Tibial Plateau Leveling Osteotomy

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Cranial cruciate ligament (CCL) rupture is the most common orthopedic condition that we treat and occurs in all ages and breeds of dogs. The evolution of CCL repair techniques in the dog over the past 30 years has been an interesting journey. Initially, research on various techniques for repair of cruciate ligament injury in the dog and human followed parallel courses. (In fact, Dr. Patterson was involved in research on a knee repair technique in dogs that had been performed on his own knee several years before!) Dissatisfaction with outcomes in larger and more active patients, however, led investigators down a path which has deviated considerably from our human surgical counterparts.

In the early and mid 1980’s Dr. Barclay Slocum, a veterinary surgeon from Eugene, Oregon, began experimenting with a new concept for restoring stability to the dog knee after CCL injury. By around 1990, he was performing Tibial Plateau Leveling Osteotomy (TPLO) in its earliest form and by 1995 he began to train others to perform the procedure. The Animal Surgical Clinic of Seattle was one of the first hospitals in the world to perform this surgery outside of Dr. Slocum’s clinic and we have performed in excess of 2500 of these surgeries over the last 11 years! In other words, we have as much (or more) experience with the TPLO as any clinic out there. The TPLO is truly a NW export and we are proud to have been at the forefront of providing this significant surgical advancement to our clients and patients.

In most dogs, it appears that the cranial cruciate ligament (CCL) degenerates or weakens over time, which predisposes it to rupture with relatively minimal trauma. Some surgeons feel that this degenerative process is a result of an abnormal slope of the top of the tibia (shin bone), which causes chronic stressing of the CCL, but this is yet to be fully understood.

Early signs of CCL stress or partial tear include stiffness or very mild lameness. The dog may show subtle changes in gait, a tendency to shift weight off the affected leg when standing in place, or the inability to sit straight. As the CCL continues to tear further, symptoms increase. A full tear usually results in complete lameness in the affected leg. In some cases, the knee will make a clicking or popping sound as the dog walks. This often indicates damage to the cartilage pads within the stifle (menisci).

Figure 1: Lateral Stifle A - Ruptured Cranial Cruciate B - Intact Caudal Cruciate

Figure 1: Lateral Stifle
A – Ruptured Cranial Cruciate
B – Intact Caudal Cruciate

The cruciate ligaments are important stabilizing elements within the canine stifle joint (knee).

There are two cruciate ligaments in the stifle, called the cranial and caudal cruciate ligaments. These same structures are present in the human knee, but they are called the anterior cruciate ligament (ACL) and posterior cruciate ligaments. The cranial cruciate ligament is commonly injured in both canines and humans.

Two cartilage pads called menisci are also found within each knee (the medial meniscus and the lateral meniscus). Due to anatomical reasons, the medial meniscus is often damaged secondary to the rupture of the CCL and the resulting joint instability. This by itself frequently results in significant pain and lameness.

When the CCL is ruptured, stability of the stifle is lost. The slope of the top of the tibia (tibial plateau) and the forces exerted by nearby muscles cause the lower end of the femur (thigh bone) to slide backward and down over the top of the plateau. This means that the top of the tibia thrusts forward with each weight-bearing stride. This is called cranial tibial thrust or cranial drawer movement. Tibial thrust causes excessive wear of the cartilage on the ends of the bones within the joint, and stretches the surrounding tissues, causing pain. It can also tear the medial meniscus within the stifle.

The Tibial Plateau Leveling Osteotomy (TPLO) can eliminate excessive cranial tibial thrust, thus creating a more functionally stable joint and sound gait.

Diagnosis of a ruptured CCL is done by palpation (feeling the knee) and radiographs (x-rays). Most dogs with a ruptured CCL will have cranial drawer movement on palpation. This is the hallmark physical finding.

Occasionally, in dogs with a chronic or partial tear of the CCL (or in very tense dogs), cranial drawer movement will not be detected. In these cases, radiographs are very helpful. The radiographic findings associated with a ruptured CCL include osteoarthritis and joint effusion (swelling). The actual ligament cannot be seen radiographically.

The TPLO technique has gained acceptance throughout the world due to consistent reports indicating that dogs treated with TPLO have a better functional outcome and decreased development of osteoarthritis than dogs treated with “traditional” repairs.

The exciting aspects of this technique are the possibility of returning your dog to nearly normal long-term function following CCL rupture (which has not been possible with any of the traditional techniques attempted to date) and the prospect of a reduction in the future progression of arthritis.

Lateral view pre-op

Lateral view pre-op

The surgeon will first examine the inside of the stifle and will remove the torn ends of the CCL. This can be done as a conventional, open surgery or with an arthroscope. Ask your surgeon if you are interested in the arthroscopic option. He will also remove torn portions of the lateral or medial meniscus if a tear is found. Fibrocartilage (scar tissue cartilage) will later fill in this void and replace the function of the damaged meniscus.

