Lanark Branch: 01555 660000

Lanark branch: 01555 660000

Cranial Cruciate Ligament Injury

Cranial cruciate ligament rupture (CCLR) is the most common orthopaedic injury in dogs. In people the same ligament is called the anterior cruciate ligament (ACL). In both species the ligament may stretch or tear, leading to pain and osteoarthritis. CCLR can make the menisci vulnerable to tearing, which is quite painful. The menisci are two small cushions of fibrocartilage that sit between the bones of the knee.

  1. Trochlea of femur
  2. Tibia
  3. Fibula
  4. Cranial cruciate ligament
  5. Caudal cruciate ligament
  6. Lateral meniscus
  7. Medial meniscus

Illustration of a normal left knee

Typical symptoms of CCLR damage:

  • Toe touching
  • Swelling of medial aspect (inside) of knee
  • Painful on palpation
  • When sitting holding the leg to one side
  • Cranial drawer (forward movement of the shinbone in respect to thighbone)

Illustration of ruptured left cranial cruciate ligament

The clinical signs of lameness with CCLR can vary. Some dogs initially show an acute onset of lameness followed by mild improvement over the following weeks. Other dogs experience a moderately progressive lameness particularly associated with exercise, or lameness when the dog gets up after resting.


CCLR is first diagnosed by palpation (examination and manipulation by hand). This is best done under heavy sedation or general anaesthesia. While x-rays are routinely taken in dogs with CCLR to ensure no other problems are present, and to assess the degree of secondary arthritic changes, this disease cannot be directly diagnosed on x-rays because the ligament does not appear on radiographs.

Normal Left Knee

Arthritic Left Knee due to CCL Rupture


  • Conservative treatment (i.e. rest and the use of painkillers)
  • Lateral fabellar suture
  • TPLO

Conservative Treatment

In very small dogs (less than 10 kg) it is possible for the knee to improve in stability without surgery, as the body lays down scar tissue over the months following the injury. However in most dogs, and certainly all weighing more than 20 kg, adequate stabilization of the knee will usually not be achieved with rest alone, and the pain and lameness will continue for the remainder of the animal’s life

Lateral Fabellar Suture

Surgery is recommended for most dogs with CCLR. More traditional surgical treatments of CCLR involve replacing the ligament with either a natural or synthetic material. In these procedures, natural fibrous tissue, nylon suture, wire or leader line is used to stabilize the knee. These procedures have been used for more than half a century, and the results are good in many cases. The main concern with these procedures is that the stabilizing material can stretch or break, after which the knee is stabilized by scar tissue. This may lead to a decrease in the range of motion of the joint. We currently recommend an extra-capsular suture surgery for smaller dogs (less than 20 kg), i.e. where the stabilizing material is outside the joint. In larger dogs we would use this only when medical or financial limitations prohibit performance of a Tibial Plateau Leveling Ostotomy (TPLO).


Tibial Plateau Leveling Osteotomy

The most widely used technique in treatment of CCLR by orthopaedic surgeons is the TPLO. In this technique, the lower bone of the joint (tibia) is cut and rotated to eliminate the abnormal motion of the knee during normal activity. The advantage of this procedure is that it does not rely on materials that can stretch or break to stabilize the knee. We recommend TPLO in most of our medium and large patients and particularly in more active dogs. The CCL will not be replaced but instead the use of that ligament is obsolete after TPLO surgery.

How TPLO-Surgery Works

Slocum, an American Veterinary surgeon developed TPLO in the early 1980s. He showed that if the shinbone (the tibia) is steeply sloped at the level of the joint, the thighbone (the femur) is always sliding down the tibia. This constant sliding places strain on the CCL, possibly causing it to fail. The TPLO procedure corrects the tibial plateau angle to eliminate the sliding and thus the instability of the knee. This, in turn, reduces the accompanying pain and slows the progression of osteoarthritis.

What are the risks of TPLO surgery?

  • Any time a surgery is performed, there is always the possibility of anaesthesia complications, but these are minimized by our high quality surgical facility.
  • Failure to restrict activity after surgery, especially in the first 2 months (see the rehabilitation regime below), can cause poor healing due to straining of the patellar ligament, breakage of plates or screws, or loosening of the screws.
  • Poor healing of the bone can also be caused by steroid use (usually for allergies) or some illnesses such as diabetes.
  • Fracture of tibial plateau or shifting of the position of the bone (from falling, or too much activity) can necessitate additional surgery.
  • Infection at the surgery site, (minimized by sterile surgical techniques, antibiotic use, and prevention of licking of the incision after surgery).
  • If meniscal cartilage was not damaged at the time of surgery, it may become damaged at a later date requiring a second surgery.
  • Improvement may be reduced if your pet has arthritis or advanced degenerative joint disease before surgery.
  • Improvement may be reduced if your pet had a previous surgery of an alternate technique on the knee.

Slocum® Post-operative Care for Orthopaedic Surgery (“Courtesy of Slocum Clinic”)

For eight to twelve weeks following surgery, a strict confinement regime is required with three important principles.

Your pet can be inside, on carpeted surfaces, under your direct supervision.  It can wander around the room at a slow walk as long as it is not constant.  Running, jumping, bounding, playing, etc., are not allowed.  
Your pet must be on a leash at all times when outside for airing and going to the bathroom.  If the animal has to cross slick floors or uneven ground, you need to use a "belly-band" in case it slips or stumbles.  The "belly-band" is not used for support but rather as a safety net to protect your pet.  Your pet is not allowed to be off lead when outside or to go for an actual walk.
When not under your direct supervision, your pet is to be confined in an airline kennel or equivalent.

