The cranial cruciate ligament (CCL) Functions:

CCL is one of the main stabilizing structures of the stifle joint (knee joint). The CCL's function in the dog is to prevent the femur bone from sliding backwards down the slope of the top of the tibial bone (Shin bone).

The Cranial Cruciate Ligament (CCL) functions primarily to limit cranial translation of the tibia relative to the femur.

The CCL also limits internal rotation of the tibia; as the stifle is flexed, the cranial and caudal cruciate ligaments twist on each other, limiting the degree of internal rotation of the tibia relative to the femur.

Tibial Osteotomy Techniques

Tibial osteotomy procedures (TPLO, TTA) approach the stifle instability seen with cranial cruciate ligament rupture from a different perspective. Instead of attempting to recreate the damaged or torn cranial cruciate ligament, osteotomy techniques change the geometry of the stifle joint to eliminate the shear forces (cranial tibial thrust) seen between the femur and tibia during ambulation. It is important to note that these techniques do not eliminate static cranial drawer movement found on recumbent orthopedic examination.

On immediate postoperative examination cranial drawer movement will still be palpable but cranial tibial thrust should be eliminated on both examination and during ambulation. Over time, the amount of static cranial drawer motion palpable in dogs that have undergone tibial osteotomy techniques decreases, most likely due to capsular fibrosis.

Cranial drawer is a term used to describe excessive cranio-caudal movement of the tibia relative to the femur as a result of cruciate ligament injury

Diagnosis:

Clinical Presentation:

• Either gender and any age or breed of dog may be affected; however, most dogs brought in for treatment of CCL injury are young, active, large-breed dogs. CCL injury is uncommon in cats.

• Acute injury, chronic injury, and partial tears are three clinical presentations associated with CCL injury.

• Patients with acute tears show a sudden onset of non-weight-bearing or partial-weight-bearing lameness.

• Patients with chronic injury have a prolonged weight-bearing lameness.

• Partial CCL tears are difficult to diagnose in the early stages of injury. Initially, affected animals have a mild weight-bearing lameness associated with exercise; the lameness resolves with rest.

• Dogs of any age may have bilateral subacute or chronic bilateral CCL rupture.

Physical Examination Findings:

• Animals with acute complete tears often are apprehensive during examination of the stifle joint. Instability can be difficult to elicit because of the patient’s apprehension and the resulting muscle contraction.

• Joint effusion may be palpable adjacent to the patellar tendon.

• A positive tibial compression test may be easier to elicit than a positive drawer test.

• Cranial drawer movement is diagnostic of cruciate ligament injury. The cranial drawer test is performed with the patient in lateral recumbency.

• “The examiner must test for signs of instability with the stifle joint in extension, in the normal standing angle, and in 90 degrees of flexion.”

• Animals of all ages often have periarticular fibrosis on the medial surface of the joint between the medial collateral ligament and the proximal tibial (“buttress sign”).

• Other common exam findings include stifle joint effusion when standing, as noted by the lack of a finite edge to the medial aspect of the patella tendon, and resistance to fully flexing the knee when sitting (“sit test”).

Cranial Tibial Thrust:

• During weight bearing in the normal dog, forces across the knee joint consist of body weight and muscle forces (quadriceps, hamstrings). Cranial tibial thrust is defined as cranial movement of the tibial tuberosity in the cranial cruciate–deficient stifle when the hock is flexed and the gastrocnemius muscle contracts.

• As force is transmitted proximally, the femur and tibia are compressed together, causing a cranial thrust of the proximal tibia resulting from the caudodistal slope of the tibial plateau. This places passive restraints (e.g., cranial cruciate ligament) under great tension.

• If hamstrings are weak or forces too great (leaping, twisting, turning), the degenerate ligament tears, allowing cranial drawer movement and a positive cranial tibial thrust sign (tibial compression test). In theory, if the caudodistal slope of the tibia is reoriented to a more neutral position (research has shown the proper angle to be 6.5 degrees, with a clinical recommendation of 5 degrees), then the cranial tibial thrust is eliminated. However, excessive correction of the slope places the caudal cruciate ligament at risk.

