Dogs and humans share a very important but easily damaged joint. In people it is called the knee. In dogs it is called the stifle. The cranial cruciate ligament, or CCL, in the dog is the equivalent of the anterior cruciate ligament, or ACL, in people.
Cranial cruciate ligament injury is the most common cause of rear limb lameness. Dogs can tear or rupture this ligament when the joint is rotated or overextended. Obesity, biomechanical problems, or repeated minor stresses can also take a toll on the ligament, causing harmful changes over time.
Signs of CCL rupture:
- Limping
- Abnormal sitting posture (straight leg held out to the side)
- Difficulty rising
- Stiff gait
- Exercise intolerance
- Hindlimb muscle atrophy
- Stifle swelling and pain
Injury to the CCL can be complete or partial “rupture.” If left untreated, the ruptured ligament and resultant joint instability lead to joint swelling, pain and arthritis. When this occurs in one joint, it then places additional stress on the opposite hindlimb as the dog compensates for the resulting pain. This often causes degenerative changes in the opposite stifle (knee) as well. Therefore, a dog with CCL rupture in one stifle has a higher chance of developing the same problem in the opposite stifle within 1-2 years (approximately 50%).
Large active dogs and those that are overweight are more prone to CCL injury. Cats and small dogs can also rupture the CLL but the incidence is lower and more likely to occur later in life.
Treatment
Treatment for this painful condition requires surgical intervention in the vast majority of cases. The goal of treatment is to stabilize the joint to allow normal joint movement, thereby alleviating the dog’s pain and allowing for normal activity and a happy, healthy quality of life. Small dogs and cats (weighing less than 10 kg) can very occasionally be managed with conservative treatment consisting of exercise moderation and the use of non-steroidal anti-inflammatory pain relievers and joint supplements such as Glucosamine and chondroitin sulfate. However, intermittent discomfort continues along with the progression of degenerative joint disease (arthritis).
For more information on Glucosamine Chondroitin supplements that are available on the veterinary market go to the web site for the pet arthritis research center.
Non-steroidal anti-inflammatory drugs available for the dog are: Deramaxx, Metacam, Previcox, Rimadyl and Etogesic. In general these medications provide pain relief and are anti-inflammatory. All drugs in this group have the potential for causing gastro-intestinal irritation, so if your pet has any vomiting or diarrhea whilst on this medication you should stop giving it and contact your veterinarian.
Surgery
At Metropolitan Veterinary Associates we offer two surgical options:
- lateral suture stabilization (Extracapsular technique), and
- Tibial Plateau Leveling Osteotomy (TPLO).
We do not currently offer the Tibial Tuberosity Advancement (TTA) or the Tight-Rope technique. These two techniques are relatively new and there is currently very little published data to support their use.
With either the lateral suture stabilization or the TPLO technique the first part of the surgery is the same and involves exploring the stifle joint and removing the damaged cruciate ligament since it cannot be repaired and releases inflammatory mediators into the joint that cause continues pain, lameness and progression of arthritis.
We also evaluate the meniscal cartilages inside the joint. These cartilages act as shock absorbers and can become damaged when the cruciate ligament is damaged. If there is meniscal injury, the damaged portion of the meniscus is removed. If the meniscal cartilages are not damaged they are left in place since they provide an import role in the joint – however, dogs do have a slight risk of developing an isolated meniscal injury in the future, requiring re-exploration of the joint.
Lateral suture stabilization
This technique is a traditional technique that seeks to replace the function of the CCL with a prosthetic ligament made of strong Nylon suture material. In addition, the tough tissue outside the joint (fascia) is tightened to provide additional stability to the joint. This Nylon suture is a temporary stabilization, since over time the suture stretches and can ultimately break. The success of this technique relies on the development of fibrous tissue around the joint that takes over the function of the lateral Nylon Suture and stabilizes the joint. It has been used successfully in veterinary surgery for over 40 years in all sizes of dogs and cats.
Tibial Plateau leveling Osteotomy (TPLO)
This is a newer procedure that stabilizes the joint differently from the lateral suture technique. Many animals with cruciate ligament injury have a sloped top to their tibia (shin bone). This slope puts excess stress on the cruciate ligament and contributes to it rupturing. During surgery the top of the tibia is cut and rotated to a new position to level the top of the tibia, creating a level weight bearing platform. It is held in the new position using a bone plate and screws. This eliminates the slope of the tibia and changes the biomechanics of the joint- essentially eliminating the need for a CCL.
This technique is used most frequently in large and giant breed dogs, obese dogs, performance dogs and dogs with cruciate injury in both legs.
In our experience, dogs tend to bear weight on their operated leg a little quicker after the TPLO surgery than they do with the lateral suture technique. This is of benefit when they have cruciate ligament injury in their other knee.
This is a very strong fixation and less likely to have implant failure than the lateral suture technique, so is of benefit in very large dogs or dogs that are overweight. However, failure of the implants (breakage of the plate or screws or pull out of the screws from the bone) is possible and is more difficult to deal with than complications associated with the lateral suture technique.
Success Rate
Currently the success rate of either surgery is between 85-90%. This means your pet should get back to normal or near normal activity over a 2-4 month period. There are a small percentage of dogs and cats that do not do well following cruciate ligament injury, no matter how they are treated.
Complications of Cruciate Surgery
With any surgical technique there are risks.
Anesthesia
There is always a risk with anesthesia although it is rare that we have significant problems. All animals anesthetized at Metropolitan Veterinary Associates are continuously monitored by a veterinary nurse throughout the procedure. They are placed on intravenous fluids and their heart rates, respiratory rates and blood pressure are constantly monitored. They are also placed on a circulating warm water blanket to help maintain their body temperature under anesthesia.
