Subscapularis Repair, Coracoid Recession, and Biceps Tenodesis: An Intraoperative Masterclass

Introduction and Epidemiology

Subscapularis tendon tears represent a distinct and often challenging clinical entity within the spectrum of rotator cuff pathology. Historically considered less common than supraspinatus or infraspinatus tears, subscapularis tears are identified in 2% to 8% of all rotator cuff tears. However, true prevalence is likely higher, as these lesions are frequently missed during routine glenohumeral arthroscopy due to their anterior location and the obscuring nature of the rotator interval tissue.

Subscapularis tears present in several morphological variants: isolated tears (which can be partial or complete), partial-thickness articular-sided tears, anterosuperior tears (involving the supraspinatus), and rotator interval lesions with associated long head of the biceps tendon (LHBT) injury. There is a well-documented, high association of concomitant biceps tendon pathology in the presence of subscapularis tearing.

In younger patient populations, subscapularis tears typically occur secondary to acute trauma. The classic mechanism of injury involves forced hyperextension of an externally rotated arm or forced external rotation of an adducted arm. Conversely, in older patients, tears are typically degenerative in nature, progressing insidiously, though they may also manifest acutely following a glenohumeral dislocation. Subcoracoid impingement acts as a significant etiologic factor in both demographics. A subcoracoid distance of less than 6 mm defines subcoracoid stenosis and significantly increases the risk of attritional subscapularis tearing, whereas the normal coracohumeral interval typically measures between 8.4 and 11 mm.

Natural History and Tear Classification

Isolated subscapularis tendon ruptures remain relatively rare. More frequently, subscapularis tears are associated with posterosuperior rotator cuff extension. Large-scale magnetic resonance imaging (MRI) analyses of patients with rotator cuff tears demonstrate that of those with subscapularis involvement, approximately 27% are partial-thickness tears and 73% are full-thickness tears. Furthermore, over 50% of these patients exhibit concomitant biceps pathology, including medial subluxation, tenosynovitis, or complete rupture.

The Lafosse classification system is the standard academic framework for categorizing subscapularis tears:
* Type I: Partial lesion of the superior third.
* Type II: Complete lesion of the superior third.
* Type III: Complete lesion of the superior two-thirds.
* Type IV: Complete lesion of the entire subscapularis with a centered humeral head.
* Type V: Complete lesion of the entire subscapularis with anterosuperior humeral head subluxation and severe fatty infiltration.

Surgical Anatomy and Biomechanics

A profound understanding of anterior shoulder anatomy is prerequisite for successful subscapularis repair and biceps management. The subscapularis muscle is the largest and strongest of the rotator cuff muscles, providing more than 50% of the total cuff strength.

Myotendinous Architecture and Innervation

The subscapularis originates from the subscapular fossa of the anterior scapula. Its insertion footprint on the lesser tuberosity is broad, measuring approximately 40 mm superior to inferior and 20 mm medial to lateral. The superior two-thirds of the muscle inserts as a distinct tendinous structure onto the lesser tuberosity, whereas the inferior one-third inserts directly as muscle fibers onto the surgical neck and humeral metaphysis.

Innervation is supplied by the upper and lower subscapular nerves, originating from the posterior cord of the brachial plexus (C5-C8). The upper subscapular nerve innervates the superior portion of the muscle, while the lower subscapular nerve innervates the inferior portion. The axillary nerve passes inferior to the subscapularis muscle belly, exiting the axilla through the quadrangular space. Surgical dissection inferior to the equator of the subscapularis places the axillary nerve at significant risk.

The Rotator Interval and Biceps Pulley

The superior border of the subscapularis forms the inferior boundary of the rotator interval. The upper fibers of the subscapularis and the anterior fibers of the supraspinatus contribute to the rotator interval capsule and the transverse humeral ligament.

The coracohumeral ligament (CHL) forms the roof of the rotator interval, blending with the supraspinatus and subscapularis tendons. The CHL and the superior glenohumeral ligament (SGHL) are the primary stabilizers of the LHBT. When the superior subscapularis tears, the SGHL and CHL often tear or avulse with it, creating the arthroscopic "comma sign"—a comma-shaped arc of tissue that represents the avulsed medial sling of the biceps. Identification of the comma sign is a critical intraoperative landmark for locating the retracted superolateral corner of the subscapularis tendon.

The biceps muscle is innervated by the musculocutaneous nerve (C5-C6). The LHBT originates from the supraglenoid tubercle and superior labrum, traveling through the intertubercular groove. It provides superior shoulder stability during abduction and posterior stability during mid-ranges of elevation.

Biomechanical Principles

The subscapularis acts as the primary internal rotator of the humerus, working synergistically with the teres major, latissimus dorsi, and pectoralis major. Biomechanically, it is the anterior component of the transverse force couple of the shoulder, balancing the posterior forces generated by the infraspinatus and teres minor. This force couple is essential for maintaining concavity compression of the humeral head within the glenoid fossa. The subscapularis also resists anterior and inferior translation of the humeral head.

