The mechanism for cruciate ligament degeneration prior to rupturing is not clearly understood, but it is clear that certain factors predispose certain dogs to sustaining a cranial cruciate ligament injury. Certain breeds, such as Labradors and Rottweilers (and other large breed dogs), are much more commonly affected than others, as well as dogs that are overweight. This suggests there is an inherited component to the condition, possibly related to conformation or gait and/or the displacement of weight within the stifle (knee) joint. While there is nothing that can be done to prevent CCL injury, by recognizing the symptoms of CCL damage soon after onset you can give your dog a head start with recovery.

What Causes the CCL to Rupture? is a post from: Dog Knee Injury

Age is also a risk factor for CCL injury, and there are two types of CCL onset related to a dog’s age when the injury occurs. Chronic onset, degeneration over time with subsequent rupture (usually from aging), occurs in 80% of cases and occurs in dogs 5 to 8 years old. Acute onset, a tear caused by injury, is most common in dogs under 4 years old. Young dogs of large breeds are more susceptible to rupture than young dogs of small breeds. Older dogs are also at greater risk for CCL tears if they already have arthritis and/or have decreasing musculature, especially surrounding the knee joints.

To sum it up, there is no way you can protect your dog from a CCL injury, but there are risk factors which make dogs more likely to sustain a serious cranial cruciate ligament tear or rupture. Large and giant breed dogs do more commonly sustain CCL injury, but this is usually compounded with other risk factors, which are mentioned below.

Risk Factors in Dogs for CCL Damage:

• Age
• Arthritis
• Previous injury to knee joint
• Overweight
• Large or giant breed
• Poor musculature, especially surrounding the joints
• Structural abnormalities – luxated patella, etc.

Are CCL Injuries More Common in Certain Dog Breeds? is a post from: Dog Knee Injury

Whether or not your dog has surgery to temporarily stabilize the joint after ligament rupture, long term joint health is best assured by careful restriction during a slow return to normal activity over a period of at least several months, and by avoiding unnecessary surgical removal of all or part of the meniscus. People are sometimes told that their dog’s meniscus is damaged and that the meniscus cannot heal on its own therefore surgery is always required for meniscal injury. This is not true. In fact, there are two basic methods used by the body to repair meniscal damage:

1) Extrinsic - When meniscal tear occurs, a fibrin clot forms within its margins. This fibrin clot contains factors that act as agents for reparative cells to migrate and develop. Further inflammatory response and angiogenesis result in healing of the lesion in about 10 weeks in the dog. It may take months or even years for the scar tissue to change into fibrocartilage, resembling that of the meniscus. Differences between the newly formed fibrocartilage and mature fibrocartilage are recognizable and include increased cellularity and, at times, increased vascularity in the repair tissue.

2) Intrinsic - The cells within the meniscus itself have an inherent capability to generate a healing response. The cells of the meniscus are assisted by the fibrin clot, which not only acts as a scaffold, but also provides stimuli to promote healing.

Why should I be wary of a veterinary surgeon removing my dog’s mensicus during ccl repair surgery?

Eventually the more observant doctors woke up to the fact that the menisci were important joint components, and in recent years the more enlightened surgeons have become less aggressive in removing all or part of the meniscus. But there are still many vet surgeons who cut far too much of a meniscus away. Some of these guys just can’t stop themselves from getting in there and excising something. Their approach is often, “When In Doubt, Cut It Out” and is a rule of thumb often used in canine stifle surgery. They won’t usually tell clients that of course. The history of surgery in general is filled with examples like this of too-aggressive surgical intervention. Never be too trusting of a surgeon. They became surgeons to cut; not to tell you no cutting is needed.

Source:

About the Dog Meniscus – http://home.earthlink.net/~tiggerpoz/id16.html

Does My Dog Need a Meniscus? is a post from: Dog Knee Injury

The menisci are ‘fibrocartilaginous’ structures which can be thought of as spongy elastic pads between the bones at the joint, composed predominately of collagen and open space filled with joint fluid. The menisci contribute significantly to joint lubrication. The fluid of the joint moves through the porous structure of the menisci. Because 70+% of the total weight of menisci is fluid, normal movement causes compression of the menisci which squeezes fluid out from them into the joint space to allow smoother gliding of the joint surfaces. The menisci re-expand when the pressure is reduced, drawing in fluid. This pumping action also helps to distribute synovial fluid throughout the joint and aids in the nutrition of the articular cartilage.

By compressing under a load, the menisci also act as shock absorbers, absorbing energy and reducing the shock to the adjacent cartilage and subchondral bone. The menisci protect the cartilage by acting as buffers between the surfaces of the femur and tibia where they meet and move against each other at the joint. The menisci transmit forces across the knee joint. The menisci provide added mechanical stability to the normal gliding of the femur on the tibia by deepening the surface of the tibial plateau to increase the congruity between the femoral condyles and the tibial plateau.

