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Collateral Ligament Injuries

What is a collateral ligament injury and how do they get injured? 

  • Collateral ligaments of the knee are the ligaments which brace the sides of the knee joint. 
  • There is the Medial Collateral Ligament (MCL) and the Lateral Collateral Ligament (LCL).
  • As with other types of ligament tears, collateral ligament injuries are categorised as a grade 1, 2 or 3 injuries, where grade 1 is slightly stretched and grade 3 is a complete tear or rupture. 
  • The MCL is more frequently damaged than the LCL due it being easier to create a valgus strain versus a varus strain. 
  • These are often triggered by contact sport injuries or by a twisting injury with the planted foot stuck to the ground.

What are the symptoms of a collateral ligament injury? 

  • Pain and swelling within a few hours of injury. 
  • If the MCL is involved, this is typically on the inside of the knee and an LCL injury is typically on the outside. 
  • Bruising may occur over the next few days 
  • Instability and the feeling of the knee giving way or the knee feeling loose. 
  • Surgical treatment may be advised if the patient wishes to return to a high level of function or it may be appropriate to test the injury in a knee brace.

How is a collateral knee injury diagnosed? 

  • The MRI can clearly show a collateral tear and helps assess if other ligaments are involved. 
  • X-Rays can’t detect damage to the ligament but can detect concurrent small breaks, where a small part of the bone attached to the ligament, pulls away from the main bone. 
  • This is called an avulsion fracture.

What are the treatments for collateral knee injury tears? 

  • In many cases surgery is not required. Treatments include anti-inflammatory medications and physiotherapy to improve knee function and application of a knee brace. 
  • Icing and bracing is important as the knee needs to be protected from the sideways force that caused the injury. 
  • To further protect the knee, you may be given crutches
  • Most isolated collateral ligament injuries do not require surgery unless it is associated with other ligament injuries.