Indications and Contraindications

The decision to proceed with surgical intervention depends on patient age, functional demands, chronicity of the tear, and the degree of muscular atrophy and fatty infiltration. Clinical examination findings such as a positive lift-off test, belly-press test, or bear-hug test are highly specific for subscapularis insufficiency.

Pre Operative Planning and Patient Positioning

Thorough preoperative planning relies heavily on advanced imaging. MRI is the gold standard for evaluating subscapularis tears, assessing the integrity of the LHBT, and quantifying fatty infiltration.

Advanced Imaging Analysis

Axial MRI cuts are paramount for visualizing the subscapularis footprint on the lesser tuberosity and evaluating medial subluxation of the biceps tendon. Sagittal oblique views are utilized to assess muscle trophism and fatty infiltration using the Goutallier classification. T1-weighted sagittal images allow the surgeon to evaluate the volume of the subscapularis muscle belly relative to the scapular body.

The coracohumeral interval must be measured on axial cuts. A distance of less than 6 mm indicates subcoracoid stenosis, which necessitates a planned coracoidplasty during the surgical procedure to prevent postoperative impingement and protect the repair.

Patient Positioning and Setup

Subscapularis repair can be performed in either the beach chair or lateral decubitus position, depending on surgeon preference.

The beach chair position offers distinct advantages for anterior shoulder work. It allows for anatomical orientation of the anterior structures, facilitates dynamic examination of the arm in various degrees of rotation, and provides unencumbered access to the anterior portal for anchor placement and subcoracoid decompression. The arm is typically placed in a hydraulic or pneumatic arm positioner, allowing the surgeon to control internal and external rotation dynamically, which is critical for bringing the lesser tuberosity into the operative field.

If the lateral decubitus position is utilized, the arm is placed in balanced suspension with 45 degrees of abduction and 15 to 20 degrees of forward flexion. While this provides excellent visualization of the glenohumeral joint, accessing the inferior aspect of the subscapularis footprint can be more challenging due to the trajectory of the anterior portals.

Detailed Surgical Approach and Technique

Advanced arthroscopic repair of the subscapularis requires meticulous technique, precise portal placement, and systematic mobilization of the tendon.

Portal Placement

Standard posterior and anterior portals are established. An anterosuperior portal is often created just off the anterolateral corner of the acromion to serve as a viewing portal for the anterior compartment. An accessory anteroinferior portal (frequently placed just superior to the upper border of the subscapularis) is critical for anchor insertion at the correct trajectory relative to the lesser tuberosity.

Diagnostic Arthroscopy and Biceps Management

The procedure begins with a thorough diagnostic arthroscopy from the posterior portal. The surgeon must specifically evaluate the rotator interval and the insertion of the subscapularis. Because the subscapularis is an anterior structure, standard viewing from the posterior portal may obscure a partial articular-sided tear. Using a 70-degree arthroscope or viewing from an anterior portal is highly recommended to fully visualize the footprint.

Given the high association of biceps pathology, the LHBT must be addressed. If the subscapularis is torn, the medial sling (SGHL/CHL) is invariably compromised, leading to medial subluxation of the biceps. In nearly all cases of subscapularis repair, the LHBT should be tenotomized or tenodesed to prevent postoperative failure of the subscapularis repair caused by the mechanical disruption of an unstable biceps tendon. Biceps tenodesis can be performed suprapectorally or subpectorally, depending on the extent of tendinopathy and surgeon preference.

Subcoracoid Decompression

If preoperative imaging demonstrates a coracohumeral interval of less than 6 mm, or if intraoperative dynamic testing reveals impingement of the subscapularis against the coracoid during internal rotation, a coracoidplasty is indicated.

Using a radiofrequency wand and an arthroscopic burr through the anterior portal, the lateral and posterolateral aspects of the coracoid process are resected. The resection should achieve a minimum clearance of 7 to 8 mm between the coracoid and the subscapularis tendon. Care must be taken to avoid dissecting too medially to protect the conjoined tendon and the musculocutaneous nerve.

Tendon Mobilization and the Comma Sign

Chronic subscapularis tears often retract medially and scar to the anterior glenoid neck and base of the coracoid. The key to anatomical reduction is the identification of the "comma sign." This tissue arc represents the avulsed SGHL/CHL complex and remains attached to the superolateral corner of the retracted subscapularis tendon.

By placing a traction suture through the comma tissue, the surgeon can apply lateral tension to the subscapularis. Extensive releases are often required for Lafosse Type III and IV tears. These releases include:
1. Anterior Release: Freeing the tendon from the subcoracoid bursa and the base of the coracoid.
2. Superior Release: Dividing the interval tissue separating the subscapularis from the supraspinatus.
3. Posterior/Articular Release: Releasing the capsule from the anterior glenoid neck. Care must be taken to stay superior to the equator to avoid the axillary nerve.

Footprint Preparation and Anchor Placement

Once the tendon is fully mobilized and can reach the lesser tuberosity without undue tension, the footprint is prepared. The lesser tuberosity is debrided of soft tissue to a bleeding cancellous bone bed using a burr.