What is a Meniscus? is a post from: Dog Knee Injury

During the procedure an incision about 4 to 6 inches will be made along the dog’s stifle to provide the surgeon access to the knee tissues. The torn/ruptured cranial cruciate ligament, or CCL, is completely removed and the mensicus is examined. The veterinary surgeon will determine at the time of surgery the extent to which the mensicus has sustained damage and will work to remove the injured tissue. The doctor will take care to only remove meniscal tissue that is damaged, as dogs with some intact, healthy meniscus tend to do better long-term than dogs receiving a complete mensicectomy.

A transverse osteotomy is then performed just behind the tibial tuberosity (a non weight bearing part of the knee), which creates a groove in the bone, allowing the tibia to be advanced to its new position. The tibial tuberosity is then advanced to achieve a perpendicular relationship between the tibial plateau slope and patellar tendon, resulting in a stable joint. Examination of the stifle with a-ray radiography prior to surgery will make sure the surgeon has the proper size implants available for the procedure, and the advanced tibial tuberosity is held in place with titanium implants. Lastly, a bone graft is placed into the area of the osteotomy to stimulate healing and the incision is closed with sutures.

TTA Surgical Procedure is a post from: Dog Knee Injury

During the extracapsular imbrication a large, non-absorbable suture is placed in a figure eight pattern within the structure of the knee. The leader line is placed around the lateral fabella through a hole in the tibial crest, mimicking the course of the CCL and preventing forward movement of the tibia, also known as the clinical drawer sign. The monofilament nylon leader line has a range of tensile strengths, and depending on the size of your dog, your veterinary surgeon will select a size between 40-100 pounds. Over time scar tissue will develop on the side of the knee joint where the large suture was placed, providing stifle stability in the absence of the canine cruciate ligament.

Extracapsular Imbrication Surgery, Traditional Repair Procedure is a post from: Dog Knee Injury

How the TPLO procedure is performed:

First, the torn ends of the cranial cruciate ligament will be completely removed by the surgeon. Next, the medial and lateral meniscus cartilages will be examined for any signs of damage. The medial meniscus is damaged in about 50% of dogs with CCL ruptures, and the damaged meniscal cartilage will also be removed so as to not hinder the healing process or cause any additional discomfort. Your dog’s veterinarian will take care to remove only the parts of the meniscus that have been damaged as a result of the unstable femur bone pinching the meniscus during normal activity. Studies have shown that dogs with partial menisectomies have less arthritis than dogs with complete meniscus removal.

TPLO Surgery Procedure is a post from: Dog Knee Injury

The cranial cruciate ligament, or CCL, in canines is analogous to anterior cruciate ligament, or ACL, in humans. The CCL is the main supporting ligament within a dog’s knee, or stifle. This ligament bears the weight of a majority of the stifle’s load, which is why instability of the CCL results in lameness, arthritis and other degenerative changes of the knee joint and surrounding tissue. The strength of this ligament will decrease as a dog ages, with larger dogs experiencing an increased rate of degeneration versus smaller breed dogs. Obese dogs are at a higher risk for CCL rupture as obesity places additional stress on the ligament. Ruptures of the cranial cruciate are the most common orthopedic injury for dogs and the leading cause for arthritic tissue in the stifle.

The cranial cruciate ligament’s essential function is to prevent forward movement of the tibia relative to the femur. If this forward movement is present the dog is classified as having a positive drawer test, or displaying a positive cranial drawer sign. The caudal cruciate ligament prevents backward displacement of the tibia relative to the femur, which is known as the caudal drawer. The CCL also works to limit hyperextension of the stifle and internal rotation of the tibia during flexion.

Anatomy of the Cranial Cruciate Ligament is a post from: Dog Knee Injury

During the drawer test the veterinarian with stabilize your dog’s femur with one hand while manipulating the tibia with the other. If the tibia moves forward, known as a positive drawer because of the way the bone moves similar to a drawer being opened, the ligament is ruptured. If the rupture occurred some time ago, there will be swelling on the side of the leg that faces the other leg – this phenomenon is known as a medial buttress and is indicative of arthritis. The presence of a medial buttress, coupled with your dog’s state – if they are anxious or tense – can make it difficult to obtain an accurate drawer sign. Tense muscles can act as false stabilization of the knee, preventing demonstration of the drawer sign upon manipulation; sedation is indicated in these cases.

Your pet’s doctor will take the results from the drawer sign test into consideration when determining a treatment plan for your dog. A negative drawer sign does not necessarily mean your canine does not have a cranial cruciate injury, and the only way to be absolutely sure of injury in the absence of a positive drawer is to have an ultrasound performed; unfortunately not many vets offer this service.

Drawer Sign Test and Tibial Compression Exam is a post from: Dog Knee Injury