General Information:

  1. Playing with other animals is not allowed during confinement.  If there are other pets in your household, you will need to keep them separated. 
  2. During confinement, your pet's food intake needs to be reduced to help prevent weight gain.  Most dogs will maintain their current weight if their food intake is cut in half.  Water consumption should remain normal.
  3. The first two weeks following surgery you will need to monitor your pet's wounds.  Licking or chewing can cause infection or sutures to loosen.  If you notice that your pet has started licking, you will need to take steps to discourage it from doing so.
  4. It takes a minimum of six to eight weeks for bones to heal. 
  5. One of the most difficult aspects of confinement is that the animals will frequently feel better long before they are healed.  At this point your pet will start being more careless of the operated limb and is then more likely to be overactive and injure itself.  Until the bone is healed, you must adhere strictly to the confinement guidelines and not allow your pet to do more.  
  6. If your pet is jumping or bouncing in its confined area, it is being too active.  Tranquilizers may be required to help alleviate your pet's anxiety or control its activity.
  7. If at any time during your pets recovery and healing it does anything that causes it to cry out or give a sharp yelp, contact your veterinarian.  
  8. Following surgery your pet should maintain it's current level of mobility, or improve.  If at any time during your pet's recovery and healing it has a set back or decrease in function, contact your veterinarian. 
  9. It is imperative that you inform your veterinarian at once if your pet does something that is potentially harmful to the surgery.  If something has occurred which jeopardizes the outcome of surgery, it is usually less difficult to correct if it is caught right away, which leads to a better outcome for your pet.
  10. If your pet is too active during it's confinement it may injure itself or slow healing which increases the amount of time your pet must be confined.
  11. Follow up appointments are usually needed two weeks post-operatively to monitor incisions and healing. At eight weeks post-operatively radiographs are taken at which time your pet is started on a regulated activity regime.  A final appointment at four months post-operatively is needed for additional radiographs and final instructions before returning your pet to normal activity.

Slocum® Rehabilitation Regime (“Courtesy of Slocum Clinic”)

Once radiographs have confirmed bone healing, usually around eight weeks post-operatively, the rehabilitation regime is initiated. 
During this period the patient's activities are gradually increased to build muscle, stretch scar tissue from surgery, and strengthen bone healing. The degree of activity should progress with your pet remaining comfortable. Since increasing duration, not intensity, is the goal, explosive activities such as running, jumping or playing, are not allowed during the rehabilitation period.

Throughout the rehabilitation process the dog is allowed to go as far as it is able while remaining comfortable.  To judge your pets comfort, watch the dog when it gets up following exercise and rest.  If invigorated and excited about more activity, the animal is comfortable.  If the dog gets up with stiffness and complaint, then the amount of activity should be reduced.

The first three to four weeks of rehabilitation are comprised of progressively longer walks with the animal on a short lead, in the heel position.  Begin with a five minute walk and see how the dog responds.  If the dog does well, continue at this distance for three to four days.  If your pet has remained comfortable during this time, double the distance of the walk.  Monitor the dog’s comfort, and after three to four days double the distance of the walk again.  Continue doubling the distance of the walk every few days as the dogs comfort level permits.  If the animal appears to be uncomfortable with the increased distance, cut the length of the walk back to the last distance at which it was comfortable; go for another few days at the lesser distance, then try doubling it again.

Your pet will benefit more from several short walks in one day rather than a single long walk, so instead of doubling the length of a walk, you can double the number of walks.  Rather than going from one 10 minute walk to one 20 minute walk, go for two 10 minute walks instead.  Your pet will still be getting twice the activity, but it will be split up throughout the day.  You can continue doubling the distance or number of walks as your schedule and your pet’s comfort allow.  If your pet likes the water, you may substitute a swim for a walk at any time, allowing the swim for the same length of time as the walk you are replacing.  Your dog should not, however, be allowed to launch itself into the water, but rather be encouraged to swim after it is already belly deep.

During the fourth to the sixth week of rehabilitation the walks are continued with your dog on a long lead, such as a 10-15 foot leash or a flexible lead.  You will need to cut back the length of the walks you are currently going, as the longer lead allows the dog the freedom to trot back and forth, increasing its usage of the leg.  Usually we recommend that you quarter the distance of the walks at this point.  Once you know where your pet's comfort level is, you will double the amount of activity every few days.  As distances are more difficult to judge at this point, it is important to monitor the dog's comfort level closely during this stage of rehabilitation.

From the seventh to the ninth week of rehabilitation your pet is allowed very mild activity off the lead.  You will continue with the long lead walks but you will start letting your pet have time off the lead in an enclosed area such as your garden or yard, always under your supervision.  The area should have no other animals or distractions around.  The off-lead activity should occur after your pet has had a walk to get some energy out of its system.  Start with five minutes off lead following a walk.  As with the walks, double the time your pet is spending off lead in the yard every few days as long as your pet's comfort level permits.  The dog should remain under the voice control of the owner at all times.  No jumping, chasing a ball, or playing with other animals is permitted.  Avoid any activities where the dog's full concentration is thrown into the activity without regard for its body.

A final check-up at the end of the rehabilitation process is needed before full activity may be resumed.