Knee dislocation

Question 1

Define knee dislocation

Answer 1

Complete disruption of the integrity of the tibiofemoral articulation resulting in multi-ligament knee injury

Question 2

What is multi-ligament knee injury?

Answer 2

Rupture of at least 2 of the 4 major knee ligament structures

Question 3

Name causes of knee dislocation

Answer 3

Road traffic accidents
Sports injuries
Simple falls

Question 4

Name injuries associated with knee dislocation

Answer 4

Popliteal artery injury
Common peroneal nerve injury
Tibial nerve injury
Fractures
Patellar tendon rupture
Periarticular avulsion
Displaced menisci

Question 5

How can you investigate suspicion of vascular injury in knee dislocation?

Answer 5

ABPI <0.9

Angiography (CT/MR)

Question 6

Discuss management of knee dislocation

Answer 6

Reduce under conscious sedation and immobilize
Surgical management 
- primary repair
- repair and augmentation
- reconstruction

Question 6

Discuss management of knee dislocation

Answer 6

Reduce under conscious sedation and immobilize
Surgical management 
- primary repair
- repair and augmentation
- reconstruction

Question 7

Name complications of knee dislocation

Answer 7

Early

• arterial damage
• common peroneal nn injury
• compartment syndrome

Late

• joint instability
• stiffness

Question 8

Name predisposing factors to recurrent patella dislocation

Answer 8

1. Generalized ligamentous laxity
2. Underdevelopment of the lateral femoral condyle and flattening of the intercondylar groove
3. Maldevelopment of the patella
4. Genu valgus
5. External tibial torsion
6. Primary muscle defect

Question 9

What are the 2 indications for immediate surgery of a dislocated patellar?

Answer 9

Inability to reduce patellar

Presence of a large, displaced, osteochondral fragment

Question 10

Discuss management of patellar dislocation

Answer 10

Conservative
- knee brace
- exercises to strengthen vastus medialis mm
Surgical
- repair/strengthen the medial patellofemoral ligaments
- realign the extensor mechanism
- treat trochlear dysplasia