Cranial Cruciate Ligament Injury:  Diagnosis and Treatment

The most common orthopedic injury that presents to VOSM in our canine patient is a rupture of the cranial cruciate ligament (CCL).  A rupture of this ligament can cause pain and lameness, injury to other structures of the knee, such as the meniscus, and lead to long term osteoarthritis of the knee.  Surgical options for this injury are the Tibial Plateau Leveling Osteotomy (TPLO) and the Extracapsular Stabilization.  We recommend the TPLO to treat this injury.  Contrary to popular belief, TPLO surgery is not reserved for large breed dogs, patients weighing as little as 10 pounds can benefit from TPLO surgery.  TPLO surgery provides a more rapid recovery, improved range of motion, reduction in the progression of arthritis and can return the patient to complete pre-injury performance as compared to other surgical options.

What is a CCL and what does it do?

Although the knee joint in dogs is similar to ours, the forces applied to the joint during weight bearing are vastly different.  Our hip, knee and ankle joints are perpendicular to our weight bearing surface, our feet.  When we stand, there is minimal stress to the ligaments in our knee.  Dogs, however, stand on their toes with the ankle elevated and the knee forward.  The top of the dog’s tibia (tibial plateau) is sloped and weight bearing creates a force that pushes the femur down the slope of the tibia.  This force is called “tibial thrust” and it is the job of the CCL to prevent this motion.   Each time the dog bears weight, the CCL is called to work.   If you think of the tibial plateau as a hill and the femur as a car parked on the hill, the CCL is the break.  If the ligament ruptures, it allows the femur to slide down the slope or, in our example, the break releases and the car rolls down the hill.   When the ligament is ruptured, each time the dog bears weight this motion occurs and causes discomfort.  Within the joint, there will be inflammation and swelling, referred to as synovitis and effusion.

How does a rupture of the CCL occur?

Rupture of the CCL can occur in several different ways.  There may be a single incident which causes a sudden complete rupture of the ligament.  When this occurs the dog is typically painful and non-weight bearing.  The rupture can also occur over time.  Dogs with a high tibial plateau angle (greater slope) have greater stress to the CCL and the ligament can tear incrementally.  Dogs can also partially tear the ligament due to an incident.  With a partial rupture, the dog typically experiences an intermittent lameness.  The majority of partial ruptures will progress to a complete rupture within weeks to months.  Common causes of partial and/or complete ruptures include hyperextension and internal rotation of the knee from sudden turns, stepping into a hole; jumping – if the force of the cranial tibial thrust exceeds the breaking strength of the CCL; repetitive normal activities; and degeneration with aging .  Obesity can increase the risk of a rupture as can the “weekend warrior” routine, in which the pet is relatively inactive during the week but very active on weekends.  Dogs that have ruptured the CCL in one knee have a 50% to 70% greater chance of rupturing the CCL in the other knee.  Therefore, surgical correction is recommended as soon as possible to decrease the stress placed on the uninjured CCL, thereby decreasing the risk of CCL rupture to that knee.

What are signs that my pet has a rupture of the CCL?

If the CCL rupture is complete and acute, often the pet will be non-weight bearing lame.  With rest, the lameness may improve but will return as the pet is more active.  However, in the case of a partial or gradual rupture, the pet will be weight-bearing lame or have an intermittent lameness.  Lameness will often worsen with activity.  Stiffness upon rising and/or a stiff gait is another common complaint.  You may note that your pet sits with the affected leg out to the side.  He or she may have difficulty rising and be less active.  Physically, you may note a swelling or thickening of the knee and muscle atrophy (wasting) in the affected limb.  Dogs that have ruptured the CCL in both knees do not routinely carry or off-load a particular limb since he or she does not have a good limb to stand on.  

How is a rupture of the CCL diagnosed?