• The Tibial Compression Test is performed with the patient standing or in lateral recumbency.

Diagnostic Imaging:

Radiographs: With acute tears, radiographs are helpful in ruling out other causes of stifle joint lameness. Radiographic findings in patients with chronic ligament tears or partial tears include

1. Compression of the fat pad in the cranial aspect of the joint. “fat pad sign” and extension of the caudal joint capsule caused by joint effusion, and

2. Osteophyte formation along the trochlear ridge, the caudal surface of the tibial plateau, and the distal pole of the patella. Thickening of the medial fibrous joint capsule and subchondral sclerosis are also evident.

MRI has been used for evaluation of the cruciate ligament in dogs;

Arthroscopy. A large percentage of the surface of the cruciate ligament can be examined arthroscopically for gross tears, fibrillation, or discoloration associated with cruciate damage. The menisci and cartilage may also be examined.

Differential diagnosis:

Differential diagnoses include mild joint sprains or muscle strains, patellar luxation, caudal cruciate ligament injury, primary meniscal injury, long digital extensor tendon avulsion, primary or secondary arthritis, and immune-mediated arthritis.

Partial rupture of cranial cruciate ligament:

A surprising number of cases of stifle lameness are caused by partial rupture of the cranial cruciate ligament. The veterinarian needs only to explore joints in the face of minimal physical findings to verify this.

An increasing number of dogs (especially Labrador retrievers and Rottweilers) sustain partial tears at a young age (6 to 24 months). Often, tears are bilateral and mimic hip dysplasia clinically, which may also be a concurrent problem.

It is our experience that cruciate problems cause more clinical signs than hip dysplasia and should be addressed first before it is deemed necessary to perform any surgical procedure on the hips.

Clinical signs and history mimic those of complete rupture but are not as dramatic, and secondary arthrosis is much slower in developing, probably because the meniscus is not damaged as often as in complete ligament rupture.

Degenerative changes can be extensive given enough time. The cranial cruciate ligament functionally is composed of two parts:

• The small craniomedial band (CrMB) and the larger caudolateral band (CdLB).

• The CrMB is taut in both flexion and extension, whereas the CdLB is taut only in extension.

The ability to diagnose these injuries by examination for drawer motion depends on which part of the ligament is damaged. If the injury is caused by hyperextension, it is most likely to damage the CdLB, and no drawer motion will be present because the CrMB is intact.

An injury caused by rotation or twisting with flexion is more likely to injure the CrMB. Under these circumstances, there is a small amount of drawer motion in flexion (the CdLB is relaxed) but no motion in extension (the CdLB is taut).

Pain on full extension of a stable stifle with effusion or the “fat pad sign” is also highly suggestive of a partial cranial cruciate ligament tear.

the incidence of partial tears of the cranial cruciate ligament is not insignificant and should be carefully considered as a cause of lameness in midsize to large breeds with pain in the stifle region and minimal or no drawer motion.

“When repairing these injuries, the surgeon should approach them as if they were complete ruptures, since the ligament is no longer functional.”

Radiographs demonstrating the “fat pad sign” or osteophytes are truly significant.

if there is osteoarthrosis (and no indication of inflammatory joint disease) of the stifle without overt causes, such as osteochondritis dissecans, luxating patella, the rare instance of isolated meniscal damage, or synovial cell sarcoma, then the cruciate ligament is suspect.

Careful probing to detect tears of the caudal side of the ligament and observing the color and reflectivity of the ligament are warranted. Arthroscopic evaluation, magnetic resonance imaging (MRI), or ultrasound may have identified these unusual cases before open surgery

TPLO Technique:

Each patient’s tibial plateau angle (TPA) and the rotation needed to achieve an end point of 5 to 6.5 degrees are calculated using preoperative radiographs. As with all other surgical therapies for cranial cruciate ligament rupture, the stifle joint is explored via either medial arthrotomy or arthroscopy and meniscal injury is treated if present. This is followed by an approach to the proximal tibia through a medial incision.

“Tibial plateau angle (TPA) is the angle between a line perpendicular to the long axis of the tibia and a line parallel to the tibial plateau”

Muscle insertions of the proximal medial tibia are lifted off the bone (gracilis, semitendinosus, caudal belly of sartorius), leaving the medial collateral ligament intact.

