Comprehensive Clinical Guide: Biceps Tendon Subluxation

1. Introduction and Overview

Biceps Tendon Subluxation (BTS) represents a significant pathology of the proximal upper extremity, primarily involving the long head of the biceps brachii (LHBT) tendon as it exits the glenohumeral joint. Unlike a complete dislocation, where the tendon exits the bicipital groove entirely, subluxation is characterized by the tendon’s symptomatic, intermittent, or persistent displacement from its anatomical position within the bicipital groove, typically due to the failure of the stabilizing structures of the rotator cuff interval.

The LHBT is a unique anatomical structure; it is an intra-articular but extrasynovial structure that acts as a humeral head depressor and a stabilizer of the glenohumeral joint. When the soft tissue constraints—specifically the transverse humeral ligament, the coracohumeral ligament, and the superior glenohumeral ligament—are compromised, the tendon is prone to subluxation, leading to chronic anterior shoulder pain, mechanical symptoms, and potential secondary rotator cuff pathology.

2. Technical Specifications and Pathophysiology

The Anatomy of Stability

The bicipital groove (intertubercular sulcus) serves as the primary conduit for the LHBT. Stability is maintained by a "roof" formed by the transverse humeral ligament (THL) and the medial fibers of the rotator cuff, specifically the subscapularis and supraspinatus tendons.

The Mechanism of Failure

Pathophysiology usually involves a "peel-back" or traumatic injury to the rotator cuff interval.
* The Rotator Cuff Interval (RCI): A triangular space between the subscapularis and supraspinatus.
* The Pulley System: The "biceps pulley" is a complex of ligaments (SGHL, CHL) that anchors the LHBT. If this pulley system is disrupted—often due to a subscapularis tear—the LHBT is no longer tethered and will subluxate medially over the lesser tuberosity.

Pathological Classification

3. Clinical Indications, Presentation, and Diagnosis

Standard Clinical Presentation

Patients typically present with a history of anterior shoulder pain that radiates down the anterior aspect of the humerus.
* Mechanical Symptoms: Patients often report an audible "pop" or "click" during internal/external rotation of the arm.
* Pain Profile: Pain is exacerbated by overhead activities, lifting, and activities involving rapid rotation of the shoulder.
* Night Pain: Common, especially when lying on the affected side.

Physical Examination Maneuvers

A thorough physical exam is required to differentiate BTS from primary rotator cuff tears or SLAP lesions.

1. Speed’s Test: Resisted forward flexion of the shoulder with the elbow extended and forearm supinated.
2. Yergason’s Test: Resisted supination of the forearm with the elbow flexed at 90 degrees; a positive test reproduces pain in the bicipital groove or a palpable "snap."
3. Lippman’s Test: Manual displacement of the biceps tendon within the groove; positive if pain is reproduced.

Differential Diagnosis

It is critical to exclude the following before confirming BTS:
* SLAP Lesions: Superior Labrum Anterior to Posterior tears.
* Subscapularis Tears: Often coexist with BTS; the subscapularis is the primary medial stabilizer.
* Adhesive Capsulitis: Often presents with global stiffness rather than focal bicipital pain.
* Glenohumeral Osteoarthritis: General joint degeneration.

4. Diagnostic Imaging Protocols

Ultrasonography (Dynamic)

Dynamic ultrasound is the "gold standard" for real-time visualization of the tendon. The clinician can observe the tendon moving out of the groove during active rotation, providing immediate confirmation of subluxation.

Magnetic Resonance Imaging (MRI) / MRA

• T1/T2 Weighted Sequences: Used to visualize the "empty groove" sign, where the bicipital groove lacks the presence of the tendon.
• Magnetic Resonance Arthrography (MRA): The injection of contrast into the glenohumeral joint helps identify subtle pulley system ruptures and associated labral pathology.