Next, the surgeon will make a curved cut (osteotomy) through the tibia using a specially-designed saw blade. The top portion of the tibia is then rotated a precise number of degrees in order to level the slope of the tibial plateau and prevent the instability and sliding that occur with a CCL tear. A bone plate and screws are then placed on the tibia to stabilize it and allow healing to occur. A recent advancement in the TPLO procedure at our clinic is the use of new plate/screw technology that allows the screw heads to be “locked” into the plate for more stability.

Lateral view post-op

Lateral view post-op

The incision is closed with absorbable sutures under the skin and sometimes with skin staples. A bandage is then placed on the leg from the toe to the top of the leg to reduce swelling. The bandage will be removed before your dog is discharged from the hospital.

Pain control for your dog will be addressed throughout the dog’s stay at the hospital and the first weeks of recovery at home. All dogs will be given pain medications before, during and after surgery, and the majority will receive take-home pain control medications.

Your diligence in restricting your pet’s activity level plays a major role in the success of the surgery. Your surgeon will indicate what activity level is appropriate at discharge and at each recheck appointment.

It is also crucial to prevent your dog from gaining excess weight during the post-op period, in order to minimize additional stress to the joints.

About 50% of dogs will begin to use the affected leg to some extent within 48 hours of surgery. Within two weeks, most dogs will be moderately weight-bearing on the affected leg. Full healing and usage can be expected by four to six months after surgery.

Although each patient progresses at a different rate, the general recovery progression is as described in the following tabs.

0-6 Weeks

Your dog’s activity level must be limited to short leash walks outside to urinate and defecate. When the dog is alone, it must be restricted to a crate or small area. While you are at home and directly supervising, the dog can be tied with a short leash to a heavy piece of furniture in order to be near family activities. At no time should your dog be allowed to play with other pets in the home, or be allowed to run or jump. If the dog must go up or down stairs, you should provide support via a sling under the abdomen, to prevent an accidental fall.

During this period, your pet may benefit from passive range-of-motion (ROM) exercises two to three times a day to maintain joint flexibility. Our technicians can instruct you in proper techniques. This rehab can begin 5-7 days after surgery or when your pet will tolerate it, but should not be performed if your pet is painful.

During the first few days at home, your pet may also benefit from applications of an ice pack (or bag of frozen peas), wrapped in a thin towel, applied to the incision site three times daily for 5-10 minutes to reduce swelling, pain and inflammation.

Boredom can be an issue for many dogs. Our receptionists and technicians can suggest a variety of boredom busters for your pet.

6-10 Weeks

Recheck radiographs at six weeks post-op should show good progression of healing at the osteotomy site. Some of the younger dogs will exhibit full bone healing at 6 weeks, but most dogs above 4-5 years of age will require another set of radiographs at 10 weeks postop.

If healing is as expected, you may begin taking your dog on short leash walks, increasing in total duration throughout this period. It is better, if possible, to increase the frequency of the walks than the duration of each walk. If you see increased limping after exercise, you should decrease the amount of exercise to the previous level for several days, then gradually increase again.

If directed to do so by your surgeon, you may begin allowing your dog to swim. Entry and exit to the water must be controlled, with no jumping. Swimming in very cold water may cause temporary stiffness afterward. Application of a warm compress to the joint may relieve this.

Unless otherwise instructed by your surgeon, all other confinement and leash restrictions remain in effect.

Passive ROM continues to be beneficial throughout this stage.

10-14 Weeks

For most dogs, recheck radiographs at ten weeks post-op will show full healing at the osteotomy site. The dog may be allowed to be off-leash within the house at this point. Discourage heavy running and jumping.

Exercise should be gradually increasing at first, and rapidly increasing toward the end of this stage. It is important to use a moderate pace in walking the dog, to encourage equal use of affected and unaffected limbs.

14-18 Weeks

Exercise restrictions will be lifted for most dogs, including working dogs. You should now gear your dog’s exercise routine toward regaining muscle mass that was lost since the CCL rupture. We can provide a list of recommended exercises to rebuild the dog’s strength. Extreme activities, such as ball-chasing, all-day hikes and playing with other large dogs off-leash, are allowed as the dog’s fitness level increases.

Our surgeon may request a final outpatient recheck during this period to evaluate your pet’s outcome.

Long-term: Recheck radiographs may be considered at one year post-op and annually thereafter to assess the progression of degenerative joint disease.

As with any surgery requiring general anesthesia, there is an anesthetic risk. Anesthetic complications are rare, however, and risk is minimized by our use of best practices in anesthesia choice and extensive monitoring of your pet by our surgeons, licensed veterinary technicians, and our advanced monitoring equipment.

We see an approximate 3% complication rate with this technique, but most of the complications can be treated successfully, allowing the patient to go on to a full recovery. Complications that have been reported are similar to those seen with other types of orthopedic procedures that utilize bone plates and screws in the area of the upper tibia. They can include: infection, breakage or loosening of the bone plate or screws, delayed healing of the osteotomy site, rupture of the caudal cruciate ligament, inflammation of the patellar tendon, fracture of the tibial tubercle and post-op meniscal injury. Many of these complications can be the result of too much post-op activity. Occasionally, additional surgery may be needed to solve the problem.