Isolated injury to the subscapularis tendon can occur as a result of traumatic injury or chronic degeneration. While elderly and low-demand patients with small superior subscapularis tears are often minimally symptomatic and can be treated non-operatively, higher demand patients experience significant morbidity unless surgically repaired. The spectrum of injury ranges from small superior tears associated with biceps tendon subluxation to large tears and anterior glenohumeral instability.
Tears most often begin at the superior insertion where tendon fibers blend with the biceps pulley. Medial subluxation of the biceps occurs with loss of this restraint (Figure 1). Tear progression then proceeds inferiorly leading to increasing anterior instability and weakness. If left unchecked, large chronic tears can retract and will require mobilization to repair.
Knowledge of the anatomy surrounding the coracoid is imperative to avoiding iatrogenic neurovascular injury during mobilization. Historically, repair of the isolated subscapularis tear has been done through an open approach but arthroscopic techniques have evolved to allow for safe mobilization and secure repair.
The mechanism of acute traumatic tears most often involves forced external rotation and hyperextension. It is often associated with anterior glenohumeral dislocation. Patients with degenerative subscapularis tendon tears typically present with gradual progressive symptoms and pain felt in the anterior shoulder. Larger tears may cause internal rotation weakness and functional limitations. Tears are commonly encountered as part of a larger anterior superior tear also involving the supraspinatus tendon.
A thorough patient history and physical examination can raise suspicion for a subscapularis tear. Range of motion testing can reveal increased passive external rotation in large tears. Patients may also have shoulder stiffness upon presentation.
Focused strength testing includes:
The lift-off test: performed with the arm behind the patient’s back. The examiner separates the arm from the lower back and asks the patient to maintain the separation. Preferentially activates the lower subscapularis.
The belly-press: performed by asking the patient to press both hands against the belly while projecting the elbows forward. Preferentially activates the upper subscapularis.
The bear hug test: the patient is asked to place their hand on opposite shoulder at 45 degrees of flexion. The examiner tries to lift hand up and away while the patient resists.
In chronic tears the recruitment of other shoulder internal rotators can obscure the exam
Imaging workup typically includes plain radiographs which should include: an axillary view, a true anteroposterior (AP) view in external rotation, a true AP view, and a transscapular Y-view. MRI has high specificity but poor sensitivity. The addition of contrast has not been shown to improve sensitivity. MRI findings of atrophy and fatty infiltration are correlated with poorer outcomes. Medial biceps subluxation signifies a loss of the sling and injury to the subscapularis insertion. Dynamic ultrasound has shown promise as a diagnostic aid but operator dependence limits its use.
Non–operative management can be successful in select low demand patients with degenerative atraumatic tears. Physical therapy, activity modification, and anti-inflammatories are first line non-operative care. Partial subscapularis tears are at risk of progression and clinical exam should be followed closely
Indications for Surgery
Because of the stabilizing nature of the subscapularis tendon on the glenohumeral joint and lack of primary healing, operative intervention is usually warranted. Patients with traumatic tears will likely have better outcomes with early operative intervention. Degenerative atraumatic partial tears can often be treated non-operatively.
Anatomical structures at risk (All are >25 mm from the coracoid process)
Lateral cord of the brachial plexus
Surgical repair can be done via open or arthroscopic approaches. Our preferred approach is arthroscopic unless severe retraction has occurred, which may require allograft reconstruction or subcoracoid pectoralis transfer.
Arthroscopic surgery allows for inspection of the entire joint which may reveal additional pathology, which can be managed concomitantly.
