Correct Diagnosis is Important for Treatment of Cranial Cruciate Injuries

Correct Diagnosis is Important for Treatment of Cranial Cruciate Injuries
By Dr. Ed Mapes
Stonebridge Animal Hospital

Animal Hospital McKinney TXDamaged cranial cruciate ligaments comprise a large proportion of the rear leg lameness we see in dogs. Detecting the degree to which these structures are injured is a key consideration in devising the most appropriate treatment protocol, and using the proper technique is essential in making this diagnosis. In many cases, the owners have no idea how the injury occurred; the dogs are often running and playing in the yard and are seen favoring one of the rear legs when they come back to the house. While this ligament is a very strong structure, it can be damaged by seemingly minor trauma.


The initial pain and swelling from a damaged cranial cruciate ligament causes most of these dogs to limp when walking. This usually manifests in holding the leg up entirely and walking on three legs. This symptom, though, can be caused by trauma to several structures within the knee joint, so diagnosis of cruciate injury cannot be based on the lameness alone.

If we see these patients within three days of injury, the joint will often appear swollen and will be painful upon manual manipulation during the examination. Pain in the joint causes apprehension and anxiety in these patients, and we customarily provide sedation to calm them, allow the muscles to relax, and allow a thorough examination of the joint. This is required for us to feel the subtle abnormal motions in the joint that occur with damaged cruciate ligaments.

Discerning the degree of abnormal joint motion (anterior drawer sign) along with a grinding sensation (crepitus) and swelling are important factors in the determination of whether the ligament is strained or fully ruptured – this is what we use to recommend the best course of treatment for the injury.

If the ligament is found to be stretched less than 50%, then a recommendation is made to begin anti-inflammatory medication and to strictly curtail exercise for two to four weeks. This is usually adequate time to allow for ligament healing and a return to a normal gait. Failure to return to normal function is a signal that surgery is the best option for that patient.

Stretching of the ligament greater than 50% and of course total rupture of the ligament means the damage is more severe and the chances of recovery without surgery are very slim. I recommend surgical stabilization of the ligament at that point to enable a rapid return to normal use of the limb.

Some other considerations:

  • Even with apparent healing in the non-surgical patient, the ligament rarely returns to normal strength, and subsequent injury and total rupture often occur.
  • A structure between the femur and tibia bones – the meniscus – can also be damaged when the cranial cruciate ligament is damaged. A torn meniscus will also contribute to joint pain, and this can be dealt with during the surgery to stabilize the cruciate ligament.
  • Even stabilized joints can become painful after surgery due to vigorous activity or another injurious event, but a short course of anti-inflammatory medication is usually sufficient treatment for those patients.
  • The abnormal joint motion caused by damage or rupture of this ligament leads to early arthritic changes within the joint, which may eventually prove to be disabling and cause permanent joint pain and limping on the affected leg.

Damaged cranial cruciate ligaments are a very common cause of rear leg pain in the dog. Making the right choice for treatment is important to the earliest return to normal function for these patients. I recommend early examination by a doctor with experience with these injuries so that you receive the correct information and your pet gets the most appropriate treatment.

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