Infection
There is always the potential for infection with any surgery. Our infection rate is extremely low. In most cases infection occurs when the animal licks or chews at the surgical incision postoperatively. That is why we send you pet home with a protective collar that they should wear at all times to prevent them licking or chewing at the incision. With either surgery- if an infection develops it can delay healing and necessitate the removal of the implants (the stabilizing Nylon suture or the bone plate and screws), which is additional anesthesia and surgery for your pet and additional cost.
Implant failure
Premature breakdown of the stabilizing Nylon suture can occur and is more likely in very large, active dogs or obese dogs. It is also more likely if dogs do not have their activity restricted as directed postoperatively. If the Nylon suture breaks prematurely it can lengthen the recovery process and in some cases necessitate further surgery.
The bone plate and screws used in the TPLO are very strong but by cutting the bone – this is essentially the same as having a fractured bone that requires time to heal. Initially the strength of the repair is provided by the plate and screws alone. Over the next few weeks, as the bone begins to heal, the bone starts providing additional strength to the repair. It is rare that we have implant failure with this technique but if the plate or screws break, the plate pulls off the bone, or the bone breaks around the screws further surgery is required and it can be very difficult to perform this additional repair.
Isolated meniscal injury
As previously stated, dogs do have a slight risk of developing an isolated meniscal injury in the future, requiring re-exploration of the joint. This can occur with either the lateral suture technique or the TPLO and it is not possible to predict which dogs will be affected.
Fabella Pain
This is a potential complication of the lateral suture stabilization technique. The fabella is a small bone at the back of the dog’s knee that the Nylon stabilizing suture is placed around. In a very small percentage of dogs this can cause some discomfort and occasionally we need to remove it under a very short anesthesia.
Tibial Tuberosity fracture (fracture through the top, front part of the tibia or shin bone)
This is a potential complication of the TPLO procedure. It occurs infrequently but depending on how long it occurs after the surgery and the displacement of the piece of bone that breaks, it may require placement of metal pins to repair the damaged piece of bone.
Patellar Tendon Inflammation
This is an uncommon complication following the TPLO procedure and can prolong the recovery period. It does not require surgery but can necessitate a prolonged period of activity restriction.
Persistent Lameness secondary to osteoarthritis
This affects between 10-15% of dogs. This is a potential complication with either surgery and there is no way to predict which dogs will have significant problems with arthritic pain. It requires life-long activity moderation (less free running and jumping, more slow leash walks and swimming) and the use of non-steroidal anti-inflammatory drugs long term (drugs such as Rimadyl, Deramaxx, Metacam and Previcox).
Postoperative Treatment
Specific instructions will be given at the time your pet is discharged from the hospital including what medications to give (antibiotics and pain medications). In general animals come back in 10-14 days to have their incisions checked and the skin sutures or staples removed. The stability and comfort of the joint will be checked at this visit.
Following surgery your pet will require strict activity restriction. Patient activity is generally restricted for at least 2.5-3 months.
For the first 10-14 days your dog should be confined to a crate or small room with minimal furniture. Steps should be kept to a minimum. They should go outside on a short leash (not at the end of an extendible leash) to go to the bathroom only – no free running, jumping or playing is allowed. This can result in failure of the implants and may result in the need for more surgery.
If your dog will tolerate it you can apply an ice pack to the incision upto 4 times daily for 3-5 minutes for the first 3-5 days. Do not try to force this if your dog will not let you.
Once the skin staples have been removed you can start the following walking program at home – all other restrictions still apply and your dog should still not be allowed to roam free in the house:
Week 3 post operatively: Slow, on a short leash walks for 5 minutes upto 3-4 times daily. You can also start making your dog walk in some small circles and figures of 8 with the operated leg on the inside of the circle/8.
Week 4 postoperatively: Slow, on a short leash walks for 10 minutes upto 3-4 times daily.
Week 5 postoperatively: Slow, on a short leash walks for 15 minutes upto 3-4 times daily.
Week 6 postoperatively: Slow, on a short leash walks for 20 minutes upto 3-4 times daily.
For dogs that have had a TPLO, weeks 7 and 8 should be the same as week 6: Slow, on a short leash walks for 20 minutes upto 3-4 times daily.
If your dog is hard to control on the leash and is liable to injure themselves their activity should be completely restricted to leash walks to the bathroom only for the first 6 weeks.
Following the lateral suture surgery dogs are then seen for a recheck at 6 weeks; further activity instructions will be given at this visit.
Dogs that have TPLO performed come back for follow-up X-rays at 8 weeks to make sure that the cut in the bone is healing. There is an additional charge for these X-rays and sedation. If the cut in the bone has not healed at 8 weeks, further X-rays will be taken at 12 weeks postoperatively. Dogs that have had a lateral suture stabilization do not require follow-up X-rays in most cases.
All pets with stifle problems should maintain an ideal body weight and you may need to decrease the amount you are feeding during the postoperative recovery period.
The amount of arthritis that an animal develops after cruciate ligament injury is variable and there is no way to predict how it will affect your pet. It is important that once they have healed from surgery that they have regular exercise, maintain an ideal body weight and if possible stay on a Glucosamine/Chondroitin joint supplement for life.
In addition, some animals may require the tactical use of non-steroidal anti-inflammatory drugs such as Rimadyl, Deramaxx, Previcox or Metacam. These can be obtained from your regular veterinarian and be used on an “as needed” basis. Arthritis tends to cause more discomfort after periods of sudden very heavy exercise (free running, jumping, ball chasing) and when the weather is colder and damper.