Shoulder Dislocation: Anterior vs Posterior, Recurrent Instability & PT MCQs

Dislocation of the Shoulder (Glenohumeral Joint)

The shoulder is the most mobile joint in the body, making it the most commonly dislocated major joint (approx. 50% of all dislocations). Stability is sacrificed for mobility.

[Image of Shoulder Dislocation X-ray]

1. Classification

• Anterior Dislocation (95-98%): The humeral head sits anterior to the glenoid (Subcoracoid position is most common).
  • Mechanism: Abduction + External Rotation (e.g., throwing, fall).
• Posterior Dislocation (2-4%): The humeral head sits posterior.
  • Mechanism: The "3 Es": Epileptic seizures, Electric shock, Extreme trauma.
• Inferior (Luxatio Erecta): Rare. Arm is stuck in full elevation.

2. Associated Lesions

• Bankart Lesion: Avulsion of the antero-inferior glenoid labrum.
• Hill-Sachs Lesion: Compression fracture (dent) on the posterolateral humeral head.
• Axillary Nerve Injury: Common in anterior dislocation (check regimental badge sensation).

3. Recurrent Instability (TUBS vs AMBRI)

Acronyms to Remember:
TUBS: Traumatic, Unilateral, Bankart lesion, Surgery required.
AMBRI: Atraumatic, Multidirectional, Bilateral, Rehabilitation (treatment), Inferior capsular shift (if surgery needed).

4. Physiotherapy Management

• Phase 1 (Immobilization): Sling for 3 weeks (young) to allow capsular healing. Avoid External Rotation + Abduction.
• Phase 2 (Mobilization): Isometrics, Scapular setting, Pendulum exercises.
• Phase 3 (Strengthening): Rotator cuff strengthening (Dynamic stabilizers) and Proprioception drills.

25 Practice MCQs

Q1. What is the most common type of shoulder dislocation?

Answer: A). Accounts for >95% of cases.

Q2. Which nerve is most commonly injured in anterior dislocation?

Answer: B). Check for sensation over the "Regimental Badge" area (Deltoid).

Q3. A "Lightbulb sign" on AP X-ray indicates:

Answer: B). The humerus is locked in internal rotation, making the head look round like a bulb.

Q4. The Hill-Sachs lesion is a defect on the:

Answer: A). Caused by the head hitting the sharp anterior glenoid rim.

Q5. Which position must be AVOIDED in early rehab for Anterior Dislocation?

Answer: C). This is the mechanism of injury/redislocation (Apprehension position).

Q6. The Bankart lesion involves:

Answer: A). The "essential lesion" of instability.

Q7. In the AMBRI classification, "M" stands for:

Answer: B). Patients often have general ligamentous laxity.

Q8. Which reduction method involves pulling the arm with a foot in the axilla?

Answer: A). The oldest method (caution: risk of nerve injury).

Q9. Posterior dislocation is most commonly caused by:

Answer: B). Intense contraction of internal rotators (Lat. Dorsi/Pecs) overpowers external rotators.

Q10. The "Apprehension Test" is positive if:

Answer: B). Pain alone is not a positive test; fear of dislocation is.

Q11. Luxatio Erecta refers to:

Answer: B). The patient presents with the hand above the head.

Q12. Which surgical procedure involves transferring the coracoid process to the glenoid rim?

Answer: B). A bone block procedure for significant bone loss.

Q13. In young patients (< 20 years), the recurrence rate after first dislocation is:

Answer: A). Age is the biggest predictor of recurrence.

Q14. Bony Bankart lesion involves fracture of:

Answer: A). Loss of glenoid bone stock makes the joint very unstable.

Q15. Kocher's method of reduction sequence is:

Answer: B). Remember "TEAM" (Traction, ER, Adduction, Medial rotation).

Q16. Stimson's technique relies on:

Answer: A). A gentle method allowing muscles to relax.

Q17. Which muscle is the primary dynamic stabilizer preventing anterior translation?

Answer: A). It is the anterior cuff muscle.

Q18. Sulcus sign tests for:

Answer: B). A gap appears below the acromion when the arm is pulled down.

Q19. A "Reverse Hill-Sachs lesion" is seen in:

Answer: B). An anteromedial defect on the humerus head.

Q20. Is open surgery common for first-time traumatic dislocation?

Answer: A). Conservative trial is standard.

Q21. Axillary nerve palsy results in weakness of:

Answer: A). Loss of abduction > 15 degrees.

Q22. Arthroscopic Bankart repair involves:

Answer: A). Restores the "bumper" effect of the labrum.

Q23. ALPSA lesion stands for:

Answer: A). A variant of Bankart where the labrum rolls up medially.

Q24. Late complication of dislocation in elderly patients (>40) is often:

Answer: B). Recurrence is low, but cuff tears and frozen shoulder are high.

Q25. Jerk Test is used for:

Answer: B). Axial load + Adduction + Internal Rotation causes a "jerk" as the head subluxes.