Diagnosis of a rupture of the CCL typically involves an orthopedic examination.  Dr. Canapp will check for cranial drawer by holding the femur with one hand and the tibia with the other.  He will then check for forward motion of the tibia.  If this occurs, it is an indication that the CCL is ruptured.  To further test for a rupture of this ligament, he will perform a tibial thrust test.  This involves placing a hand over the knee joint and flexing the hock (ankle) with the other hand.  If the tibia has forward motion, it is an indication that the CCL is ruptured.  In the case of a partial cruciate rupture, these motions will be noted in flexion of the knee, however; these motions may be difficult to assess.  Radiographs of the knee will be taken to evaluate the presence of effusion (excessive fluid within the knee joint) and arthritis.  If these tests alone are not completely diagnostic, arthroscopic evaluation of the joint and structures may be recommended.  If arthroscopic evaluation reveals the ligament is injured, a TPLO will be performed at that time.

What are the surgical options for a ruptured CCL?

There are two surgical options for correction of this injury, the TPLO or an Extracapsular Stabilization.  The Extracapsular Stabilization stabilizes the joint with a prosthetic ligament.  This technique relies on scar tissue to ultimately stabilize the joint.  The reported recovery time following the Extracapsular Stabilization is approximately 3 to 5 months.  The reported recovery time following the TPLO procedure is approximately 2 to 3 months.  Following TPLO surgery, patients use the limb and are more comfortable much sooner than they do following the Extracapsular Stabilization.  Additionally, studies show that there is less arthritic development long term following the TPLO verses the Extracapsular Stabilization (Lazar T, Vet Surg, 2005).  For these reasons, the TPLO is considered by most veterinary surgeons to be the “gold standard” for correcting this injury. 

What is a TPLO?

The TPLO procedure stabilizes the knee by leveling the tibial plateau.  In our example of a car parked on a hill, the hill is leveled eliminating the need for the break.  Radiographs of the knee are taken prior to surgery.  Using specific landmarks, Dr. Canapp will measure your pet’s tibial plateau angle (slope) and accurately and precisely determine the amount of rotation that is needed to reduce the angle to between 5 and 10 degrees.  During the TPLO procedure, Dr. Canapp will make a circular cut (osteotomy) in the top of the tibia and rotate the segment so that the load-bearing surface of the tibia is between 5 to 10 degrees.  A plate is then applied to hold the tibia in this position and allow for the bone to heal.  Restricted activity is required while the bone heals.    

The menisci are the “shock absorbers” of the knee and are located between the bottom of the femur and top of the tibia.  There is a meniscus located on the inside (medial) and outside (lateral) aspects of the knee.  When the knee is unstable due to a CCL rupture, either complete or partial, these structures are at risk for injury.  Prior to the TPLO procedure, Dr. Canapp can perform a stifle arthroscopy to evaluate these structures, and if either menisci have sustained an injury, the damaged portion will be treated. 

What can I expect after TPLO surgery?

After surgery, dogs are typically non-weight bearing to toe-touching lame for the first few days.  Shortly thereafter, dogs begin to bear weight with an obvious lameness.    When walking, they will use the limb but they will often hold the leg up when standing.  Within two to three weeks, however, they are using the limb consistently, although a lameness will still be obvious.  Patients are typically quite comfortable 2 or 3 days following surgery.  Most owners report that the greatest challenge they faced while caring for their recovering pet is preventing him or her from being too active!  By the four week recheck and radiographs, the pet is typically fully weight bearing.  By the eight week recheck and radiographs, most pets are 90% healed.  At the twelve week recheck, your pet will be healed and may begin a gradual return to normal activity. 

How do I prepare my pet for surgery?

Blood work (CBC/Chemistry Profile) is required prior to surgery.  If this bloodwork has been performed within the past three months and there are no concerning abnormalities, no additional bloodwork is required.  We will request a copy of the bloodwork results from your veterinarian.  If this bloodwork has not yet been performed, please schedule an appointment with your regular veterinarian at least 2 business days prior to surgery.  Please ask your veterinarian to fax the results to our office for evaluation.  Alternatively, bloodwork may be performed at VOSM at the time of your consultation.  If any concerning abnormalities are noted, Dr. Canapp will call you to discuss the results.   

