It is important to discuss the history of the lameness, whether the problem was sudden in onset or appeared gradually over a period of months, improving with rest but always getting worse after exercise. Observation. Your veterinarian will observe your dog at rest, taking note how your pet stands in the examination room and how he sits. The dog may not touch the leg to the ground in an acute injury or just touch the toes down. Most dogs with cruciate problems will not sit squarely, deviating a partially flexed knee out to the side. A walk, followed by a trot, will be most helpful to define a more subtle lameness perhaps due to a partial cruciate tear.
Palpation. Your veterinarian will carefully palpate the knee to assess for joint swelling and thickening. More long standing cruciate injury results in thickening on the inner aspect of the knee to produce a firm bump called a "medial buttress."
Flexion and extension. The knee will be put through flexion and extension to assess the range of motion prior to evaluation for abnormal range of motion. Popping or clicking of the knee may occur during flexion and extension, which is suspicious for, but not diagnostic of, meniscal injury.
Cranial drawer or tibial compression tests. Performing these tests is extremely important. Both tests are looking for abnormal sliding of the tibia on the femur, a motion that should not be produced with an intact cruciate ligament. Certain partial tears will only produce a cranial drawer sign in knee flexion, and some partial tears will not produce a drawer sign at all.
Radiographs of the knee joint. X-rays can help to evaluate joint swelling and early subtle bony arthritic changes. In more chronic cases, the x-rays can help define the amount of arthritis that already exists to help in discussions about overall prognosis.
Arthroscopy or MRI. In certain cases of suspected partial cruciate injury, these further diagnostic techniques may prove helpful prior to an exploratory surgery of the knee.
The majority of small dogs (86 percent in one study) did not require surgical intervention and did just as well with strict rest, weight loss and the use of short courses of anti-inflammatory medication. Should the lameness persist, then surgery is recommended. Restriction like this for 6-8 weeks will not detrimentally affect the surgical outcome, should it prove necessary later on. Lateral suture technique. This procedure is quite straight forward and works well on many dogs, particularly those less than 70 to 80 lbs. Under anesthesia, having examined the inside of the knee joint to tidy up the remnants of the cruciate ligament and assess and address meniscal injury, a suture is passed around the knee joint, below the skin, in a configuration that will restore the normal position and stability of the femur on the tibia, acting to produce the same result as an intact cruciate ligament. With time, the implant may give a little, may stretch or even break, which will lead to increased thickening of the soft tissue around the knee and progression of bony arthritis. Despite this, the vast majority of dogs do well with this technique.
Broadly speaking there are two categories of surgery known as intracapsular techniques, where an effort is made to replace the damaged cruciate ligament with a natural or synthetic replacement, or extracapsular techniques, which aim to restore the function of the cruciate rather than the ligament that was damaged. Over recent years, intracapsular techniques have become less popular. The following are major extracapsular techniques:
Fibular head transposition. This procedure uses a natural ligament, the lateral collateral ligament, to stabilize the femur on the tibia by modifying its normal position and function, by changing its attachment to the fibular, the smaller of the two bones below the knee joint. Some surgeons are very pleased with the clinical results they can achieve with this technique.
Tibial plateau leveling osteotomy (TPLO). This surgery has been described and patented by Dr. Barclay Slocum of Eugene, Ore. In simple terms, the femur slides on the tibia, in fact, the tibial plateau, because a slope exists, a slope, that to a large extent, is combated by virtue of an intact cruciate ligament. So, in a normal knee, no sliding takes place, but if the cruciate is damaged, the sliding, as seen with a cranial drawer test, occurs every time the dog puts weight on the leg.
The idea behind this surgery stems from the fact that any kind of replacement for the cruciate ligament, be it natural or synthetic, can never be as good as the original. So, instead of trying to replace the damaged ligament, why not try to make it redundant, by getting rid of the slope that it was trying to offset. In other words, if we make the slope, the tibial plateau, level, then there is no need for a cruciate ligament; the ligament becomes redundant. This is a complicated surgical procedure and requires certification from Dr. Slocum in order to be performed.
Following surgery, many dogs remain hospitalized overnight in order to be monitored for full anesthetic recovery and to receive appropriate analgesic medication.
The use of a soft padded bandage to cover the leg after the procedure varies with the surgery and the surgeon. The bandage offers some comfort and reduces some of the postoperative swelling but, in fact, offers minimal support. If a bandage is used it should be kept clean and dry by placing a plastic bag over the foot every time the dog goes outside. The toes should be felt at the bottom of the bandage and assessed for swelling, sweating or pain, at least once a day.
If there is no bandage present, the incision can be assessed for swelling redness or discharge. In the case of a TPLO surgery, there is also a small incision lower down the leg, toward the ankle. Some swelling around the ankle may occur. This is not uncommon and usually responds well and quickly to the use of hot compresses.
Stiches or staples should be removed in 10-14 days.
Strict rest is essential for the first six weeks following surgery which means, ideally, no going up or down stairs, no jumping on or off furniture, avoiding slippery surfaces and walks, and going out on a leash for bathroom purposes only. With the TPLO surgery in particular, many dogs can recover extremely quickly. Owners should beware of this "false sense of security" afforded by dogs doing very well very early following surgery, and continue the rest for the full six week period.
Anti-inflammatory medication can be helpful for the first week following surgery, such as deracoxib, aspirin or carprofen (Rimadyl®).
After six weeks of rest, a slow, gradual increase in exercise should begin, with slow leash walks getting longer and longer in small increments such that over a further six weeks your dog is going on thirty minute walks, with short periods off the leash with far greater freedom around the house, including the use of stairs. By sixteen weeks after surgery, there should be no restriction on exercise.