ACL & PCL Injury: Lachman Test, Graft Types & Rehab Protocols

Knee Ligament Injuries (ACL, PCL, MCL, LCL)

Ligament injuries are common in sports. The ACL (Anterior Cruciate Ligament) is the most frequently injured, often requiring reconstruction to restore stability.

1. Mechanisms & Diagnosis

• ACL: Non-contact twisting (Deceleration + Valgus + Rotation). Tests: Lachman (Best), Anterior Drawer, Pivot Shift.
• PCL: "Dashboard Injury" (Direct blow to proximal tibia with knee flexed). Tests: Posterior Drawer, Sag Sign.
• MCL: Valgus blow. Test: Valgus Stress Test (at 30° flexion).
• LCL: Varus blow. Test: Varus Stress Test.

2. O'Donoghue's Unhappy Triad

Classic combination: ACL + MCL + Medial Meniscus (though Lateral Meniscus is actually more common in acute ACL tears).

3. Management

• Conservative: For MCL (heals well) and isolated PCL (often asymptomatic).
• Surgical (ACL Reconstruction):
  • Bone-Patellar Tendon-Bone (BPTB): Gold standard for elite athletes.
  • Hamstring Graft (Semitendinosus/Gracilis): Common, less donor site pain.

4. Physiotherapy Rehab

Key Concept: Closed vs Open Kinetic Chain
- Closed Chain (Squats): Safe early. Co-contraction protects graft.
- Open Chain (Leg Extension): Avoid in early phase (shears tibia anteriorly, straining ACL).

25 Practice MCQs

Q1. The most sensitive clinical test for acute ACL tear is:

Answer: A). Done at 20-30 degrees flexion; eliminates hamstring spasm.

Q2. Mechanism of ACL injury is typically:

Answer: A). "Pop" is often heard.

Q3. PCL injury is classically caused by:

Answer: A). Tibia is pushed backward.

Q4. "Unhappy Triad" includes:

Answer: A). Result of severe valgus stress.

Q5. Which graft has the strongest initial tensile strength?

Answer: B). Bone-to-bone healing is faster and stronger.

Q6. Sag Sign indicates:

Answer: A). Seen when hips and knees are flexed to 90.

Q7. Valgus Stress Test at 0 degrees extension tests:

Answer: A). Test at 30 degrees isolates MCL. Test at 0 indicates massive damage.

Q8. Open Kinetic Chain (OKC) extension (e.g., leg extension machine) is avoided early in ACL rehab because:

Answer: A). Shear forces are high in OKC extension (last 30 degrees).

Q9. Segond Fracture is pathognomonic for:

Answer: A). Avulsion of lateral capsule.

Q10. Pivot Shift Test assesses:

Answer: A). The tibia subluxes and reduces with a clunk.

Q11. Which bundle of ACL provides rotational stability?

Answer: B). Tight in extension.

Q12. Cyclops Lesion is:

Answer: A). Complication of ACL surgery.

Q13. MCL injuries are usually treated:

Answer: A). Unless part of multi-ligament injury.

Q14. Dial Test differentiates:

Answer: A). Increased rotation at 30 deg = PLC; at 90 deg = PCL + PLC.

Q15. Ligamentization is:

Answer: A). Graft is weakest at 6-12 weeks during necrosis/revascularization phase.

Q16. Hamstring graft usually harvests:

Answer: A). "Semi-G".

Q17. Return to sport after ACL reconstruction typically takes:

Answer: B). Depends on functional testing.

Q18. Pellegrini-Stieda lesion is:

Answer: A). Chronic medial knee pain.

Q19. Anterior Drawer test can be False Negative if:

Answer: A). That's why Lachman is better.

Q20. LCL injury is rare and often associated with:

Answer: A). Varus force stretches the nerve.

Q21. PCL reconstruction is indicated for:

Answer: A). Isolated PCL usually copes well without surgery.

Q22. What is "Killer Turn"?

Answer: A). Leads to graft failure in PCL surgery.

Q23. Primary restraint to anterior tibial translation is:

Answer: A). Loss leads to instability.

Q24. Donor site morbidity for BPTB graft includes:

Answer: A). Pain on kneeling.

Q25. Proprioception training is important because:

Answer: A). Prevents re-injury.