We ask that you withhold food after midnight the evening prior to surgery.  Your pet may have water through the time of drop off.  If your pet is on a non-steroidal anti-inflammatory (Rimadyl, Deramaxx, Etogesic, Previcox, etc.) it should be discontinued 2 days prior to surgery.  We ask that you drop off your pet between 7:30 and 8:00am the morning of surgery.  If your pet is on any special diet, please bring 3 meals worth of food with you.  Additionally , if your pet is on any medication that should be continued during hospitalization, please bring the medication and instructions.  The morning of surgery, our receptionist will review the surgical consent form with you and you will be asked to provide a deposit for half of the surgical estimate.  One of our technicians will escort your pet to our ward area.   

What is the protocol during my pet’s hospitalization?

Upon arrival, an IV catheter will be placed.  Your pet will be given a sedative prior to anesthesia to help him or her relax.  The anesthetic used is similar to that used in human medicine.  While anesthetized, your pet will be closely monitored.  We monitor your pet’s heart rate, ECG, breathing, oxygenation, blood pressure, temperature, and CO2 output.  Your pet’s affected leg will be shaved from the hip to the hock (ankle).

After surgery, a technician will recover your pet.  Your pet will be closely monitored and comforted by the technician as he or she wakes from anesthesia.  Dr. Canapp will call you after surgery with an update.  You may call anytime to get further updates (after 7pm, please call 410-750-1177).  Your pet will spend the night of surgery at the hospital, under direct supervision by a veterinarian.  He or she will receive IV fluid therapy, IV antibiotics, and pain medication.  Cryotherapy will begin that evening.  Food, water and walks will be offered once your pet is awake. 

The next morning, Dr. Canapp will perform a physical examination.  Your pet’s bandage will be changed, cryotherapy performed and the catheter will be removed.  We ask that you call our office between 9:00 and 10:00am to schedule a pick-up time.  Typically discharges are scheduled between 11:00am and 6:00pm.  When you arrive, please notify our receptionist you are picking up your pet.  Lisa Fair, our Surgical Services Manager, will review discharge/post-operative care instructions and medications with you as well as answer any questions you may have.  You will be provided with the prescribed antibiotics, pain medication, and an Elizabethan Collar (to prevent licking and chewing at the bandage and incision).  If you prefer a Bite Not Collar, you can purchase one at your local pet supply store or through www.dog.com.   Once the instructions have been reviewed, our receptionist will assist you with payment of your balance.  We will then assist you with getting your pet into your car.

What is the post-operative care following TPLO surgery?

At home care and rehabilitation therapy are the most important aspects of a successful recovery.  A soft padded bandage will be applied to the leg post-operatively to help reduce swelling.  This bandage will be removed in 2 to 3 days after surgery.  An Elizabethan Collar or Bite Not Collar will be needed following surgery until the incision has healed and the staples are removed (10 to 14 days).  Your pet will need to be confined to either a crate or a small area of the house where he or she does not have access to stairs or furniture.  A crate is only recommended for pets that are normally confined in this manner.  Your pet should not run, jump, or play for at least two months following surgery.  Stairs should be limited to only those necessary.  A sling and leash should be used when performing stairs, crossing slippery surfaces, and on uneven ground.  You will be given rehabilitation exercises to perform at home.  Your pet will be limited to short leash walks for elimination only for the first 2 weeks.  Thereafter, your pet will be allowed gradually increasing leash walks as part of the rehabilitation therapy.  Radiographs will be needed at 4, 8, and 12 weeks post-operatively.  This service will be performed by Dr. Debra Canapp, VOSM’s veterinary rehabilitation therapist.  At those appointments, based on the amount of healing noted, physical examination, and your evaluation of your pet’s progress, changes to your at home therapy program will be provided.  All at home care and rehabilitation exercises will be reviewed with you in detail.  Rehabilitation therapy will help to speed your pet’s recovery and return to full function.  Dr. Debra Canapp’s schedule tends to fill quickly; therefore, we recommend you schedule your post-operative rechecks (4, 8, and 12 weeks post-op) at the same time you schedule a surgery date.