Subscapularis Tears

The subscapularis accounts for 10-25% of rotator cuff tears and was historically underdiagnosed. A tear costs internal-rotation strength and anterior shoulder function, and associated biceps problems are common. Recognising the tear and treating it appropriately improves outcomes.

Who. Males predominate, which is attributed to occupational factors, and heavy labourers are at higher risk. The fifth and sixth decades are the common ages. The tear often comes with other cuff tears, as part of an anterosuperior pattern.

Causes. The aetiology is traumatic or degenerative. The tendon also fails after surgery and in massive cuff tears, and subcoracoid stenosis contributes:

• Traumatic - hyperextension or forced external rotation
• Degenerative - anterior impingement
• Iatrogenic - after shoulder surgery, arthroplasty in particular
• Massive cuff tears - the subscapularis tear is associated with them
• Subcoracoid stenosis - a contributing factor

The muscle. The subscapularis is the only internal rotator of the rotator cuff, and inserts on the lesser tuberosity through a broad tendon. The long head of biceps runs in the groove between it and the supraspinatus.

Tendon above, muscle below. The upper 60% of the insertion is tendinous and holds sutures, so it can be repaired to anchors. The lower 40% is muscular, holds sutures poorly, and may need margin convergence.

Why the upper fibres fail first. The upper fibres are intra-articular, within the biceps sheath, and they tear first; full-thickness tears then extend from superior to inferior. The lower fibres are extra-articular and better protected.

What the muscle does. Internal rotation is its primary function. It is also an anterior stabiliser of the humeral head, a humeral head depressor with the rest of the cuff, and it forms a force couple with the posterior cuff, infraspinatus and teres minor, the external rotators. Losing it disrupts that force-couple balance, and repair restores the anterior restraint and the balance with it.

Landmarks. Five structures frame the subscapularis:

• Lesser tuberosity - the insertion
• Biceps groove - the lateral border
• Comma sign - the SGHL complex at the superior edge
• Coracoid process - anterior
• Biceps pulley - at the junction with supraspinatus

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What the pulley is. The biceps reflection pulley is a sling at the entrance of the bicipital groove that holds the long head of biceps in the groove. It is formed by the superior glenohumeral ligament (SGHL) and coracohumeral ligament (CHL), reinforced medially by the superior border of the subscapularis and laterally by fibres of the supraspinatus.

Why an upper subscapularis tear destabilises the biceps. The upper subscapularis is the medial wall of the sling, so a tear of the upper fibres opens the medial pulley and the biceps subluxes or dislocates medially. On axial MRI the biceps lies medial to the groove, often draped over or into the torn subscapularis. This is the classic "hidden lesion", easily missed if only the main cuff is inspected, and the biceps may also be torn.

The comma sign. The SGHL/CHL complex runs with the superior edge of the subscapularis. In a complete tear it is avulsed with the superolateral corner of the tendon and becomes visible, hanging like a comma. Following the comma leads to both the retracted subscapularis stump and the disrupted pulley, and it marks where the repair should begin, which makes it a key arthroscopic landmark.

The practical consequence. The tear and the biceps instability share the pulley, so the biceps is evaluated whenever the subscapularis is assessed. An unstable biceps must not be left in situ, which is why tenotomy or tenodesis is routine at subscapularis repair when the pulley has failed. The biceps-side decision-making is developed in the biceps topic.

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Fox and Romeo grade the tear by how much of the tendon has failed, from a partial articular-surface lesion to complete detachment. Lafosse grades extent as well and adds fatty infiltration as a prognostic factor, with a global anterosuperior tear at the top of the scale.

What the grade does not decide. The Fox and Romeo grade has been linked to treatment: debridement with or without repair for Type 1, arthroscopic repair for Types 2 and 3, and repair with or without tendon transfer for Type 4. Classification communicates morphology, though; it does not replace the clinical indication or the assessment of reparability.

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History. Anterior shoulder pain and internal-rotation weakness, noticed in tasks such as tucking in a shirt. Ask about:

• Trauma - hyperextension or forced external rotation
• Prior shoulder surgery - arthroplasty carries a particular risk
• Symptoms of associated biceps pathology

Examination. Tests that target the subscapularis:

• Lift-off (Gerber) - the hand behind the back is lifted off it against resistance; positive if the patient cannot
• Bear-hug - the hand on the opposite shoulder resists the examiner pushing the arm into external rotation; positive if weak
• Napoleon (belly-press) - the hand presses into the abdomen; the wrist flexing rather than staying straight is positive, the patient compensating for a weak subscapularis
• Internal-rotation lag sign

Assess the biceps as well, with Speed's and Yergason's tests.

Radiographs come first: AP, axillary and outlet views. They are of limited value for soft tissue, but may show lesser tuberosity changes or abnormalities of the biceps groove, and they rule out arthritis or fracture.

Ultrasound is optional. It assesses the subscapularis dynamically and can visualise tears, but it is operator-dependent and less reliable than MRI for the subscapularis specifically.

MRI is the best imaging modality and the essential one. Axial views show the subscapularis and its lesser tuberosity insertion: look for tendon discontinuity at the footprint and biceps subluxation medial to the groove. Sagittal views assess fatty infiltration, graded by Goutallier, and the scan should also be read for associated supraspinatus pathology, the anterosuperior cuff tear.

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Muscle quality. The sagittal series below runs from a normal muscle through the grades of atrophy and fatty infiltration.

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Non-operative care is worth considering when:

• Symptoms and the functional deficit are acceptable
• A low-grade lesion is not clearly the pain generator
• Host risk or chronic irreparability outweighs the expected benefit of surgery

Repair is worth considering when:

• A traumatic or progressive tear causes meaningful internal-rotation weakness, pain or anterior force-couple failure
• The tendon can reach the lesser tuberosity with acceptable tension and tissue quality
• Associated cuff or biceps-pulley pathology is being addressed and repair improves the global construct

The irreparable complete tear. The choice lies among compensation, arthroplasty and tendon transfer, according to glenohumeral arthritis, humeral-head centring, deltoid and cuff function, age, goals and the available donor.

