Posterior Subluxation

Modern Study Review (AI-Generated)

High-Yield Summary

Posterior shoulder subluxation is the most common form of posterior glenohumeral instability, often presenting without a history of significant trauma. Patients typically report a sensation of the shoulder slipping posteriorly, frequently associated with overuse rather than acute injury. Diagnosis relies on clinical examination, with the jerk test being the most sensitive provocative maneuver. Treatment prioritizes pain relief and functional restoration, with physiotherapy as first-line management and surgery reserved for refractory cases or significant functional impairment.

Key Diagnostic Findings

Anatomy

• Posterior shoulder instability involves laxity or insufficiency of the posterior capsule and posterior band of the inferior glenohumeral ligament.
• Inferior capsular laxity is a critical factor contributing to recurrent posterior subluxation.

Clinical Presentation

• Recurrent posterior subluxation often presents without a clear traumatic event.
• Primary symptom: posterior shoulder pain and a sensation of the joint slipping or giving way.
• Apprehension test is usually negative, distinguishing it from anterior instability.
• Jerk test: arm flexed and internally rotated, then adducted; a sudden jerk or clunk indicates posterior instability.
• Voluntary or involuntary muscular contraction can reproduce subluxation.

Imaging

• Standard radiographs: AP, axillary, and scapular Y views to assess glenoid version and posterior humeral head subluxation.
• MRI/MRA: evaluates posterior capsulolabral complex, posterior labral tears, and capsular laxity.
• CT scan: useful for assessing glenoid bone loss or retroversion, especially preoperatively.

Classification Systems

• No universally accepted classification specific to posterior subluxation; however, Rockwood’s classification of posterior instability includes subluxation and dislocation patterns.
• Recognition of inferior capsular laxity is essential but not formally classified.

Current Gold Standard Treatment

Non-operative

• First-line treatment for most patients with minimal pain and functional limitation.
• Focus on rotational and scapular strengthening programs to improve dynamic stability.
• Activity modification and pain management are key.
• Close monitoring for progression or persistent symptoms.

Operative Indications and Treatment

• Surgery is indicated for persistent pain, functional disability, or recurrent instability despite adequate physiotherapy.
• Surgical options include:

– Recognition and management of inferior capsular laxity is critical for surgical success.

Modern Complications & Outcomes

Complications

• Persistent instability or recurrence after surgery, especially if bone loss or capsular laxity is unaddressed.
• Stiffness or loss of range of motion postoperatively.
• Neurovascular injury is rare but possible.
• Hardware-related complications if bone block procedures are performed.

Outcomes

• Non-operative management yields good pain control and functional improvement in most patients.
• Surgical outcomes are generally favorable when appropriate patient selection and technique are applied.
• Arthroscopic techniques have improved recovery times and reduced morbidity compared to open procedures.
• Long-term outcomes depend on addressing all pathoanatomic contributors, including capsular laxity and bony abnormalities.

Classic Clinical Notes

Posterior Subluxation

• Recurrent Posterior Subluxation is the most common form of posterior instability.
• Most do not present with an initial episode of significant trauma requiring reduction; more commonly, the sensation of the joint slipping posteriorly follows overuse.
• Pain may be the primary presenting feature.
• Can sometimes be demonstrated by muscular contraction (voluntary) or by arm positioning (involuntary).
• Most provocative test is the jerk test—bringing the arm into flexion and internal rotation, then adducting the shoulder.
• Apprehension is usually absent.

Treatment

• Most have minimal pain and functional disability, and physiotherapy remains the main focus of treatment, consisting of a rotational and scapular strengthening program.
• Pain may ultimately be the primary indication for surgery.

Surgical Options

• Posterior inferior capsular shift – Tibone and Bradley, Neer and Foster.
• Posterior inferior capsular shift with posterior bone block – Warren.
• Glenoid osteotomy – Rockwood.
• Arthroscopic capsular plication – Wolf & Eakin.

• An important consideration is the recognition of inferior capsular laxity.

Last Updated on January 25, 2026 by orthonet