A jig is applied to the medial tibia and guides a curved osteotomy, which will allow reorientation of the plateau to the desired angle.

During this Surgery, the orthopedic surgeon performs a curved osteotomy (cut in the bone) on the tibia with a biradial saw blade, and the proximal tibia fragment closest to the joint with relation to the rest of the tibia is rotated to the proper TPA angle. The distance of this rotation is based on calculations the surgeon performs before the operation. The surgeon compresses the two resulting pieces of the bones and fixes the tibia in its new orientation with a TPLO plate and screws; both are made of surgical grade stainless steel.

There are different kinds of bone plate and screws are used to repair. We use TPLO locking System (Plate and Screws) from DePuy-Synthes Vet.

Please watch The DePuy Synthes Courtesy Video below for more information about TPLO procedure and Implants.

TPLO is widely accepted to give the best functional outcome and has enabled working/performance animals to return to high functional standards. There is a trend to a slower progression of arthritis following TPLO surgery, versus dogs that received the MRIT (modified retinacular imbrications technique). however, arthritis usually will develop regardless of technique.

Post-operative Complications:

Post-operative risks associated with this operation and patients’ recovery include: delayed or abnormal healing, breaking and/or loosening of the plate and/or screws, and infection.

To minimize the risk of complications while the tibia is healing, we recommend that TPLO patients be always kept in a crate (cage) until radiographs (X-ray images) are taken, usually at 4 and 8 weeks after the operation.

Bone healing may take up to 16 weeks in some patients.

Rehabilitation exercises are performed at home during this recovery period and may be continued at the Animal Rehabilitation Center.

Expected Outcome:

Most animals will be partially weight bearing within 3 to 7 days after surgery and walking comfortably with only a slight limp at 3 to 4 weeks.

Choosing a Veterinary Surgeon:

TPLO surgery has a very steep learning curve and may be performed by a Slocum TPLO Certified Veterinarian with advanced training for the procedure and experience with successful cases. Dr. Ajaib Dhaliwal has experience of performing advanced orthopedic procedures. When this procedure was developed a few years ago, he recognized it as a superior procedure to the other available options and received his certification for performing the TPLO procedure. He also got more training and experience with Dr. Terri Zachos (Ex Assistant Prof. MSU) and Claude Gendreau (Owner of Veterinary Orthopedics Center) Board-Certified Orthopedic Surgeon.

Dr. Dhaliwal is available for Free TPLO consultation, Second opinions, or Referrals for the TPLO surgery procedure.

Slocum® Post-operative Care for Orthopedic Surgery

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

1. Your pet can be inside, on carpeted surfaces, under your direct supervision. It can wander around the room at a slow walk if it is not constant. Running, jumping, bounding, playing, etc., are not allowed.

2. Your pet must be always on a short leash (3 feet) when outside for airing and going to the bathroom. If the animal must 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.

3. When not under your direct supervision, your pet is to be confined in an airline kennel or equivalent.

General Information:

Playing with other animals is not allowed during confinement. If there are other pets in your household, you will need to keep them separated.

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.

The first two weeks following surgery you will need to monitor your pet's incisions. 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.

It takes a minimum of six to eight weeks for bones to heal.

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.

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.

If at any time during your pet’s recovery and healing it does anything that causes it to cry out or give a sharp yelp, contact your veterinarian.

Following surgery your pet should always maintain at its current level of function, or improve. If at any time during your pet's recovery and healing it has a setback or decrease in function, contact your veterinarian.

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.

If your pet is too active during its confinement it may injure itself or slow healing which increases the amount of time your pet must be confined.

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:

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 dog’s 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 pets 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 through 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 you are currently going on the short lead walks. 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.

During the seventh through the ninth week of rehabilitation your pet is allowed very mild activity off lead. You will continue with the long lead walks and you will start letting your pet have time off lead in the yard, 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 if your pet's comfort level permits. The dog should always remain under the voice control of the owner. No jumping, chasing a ball, frisbee, 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 checkup at the end of the rehabilitation process is needed before full activity may be resumed.