Cranial Cruciate Ligament

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Cranial Cruciate Ligament Rupture

Cranial cruciate ligament (CCL) is one of the most common orthopaedic injuries in dogs, and is the most common cause of degenerative joint disease in the stifle joint (=knee). Female dogs (especially spayed), overweight, and poorly conditioned dogs have a higher incidence. CCL rupture occurs in dogs of all sizes, but is most prevalent in large and giant breeds, usually less than 4 years of age. This may be due to abnormal conformation (congenital) of the stifle. Smaller breeds tend to be more affected after 7 years of age. Regardless of surgical technique, 85% of dogs show clinical improvement following surgery. Acute CCL rupture occurs more commonly in large dogs; partial CCL rupture frequently precedes complete rupture, especially in middle aged large dogs.

CCL rupture results in partial or complete joint instability, pain, and lameness. Torn ligaments retract, do not heal, and cannot be repaired completely. If the injury is not treated, be it conservatively or surgically, damage to connective tissues and degenerative joint disease often results. In other words; there is no “wait and see” opportunity with this condition, especially when there is a perfect window of opportunity for intervention.

Anatomy

The cranial cruciate ligament (CCL) has two parts, a craniomedial band and a caudolateral band. The role of the CCL is to stabilize the highly mobile and weight bearing stifle (knee). Partial or complete rupture causes instability of the stifle, and the dog will become lame. If left untreated degeneration and osteoarthritis will develop within a relatively small time frame (weeks).

Acute rupture of the cranial cruciate ligament (CCL) is caused by sudden, severe twisting and stretching of the ligament. Acute onset (tear caused by injury) is most common in dogs under 4 years old. Young dogs of large breeds are more susceptible to rupture than young dogs of small breeds. The injury usually occurs when the animal steps in a hole while running, or suddenly turns with its paw remaining planted. The twisting motion causes the joint to hyperextend and/or rotate excessively, and partially/completely rupturing the CCL. The meniscus is often damaged as well.

Chronic rupture occurs in 80% of cases and occurs in dogs 5 to 7 years old, after the ligament has degenerated with age. The fibres weaken and partially tear, the joint becomes unstable, and subsequent degenerative joint disease (DJD or OA) develops. A chronic partially torn CCL eventually tears completely, so treatment/intervention is best pursued sooner rather than later.

Anatomy of the Stifle

The femur (large bone of the thigh) and the tibia and fibula (two smaller bones in the shin) meet to form the stifle joint. Articular cartilage attaches to and covers, the ends of bones, protecting and cushioning them. Ligaments, tendons, and muscles hold the bones in relative place to each other, stabilize the joint, and enable movement. The joint capsule, filled with nourishing and lubricating synovial fluid, surrounds the entire joint.

Four major ligaments (dense bands of fibre) support and stabilize the stifle joint by connecting the femur to the tibia, and the joint capsule to the bones. The medial and lateral collateral ligaments are located outside the joint and the caudal and cranial cruciate ligaments are located inside the joint.

The CCL attaches to the femur, runs distally across the stifle joint, and attaches to the tibia. The CCL holds the tibia in place and prevents internal rotation and hyperextension during normal movement.

The meniscus (fibrocartilage located between the femur and tibia) absorbs impact and provides a gliding surface between the femur and tibial plateau. The patella (kneecap) protects the tendon of insertion of the cranial thigh muscles, and the front of the stifle.

Treatment of CCL injuries

The goal of treatment is to alleviate pain, cease degenerative impact on joint, and increase functional use and mobility of the stifle joint. Factors to considered when planning treatment include the following:

Age, size, and health of dog

Cost of surgery

Ability of owner to comply with aftercare requirements (very important consideration)

Availability of surgeon

Intended use of dog

Surgical Treatment

Surgery is the preferred treatment, especially so in dogs over 25kg. It may not completely restore function, but does provide good results if performed within a few weeks of the injury. Surgery will slow, but not stop completely the imminent onset of degenerative joint disease.

Multiple surgical procedures are available, all with comparable results. This means that to date there is no scientific and convincing evidence for one technique over another. The surgeon's expertise, and the size and type of the dog, determine the surgical technique used to replace the function of the torn ligament.

In all procedures, the joint first is opened and the remnants of the CCL are removed. A torn CCL will be inflamed and continually trigger and inflammatory response within the joint, hence degenerative joint disease (DJD). The meniscus is assessed, and if damaged, it is removed. The joint is flushed and closed, and the surgeon stabilizes it. Scar tissue forms as predicted, providing additional joint stability.

Conservative Treatment

Conservative treatment (weight control, rest, medication) is often combined with surgery (removal of CCL remnants), but it can be used alone for dogs that weigh less than 25kg and for cats. Lameness may continue until surgical repair is performed, however. Degenerative joint disease often progresses regardless of treatment.

Losing weight obviously reduces stress on the joint. A diet may be recommended diet, which has low fat, high protein content, and which may be recommended given at specific times of the day.

Aftercare / Recovery

The animal must be confined, and activity strictly limited, for several weeks following surgery/conservative treatment. Diet should be modified to prevent weight gain. The animal is initially allowed outside only to eliminate, gradually increasing its weight bearing and tolerance to movement. Pain medication may be necessary, and is recommended. A cold pack applied several times a day for brief periods helps to decrease swelling and control pain.

Exercise may be gradually increased after 6 weeks providing progress is evident and satisfactory. Normal activity can be expected to resume within 3 months.

Physiotherapy

Physiotherapy aims at maintaining and restoring;

Weight bearing

Joint range of movement

Muscle mass and strength

Proprioception

Function

Upon discharge or first follow-up the physiotherapist will give instructions on the following;

Restrictions (what to do and what not to)

Food allowance (weight gain would be particularly detrimental to the patient’s condition)

Home exercises and condition management

Physiotherapy and rehabilitation should be pursued immediately after any orthopaedic surgery, to be of optimal benefit to the recovery of the patient. Appropriate aftercare is the most important aspect of recovery, and actively adhering to physiotherapy advice will help ensure a successful outcome.

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