Hip Dislocation: Posterior vs Anterior, Reduction & Rehab MCQs

Dislocation of the Hip

The hip joint is inherently stable. Dislocation requires high-energy trauma (e.g., Car accidents). It is an orthopedic emergency due to the risk of Avascular Necrosis (AVN).

1. Classification

• Posterior Dislocation (90%): Most common. "Dashboard injury" (Knee hits dashboard, driving femur backward).
• Anterior Dislocation (10%): Forced abduction and external rotation (e.g., fall from height with legs apart).
• Central Dislocation: Femoral head punches through the acetabulum into the pelvis (Acetabular fracture).

2. Clinical Features

Classic Attitudes:
- Posterior: Flexion + Adduction + Internal Rotation (FADIR). Limb appears shortened.
- Anterior: Flexion + Abduction + External Rotation (FABER).

3. Management

• Reduction: Must be done < 6 hours to save the head.
  • Posterior: Allis Maneuver (Traction in flexion) or Bigelow Maneuver.
• Complications: Sciatic Nerve palsy (Posterior), Femoral Artery injury (Anterior), AVN.

25 Practice MCQs

Q1. The most common type of hip dislocation is:

Answer: A). 90% of cases.

Q2. The classic attitude of a Posterior Dislocation is:

Answer: A). The knee rests on the opposite thigh.

Q3. Which nerve is at risk in Posterior Dislocation?

Answer: A). Specifically the peroneal division (check for foot drop).

Q4. The "Dashboard Injury" typically causes:

Answer: A). Force transmitted up the femur pushes the head out the back.

Q5. Avascular Necrosis (AVN) risk increases significantly if reduction is delayed beyond:

Answer: A). It is a true orthopaedic emergency.

Q6. Allis Maneuver involves:

Answer: A). Assistant stabilizes the pelvis.

Q7. Anterior dislocation attitude is:

Answer: A). Limb looks longer.

Q8. Central dislocation is associated with fracture of:

Answer: A). Head protrudes into the pelvis (Protrusio Acetabuli).

Q9. Stimson's Gravity Method places the patient:

Answer: A). Gravity helps reduction.

Q10. Pipkin classification is for:

Answer: A). Type I (Below fovea), Type II (Above fovea).

Q11. Vascular injury (Femoral Artery) is a risk in:

Answer: A). Head pushes against the bundle.

Q12. Post-reduction, the hip is usually kept in:

Answer: A). Adduction is the danger position for posterior instability.

Q13. Late complication includes:

Answer: A). Heterotopic ossification is common if muscles were traumatized.

Q14. "Shenton's Line" on X-ray is:

Answer: A). Continuous curve from femoral neck to obturator foramen.

Q15. Simple dislocation vs Complex dislocation:

Answer: A). Complex usually needs surgery.

Q16. Weight bearing is typically restricted for:

Answer: A). To allow capsule healing.

Q17. Thompson and Epstein classification is for:

Answer: A). Types I-V based on associated fractures.

Q18. Irreducible dislocation may be due to:

Answer: A). Requires open reduction.

Q19. Bigelow's Maneuver involves:

Answer: A). "The circumduction method".

Q20. Which ligament is the strongest, preventing anterior dislocation?

Answer: A). Reinforces the anterior capsule.

Q21. Sciatic nerve palsy presents as:

Answer: A). Peroneal division is most susceptible.

Q22. Open reduction is indicated if:

Answer: A). Must remove interposed fragments.

Q23. CT scan is mandatory:

Answer: A). X-ray can miss small chips.

Q24. Obturator type anterior dislocation puts hip in:

Answer: A). Head sits in the obturator foramen.

Q25. Is congenital hip dislocation the same as traumatic?

Answer: B). Completely different pathology.