The arm is placed in internal rotation to bring the lesser tuberosity into view. For Lafosse Type I and II tears, a single-row repair using one or two suture anchors is typically sufficient. For larger Type III and IV tears, a double-row or suture-bridge construct is biomechanically superior, providing increased footprint coverage and compression.

Anchors are placed starting inferiorly and moving superiorly. The inferior anchor is the most challenging due to the neurovascular structures and the required trajectory. It is placed through the accessory anteroinferior portal.

Suture Passage and Fixation

Sutures are passed through the subscapularis tendon using a penetrating tissue grasper or a suture shuttle relay. Sutures from the inferior anchor are passed through the inferior aspect of the tendon, and sutures from the superior anchor are passed through the superior aspect.

Knot tying or knotless fixation is performed with the arm in approximately 20 to 30 degrees of internal rotation to minimize tension on the repair. If a double-row technique is utilized, the medial row is tied, and the suture tails are brought laterally to knotless anchors on the lateral aspect of the lesser tuberosity, creating a compression bridge.

Complications and Management

Arthroscopic subscapularis repair is a technically demanding procedure with a specific complication profile. Anticipation and prevention are the mainstays of managing these risks.

Management of the Failed Repair

In cases of catastrophic structural failure or massive, irreparable subscapularis tears (Lafosse Type V), salvage options must be considered. Pectoralis major tendon transfer is the historical gold standard for irreparable subscapularis deficiency in young, active patients. The sternal head of the pectoralis major is transferred either over or under the conjoined tendon to the lesser tuberosity. In older patients with pseudoparalysis or concomitant glenohumeral arthritis, Reverse Total Shoulder Arthroplasty (RTSA) is the treatment of choice, providing reliable pain relief and restoration of forward elevation.

Post Operative Rehabilitation Protocols

Rehabilitation following subscapularis repair requires a delicate balance between protecting the healing tendon and preventing anterior capsular stiffness. The protocol is highly dependent on the size of the tear, the tension of the repair, and the quality of the tissue.

Phase I: Maximum Protection (Weeks 0-6)

The patient is immobilized in a sling with an abduction pillow, typically positioning the arm in neutral to slight internal rotation.
* Passive range of motion (PROM) is initiated early to prevent stiffness, but external rotation (ER) is strictly limited. The safe zone for ER is determined intraoperatively (usually limited to neutral or 30 degrees).
* Forward elevation in the scapular plane is permitted up to 90-120 degrees.
* Active internal rotation and extension are prohibited to prevent active firing and stretching of the repaired tendon.

Phase II: Active Assisted and Active Motion (Weeks 6-12)

The sling is discontinued.
* Active-assisted range of motion (AAROM) transitions to active range of motion (AROM).
* External rotation stretching is gradually progressed beyond the intraoperative safe zone.
* Isotonic strengthening of the posterior cuff and periscapular stabilizers is initiated.

Phase III: Strengthening and Return to Activity (Weeks 12-24)

• Resisted internal rotation strengthening begins at 12 weeks.
• Progressive functional strengthening is implemented.
• Return to heavy labor or contact sports is generally restricted until 5 to 6 months postoperatively, contingent upon the recovery of symmetrical strength and dynamic stability.

Summary of Key Literature and Guidelines

The academic understanding of subscapularis pathology has evolved significantly over the past two decades. Key literature emphasizes the importance of early recognition and the biomechanical necessity of restoring the anterior force couple.

1. Lafosse et al. (2007): Established the standard classification system for subscapularis tears based on arthroscopic findings, guiding both the surgical approach and the expected prognosis. Their work highlighted that arthroscopic repair of isolated subscapularis tears yields excellent clinical outcomes with low retear rates when the comma sign is utilized for reduction.
2. Burkhart and Tehrany (2002): Popularized the concept of the "comma sign." Their anatomical studies demonstrated that the superior glenohumeral ligament and the coracohumeral ligament consistently remain attached to the superolateral corner of the torn subscapularis, providing a reliable landmark for identifying and mobilizing retracted tears.
3. Gerber et al. (1996): Provided foundational biomechanical data on the transverse force couple of the shoulder. Their work elucidated how subscapularis insufficiency leads to altered glenohumeral kinematics, increased superior translation of the humeral head, and progressive degeneration of the remaining rotator cuff.
4. Richards et al. (2014): Evaluated the relationship between subcoracoid stenosis and subscapularis tears. Their MRI analysis confirmed that a coracohumeral distance of less than 6 mm is a significant independent risk factor for subscapularis tearing, validating the routine use of coracoidplasty in these patients.
5. Denard et al. (2012): Investigated the outcomes of biceps tenodesis versus tenotomy in the setting of subscapularis repair. The consensus literature now strongly supports mandatory intervention for the LHBT in the presence of subscapularis pathology to prevent mechanical disruption of the repair construct.

In conclusion, the successful management of subscapularis tendon tears demands rigorous preoperative evaluation, advanced arthroscopic proficiency, and a comprehensive strategy for addressing concomitant biceps and subcoracoid pathology. Adherence to these academic principles ensures the restoration of the anterior force couple and optimal functional outcomes for the patient.

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