Cruciate Lameness in Dogs

What is a cruciate ligament?

In your dog’s knee there are two cruciate ligaments. The job of the cruciate ligament is to provide stability to the knee joint between the femur (thigh bone) and the tibia (shin bone). The top of the shin bone is sloped slightly and when your dog walks or stands the force means that the bones want to slide over each other which is counteracted by the cruciate ligament. If the ligament is torn the force causes the shin bone to move forward abnormally. This causes a lameness and pain in the leg. Typically a dog with a torn cruciate will hold up the hind leg, sometimes they will touch their toe down and then feel the abnormal movement and pick the leg up again. When they sit they will throw their knee out in an abnormal position.

Image one shows a normal knee and second image is torn cruciate

What Causes Cruciate ruptures?

Fraying of the ligament is simliar to wool fraying and breaking

Rupture of the cruciate is usually due to wear and tear in the joint. Slowly over time degeneration of the ligament happens until it snaps. On occasion with trauma the ligament can rupture forcefully

How do I know my pet has torn their cruciate?

  • Lame on hind leg
  • Vet will check movement in the knee with a cranial drawer test
  • Radiographs- Rule out other problems and assess the joint
Xray of dog’s knee

Treatment

Treatment involves surgery. Surgery performed is either extra articular (outside the joint) or intra articular (inside the joint).

Extra Articular Surgeries: Lateral Suture- this is where a false ligament is placed to stabilise the joint. Usually suitable only for small light dogs or cats

Intra Articular Surgeries: These surgeries involve changing the mechanics of the joint to remove the force on the shin bone and stop the movement in the joint. Examples are TPLO, TTA, CCWO.

The surgery that is chosen for your pet depends on some factors:

  • Size of the dog
  • The activity level of the dog
  • Breed of the dog
  • Other injuries
X ray from an intra-auticular Surgery: Cranial closing wedge osteotomy

Rehabilitation after Surgery

Generally your pet will require 4-6 weeks cage rest with lead only exercise. They will be on anti inflammatory pain relief to stay comfortable. Physio therapy from about 10 days post op is important for your pet to return to full use of their leg and avoid future lameness and arthritis.