Anterior Cruciate Ligament Rupture

            A ligament consists of tough, fibrous tissue connecting two bones. The cranial cruciate ligament stabilizes the bones of which meet in the knee.  It prevents the tibia from sliding forward in relation to the femur.   In the knee, rupture of the cranial cruciate ligament allows the femur (thighbone) to slide back and forth over the tibia (shinbone).   This ligament may have abnormal stress on it due to your pet's conformation.  The greater the stress on the ligament, the more likely it will be injured.        The ligament is made up of multiple strands, similar to how tough ropes are made.  The ligament may have a partial rupture, similar to how a rope might fray.  The remaining tissues are then weaker, but have more stress upon them.  The ligament may also suddenly be fully ruptured.  This is frequently seen with larger active dogs when they may vigorously twist and turn in their play or work. 

         Normal stifle, view from front                                    Ligament Rupture 

            Diagnosis is made by demonstration of laxity, radiographic appearance or imaging with CT scan or MRI.  The laxity is palpated.  Many times, the pet may need to be sedated to demonstrate this.  Pain, fear or other reasons can make a pet tense up, preventing the joint to be properly manipulated.  Sedation allows the pet and their muscles to relax, and allow proper manipulations.  If radiographed soon after injury, X-rays have characteristics that indicate injury in the area of the ligament. 

            If torn or ruptured, the joint has an abnormal laxity causing other tissues around the knee to be stressed, causing them to be stretched and used improperly. This causes pain then abnormal wear and tear of the joint, leading to arthritis.  Once a joint is damaged or injured, the bones and joint tissues are very active in trying to compensate for injuries, but are not so capable. Unfortunately, the changes these tissues can make are not sufficient to keep the pet pain free. This is the reason the onset of arthritic changes occurs relatively fast. Arthritic changes will become evident surgically after only 1-2 weeks after a joint is damaged.   Arthritis is progressive.  As time goes on, it worsens to the point a joint may not support the animal's body weight, or is unable to be flexed or extended without pain.  The sooner a repair can be made, the sooner the arthritis will be slowed down. X-rays are taken just prior to surgical repair to help document arthritic changes that already exist.

            Depending on the severity of the rupture, concurrent joint damage (meniscal injury, etc.), your pet's activity level, preexisting disease to the limb, and size of pet, treatment may consist of limited exercise and rest or surgical repair of the torn ligament.  In general, the larger, younger, more active pets should have 'reconstructive' surgery performed.  Several surgical options are available.  Since the torn ligament is too small and compromised to be repaired, various techniques are utilized to stabilize the joint otherwise.  Again, the procedure selected will be based on your pet's needs. The goal of the surgery is to once again stabilize the joint.  If surgery is completed relatively soon after the ligament was damaged, less arthritis will occur.  However, even the most complete surgery will not completely prevent arthritis in the limb.  Surgery should allow your pet to use the limb for a much longer period in relative comfort.

            Initially following surgery, your pet will not be expected to bear weight on that limb for a period of several days, to several weeks, depending on the techniques used.  It is important that the uninjured limb be healthy enough to bear the pet's weight.  If obese, it is recommended the dog first lose weight to reduce the stress on the 'normal' limb.  It is important to note that depending on how or why the stifle was injured, the 'normal' limb may be compromised also.  It is not unusual for this limb to require treatment soon also.

Important Points in Treatment

1.         Activity: It takes time for the surgically manipulated tissues to heal, and become functional. Even if your pet feels good, it is too early to allow activity.   During this time, activity can cause tearing and other damage.  Damage caused by activity at this time may not be readily repairable. Tranquilizers may be prescribed to help keep your pet quiet and inactive.   Restrict your pet's activity for _____  days. Do not let your pet run unrestrained. On-leash walking is the only activity permitted inside or outside the home. Prevent jumping whenever possible. Begin increasing exercise gradually after _____  days/weeks.

2.         Pain:  Your pet will be prescribed medication to reduce pain and inflammation.  It is important that you use this medication at the lowest dose effective.  Keep in mind that pain helps keep your pet from using this leg, if your pet does not feel pain, he is much more likely to start to use the limb before it is ready.

3.         Pain patch:  The pain patch can be removed in 3-5 days at the clinic.  While the pain patch is working, your pet may seem drowsy and have a decreased appetite.

4.         Diet: Ordinarily no special diet is required for healing, but it is advisable to reduce calories when your pet is inactive.  If your pet is overweight, weight reduction can speed recovery and possibly prevent further injury. The doctor will discuss weight control with you if necessary.

5.         Care of the splint/bandage: Certain surgical corrections require use of a splint or bandage for 1 to 6 weeks after surgery. If your pet has a splint or bandage, extra care is needed to protect it. Do not let the apparatus become wet. In damp weather, place a plastic bag over it when you walk your pet. Do not allow unrestrained exercise. Your pet will be evaluated for bandage removal in _____  days.

6.         Incision: Check the incision daily and report abnormalities to the doctor. Your pet will be evaluated for suture removal in _____  days.

Notify the Doctor if Any of the Following Occur

o Your pet seems to be in pain or is uncomfortable.

o Your pet chews or damages the splint/bandage or stitches.

o Your pet's health changes.