesis.

FIGURE 21-39 Three-dimensional CT scan outlet view of repaired lesser tuberosity fracture.

FIGURE 21-40 Three-dimensional CT scan anteroposterior view of repaired lesser tuberosity fracture.

Pectoralis Minor Transfer

Due to atrophy, fatty degeneration, or denervation of the subscapularis muscle, a chronic subscapularis tendon tear is not always totally reparable. These complete tears of the subscapularis tendon with retraction can lead to an eccentric humeral head that is displaced anteriorly and superiorly on the glenoid because of disruption of the force couple of the rotator cuff. The humeral head comes in contact with the coracoid, which makes it a type V subscapularis tendon lesion in our proposed classification (Fig. 21-41). Deterioration of shoulder function, instability, and degenerative articular changes can be present or can develop. Some type IV lesions can be augmented after repair by this transfer.

FIGURE 21-41 Type V lesion of the subscapularis. Inset, External view.

The recommended treatment options range from débridement to reversed shoulder arthroplasty. In young patients with higher functional demand, open pectoralis major transfer is an acknowledged option.²² Open pectoralis minor transfer with or without transfer of the pectoralis major has also been described but is not normally used.²³

In indications for repair, when the subscapularis muscle is at least partially reparable, we perform a combined arthroscopic pectoralis minor transfer to the lesser tuberosity. In our experience, a partial repair of the inferior portion of the subscapularis is at least arthroscopically often possible and will bring at least a passive inferior sling effect even if the muscle has fatty degeneration greater than Goutallier stage 3. This repair is managed first and is then reinforced by the pectoralis minor transfer.

Traction sutures are passed in a lasso-loop technique at the superior and inferior border of the distal pectoralis minor tendon before it is detached from the coracoid (Figs. 21-42 and 21-43). First the traction sutures (Fig. 21-44) and then the pectoralis minor tendon are shuttled underneath the coracoid and posterior to the conjoint tendon (Fig. 21-45). In the next step, these same sutures are used to arm suture anchors for fixation to the lesser tuberosity. A coracoplasty is performed in all cases to prevent development of lateral thoracic outlet syndrome behind the conjoint tendon. This is an important issue because the combined bulk of the muscles can cause a compression of the brachial plexus or a subcoracoid impingement.

FIGURE 21-42 Brachial plexus medial to the coracoid process. Inset, External view.

FIGURE 21-43 Tenotomy of the pectoralis minor. Inset, External view.

FIGURE 21-44 Shuttling of the pectoralis minor traction sutures underneath the coracoid process. Inset, External view.

FIGURE 21-45 Shuttling of the pectoralis minor over the subscapularis partial repair. Inset, External view.

Depending on where the musculocutaneous nerve passes the conjoint tendon, significant tension might be placed on this nerve and need to be dealt with by a release. This technique allows a nonanatomic reconstruction by transferring the pectoralis minor as augmentation of the partially repaired subscapularis (Figs. 21-46 and 21-47). There are two distinct biomechanical consequences: The transferred tendon is reoriented to approach the force vector of the subscapularis muscle, and a passive restraint for anterior humeral excursion is restored.

FIGURE 21-46 Final view of the pectoralis minor reinsertion. Inset, External view.

FIGURE 21-47 Subscapularis partial repair underneath pectoralis minor transfer. Inset, External view.

Coracoid Fracture

Coracoid fractures are rare. Most coracoid fractures are seen after severe trauma and are associated with other lesions of the shoulder, such as glenohumeral or acromioclavicular dislocation, intra- and extra-articular scapula fractures, or subscapularis tendon tears. Treatment of those coracoid fractures is part of the reconstruction of the shoulder. Fractures of the lateral coracoid are often minimally displaced due to stabilizing insertions of the acromioclavicular ligament, conjoint tendon, and pectoralis minor.

Most of these fractures are treated conservatively. In significant displacement or painful pseudarthrosis, an open reduction and internal fixation is indicated.

In our experience, the coracoid, as a key landmark, is perfectly accessible to arthroscopic exploration of the anterior area. Stabilization of these rare fractures (Figs. 21-48 to 21-50) can therefore be performed arthroscopically. For osteosynthesis, depending on the fracture type, suture anchors or cannulated screws may be used (Figs. 21-51 to 21-53). The associated lesions may be treated during the same procedure. Other advantages of arthroscopic treatment are the good visual control in case of associated articular glenoid fractures and easy access to the suprascapular notch in case of suprascapular nerve entrapment in certain fracture patterns.^24,²⁵