Cranial Cruciate Ligament Disease

Dr. April Guille

Damage to the cranial cruciate ligament (CCL) is one of the most common orthopedic injuries in dogs.  The majority of dogs have secondary degenerative changes in the ligament that lead to rupture.  The causes for cranial cruciate ligament degeneration are multifactorial (a combination of genetic and environmental factors).  Trauma leading to rupture is seen in a smaller percentage of patients.

The cranial cruciate ligament is a major stabilizer in the stifle (knee) joint, both limiting forward motion of the tibia in relation to the femur (termed cranial thrust) and internal rotation in the joint.  Unfortunately, the torn ligament will not heal itself and partial tears almost always progress to complete rupture of the ligament. After rupture, the stifle joint becomes unstable, leading to inflammation, pain, meniscal injury, fibrosis, and osteoarthritis in the joint. 

Clinical signs:  CCL rupture causes pain and lameness in the affected leg.  Dogs with partial tears may initially improve after restriction of activity, but the lameness will typically return as they continue to tear their ligament, leading to a cyclical course of lameness and improvement with rest.  The lameness often becomes progressively worse to the point of a permanent lameness of varying degrees.  Dogs can also become very lame after tearing their medial meniscus.  Other clinical signs include stiffness, sitting with the leg out to the side, muscle atrophy, decreased activity, and occasionally, owners may hear an audible “click” if the medial meniscus is torn.

Diagnosis:  The diagnosis is based on history, physical exam, and radiographic findings.  On physical exam, we will check the stifle for drawer motion, or an abnormal forward motion of the tibia in relation to the femur, and cranial thrust.  Joint effusion (swelling) is present in the joint and long-standing ruptures will have secondary fibrosis around the joint, especially on the inner aspect, termed medial buttress.    The cruciate ligament is not visible on plain radiographs, but radiographs are taken to rule out other causes of the lameness, evaluate the joint for evidence of effusion and osteoarthritis, and pre-operative planning.  Occasionally, some dogs can be very tense, and sedation will allow better evaluation of the stifle for abnormal motion.


Medical Management:
  Cruciate ruptures are best handled with surgery (see below).  But in addition to surgery, medical management is used to assist with the joint health, manage osteoarthritis, and assist with the recovery from surgery.  This may include but is not limited to: glucosamine and chondroitin supplementation, non-steroidal ant-inflammatories, physical therapy, and alternative therapies such as laser or acupuncture treatments.  Please see the page on managing osteoarthritis. 

Surgical Treatment:  Although the arthritis in the joint cannot be reversed, early surgical intervention may mitigate the progression of osteoarthritis and therefore improve overall long-term function of the joint.  Surgical techniques can broadly be divided into intracapsular (within the joint) and extracapsular (outside of the joint) repair.  Regardless of the technique used, the joint is entered and the medial meniscus is evaluated at the time of surgery.  The two menisci in the joint act as a cushion and shock absorber.  A portion of the medial (inner) meniscus can become pinched and torn due to the abnormal motion present in a CCL deficient stifle joint.  This torn piece, if present, is removed. 

Below is a summary of the three surgical treatments we use here at PVS for treatment of CCL rupture.  We will discuss these options with you at the time of your appointment and what might be best suited to you and your pet’s needs.

Lateral Fabellar Suture Technique

After closure of the joint capsule, two sutures are passed around a small bone (lateral fabella) on the back side of the femurand through a bone tunnel created in the top of tibia.  They are then tied to an appropriate tension.  This orientation mimics the cranial cruciate ligament, providing temporary stability.  The ultimate stability is provided by scar tissue that surrounds the joint.    

Patients that receive this surgery typically take a little longer (up to 6 months) to be at their best function post-operatively.  There is a subset of larger dogs, especially active dogs, who may not do as well with this surgery compared with the biomechanical stabilizations (discussed below). 

Tibial Plateau Leveling Osteotomy (TPLO)  

The TPLO is a form of biomechanical stabilization that eliminates the need for the cranial cruciate ligament by altering the forces acting on the stifle joint and preventing cranial thrust of the tibia.   After evaluation of the menisci, the joint is closed and the tibial bone is cut.  The bone is rotated several millimeters and plated in a new position.  These measurements are determined based on preoperative evaluation of specific radiographic positions.  The tibia heals in its new orientation, “leveling” the tibial slope and stabilizing the stifle joint. 

Tibial Tuberosity Advancement (TTA)

The TTA is another form of biomechanical stabilization of the stifle joint.  Like the TPLO, the TTA eliminates cranial thrust by cutting the tibial tuberosity and repositioning it with a spacer and a titanium plate.  The measurements for the implants are determined on specific pre-operative radiographic views. 


Which surgery is right for your pet?

