Reverse Bankart Lesion: Understanding Causes, Symptoms, Diagnosis, and Treatment

What is Reverse Bankart Lesion?

A reverse Bankart lesion is a specific type of injury involving the posterior aspect of the shoulder's glenoid labrum, most commonly resulting from a posterior shoulder dislocation, leading to instability and pain.

Understanding the Shoulder Joint Anatomy

To comprehend a reverse Bankart lesion, it's crucial to first understand the anatomy of the shoulder joint. The shoulder, or glenohumeral joint, is a ball-and-socket joint formed by the head of the humerus (upper arm bone) and the glenoid fossa (a shallow socket) of the scapula (shoulder blade). This design offers an extraordinary range of motion, making it the most mobile joint in the body.

However, this mobility comes at the cost of inherent stability. Several structures contribute to shoulder stability:

• Glenoid Labrum: A fibrocartilaginous rim that surrounds the glenoid fossa, deepening the socket by approximately 50%. It acts like a bumper, enhancing the contact area between the humeral head and the glenoid.
• Joint Capsule: A fibrous sac enclosing the joint, reinforced by ligaments.
• Rotator Cuff Muscles: A group of four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) and their tendons that surround the shoulder joint, providing dynamic stability and facilitating movement.
• Ligaments: Strong fibrous bands that connect bones and provide passive stability.

What is a Bankart Lesion?

The term "Bankart lesion" typically refers to an injury to the anterior-inferior aspect of the glenoid labrum. This is the most common type of labral tear associated with shoulder dislocations, particularly anterior shoulder dislocations, where the humeral head moves forward and out of the socket. During such a dislocation, the humeral head can forcefully peel the labrum away from the bone, sometimes even taking a piece of bone with it (a bony Bankart lesion). This detachment compromises the shoulder's stability, making it prone to recurrent dislocations.

Defining the Reverse Bankart Lesion

A reverse Bankart lesion is the anatomical inverse of the more common anterior Bankart lesion. It involves the detachment of the posterior-inferior aspect of the glenoid labrum from the posterior rim of the glenoid. This injury is almost exclusively associated with posterior shoulder dislocations, where the humeral head is forced backward and out of the socket.

Mechanism of Injury

Posterior shoulder dislocations, and consequently reverse Bankart lesions, are far less common than anterior dislocations, accounting for only 2-5% of all shoulder dislocations. They typically result from:

• Direct Trauma: A direct blow to the front of the shoulder while the arm is internally rotated and adducted.
• Indirect Forces:
  • Falls: Falling on an outstretched arm that is internally rotated and adducted.
  • Seizures: Uncontrolled muscle contractions during a seizure can generate powerful forces that dislocate the shoulder posteriorly.
  • Electrocution: Similar to seizures, high-voltage electrical shocks can cause violent muscle contractions leading to posterior dislocation.
  • Sports Injuries: Less common, but can occur in contact sports or activities involving forceful internal rotation and adduction (e.g., a lineman blocking in football, a forceful tackle).

The force drives the humeral head posteriorly, tearing the labrum from its attachment to the posterior glenoid rim.

Associated Injuries

A significant proportion of reverse Bankart lesions are accompanied by a reverse Hill-Sachs lesion. This is an impaction fracture (a dent or divot) on the anterior aspect of the humeral head. It occurs when the humeral head impacts the posterior glenoid rim during the dislocation event, causing a compression fracture on the opposite side of the humeral head from a standard Hill-Sachs lesion. The presence of both a reverse Bankart and a reverse Hill-Sachs lesion indicates a more severe injury and often contributes to persistent instability.

Signs and Symptoms

Individuals with a reverse Bankart lesion typically present with symptoms related to shoulder pain and instability, often following a traumatic event. Common signs and symptoms include:

• Posterior Shoulder Pain: Pain localized to the back of the shoulder, often exacerbated by movement.
• Shoulder Instability: A feeling that the shoulder is "giving way" or "slipping out" of joint, particularly with certain arm positions (e.g., internal rotation and adduction).
• Limited Range of Motion: Difficulty moving the arm, especially into external rotation and abduction.
• Weakness: Perceived or actual weakness in the affected arm.
• Crepitus: A grinding, clicking, or popping sensation within the joint.
• Deformity: In acute dislocations, a visible deformity of the shoulder may be present, with the arm often held in internal rotation and adduction.
• Apprehension: A feeling of fear or apprehension when the arm is moved into positions that might provoke another dislocation.

Diagnosis

Diagnosing a reverse Bankart lesion requires a thorough clinical evaluation and advanced imaging.