Arthroscopic surgical technique
The patient is positioned in beach chair or lateral decubitus position based on surgeon preference
The shoulder is examined under anesthesia for any range of motion deficits and gentle manipulation is performed if needed
Standard posterior viewing portal
Anterior portal just lateral to coracoid process used for anchor placement into the lesser tuberosity (LT)
Anterosuperior portal, anterolateral corner of the acromion with 5-10 degree angle toward the LT, this is the primary working portal
Biceps tendon inspection
Subscapularis tears are often associated with long head of the bicep (LHB) instability and medial subluxation
Any evidence of LHB instability or intrinsic tendon injury warrants tenotomy/tenodesis
Tenotomy improves visualization for subscapularis repair
Coracoid process identification
A window is made in the rotator interval with care taken to preserve the middle glenohumeral ligament (MGHL)
In cases where the subscapularis is significantly retracted, the coracoacromial ligament can be followed to the coracoid tip
Care is taken to preserve the attachments of the conjoined tendon
Performed through the anterosuperior portal
Recessed parallel to the plane of subscapularis
Coracoidplasty is most commonly needed in degenerative tears with a decreased coracohumeral distance (normal is 7-10 mm)
Goal of coracoidplasty is to create at least 7 mm of space between the coracoid and the anterior subscapularis
Coracoidplasty can protect the repair from impingement as the arm moves into cross-body adduction (roller-wringer effect)
Inspection of the Subscapularis
Complete tears can retract significantly. It must be differentiated from the conjoined tendon and the coracoacromial (CA) ligament
The “Comma Sign” represents an arc of tissue found at the superolateral border of the torn subscapularis (Figure 2).
It is a remnant of the avulsed medial biceps sling
Identifies the superolateral aspect of the subscapularis tendon
Mobilization of the tendon
A traction suture is placed at the junction of the comma and the superolateral subscapularis tendon
A three-sided release is needed for adequate mobilization
Anterior: Use shaver/radiofrequency (RF) ablation to release adhesions to the posterolateral coracoid by skeletonizing the neck and base of coracoid (a 70 degree scope may be helpful) (Figure 3).
Superior: 15/30 elevators are used to release along the upper border of the subscapularis to the lateral arch of the coracoid, careful to stay lateral to the coracoid base
Posterior: 15/30 elevators are used to release any adhesions between subscapularis and anterior glenoid neck
Preparation of the lesser tuberosity
Shaver and burr is used to create a bleeding base for repair on the footprint
Consider medializing the footprint up to 5 mm onto the articular surface to take tension off repair if mobilization is inadequate (Figure 4).
Burkhart recommends 1 suture anchor for each vertical centimeter of tendon tear
50% tear is fixed with 1 anchor and 100% tear with 2 anchors
The inferior anchor is placed first
Anchors are placed through the anterior portal
Tension is applied to the traction suture while sutures are passed antegrade through the tendon
If two anchors are used, pass and tie the inferior anchor prior to insertion of the superior anchor
Sutures are tied through the anterosuperior portal
Open surgical technique
Allows for direct visualization of partial tears in the superior portion of the tendon that can be difficult to see with an arthroscopic approach
The deltopectoral approach is utilized
The biceps tendon, pulley, and subscapularis are inspected
The rotator interval is opened
The subscapularis tendon insertion is probed for evidence of detachment
Traction sutures are placed in the torn lateral tendinous portion of the subscapularis
A biceps tenodesis or tenotomy is usually then performed as rupture of the pulley is often present
The mobility of the subscapularis is then assessed with releases performed as necessary
Metzenbaum scissors/elevator are used to release along the superior/inferior/anterior borders
Release glenohumeral ligaments from glenoid rim as necessary
The axillary nerve is identified and if necessary a safe release of the inferior glenohumeral ligament (IGHL) is performed
The footprint on the lesser tuberosity is then prepared for the tendon insertion
Suture anchors are inserted into the lesser tuberosity placing the inferior anchors first if using more than one. Normally one is used for tears <50% and two anchors used for tears >50%
The sutures are passed in a horizontal mattress pattern through the tendon and tied (Mason-Allen used if poor tendon quality)
The rotator interval is then closed with a number-1 absorbable suture
Deltopectoral interval closed
Pearls and Pitfalls of Technique
The needle can be used to estimate the angle of anchor insertion and determine the site for the anterior portal.
The “posterior lever push” can be performed by placing a posterior directed force on the proximal humerus. This allows the intact subscapularis fibers to pull away from the footprint allowing better visualization of the insertion site.
Locating the “Comma sign” will help in identifying the superolateral aspect of the subscapularis tendon.
Small upper border subscapularis tears are often missed on MRI and definitive diagnosis can only be made upon arthroscopy.
