Limping Dogs, Cruciate Injuries

Jennifer Lesser, DVM  Norwich Regional Animal Hospital

What are cruciate ligaments?

In the knees of our dogs and cats are two strong ligament bands, arranged like an X, crisscrossing front to back.  Our dogs tend to injure the cranial cruciate ligament (CCL).  Cats generally are spared from this type of injury.  The effect of a torn CCL is an unstable joint in which the tibia (shin) pushes forward, causing pain and progressive arthritis.

What are some risk factors of a torn CCL?

Obesity, advancing age, body conformation, long term steroid use and some medical conditions may increase risk of injury.  Also, certain breeds such as Staffordshire Terriers, Retrievers, Mastiffs and Newfoundlands are prone to cruciate tears.  Early neutering (less than 6 months old) may be a risk factor as well.  

How does a CCL rupture?

A partial tear is the most common cruciate injury.  The typical patient is a dog of middle to advanced age whose ligament degenerated, allowing for susceptibility to tearing fibers.  Very minor “tweaks” of the joint may cause the partial tear to become complete.  Often a partial tear will progress to a full tear.

A full tear, at the onset of disease, is much less common and is often the result of a trauma.  Example: your dog Summit is racing up Cardigan Mountain and attempts to run through the boulder rather than around it.  His forward momentum coupled with a sudden halt of his leg results in a torn CCL.  

Good thing our pals have two knees!  However, about half of affected dogs will at some point experience a ruptured ligament in the opposite knee.

What are common symptoms of a partial CCL tear?

Most families notice a mild, intermittent lameness.  Other symptoms: the dog begins to put one leg to the side when she sits down and no longer sits ‘square’.  With a long term injury, the leg’s muscle may become decreased due to disuse.  At this point, you may notice decreased activity, less desire to play and possibly irritable behavior due to pain.

What are common symptoms of a complete CCL tear?  

Symptoms may include sudden disuse of the hind leg, reluctance to stand from a sitting position, hesitancy to jump into the car or onto their favorite resting spot such as your couch.

How is a CCL tear typically diagnosed?

Diagnosis may be made with a physical exam by your veterinarian.  Symptoms we often find include pain with ‘range of motion’ of the knee, ability to move the tibia (shin) forward in relation to the femur (thigh), excess joint fluid around the patellar ligament and scar production on the tibia.  

How are radiographs (x-rays) helpful?

The purpose of radiographs is to look for classic changes associated with the rupture, evaluate for arthritis present in either the knees and the hips and to search for any concurrent bone disease.  Radiographs generally do not involve sedation and the images are immediately available for viewing.  For certain surgical procedures such as TPLO or TTA that are generally performed by a board-certified surgeon, specific radiographs are required for proper therapeutic planning.

How is a CCL injury treated?

Surgical repair is generally the preferred therapeutic approach.  Several highly effective surgical techniques exist.  Illustrative and descriptive reviews are available online.  Many factors affect the recommended surgical technique for the patient.  These include age, weight, body condition, desired activity, surgical cost and concurrent disease.  Each case is unique and deserves careful consideration by the pet’s medical provider and family.  

Medical care may include joint protectants such as high quality fish oil, glucosamine/ chondroitin sulfate supplement, antioxidants, restricted activity and appropriate canine pain analgesics.  Medical therapy is often a supplement to surgical care.  In select cases, it may be the only therapy provided.  

Who performs the orthopedic surgery?

Board-certified veterinary surgeons (Diplomate ACVS) are the most qualified veterinarians to provide surgical care of torn cruciate ligaments.  They have undergone an additional  1-year internship followed by a 3-year residency that focuses only on surgical technique, equipment and procedures.  Board certification is granted with achievement of training and caseload requirements, published research and a final exam.  Advanced surgical techniques, often indicated in the repair of damaged cruciate ligaments, are generally best performed by a surgical specialist.  A list of ACVS board-certified surgeons is available online.

Several general practitioner veterinarians have been trained in appropriate surgical repair of torn cruciate ligaments, particularly in a technique known as extracapsular repair.  Be confident in inquiring of the number of repairs done by your veterinarian, modality of pain relief offered during and after surgery, anesthetic complication rate, expectations of post-op function and requirements of rehabilitation.  Our office recommends that any advanced surgical repair such as TPLO and TTA only be performed by a veterinarian who is specifically board certified in surgery.  

Early intervention is critical in preventing arthritis and permanent joint changes. Approximately 50% of dogs that tear one CCL, will tear their other CCL within a year. If you are concerned that your dog may have injured its CCL, please contact your veterinarian.

Dr. Lesser is happily settled in Norwich with her three children who attend the wonderful Marion Cross Elementary.  Following her work with the Human Genome Project, she earned her veterinary doctoral degree in May 2000.  Norwich Regional Animal Hospital is owned by Dr. Lesser and further supported by Dr. David Sobel, DVM, MRCVS and surgical specialist Dr. Paul Howard, DVM, DACVS whose work is made possible by a highly valued staff.