Physiotherapy Management for Posterior Shoulder Instability

Posterior Shoulder Instability (PSI) occurs when the humeral head moves abnormally toward the back of the shoulder joint, causing dislocation, subluxation or excessive translation. It affects joint function, leading to pain, weakness and instability. PSI accounts for 2–10% of shoulder instability cases, mostly acute injuries, though chronic prevalence is unclear. It can impair daily activities, work and sports, particularly in athletes and physically active individuals.

Types of Posterior Shoulder Instability

 

Signs and Symptoms of Posterior Shoulder Instability

• Pain is typically felt in the posterior shoulder, especially during activities involving pushing or weight-bearing through the arm.
• Sensation of the shoulder "slipping" or feeling unstable is felt, particularly with movements like pushing or bench pressing.
• Reduced strength, especially in posterior shoulder movements is noticed.
• Discomfort or restriction in certain movements, especially with internal rotation or horizontal adduction.
• Crepitus felt during shoulder movement.
• Recurrent subluxation or dislocation, often with specific movements or trauma.
• Apprehension (fear or discomfort) with positions that stress the posterior capsule (e.g., forward flexion combined with internal rotation).
• Weakness or tightness of the rotator cuff and scapular stabilizers. 

Causes of Posterior Shoulder Instability

• Trauma - direct blow or fall on outstretched arm.
• Repetitive Overuse - pushing motions (e.g., bench press) or overhead sports.
• Capsular Laxity - congenital hypermobility or microtrauma.
• Glenoid/Labral Issues - posterior labral tear, glenoid retroversion.
• Muscle Imbalance - weak rotator cuff, tight anterior muscles.
• Iatrogenic - post-surgical complications

 

Diagnosis

This questionnaire helps physiotherapist’s gather relevant information to diagnose and develop a tailored treatment plan for posterior shoulder instability.

Differential Diagnosis

• Posterior labral tear
• Reverse Hill-Sachs lesion
• Posterior rotator cuff tear
• Glenohumeral arthritis
• Scapular dyskinesis
• Multidirectional instability
• Suprascapular nerve entrapment
• Parsonage-Turner syndrome
• Posterior capsular laxity
• Acromioclavicular joint pathology
• Subscapular bursitis
• Internal impingement
• Osseous glenoid dysplasia

Physiotherapy Treatment for Posterior Shoulder Instability

Posterior shoulder instability requires a multifaceted approach tailored to the type of instability (atraumatic, traumatic or microtraumatic) and individual patient needs. Effective management integrates assessment, progressive rehabilitation and functional retraining, emphasizing scapular mechanics and posterior shoulder stability.

Management Overview

Atraumatic PSI:

• Focus on strengthening posterior stabilizers.
• Emphasize motor control and scapular mechanics.
• Surgery is reserved for refractory cases.

Traumatic PSI:

• Conservative rehabilitation initially.
• Surgical repair for labral tears if conservative management fails, particularly in athletes or those with structural damage.

Microtraumatic PSI:

• Emphasize a structured 6-month rehabilitation program.
• Surgery is considered if rehabilitation does not achieve desired outcomes.

 

Rehabilitation Framework

Assessment and Motor Control Reeducation

Scapular Correction

• Evaluate scapular dyskinesis through clinical tests (e.g., active flexion/abduction).
• Therapist manually corrects the scapular position to facilitate upward rotation and reassesses symptoms.
• Corrected positions guide motor retraining exercises.

Humeral Head Correction

• Assess posterior humeral head translation during active movements (e.g., flexion, horizontal flexion).
• Apply posterior-to-anterior support during movements and reassess symptoms.
• Retrain positions that improve symptoms for stability.

Combination Corrections

• For many PSI patients, both scapular and humeral head corrections are necessary.
• Combine findings to develop targeted rehabilitation protocols.

Progressive Rehabilitation Stages

Stage 1: Scapular Phase

Objective: Regain motor control of the scapula in corrected positions.

Exercises:

• Scapular Upward Rotation Drill with Resistance Band: Improves scapular motor recruitment and stability.
• Standing Extension Row with Theraband and Scapular Resistance Band: Enhances scapular control and strengthens posterior stabilizers.

Progression:

• Begin with movements under the weight of the arm.
• Introduce light resistance (0.5–2 kg) for scapular motor control.

Stage 2: Higher Elevation Scapular Control

Objective: Strengthen scapular control at higher ranges of elevation.

Exercise:

• Standing Extension Row at 45 Degrees of Abduction: Focus on upward rotation and posterior stabilization.

Stage 3: Scapular Control at 90° Elevation

Objective: Build control and strength at 90° of elevation.

Exercises:

• Standing Extension Row at 90 Degrees of Abduction: Targets scapular upward rotation control in higher ranges.
• External Rotation at 90 Degrees of Abduction with Theraband: Strengthens external rotators in the coronal plane.

Stage 4: Vulnerable Planes Progression

Objective: Train control in positions of instability (e.g., sagittal and coronal planes).

Exercises:

• Supported External Rotation at 90 Degrees of Elevation (Sagittal Plane) with Weight: Enhances control and stability in elevated ranges.
• Bent Over Row with Weight: Strengthens posterior shoulder muscles and scapular control.

Stage 5: Sports-Specific and Functional Phase

Objective: Transition to sport-specific or functional tasks.

Exercises:

• Tailor rehabilitation to mimic athletic or functional demands (e.g., throwing, lifting).
• Include compound movements replicating specific tasks.

Additional Exercises

Side-Lying External Rotation with Weight:

• Focuses on isolated rotator cuff strengthening (infraspinatus, teres minor).
• Stabilizes the shoulder in a controlled environment.

External Rotation at 90 Degrees of Elevation (Scapular Plane):

• Builds strength and control in the scapular plane, critical for overhead movements.

Supported External Rotation at 90 Degrees of Abduction (Coronal Plane):

• Strengthens external rotators with precise scapular stability control.

Key Challenges in Rehabilitation

• Lack of Standardized Protocols:

Customize programs to individual needs based on assessment findings.

• Motor Control Reeducation:

Emphasize progressive strengthening and functional retraining.

• Adherence and Motivation:

Regularly monitor progress and adapt exercises to maintain engagement.

Clinical Pearls

1. Begin rehabilitation with low-resistance, high-control exercises.
2. Progress systematically, ensuring scapular and humeral head stability at each stage.
3. Reinforce proper movement mechanics to prevent recurrent instability.
4. Integrate functional and sport-specific training for optimal outcomes.

By adhering to these structured stages and emphasizing scapular mechanics and stability, physiotherapists can effectively manage PSI, reducing pain and improving functional outcomes.