During mobilization, extreme care should be taken not to pass instruments medial to the coracoid base and avoid plunging in the medial or inferior directions.
An unstable biceps tendon will cause repair failure if left unchecked.
Iatrogenic neurovascular injury
Inadequate mobilization and inability to perform repair
Continued pain secondary to unchecked biceps tendon pathology
Failure of repair can occur by the following mechanisms:
Persistent medial biceps instability
Inadequate coracoplasty leading to continued impingement
Insufficient tendon-bone contact area at repair site
Sling immobilization x6 weeks
Complete tears: no external rotation past 0 degrees
Partial/Small tears: passive external rotation to 30 degrees
6 weeks post-op patient may start passive stretching
12 weeks post-op patient may start strengthening
6 months post-op unrestricted activity allowed
Outcomes/Evidence in the Literature
LaFosse, L, Jost, B, Reiland, Y. “Structural integrity and clinical outcomes after arthroscopic repair of isolated subscapularis tears”. J Bone Joint Surg. vol. 89-A. 2007. pp. 1184-1193. (Seventeen consecutive patients treated with arthroscopic repair. Twelve very satisfied, 4 satisfied, 1 unsatisfied. With representative improvements in outcome scores.)
Mall, NA, Chahal, J, Heard, WM. “Outcomes of arthroscopic and open surgical repair of isolated subscapularis tendon tears”. Arthroscopy. 2012. pp. 1306-14. (Systematic review of isolated subscapularis tendon tears showing 90-95% healing rates and excellent outcomes via both arthroscopic and open techniques.)
Hinton, MA, Parker, AW, Drez, D. “An anatomic study of the subscapularis tendon and myotendinous junction”. J Shoulder Elbow Surg. vol. 3. 1994. pp. 224-229. (Superior 60% of subscapularis tendon inserts on LT as tendon, inferior 40% inserts on humeral shaft as muscle.)
Richards, DB, Burkhart, SS, Tehrany, A. “The subscapularis footprint: An anatomic description of its insertion site”. Arthroscopy. vol. 23. 2007. pp. 251-254.
Denard, PJ, Jiwani, AZ, Ladermann, A. “Long-term outcome of a consecutive series of subscapularis tendon tears repaired arthroscopically”. Arthroscopy. vol. 28. 2012. pp. 1587-1591. (At an average of 104 months post-op, patients showed >90 satisfaction.)
Adams, CR, Schoolfield, JD, Burkhart, SS. “Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy”. Arthroscopy. vol. 26. 2010. pp. 1427-1433. (MRI diagnosed 16/44 tears displaying its poor sensitivity for subscapularis tear recognition.)
Barth, JRH, Burkhart, SS, De Beer, JF. “The bear-hug test: A new and sensitive test for diagnosing a subscapularis tear”. Arthroscopy. vol. 22. 2006. pp. 1076-1084.
Lo, IKY, Burkhart, SS. “The etiology and assessment of subscapularis tendon tears: A case for subcoracoid impingement, the roller-wringer effect, and TUFF lesions of the subscapularis”. Arthroscopy. vol. 19. 2003. pp. 1142-1150.
Ferrick, MR. “Coracoid impingement: A Case Report and Review of the Literature”. Am J Sports Med V28. 2000. pp. 117-119.
Edwards, TB, Walch, G, Sirveaux, F. “Repair of tears of the subscapularis”. J Bone Joint Surg. vol. 87-A. 2005. pp. 725-730. (Tenodesis/Tenotomy of the biceps tendon was associated with improved outcomes.)
Isolated subscapularis tears can lead to significant pain and loss of function if left untreated. Degenerative atraumatic partial tears in low demand patients can often be treated non-operatively. Modern advances in arthroscopy now allow for safe mobilization of retracted tears and secure fixation. Pain and function can be reliably restored with open or arthroscopic repair techniques. Biceps tenodesis/tenotomy is associated with improved patients outcomes and should be considered in all cases.
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- The Problem
- Clinical Presentation
- Diagnostic Workup
- Non–Operative Management
- Indications for Surgery
- Surgical Technique
- Pearls and Pitfalls of Technique
- Potential Complications
- Post–operative Rehabilitation
- Outcomes/Evidence in the Literature