Anterior Cruciate Ligament Injury

By: Dr. Heather Matheson TOL Newsletter 2008

Sports fans hear about Anterior Cruciate Ligament or ‘ACL’ tears on a daily basis.  ACL tears are a common injury among our top human athletes.  Unfortunately this is also a very common injury seen in our canine companions.  The anterior cruciate ligament has a big role in stabilizing the stifle or knee joint and can be surprisingly easy to injure.  The typical history we get is “ Rover took off after a bunny or jumped out of the truck, we heard a yelp and now he won’t use his back leg.”  It is not that a lot of force is needed to damage the ACL, so typically there is no history of trauma; it is more of a compression, a slight twist and then ‘POP’, there it goes.  Like stepping in a hole racing after the “wrascally-wrabbit”.

Post “wrascally-wrabbit” incident, our canine buddy will likely be 3-legged lame or just toe-touching on the injured leg.  Rest often improves the situation and sometimes we get lucky; if the ACL is only stretched or partially torn, then rest may be all that is required for a full recovery.  With this particular injury doing the ‘wait and see’ for a period of time is fine; it is unlikely the dog will further damage the injured leg.  However, remember that the good leg is now doing twice as much work and bilateral ACL tears do happen.  Literally, having no good leg to stand on is not a good time for anyone.

ACL tears are diagnosed upon physical exam.  What we look for is swelling or ‘medial buttress’ on the inside of the knee.  Remember that the ACL stabilizes the joint and without it, the other ligaments have to do a lot more work, hence the swelling.  We check for a ‘clunk’ on flexion or extension of the knee, this checks for a tear in the ‘medial meniscus’ which is the cartilage flap in the joint.  Finally we check the ACL itself by doing a ‘cranial drawer’ which challenges the knee in the direction the ACL stabilizes.  X-rays are helpful to rule out any other problems, however an ACL tear is a soft tissue injury so will not show up on X-ray.

So we have our canine buddy with a buggered ACL.  What is the treatment? If the ACL is only partially torn acupuncture is very helpful.  Acupuncture once weekly for 4 weeks will increase circulation to the joint, stimulate healing, strengthen the ligament and reduce both pain and swelling.  We also recommend a herbal formula called Bones and Sinews and Traumeel, a homeopathic, to aid in healing.  Of course rest, physiotherapy at home and slowly building the dog back up are all part of the process. Unfortunately if the ACL is completely torn, acupuncture may make the dog feel a bit better but it will not stabilize the joint.  Surgery is the only option.

There are two types of surgical repairs. In the standard repair, a strip of fascia (the tough tissue overlying muscle) is threaded through the joint and this acts as a false ACL stabilizing the joint.  A non-absorbable suture is also placed on the outside of the joint to further stabilize the joint.  Most dogs will do very well with this type of repair, however the aftercare is as important as the surgery.  There can be no escaping to continue the “wrascally-wrabbit” chase during the recovery period so owners must be very diligent.

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