While all three surgeries help improve the lives of our pets, many factors determine which specific surgery is best for you and your pet.  We generally find that dogs undergoing a biomechanical stabilization (TTA or TPLO) will have a better short-term and likely long-term recovery.  However both of these surgeries, while approximately the same price, will cost more than the lateral fabellar suture technique due to the required equipment and expertise.  Of the two biomechanical surgeries, the TTA is generally preferred by Dr. Guille.  In comparison with the TPLO, the TTA is less invasive, requires a shorter anesthesia time, patients typically make a quicker recovery, and the complications are usually less serious in nature if they occur.  Studies have also shown that of the three procedures, the TTA is the only one to restore the contact mechanics in the joint back to “normal”, or what existed prior to rupture of the cruciate.  The TPLO, however, is able to be used in a broader category of bone conformations, so some dogs are not suited to the TTA procedure.  The discussion of the pros and cons of each surgery, along with the recommendation for your pet, will be determined at the time of your consultation.  Specific radiographic views may be required prior to surgery to make the final determination.


Osteoarthritis afflicts a large number of pets in the United States.  It is a slowly progressive disease that results in the degeneration of cartilage, fibrosis of the soft tissues surrounding the joint and new bone formation.  Osteoarthritis can be the end result of several initiating causes, including congenital problems, traumatic events, certain diseases, or wear and tear on the joints.  Osteoarthritis in animals is caused more often by an initiating cause than by normal aging and degeneration of the cartilage.  Whatever the inciting cause, initial cartilage degradation results in the release of inflammatory substances which further contribute to cartilage breakdown.  A vicious cycle ensues, resulting in cartilage loss, hardening of the underlying bone, fibrosis of the surrounding tissues, formation of new bone called osteophytes, and inflammation of the lining of the joint.  The end result for your pet is pain and a loss of function in the affected joint or joints.

Some inciting causes of osteoarthritis:
-    Cranial cruciate rupture
-    Patellar luxations
-    Hip dysplasia
-    Fractures entering the joint
-    Joint conditions such as osteochondritis dissecans, fragmented medial coronoid process, ununited anconeal process and elbow incongruency
-    Inflammatory joint diseases
-    Septic arthritis

Signs of arthritis include:
-    Reluctance to take walks
-    Stiffness  
-    Difficulty climbing stairs, climbing in the car, on the bed or a sofa
-    Difficulty rising from rest
-    Limping
-    Acting withdrawn, spending less time playing with family
-    Soreness when touched  
-    Rarely, aggression

Once a joint has progressed to arthritis, we cannot reverse the changes present in the joint.  However there are several options to help manage your pet’s discomfort, thus improving their quality of life.

Weight Reduction (if applicable):   It is very important that dogs and cats afflicted with osteoarthritis maintain an ideal body weight.  The extra weight carried by an overweight or obese animal places additional stress on the joints. In animals at an ideal body weight, you should easily be able to palpate their ribs through a minimal layer of fat and your pet should have a nice “waistline tuck” behind the ribs when viewed from above and the side. If you have any questions on body condition or diet, please consult a veterinarian.  Weight loss for overweight osteoarthritic pets is one of the easiest and important things you can to improve your pet’s comfort.  

Moderate Daily Exercise:   Arthritic joints function better when they are mobilized during low-impact exercise on a daily basis.  Swimming is an excellent option.  Leash walking or controlled jogging are also acceptable.  Important things to remember are avoiding high impact activities, especially things like chasing a ball, which has sudden stops and turns.  Also try to avoid having your pet receive no exercise for several days followed by strenuous activity.

Nutraceuticals:   Glucosamine and Chondroitin are two examples of nutraceuticals and they are often found in combination tablets.  Glucosamine and chondroitin are molecules normally found in cartilage.  Both substances may support cartilage structure, prevent further deterioration in the joint, suppress inflammation, and reduce free radical damage.   Using both in combination has been shown to slow down cartilage damage better than using either of these products alone.  It is important to remember that nutraceuticals are not drugs, and are therefore not directly regulated by the Food and Drug Administration.  Independent studies have shown that many human products do not contain the amounts of glucosamine and chondroitin stated on the label, and some may even contain substances harmful to the health of your pet.  (In fact, only 16% of products that were studied met the overall claims on their label, according to one study).  For this reason, we recommend using veterinary approved products that undergo routine testing to ensure the content of the product matches the label.  Dasuquin and Cosequin are two such products.  The major difference between these two products is that Dasuquin includes avocado and soybean unsaponifiables, which have also been shown in multiple studies to support joint health.

Omega Fatty 3 Acids:   Studies have shown that Omega Fatty 3 Acids, typically found in fish oil, can reduce joint inflammation.  Fish oils are typically a mixture of different fatty acids (FA).  Recent research by Hills shows that the EPA strength is the most important to determine dosing.  They recommend 50-100 mg EPA per kilogram of body weight per day.  Fish oil capsules can be stored in the freezer to reduce “fish breath”.  Some people prefer to simplify matters by feeding a diet that already contains fish oil, such as Hills j/d diet.  This is a prescription diet and can typically be purchased through your regular veterinarian’s office.

