Knee - Ligament Injuries

Question 1

What are the attachments of the ACL?

What is the function of the ACL?

Answer 1

Attachments: Lateral intercondylar ridge of the femur to between the intercondylar eminences of the tibia

Function: Prevents anterior translation of the tibia relative to the femur

Question 2

What are the symptoms and signs of an ACL injury?

Answer 2

Symptoms:

• Post trauma (non-contact pivoting injury)
• Felt a pop
• Pain deep in the knee
• Immediate swelling/hemarthrosis

Signs:

• Hemarthrosis
• Anterior drawer positive
• Lachman’s test positive (PCL tear may have false positive)
• Pivot Shift

Question 3

What investigations would you do for an ACL tear?

Answer 3

• Knee X-ray to assess knee fracture
• MRI: Finds torn ACL

Question 4

What would your management be of an ACL tear?

What are the post-operative management steps?

What are the complications of such an operation?

Answer 4

• Management
  
  • Conservative
    
    • RICE
    • Physical therapy and lifestyle modification
    • Bracing and support
  • Surgical
    
    • Indications
      
      • Younger, more active patient
      • Children
      • Older active patient
    • Technique
      
      • ACL reconstruction
• Post-Operative
  
  • Immediate: Cryotherapy, immediate weight bearing, early full passive extension
  • Early Rehab
  • Back to sports in 3 months
• Complications
  
  • Failure
  • Infection
  • Stiffness (arthrofibrosis)
  • Patellar tendon rupture
  • Late arthritis

Question 5

What are the attachments of the PCL?

What is the function of the PCL?

Answer 5

Attachments: Medial femoral condyle to between posterior tibial sulcus below the articular surface

Function: Prevents posterior translation of the tibia relative to the femur

Question 6

What are the symptoms and signs of a PCL tear?

Answer 6

Symptoms:

• Post trauma (Dashboard injury – direct blow to proximal tibia with flexed knee), hyperextension injury.
• Posterior knee pain
• Instability

Signs:

• Hemarthrosis
• Medial tibial step-off
• Posterior sag sign
• Posterior drawer positive

Question 7

What are the investigations you would do for a PCL tear?

Answer 7

• Knee X-ray to assess knee fracture (AP, lateral, lateral stress)
• MRI: Finds torn PCL

Question 8

How would you manage a PCL tear?

What are the post-operative steps to managing a PCL tear?

What are the complications of a PCL tear?

Answer 8

• Management
  
  • Conservative
    
    • Protected weight bearing and rehab
    • Relative immobilization in extension for 4 weeks
  • Surgical
    
    • Indications
      
      • Combined ligamentous injuries
      • Bony avulsion
      • Functionally unstable knee
    • Technique
      
      • Primary repair of bony avulsion fractures with ORIF
      • PCL reconstruction
• Post-Operative
  
  • Immediate: Immobilize in extension
  • Early Rehab
• Complications
  
  • Popliteal artery injury
  • Patellofemoral pain
  • Arthritis

Question 9

What are the attachments of the MCL and LCL?

Answer 9

Attachments:

• MCL: Medial femoral epicondyle to proximal tibia deep to pes anserinus
• LCL: Lateral femoral epicondyle to anterolateral fibula head

Function

• MCL: Primary restraint to valgus stress
• LCL: Primary restraint to varus stress

Question 10

What are the signs and symptoms of a MCL/LCL tear?

Answer 10

• Clinical Presentation:
  
  • Trauma/stress
    
    • Varus for LCL, Valgus for MCL
  • Instability near full knee extension
  • Difficulty ascending and descending stairs
  • Difficulty with cutting and pivoting activities
  • Lateral/Medial joint line pain and swelling
• Physical Examination
  
  • Inspection/palpation: ecchymosis/lateral joint line tenderness
  • ROM and stability:
    
    • Varus/valgus instability stress test
      
      • Instability at 30 degrees: isolated CL injury
      • Instability at 0 and 30 degrees: combined LCL and PCL/ACL
  • Assess for ACL, PCL, menisci tears and Patellar dislocation
  • Must assess neurovascular status

Question 11

What investigations would you do for a suspected MCL/LCL injury?

Answer 11

• AP, lateral and varus/valgus stress X-rays
• MRI (Imaging modality of choice)

Question 12

What is the management of MCL/LCL injuries?

Answer 12

Management

• Nonoperative
  
  • Rest
  • Analgesia with NSAIDS
  • Limited Immobilization
  • Functional rehabilitation with progress ROM.
• Surgical
  
  • Indications: Grade 3 injury, rotatory instability, posterolateral instability
  • LCL/MCL repair/reconstruction +/- PCL/PCL repair
  • Complications:
    
    • Failure
    • Peroneal nerve injury/saphenous nerve injury
    • Stiffness
    • Hardware irritation