Cruciate Damage and Repair

SURGERY FOR CRUCIATE LIGAMENT DAMAGE AT DVG

Cranial, or anterior, cruciate ligament rupture is a common cause of lameness in dogs. The dog’s stifle joint, or knee, acts as a hinge and has various ligaments which aid this action by preventing abnormal movements. On either side of the joint there is a collateral ligament which prevents sideways movement. Internally there is a pair of cruciate ligaments arranged in a cross which prevents the tibia (shin bone) from being pulled forwards as the quadriceps muscle contracts.

The cranial cruciate ligament is the most commonly affected and in many species, including humans, the ligament is usually damaged by a traumatic force such as being hit by a car or getting the leg caught. Although this is can also be the case in dogs, more commonly the ligament is damaged, or ruptured, during moderate or normal exercise. This is due to the fact that the ligament has degenerated over time and the first subtle signs of a problem can be easily missed. In other dogs, a low-grade chronic lameness may have been present before a sudden deterioration as the ligament ruptures.

Commonly dogs will prevent with lameness along with pain and swelling in the stifle joint. Damage to the ligament can be confirmed by finding instability in the joint by doing a test called a ‘cranial draw’, however some animals may need to be sedated or anaesthetised to perform this. To make a full diagnosis radiographs will be taken under general anaesthesia and the joint will be fully manipulated.

In very small/light dogs conservative management, consisting of rest and pain killers, may help but the results are often very slow and unrewarding. In almost all cases surgical intervention is advised.

There are several different techniques reported for the repair of cruciate ligament rupture. The one chosen will depend on the characteristics and conformation of the individual affected as well as the preference and surgical ability of the surgeon. At the Downland Veterinary Group we offer 2 forms of surgical repair, either a Lateral Suture or a Tibial Tuberosity Advancement (TTA).

LATERAL SUTURE

For this procedure a strong nylon line is passed through a hole drilled in the tibia (shin bone) and then secured at the back of the femur (thigh bone) by either hooking it under the fabella (shown in picture) or by securing it to the bone using a suture screw. The two ends of the line are then secured using a metal crimp. This line effectively acts as an artificial ligament.

This procedure is used more commonly in smaller dogs, and in cats, but can be used in larger animals as well. A different strength line is used depending on the weight and activity level of the dog.

TIBIAL TUBEROSITY ADVANCEMENT (TTA)

This is a more advanced technique and relies on changing the geometry of the stifle joint. Radiographs are taken prior to the surgery and calculations are made to determine the size of implant required. The front part of the tibia (shin bone), where the patella tendon attaches, is cut off and move forward by inserting a titanium implant into the bone. This is then held in place using a titanium plate, screws and folk. By changing the angle of the stifle joint the effects of the quadriceps muscle on the tibia are eliminated, taking the strain off the cranial cruciate ligament. Therefore in this procedure the ligament is not replaced but is no longer required.

This procedure is typically used in medium and large breeds although can be performed in most cases. The dogs usually recover function of the limb very quickly and are usually weight bearing 24-48hrs after surgery. As the angle of the joint has been altered recurrence is not a problem.

Following this surgery the animals require 6-10 weeks of strict rest to allow the bone to heal and follow up radiographs are taken at this point before exercise is reinstated.