Non-steroidal Anti-Inflammatories (NSAIDs):   These medications are commonly prescribed for arthritis pain and include the drugs Rimadyl (carprofen), Metacam (meloxicam), Previcox (firocoxib), and Deramaxx (deracoxib), among others.  These medications are similar to humans taking ibuprofen or aspirin; however, dogs can be very sensitive to the human formulations and should not be given any human non-steroidal anti-inflammatories without a veterinarian’s guidance.  (Aspirin also inhibits platelet function and should be stopped 2 weeks prior to any planned surgery.)  NSAIDs both reduce inflammation and provide pain relief.  A veterinary formulation is a good medication to have on hand and give to your pet prior to activities you know may exacerbate the arthritis or if your pet seems to be having a sore day.  The most common side effects of NSAIDs are gastrointestinal in nature.  If you notice any vomiting, diarrhea, inappetence lasting greater than 24 hours, or black tarry stools, please stop the medication and contact your veterinarian.  In rare cases, these medications can cause bleeding or perforating ulcers.  These medications are not routinely used in pets with liver or kidney problems, or pets who are receiving steroids.  Patients on long-term routine usage of NSAIDs should have bloodwork performed every 6 months or according to your veterinarian’s recommendation to confirm the liver and kidneys are functioning well.  Very rarely, idiosyncratic liver reactions to NSAIDs have been reported, leading to serious illness or death.

Acupuncture:   Acupuncture has a long history of being useful for managing pain.  It can serve well as a complimentary treatment for dogs with pain and mobility issues due to osteoarthritis.  Dr. Gary Stuer provides acupuncture services at PVS every Wednesday. (read more on acupuncture)

Laser Therapy:   Treating arthritis pain is one of the many uses for laser therapy.  Laser therapy is a noninvasive procedure that uses light to stimulate cells, increasing blood circulation, decreasing swelling, and speeding up healing. At the correct laser wavelength, pain signals are reduced and nerve sensitivity decreases. The procedure also releases endorphins, which are natural painkillers.  Laser therapy it is not recommended for animals with cancer because the device can stimulate blood flow to cancer cells.  Light is absorbed into the cells during laser therapy. The process, known as photobiotherapy, stimulates protein synthesis and cell metabolism, which improves cell health and functionality.  The therapy can take as little as 5 minutes or up to about a half hour for bigger dogs with multiple treatment areas.  Chronic, or long-standing problems, may take several treatments before noticeable results are seen.  Treatments should also be done more frequently in the beginning (2-3 times a week) prior to going on a “maintenance” schedule.  Therefore, laser treatments are often sold in packages of 6 treatments.  Please consult Dr. Guille for further information on the treatments and if it would be right for your pet.

Physical Therapy:   Physical therapy is used extensively in human patients with osteoarthritis and can be of benefit in our canine and feline patients as well.  Treatments such as heat and cold, massage therapy, and passive joint manipulation can all help. In addition, specific strengthening activities/exercises can be very beneficial to some arthritic patients.  Most programs are best under the direct supervision of a certified canine rehabilitation therapist (CCRT).  The distance that most people live from a CCRT can limit the amount of treatments performed directly by the physical therapist, but even one consultation can be very helpful by showing you exercises you can perform at home to help with your pet’s condition. 

Injectable Chondroprotective Agent:  There are two separate injectable products that have been used for arthritic joint pain.  One is a formulation of polysulfated glycosaminoglycans (PSGAGs) and goes under the trade name of Adequan.  The exact mechanism of action is not known, and studies have shown conflicting results.  It is usually injected in the muscle twice weekly for 3-4 weeks.  This medication is best suited for joints where there is the chance the cartilage will heal (i.e. a fracture in the joint).  Otherwise, the benefit is likely limited to pain control.  We often use this medication when other treatments are not enough.  Another injectable agent is hyaluronan, which is naturally found in the joint and is given as an injection directly into the affected joint.  It is often administered every 2 weeks for three injections.  Unfortunately, the cost can be expensive, since your pet must be sedated and the joint sterilely prepped prior to injection.  About half of dogs respond positively to the injection.  

Surgery:   In certain situations, surgery may be applicable to help with osteoarthritic pets.  This can be determined during a consultation with a veterinary surgeon.

Stem Cell Therapy:   Stem cell therapy is a relatively new treatment modality in veterinary medicine.  The thought process behind the treatment is to gather stem cells from the patient’s own body for the repair or replacement of damaged or diseased tissue.  The typical procedure is as follows:
-    Harvesting of the patient’s fat through a surgical procedure under anesthesia  
-    The fat is then sent to a lab overnight where the stem cells are harvested
-    After a day, the stem cells are sent back by the lab
-    48 hours after the initial surgery, the patient is sedated for injection into the affected joints and/or IV injection, depending on the individual case
This procedure is typically reserved for use after other treatments have failed, because the cost can be much higher than other treatments.  If you are interested in the procedure for your pet, please consult Dr. Guille for further information.  The procedure will not be performed the day of the consultation, as preplanning with the laboratory is required.

The key points in managing osteoarthritis are remembering it is a disease that can be managed, not cured, and that there are many different options to help manage your pet’s discomfort and provide the best quality of life possible.