Anterior Cruciate Ligament Sprain

Question 1

What causes an ACL tear

Answer 1

1. Twisting of the knee
2. Hyperextension
3. Sudden stopping/cutting movement
   *femur is pushed across the tibia
   *stretching or tearing occur with increased torsional force

Question 2

What is the purpose of an ACL?

Answer 2

1. To prevent the femur from siding forward or turning on the tibia

Question 3

If the ACL is torn how will the knee feel?

Answer 3

1. There will be rotational instability
   *knee “gives way”

Question 4

What is a grade I ACL injury

Answer 4

1. Pain with minimal damage to the ACL

Question 5

What is a grade II ACL injury

Answer 5

Ligament damage with mild laxity

Question 6

What is a grade III ACL injury

Answer 6

Complete ACL tear with significant laxity/instability
*ACL is no longer functional

Question 7

How will a patient present with an ACL tear?

Answer 7

1. Patient hears a POP
2. Swelling
3. Knee feels unstable with twisting/pivoting

Question 8

What are the PE findings?

Answer 8

1. Tenderness
2. Swelling
3. Anterior drawer sign
   *knee flexed at 90
4. Lachman’s
   *knee flexed at 30
5. Pivot shift test
   *knee is flexed and internally rotated and then extended
   *done under anesthesia

Question 9

What are the diagnostic tests to order?

Answer 9

1. X -rays
2. MRI (best test)
3. Knee test.KT arthrometer
   *will assess the ability of the ACL to stabilize the joint

Question 10

What can lead to a poor prognosis?

Answer 10

1. Presence of additional injuries

Question 11

What is the treatment?

Answer 11

1. PRICE
2. Knee immobilization
   *short time frame to avoid stiffness
3. Surgery indicated for complete tears (2-6 weeks after)

Question 12

What are the different surgery options?

Answer 12

1. Autograft
2. Allograft/cadaver
3. Holes drilled into the distal femur and proximal tibia, graft is then slid into place
   *1/3 central patella tendon autograft