Anterior Cruciate Ligament Injuries

An exercise in making the best of a difficult injury

Knee injuries in the canine constitute about 60% of all injuries to their joints. When we are presented with a lameness in the rear limb, a progressive evaluation of all the joints of the limb is performed. The intent is to thoroughly evaluate the limb as a whole prior to the above bias entering into our differential diagnosis. This leads to the discovery of concomitant injuries that are often over looked. This article deals with just the knee and its potential abnormalities.

The physical exam will reveal the presence of several abnormalities that support the diagnosis of an ACL (anterior cruciate ligament) injury. Lameness can range in severity of 1 to 5 out of 5. 1 being a subtle lameness at walk and trot and 5 being 3 legged (not using the injured leg). The joint is often swollen with poor distinction of the regional structures. The inside or medial joint is painful. The range of motion of the joint is reduced. This can be determined by a comparison with the normal limb. This applies to evaluating all aspects of the joint, limb and lameness. The condition of the joint’s stability is determined by several manipulations. Lateral and medial distraction checks the collateral ligaments. Anterior and posterior drawer evaluates the cruciate ligaments. The anterior drawer movement is checked in a flexed and extended posture. Pops or rough sounds are noted during any of the above manipulations. Following the complete evaluation and diagnosis of an anterior cruciate ligament injury, we can then begin to decide on a course of action to modify and assist in the joints re-stabilization.

The first thing to understand is that the joint can not be returned to its original condition. All procedures and support is aligned at making the best of a difficult injury. Two goals exist in all cases. First relieve a substantial amount of the discomfort and second reduce the rate of inevitable arthritis.

We start all patients on adequan (glucosaminoglycan), glucosamine/condroitin sulfate, and omega 3 fatty acids. These nutritional supplements provide the building blocks for healing of or maintaining the remaining structure of the joint. Non-steroidal anti-inflamatory agents are used to reduce the swelling and pain. This is similar to us taking an Advil, Aspirin or Tylenol for swelling and/or pain.

Correction of the injury surgically is based on radiographic evaluation of the joint and the athletic potential of the patient. Doing nothing is probably not an option. The joint will remain painful and continue to degenerate at an accelerated rate. Two procedures currently are considered the best options for the athletic patient. They are the tibial tubercle advancement and the tibial plateau leveling osteotomy. They are complicated procedures that do not reconstruct the anterior cruciate ligament, but create new physics of the joint that impart improved stability. The physics of the repairs are beyond the scope of this article. We prefer to perform one of the surgical repairs on a partially torn cruciate ligament rather than waiting for it to completely fail. This provides for the opportunity of the ligament to have support that may prevent it from completely failing.

Rehabilitation of the injury following a surgical repair takes about 4 months. The exercises are specific and need to be followed closely for the most optimal outcome. Our hope is that you will never have to make decisions regarding an anterior cruciate ligament injury.

Submitted by Animal Health Services of Cave Creek