• Clinical Examination:
  • History: The physician will inquire about the mechanism of injury, prior dislocations, and current symptoms.
  • Physical Exam: Assessment of pain, range of motion, stability, and specific provocative tests. The posterior apprehension test (attempting to dislocate the shoulder posteriorly while monitoring patient apprehension) and posterior load and shift test can indicate instability.
• Imaging Studies:
  • X-rays: Initial plain radiographs (AP, Y-view, axillary lateral views) are crucial to identify dislocations, fractures (including a reverse Hill-Sachs lesion), or other bony abnormalities. Posterior dislocations can sometimes be subtle on standard X-rays.
  • Magnetic Resonance Imaging (MRI): An MRI, particularly an MRI arthrogram (where contrast dye is injected into the joint before the scan), is the gold standard for visualizing soft tissue injuries like labral tears. The contrast helps outline the labrum and detect detachments more clearly.
  • Computed Tomography (CT) Scan: A CT scan may be used to assess complex bony injuries, such as significant glenoid rim fractures or large reverse Hill-Sachs lesions, providing detailed 3D anatomical information.

Treatment Options

Treatment for a reverse Bankart lesion depends on several factors, including the severity of the tear, the presence of associated injuries, the patient's age, activity level, and the degree of instability.

Non-Surgical Management

For less severe labral tears, first-time dislocations with no significant instability, or in patients who are not surgical candidates, non-surgical approaches may be considered:

• Reduction: For acute posterior dislocations, the shoulder must be promptly and gently reduced (relocated) back into the socket by a medical professional.
• Immobilization: The arm is typically immobilized in a sling, often in slight external rotation, for a period to allow initial healing.
• Pain and Inflammation Management: Over-the-counter or prescription anti-inflammatory medications (NSAIDs) and ice application can help manage pain and swelling.
• Physical Therapy: A structured rehabilitation program is essential. It focuses on:
  • Restoring Range of Motion: Gradual progression to regain full, pain-free movement.
  • Strengthening: Targeting the rotator cuff and periscapular muscles to improve dynamic stability.
  • Proprioception: Exercises to enhance the joint's sense of position and movement.
  • Activity Modification: Avoiding positions and activities that place stress on the posterior shoulder.

Surgical Intervention

Surgical repair is often recommended for reverse Bankart lesions that cause persistent instability, recurrent dislocations, or in active individuals, especially athletes. The goal of surgery is to reattach the torn labrum to the glenoid bone and restore shoulder stability.

• Arthroscopic Repair: This minimally invasive technique is the most common approach. Small incisions are made, and a camera (arthroscope) and specialized instruments are used to visualize and repair the tear. Sutures are used to reattach the labrum to the glenoid.
• Open Repair: In some complex cases, such as those with large bony Bankart lesions or significant glenoid bone loss, an open surgical approach (requiring a larger incision) may be necessary to allow for better visualization and reconstruction.
• Addressing Associated Injuries: During surgery, any associated injuries like a reverse Hill-Sachs lesion might also be addressed (e.g., by filling the defect with bone graft or transferring a tendon into it to prevent engagement).

Rehabilitation and Recovery

Regardless of whether the treatment is surgical or non-surgical, a comprehensive and progressive rehabilitation program is critical for optimal recovery and return to function.

• Phased Approach: Rehabilitation typically follows a structured, multi-phase approach:

  • Phase 1 (Protection & Early Motion): Focus on pain control, protecting the repair (if surgical), and gentle, passive range of motion exercises.
  • Phase 2 (Gradual Strengthening): Introduction of active range of motion, isometric strengthening, and light resistance exercises.
  • Phase 3 (Advanced Strengthening & Proprioception): Progressive resistive exercises, core stability, and proprioceptive drills.
  • Phase 4 (Return to Activity/Sport): Sport-specific drills, plyometrics, and functional training to prepare for return to full activity.

• Duration: Recovery can be a lengthy process, often taking 6-12 months or longer, particularly after surgery, before returning to high-impact activities or sports. Adherence to the physical therapy program is paramount for a successful outcome.

Prognosis and Long-Term Outlook

The prognosis for a reverse Bankart lesion is generally good with appropriate treatment. Surgical repair has high success rates in restoring stability and reducing the risk of recurrent dislocations. However, the exact outcome depends on factors such as:

• Severity of the Initial Injury: More extensive tears or those with significant bone loss may have a longer recovery.
• Presence of Associated Injuries: A large reverse Hill-Sachs lesion can complicate recovery.
• Patient Compliance: Adherence to the rehabilitation protocol is crucial.
• Activity Level: Athletes returning to high-demand sports may face a higher risk of re-injury if not fully recovered.

While most individuals regain excellent shoulder function, some may experience residual stiffness or mild pain, especially during extreme movements or after prolonged activity.

Prevention

While not all reverse Bankart lesions are preventable, especially those from high-impact trauma or medical conditions, general shoulder health strategies can reduce overall risk:

• Strengthen Shoulder Stabilizers: Regular exercise targeting the rotator cuff and periscapular muscles enhances dynamic stability.
• Maintain Flexibility: Ensure adequate shoulder range of motion to prevent stiffness.
• Proper Technique: Use correct form during sports and exercises to minimize undue stress on the shoulder joint.
• Awareness of Risk Factors: Individuals with a history of seizures or those in occupations with high risk of electrocution should be aware of the potential for posterior shoulder dislocation.

Understanding the unique nature of a reverse Bankart lesion is key to effective diagnosis and management, guiding a comprehensive approach to restore shoulder stability and function.