WESTIES HEALTH -- FROM EARS TO TAIL.
KATIE WYATT·TUESDAY, DECEMBER 29, 2015
All Dogs Are Predisposed To ACL Injuries
The ACL (Anterior Crucial Ligament) tear or rupture is a relatively common canine injury, affecting almost 1 million dogs a year in the USA.
Currently, national costs to treat this injury in dogs are over $1.5 billion dollars a year, and the surgical standard of care treatment per dog costs on average between $3000-3500. Additionally, dogs receiving surgical intervention can expect a substantial rehabilitation time of up to 3 months for successful surgeries. Approximately 5% of surgical interventions are unsuccessful, a relatively low number unless your dog is a member of that statistic.
Today the standard of care typically involves one of two surgeries, TPLO or LFS, however a new much less expensive and non-invasive treatment option Platelet Rich Plasma (PRP) is being tested with good results.
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ACL Tears And Ruptures – Why Is It A Common Injury in Dogs
The physical dynamics of the dog’s hind leg, predispose him to ACL tears and ruptures. Because the dog stands on his toes, unlike humans who stand flat footed, there is constant pressure to thrust the tibia (the main lower leg bone) forward and out from under the femur (the main upper leg or thigh bone).
Dogs can experience a tear or rupture as a result of intense physical activity or even just by walking to the mail box.
The femur and tibia are held in place by two ligaments, the cranial or anterior crucial ligament (ACL) and the caudal or posterior crucial ligament. These two ligaments join the femur to the tibia by crossing each other inside the knee joint from front to back. The ACL prevents the tibia from slipping out of position.
When the ACL tears partially or ruptures completely (a torn or ruptured cruciate ligament) it causes instability in the joint. Without the restraint of the ACL, the tibia is now freer to move forward of the femur, potentially causing damage to the medial and lateral meniscus (the protective pads between the two bones).
Additionally, the instability causes joint inflammation, pain and ultimately arthritic changes to both the tibia and femur, resulting in long term damage when left untreated.
Diagnosing ACL Tears and Ruptures
Generally, dogs with ACL tears or ruptures present by not putting weight on the affected leg when standing. As they move or increase the speed of their gait, they may appear normal, however when returned to a standing position, they will remove weight from the affected leg.
This condition may wax and wane. Dogs may have worse days than others and may “warm” out of the condition as they exercise. However, the knee joint remains swollen and abnormal wear between the femur and tibia and on the meniscal pads begins to develop loss of range of motion as a result of arthritic changes. Bone spurs may begin to develop as well.
ACL tears are diagnosed by a combination of physical exam and x-rays. X-rays will not show the actual ligament however, they can show secondary symptoms of a torn ligament. These include excess fluid in the knee both in front of and behind the knee joint. Granulation of the bone (remodeling) and osteophytes (bone spurs) can be seen as well, and may begin to develop within 3-4 weeks of the injury.
The physical exam involves a procedure known as the “drawer test.” In this exam the dog’s femur is immobilized, while the examiner attempts to move the tibia out in front of the femur. If it moves out forward of the femur like a drawer opening, then a torn ACL is indicated.
Dogs may be able to stabilize their knees by tensing their other muscles against the action. An especially nervous dog may need to be slightly anesthetized to determine the true range of motion in the drawer test.
In a second physical test, the femur is held in place while the ankle is flexed. If the tibia moves forward abnormally, a ruptured ligament is suspected.
Additionally, examination of the knee joints of the healthy leg and affected leg is performed to determine the degree of swelling. Swelling on the inside of the knee, called a “medial buttress,” will indicate the development of arthritis in dogs with old ACL injuries.
Treatment of ACL Tears and Ruptures
In instances where the ACL is completely torn, surgery is the only option to stabilize the joint. In cases where the ACL is partially torn, it is inevitable that the ACL will fully rupture without some type of intervention, as the remaining weaker ligament must fully restrain the tibia.
The knee joint has a relatively low blood supply, and the torn pieces of the ligament are resorbed by the body. To generate new tissue either a growth factor must be introduced or replacement ligament must be surgically introduced.
Until recently, non surgical treatment has been largely holistic in its nature. Herbs and supplements such as turmeric, glucosamine, Omega 3’s and Glycoflex are administered to reduce inflammation and further damage to the joint. Nonsteroidal anti-inflammatories, NSAIDs, may be given as well.
Adequan, frequently used for horses, may be injected as it can help prevent cartilage in the dog’s joint from wearing away. Another drug frequently used, Polyglycan, a less expensive substitute for Adequan, has been shown in studies to not be as effective as Adequan in reducing swelling in horses. Additionally, it has side effects which may include sterility with prolonged use. Owners can be taught to administer Adequan themselves at home. Injections are given twice a week until symptoms improve, and then once a week for maintenance.
Rest and limited exercise while avoiding weight gain are also critical in the management of joint disease and damage.
Promising New Nonsurgical Treatment: Platelet Rich Plasma Therapy
Platelet rich plasma therapy has been used with success to treat arthritis in joints, muscle, tendon and ligament damage. In this process the blood is drawn from the patient and then centrifuged to concentrate the platelets as well as remove the majority of white and red blood cells. Then the plasma is injected back into the patient at the site of the injury. Its injection may be peppered along the site of the injury to maximize its beneficial effects.
The rationale behind this treatment is twofold. Inflammation must be removed from the site for the healing process to begin, and growth factors must be introduced to aid in the healing process and to encourage new tissue growth. Platelet rich plasma, or PRP, accomplishes both of these tasks.
When tissue is initially injured the inflammation that is triggered stops the spread of infection and clears away damaged tissue. But healing of the tissues will not begin until the inflammation process is turned off. Platelets introduced to the site of the injury attract white blood cells to the injured area that will clear away the remains of the dead and injured cells.
Additionally, the blood platelets release growth factors that are directly responsible for tissue regeneration. Known as cytokins, they include a series of growth factors including epithelial growth factor, transforming growth factor, insulin growth factor, and other important growth factors. Because it comes from the patient, there is no risk of rejection. It is for these two reasons PRP treatment is being promoted and tested for ligament, muscle, tendon, joint and bone injuries, which are normally slow to heal.
PRP can be used as a treatment of the injury or to aid in healing following surgical intervention. Additionally, PRP is substantially less expensive than surgery. The typical TPLO surgery ranges from $3000-3500, while PRP is approximately $500 per treatment with a recovery time of about six weeks of leash walking. Dogs may need to be retreated with PRP in order to continue the growth of new ligament tissue; the long term benefits of PRP therapy have not yet been fully determined.
Stem Cells Versus PRP Therapy
Stem cells have also been researched in conjunction with new tissue generation. Just as in PRP therapy, stem cells bring growth factors to the site of the injury. However, within 24 hours of injection as many as 95% of the stem cells have already died. Given that stem cell treatments cost on average $3000 per treatment, PRP seems the better alternative for experimental nonsurgical treatment for canines.
At this point in time, neither PRP nor stem cell treatment will guarantee that your dog will never require surgery; long term case studies will be required to understand the benefits of PRP and how long they can be expected to last. However, a study on Standardbred race horses with severe ligament injuries did show that PRP treatment allowed them to return to racing. With a shorter recovery period and a much lower cost compared with surgery, PRP is worth exploring with your orthopedic veterinarian.
Suggestions for Further Reading
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