5. Management Strategies

Conservative Management

For mild or acute presentations, a conservative approach is the first line of defense:
* Activity Modification: Avoidance of overhead loading.
* NSAIDs: To manage the inflammatory component (tenosynovitis).
* Physical Therapy: Focus on rotator cuff strengthening (specifically the subscapularis) and scapular stabilization.

Surgical Intervention

If conservative measures fail (typically after 3–6 months), surgery is indicated.
* Biceps Tenodesis: The gold standard for symptomatic, recalcitrant subluxation. The tendon is detached from its proximal attachment and re-anchored to the humerus.
* Biceps Tenotomy: Indicated for older, lower-demand patients; the tendon is released, allowing it to retract into the groove.

6. Risks, Side Effects, and Contraindications

Surgical Risks

• Popeye Deformity: More common with tenotomy, where the muscle belly bunches distally.
• Infection: Standard risks associated with arthroscopic procedures.
• Hardware Failure: In tenodesis, the anchor may pull out if the patient returns to heavy lifting too early.

Contraindications

• General Health: Patients with severe systemic illness or active infection.
• Clinical Misdiagnosis: Do not perform tenodesis if the primary source of pain is actually a massive irreparable rotator cuff tear or advanced arthritis, as the procedure may not yield symptomatic relief.

7. Frequently Asked Questions (FAQ)

1. Is Biceps Tendon Subluxation the same as a SLAP tear?

No, they are distinct. A SLAP tear involves the superior labrum where the biceps attaches. Subluxation involves the tendon moving out of the bicipital groove. However, they frequently coexist.

2. Can I heal a subluxated tendon without surgery?

Yes, minor subluxation can be managed with physical therapy focused on the subscapularis, which acts as the "gatekeeper" for the tendon.

3. What is the "Popeye Deformity"?

It is the cosmetic appearance of a prominent muscle belly in the mid-upper arm, caused by the biceps muscle retracting after a tenotomy or a spontaneous rupture.

4. How long is the recovery after Biceps Tenodesis?

Generally, 3–6 months. The first 6 weeks require a sling to protect the anchor, followed by progressive strengthening.

5. Why does my shoulder "pop" when I move it?

The pop is likely the biceps tendon snapping over the lesser tuberosity as it slips out of its groove during rotation.

6. Is ultrasound better than MRI for this diagnosis?

Ultrasound is better for dynamic assessment (watching the movement), while MRI is better for evaluating the entire joint (labrum, cartilage, and cuff).

7. What happens if I ignore the symptoms?

Chronic subluxation leads to progressive tenosynovitis, fraying of the tendon, and eventually, a full-thickness rupture of the biceps tendon.

8. Will I lose strength if I have a tenodesis?

Most patients regain full function, though there may be a minor loss in peak supination strength.

9. Who is most at risk for this condition?

Athletes involved in throwing sports, overhead laborers (painters, construction workers), and patients with existing rotator cuff disease.

10. Does a steroid injection help?

Steroid injections into the bicipital groove can provide temporary relief of inflammation but must be used sparingly, as they can weaken the tendon and increase the risk of subsequent rupture.

8. Long-Term Prognosis and Clinical Outcomes

The prognosis for surgically treated Biceps Tendon Subluxation is excellent. Most clinical studies report that patients experience high levels of pain relief and a return to pre-injury activity levels. Success is heavily dependent on the integrity of the associated rotator cuff; if a subscapularis tear is present and left unaddressed during the biceps procedure, the clinical outcome will be suboptimal.

Summary Table: Treatment Decision Matrix

Clinical Conclusion

Biceps Tendon Subluxation is a mechanical failure of the shoulder's stabilization system. Success in clinical practice requires a high index of suspicion, precise diagnostic imaging, and a surgical strategy that addresses both the biceps tendon and the underlying rotator cuff pathology. By prioritizing the restoration of the "pulley" anatomy, orthopedists can effectively restore function and eliminate the chronic mechanical pain associated with this condition.