We are commonly presented with pets for suffering from lameness in the hind limb. Frequently this lameness can be localized to the knee or stifle joint. One of the most common injuries that occur to the stifle joint is the rupture or tear of the anterior cruciate ligament. This ligament is found inside the joint and it serves the purpose of limiting the forward motion of the tibia or shinbone relative to the femur or thighbone. When the cruciate ligament is torn, ither partially or fully, the knee becomes unstable and painful. Sometimes the ligament may deteriorate slowly over time and the pets will develop chronic arthritis. In other times, ligament ruptures suddenly and pet may be unwilling and unable to their weight on the affected limb.
The anterior cruciate tends to rupture in dogs so often because of the relationship between the tibia and the femur. The tibial plateau (the weight bearing surface of the tibia) tends to be angled from front to back. This causes the Femur to slide down the slope during weight bearing and the anterior cruciate ligament is used to prevent this motion. Constant strain on this ligament leads to its degeneration and ultimate collapse.
When the anterior cruciate ligament ruptures, it is common to also damage a structure called the medial meniscus. The structure acts as a glide plate between the tibia and the femur, allowing them to move smoothly relative to one another.
How do our veterinarians diagnose ruptured cruciate ligaments?
Diagnosis of this problem relies on physical examination, palpation of the joint in question as well as radiographs of the affected limb. Frequently, pets must be sedated or anesthetized to adequately evaluate the joint. When the pet is relaxed, the doctor can elicit movement of the tibia relative to the femur, which is known as the anterior drawer sign. Radiographs allow our veterinarians to see if there are any fractures of the bone for if there is chronic arthritis associated with the ruptured ligament.
How can our veterinarians treat ruptured cruciate ligaments?
Once the cruciate ligament and/or the medial meniscus are damaged, it cannot repair itself and must be repaired surgically. There are many surgical procedures that can be used to repair the cruciate ligament. All of the techniques require the removal of the fragments of the cruciate ligament as well as removal of the torn meniscus. This is accomplished by surgically opening the joint and inspecting the structures therein. Any damaged structures are removed to reduce the inflammation that their presence causes in the joint. The joint is than thoroughly irrigated and close surgically.
At this point, our veterinarians perform a surgical procedure which will alter the forces in the knee so that the tibia does not slip out from under the femur. The Tibial Tuberosity Advancement (TTA) surgery is our technique of choice. In this surgery, the tibial crest (front part of the bone) is cut and advanced cranially to alter the angle of the patella ligament to the plane of the tibial plateau. It turns out that if we can make this angle close to 90 degrees, the tendency for the tibia to slip out from under the femur is minimized or eliminated. A small plate is placed in the leg and a bone graft is placed to fill in the gap between the bones. Recovery takes 6 to 8 weeks.
An alternate surgical technique known as the Tibial Plateau Leveling Operation (TPLO) can be performed as well, however, this procedure is more technically challenging and may have slightly longer recovery periods and slightly more complications.
For small pets, under 30 pounds, a less invasive technique which does not involve having to cut the bone may be utilized. This is known as an extracapsular repair, wherein, a strong nylon cable is placed outside the joint to “recreate” the functionality of the ligament.
What can veterinary clinic expect from surgical intervention?
Most pets from Alta Loma, Rancho Cucamonga, Upland, Ontario, Claremont, Fontana andthe Inland Empirethat undergo surgical repair of the cruciate ligament will regain seventy to one hundred percent usage of the leg. If the pet as existing arthritis in the joint, surgery will slow the progression of the arthritis and generally improve the pets function significantly. If the meniscus is damaged from the ligament rupture, there is more potential for post op pain.
It usually takes six to eight weeks for the pet to return to function after surgery. During the recovery period it is very important to restrict activity of the pet. Frequently we’ll ask the owners to keep the pet confined in a crate or cage for two to four weeks post-operatively. Typically pets are discharged from the hospital with anti-inflammatory drugs as well as chondro-protectant drugs such as Dasequin to help reduce inflammation in the joint and subsequent pain.
As many as 60 percent of dogs that suffer from anterior cruciate ligament rupture of one limb, may experience rupture of the opposite knee within 2 years from the first injury. Frequently this may occur during the recovery phase from the first surgery as the pets relying on the other knee support themselves. In order to protect the other knee, restricted activity and weight control are essential. Many dogs that suffer from cruciate ligament rupture are overweight or obese. Therefore we will commonly recommend a strict diet to help bring the dog back to its ideal weight.
Are there any complications associated with this surgery?
As with any orthopedic surgery, there is a small chance of infection during the surgery. For this reason all pets of Alta Loma, Rancho Cucamonga, Upland, Ontario, Claremont, Fontana and the Inland Empireare placed on antibiotics before during and after surgery. In our experience, the likelihood of infection from the surgery is less than two percent. I
In rare cases, the surgical implants can break or fail. These materials are made of pure titanium and with proper exercise restriction after surgery, this should not occur.
Fracture of the tibia is another rare, but possible complication from this surgery.
In general, cruciate repair surgery is very rewarding and will give the pets the best chance of continued use of their leg with the least amount of pain. In recent studies of over 1000 dogs undergoing TTA procedure, the incidence of complications was under 6%. Over 95% of the owners reported good to excellent results from the surgery.