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The Normal Cranial Cruciate Ligament

The normal cranial cruciate ligament, or ACL as it is known in humans,
 is the primary stabilizer in a dog’s knee when he/she walks and runs. The ligament prevents hyperextension, internal rotation, and forward movement of the tibia relative to the femur. The ligament is made up of numerous bands which wrap around each other, much like a rope.  The ligament has no significant blood supply, so it cannot heal naturally.

What Causes The Ligament To Tear

In humans, an ACL tear is considered a sport-related injury that occurs with acute trauma.  In our pets, however, ligament tears are more complicated.  In the majority of cases, they occur due to age-related degenerative change in which the ligament becomes weaker over time, much like fraying of a rope.  This leads to tearing with just mild activity. Predisposing factors include breed specifics, obesity, and certain bone confirmations.

Symptoms Of A Torn Cranial Cruciate Ligament

Limping is the most common symptom of a damaged or torn cranial cruciate ligament. Most dogs will not use the leg immediately following the tear, but as inflammation subsides they begin to use the leg with a limp. From that point, the limp can be consistent to intermittent but is usually worse following exercise. Dogs will often improve with anti-inflammatory medication but typically become refractory over time.

How Is A Torn Cranial Cruciate Ligament Diagnosed

The diagnosis of a torn ligament happens during a physical exam. Dogs with a ligament tear have pain, swelling, and instability in the knee which can be palpated.  Some dogs may also have muscle loss and loss of range of motion if the tear is more chronic. While the cranial crucial ligament cannot be seen on x-rays, classic changes are seen that support the diagnosis.

What Will Happen If Left Untreated

Since the ligament has no significant blood supply, it cannot heal naturally.  Furthermore, almost all partial tears will develop into complete tears. Without surgery, most dogs develop arthritis which leads to chronic limping, decreased activity, weight gain, and reduced quality of life.

What Are The Treatment Options

In any size dog, surgery is the gold standard for treating torn cruciate ligaments. In some small breed dogs, medical therapy can be attempted to allow the knee to “self stabilize” by building scar tissue around the joint. Medical therapy involves strict cage rest for 8 weeks, anti-inflammatory medications, and formal physical therapy.

The most well researched and common surgical procedure performed to stabilize the knee after a torn cruciate ligament is a TPLO or tibial plateau leveling osteotomy. In this procedure, the geometry of the knee is changed to eliminate the instability that occurs with a cranial cruciate ligament tear. In the TPLO surgery, a semi-circular cut is made in the top of the tibia, the bone is rotated, and a stainless steel plate and screws are applied to hold the bone stable while it heals.

Recovery from the procedure is approximately 8-12 weeks. Patients are discharged the day following surgery with anti-inflammatories, pain medications, and instructions on at-home activity restriction and rehabilitation. Most dogs limp on the leg immediately following the procedure but make dramatic improvement over the first 1 to 2 weeks. 95% of dogs, once recovered, return to full pet quality function.  This means they can run, jump, and play with no limp or pain.

At Elite Veterinary Surgery, the TPLO surgery is completed by a board certified surgeon who has undergone extensive training in the procedure. Patients receive multi-modal pain control including injectable medications, oral medications, a local nerve block, and topical therapies.  Patients recover in our 24-hour care facility and are monitored by a full team
 of doctors and technicians. During all times of the recovery process, you and your dog have immediate access to the surgeon who performed the procedure.

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