Cruciate Disease in Pets

Facts about Cruciate Disease

• Cruciate disease is the most commonly operated orthopedic disease in dogs and the main cause of stifle joint osteoarthritis (OA).
• It was estimated that owners spent $1.32 billion (November 2005 study) for the treatment of ruptured cranial cruciate ligaments (RCCL) in the United States in 2003.
• The average cost of a cruciate surgery is $1000-$3000 per knee.
• Rupture occurs when the breaking strength of the ligament is exceeded, thought to be four times the body weight of the dog. CCL rupture occurs in all sizes of dogs but occurs more frequently in the larger breeds, and at a younger age.
• Once one leg is effected there is a 50% chance other leg will rupture the ligament due to the over compensation of weight bearing of the healthy leg.

Predisposing Factors

• Certain breeds such as the Rottweiler, Boxer, Newfoundland and Labrador Retriever are most commonly affected.
• The confirmation of the hind limbs in some breeds are more straight or "peg legged", this places more stress on the knee joint causing the ligament to rupture.
• Over weight pets- Active overweight pets may be the most common cause of ruptured cruciates.



How the Cruciate Ligament Works

The knee joint is comprised of two main bones the femur and tibia.  The tibia has a flat floor which the femur sits on.  There are two main tendons that hold the bones together during movement called the cranial and caudal cruciate ligaments.  When your pet takes a step the cruciate ligaments tighten and keep the bones from moving apart. One problem with the knee joint is that the floor of the tibia is sloped backwards and when lots of force is placed on the knee the femur slides back.  This can cause the cruciate ligament to rupture.  . 




What Signs to Look For

• Dogs may rock from one side to the other, but usually sit with the affected rear leg extended outward.
• They rise from sitting by leaning forward which helps alleviate discomfort in the painful knee.
• They rise from sitting by leaning forward which helps alleviate discomfort in the painful knee.
• Common history of physical activity and then the dog is lame on one limb for a couple days. The leg will get better but then the lameness returns in 3-4 weeks.
• During walking, one may notice internal rotation of the tibia, a phenomenon known as pivot shift due to weakness of the biceps femoris muscle group
• Significant atrophy (muscle shrinkage) of the quadriceps and hamstring muscles is a common finding.
• Older dogs will be unable to rise in the rear limbs one day, this be confusing and is often complicated with over weight patients with chronic arthritis.



Medical Options :

1. Since cruciate ruptures are the number one cause of Osteoarthritis in the dog knee, appropriate medical therapy should be started to protect the cartilage.
2. Omega -3 fatty acids and Sam-e can be given daily to protect the joint from damage.



Surgical Options

Categories of Different Fixation Methods:
1. Extracapsular-lateral retinacular imbrication


2. Extra-articular- TPLO and TTA 



Extracapsular- The lateral retinacular imbrication is the oldest and most performed surgery for cruciate disease.  The procedure is performed by placing a suture outside the knee joint which acts as a cranial cruciate ligament.  This procedure is generally half the price of the other options and studies have shown the success rate it the same.  This procedure sometimes does not allow the same range of motion as the extra- articular procedures and is often recommended for small and medium sized dogs.  The procedure is much less invasive and the complications are much less severe.  The major complication with this surgery is the suture may break.    

Extra- articular 

TPLO- tibial plateau leveling osteotomy and tibial tuberosity advancement

This procedure was invented 1993 by Dr. Barclay Slocum.    flattening" the slope of the tibia, the TPLO provides stability in the stifle by neutralizing forces and providing "stability" in the stifle when axial forces are placed upon the tibia by the femur (standing, walking, running). The advantage of the TPLO is that this technique allows for correction of abnormal limb alignment at the same time as one is leveling the tibial plateau. Complications can include implant failure which can result in a fracture of the bone and the metal plates may have to be removed.   

TTA-Tibial tuberosity advancement  This is one of the newest fixation for cruciate disease on the market.  It was invented for large athletic dogs.  It is less invasive that the TPLO and some say it has less complications. This surgery moves the knee cap tendon ( patellar tendon) forward to neutralize the forces placed on the tibia.  Very few studies have been done on this technique.    Complications (similar to TPLO) can include implant failure which can result in a fracture of the bone and the metal plates may have to be removed.