The non-operative programme. Activity modification, analgesia, restoration of range and progressive cuff and scapular strengthening. Painful resisted internal rotation is modified early, then function is rebuilt. An injection may control symptoms but does not heal the tendon.

When it is not working. Reassess persistent weakness, instability or progression, rather than declaring non-operative treatment a failure after a fixed duration.

The imaging review confirms the tear extent on MRI and records the Goutallier grade, the position of the biceps, any associated supraspinatus tear and the coracoid morphology.

The surgical plan covers:

• Beach chair or lateral position
• Be prepared for a biceps procedure
• Plan the number and placement of anchors
• Consider subcoracoid decompression if there is stenosis
• Have a pectoralis major transfer as the backup if the tear proves irreparable

Visualisation. From the standard posterior viewing portal, rotate the arm into external rotation to see the subscapularis insertion; complete visualisation of the subscapularis requires it. Identify the lesser tuberosity, assess the biceps tendon and pulley, and in a complete tear look for the comma sign at the superior edge.

Pitfalls. Do not repair under tension, and do not place the anchors too laterally. Use the comma sign as the guide, consider subcoracoid decompression, and do not forget to assess the posterior cuff or to evaluate fatty infiltration. The repair is then protected after surgery.

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Indication. A symptomatic irreparable anterior cuff, with advanced fatty infiltration, retraction or attritional tissue, in a patient with functional demand, preserved passive motion and no significant glenohumeral arthritis. Arthritis or a massive combined tear points instead to reverse arthroplasty.

The subcoracoid (Resch) technique. The superior half-to-two-thirds of the pectoralis major is detached and ideally routed deep to (behind) the conjoint tendon to the lesser tuberosity. Passing behind the conjoint tendon, which then acts as a pulley, redirects the muscle's line of pull to better approximate the subscapularis vector.

The supracoracoid alternative. Transfer superficial to (in front of) the conjoint tendon is technically simpler but more non-anatomic, a straighter transverse pull, and it risks tethering the musculocutaneous nerve. The trade is ease against a less physiological vector.

Its ceiling, and the alternatives. Pectoralis major pulls in a different plane from the subscapularis, so the transfer reliably relieves pain and restores anterior stability but only partially restores internal-rotation strength. A lower-trapezius or latissimus dorsi transfer matches the line of pull more closely and some now prefer it, though there are no head-to-head trials to separate them.

Nerves at risk. The axillary nerve runs anteroinferiorly and the musculocutaneous nerve enters coracobrachialis near the coracoid, so anterior instrumentation should be cautious. Subcoracoid decompression must avoid overly aggressive bone removal near the coracoid tip.

The protocol exists to keep internal-rotation load off the repair, because internal rotation loads it directly.

The restrictions that sit alongside it:

• No active internal rotation for 6-8 weeks
• Avoid behind-the-back movements initially
• Sleep in the sling for 4-6 weeks
• Progress gradually to full activity

Who does well. Smaller tears (Types 1-2), acute tears, minimal fatty infiltration, younger patients and an isolated subscapularis tear predict a good result. Larger tears (Type 4), chronic tears, significant fatty infiltration (Goutallier 3-4), older patients and a combined anterosuperior tear predict a worse one.

A caution on the Goutallier grade. The grading was derived on the posterosuperior cuff, as the evidence card below sets out, so applying its thresholds to the subscapularis is an extrapolation, and the widely taught rule that grade 3 to 4 means irreparable, transfer instead, has never been validated against subscapularis outcomes in the Goutallier paper or by it.

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Global epidemiology. Subscapularis involvement is found in roughly 10-25% of surgically treated rotator cuff tears, but arthroscopic series report a far higher rate of upper-fibre lesions (up to 27-30% of all shoulder arthroscopies in some cohorts) once surgeons actively look for them. The classic isolated traumatic tear (forced hyperextension/external rotation) affects predominantly middle-aged men; degenerative anterosuperior tears affect both sexes in the 6th-7th decades.

Related pages: Rotator Cuff Tears is the parent topic and carries the posterosuperior cuff on which the Goutallier grading carded here was actually derived; Massive Rotator Cuff Tears for the anterosuperior escape pattern that a subscapularis tear produces when the supraspinatus has also failed, which is the situation none of the transfer series above studied; Biceps Tendon Pathology and Proximal Biceps Ruptures for the long head, whose medial subluxation out of the groove is the single most reliable imaging clue to a subscapularis tear and whose pulley is the 'hidden lesion' this page describes; Subcoracoid Impingement for the narrowed coracohumeral interval that both causes and accompanies upper-border tears, and for the coracoplasty decision; Lesser Tuberosity Fractures for the bony equivalent of the same avulsion, which is repaired as a fracture rather than as a tendon and is the diagnosis to exclude in the adolescent; Pectoralis Major Anatomy and Pectoralis Major Rupture for the donor in the Resch transfer, including the sternal-versus-clavicular head distinction that determines the vector; Musculocutaneous Nerve Anatomy for the structure at risk when the transfer is routed behind the conjoint tendon, and Axillary Nerve Anatomy for the nerve Gerber warns must be protected during open repair; Anterior Shoulder Instability for the differential in a patient whose dominant complaint is giving way rather than weakness; Reverse Total Shoulder Arthroplasty for the endpoint when the anterosuperior cuff is unreconstructable; and Shoulder Arthroplasty Complications for subscapularis failure after anatomic replacement, which is now the commonest setting in which this tendon is found deficient.