The Gold Ears site has been inactive lately, since there have been many changes during the past several months. In May I graduated from WSU and moved to Tacoma and began the long search for a job. In July the entire Gold Ears family had to move to a new apartment due to earthquake renovations in our old building. Now after many months of searching I have been fortunate enough to be offered a position at the Helping Hands Veterinary Clinic in Lynnwood. Gold Ears friend Nicole began working there this summer and when a position became available I was very excited to apply since Nicole had nothing but great things to say about the team there. It’s great to have the opportunity to work with a good friend but I’m even more excited about the direction of the clinic and what the future holds.  There have been some very stressful times these past few months but thanks to the Gold Ears friends and family things are now looking up.

Indy went to an AKC agility trial at Argus Ranch on September 4th and 5th. He was handled by Nicole and they had a great showing he qualified twice. Indy got first in Jumpers with Weaves and Standard for his first AKC Qs!

First, the Basics

The knee is a fairly complicated joint. It consists of the femur above, the tibia below, the kneecap (or patella) in front, and the bean-like fabellae behind. Chunks of cartilage called the medial and lateral menisci fit between the femur and tibia like cushions. Assorted ligaments hold everything together and allow the knee to bend the way it should and keep it from bending the way it shouldn’t.

There are two cruciate ligaments that cross inside the knee joint: the anterior (or, more correctly in animals, cranial) cruciate and the posterior (or, more correctly in animals, the caudal) cruciate. They are named for the side of the knee (front or back) where their lower attachment is found. The anterior cruciate ligament prevents the tibia from slipping forward out from under the femur.

Finding the Rupture

The ruptured cruciate ligament is the most common knee injury in dogs; in fact, chances are that any dog with sudden rear leg lameness has a ruptured anterior cruciate ligament rather than something else. The history usually involves a rear leg that is suddenly so sore that the dog can hardly bear weight on it. If left alone, the leg will appear to improve over the course of a week or two but the knee will be notably swollen and arthritis will set in quickly. Dogs are seen by the veterinarian in either the acute stage (shortly after the injury) or in the chronic stage (weeks or months later). The key to the diagnosis of the ruptured cruciate ligament is the demonstration of an abnormal knee motion called a drawer sign. It is not possible for a normal knee to show this sign.

The Drawer Sign

The veterinarian stabilizes the position of the femur with one hand and manipulates the tibia with the other hand. If the tibia moves forward like a drawer being opened, the cruciate ligament is ruptured.

Another test that can be used is the tibial compression test where the veterinarian stabilizes the femur with one hand and flexes the ankle with the other hand. If the ligament is ruptured, again the tibia moves abnormally forward. If the rupture occurred some time ago, there will be swelling on side of the knee joint that faces the other leg. This is called a medial buttress and is a sign that arthritis is well along.

It is not unusual for animals to be tense or frightened at the veterinarian’s office. Tense muscles can temporarily stabilize the knee, preventing demonstration of the drawer sign during examination. Often sedation is needed to get a good evaluation of the knee. This is especially true with larger dogs. Eliciting a drawer sign can be difficult if the ligament is only partially ruptured so a second opinion with an orthopedic specialist is a good idea if the initial examination is inconclusive.

Since arthritis can set in relatively quickly after a cruciate ligament rupture, radiographs (x-rays) to assess arthritis are helpful. Another reason for radiographs is that occasionally when the cruciate ligament tears, a piece of bone where the ligament attaches to the tibia also breaks off. This will require repair and the surgeon will need to know about it before beginning surgery. Arthritis that has set in prior to surgery limits the extent of the recovery after surgery, though surgery is still needed to slow or even curtail further arthritis development.

How this Happens

There are several clinical pictures seen with ruptured cruciates. One is a young athletic dog playing roughly that takes a bad step and injures the knee while playing. This is usually a sudden lameness in a young large-breed dog. On the other hand, an older large dog, especially if overweight, can have weakened ligaments and slowly stretch or partially tear them. The partial rupture may be detected or the problem may not become apparent until the ligament breaks completely. In this type of patient, stepping down off the bed or a small jump can be all it takes to break the ligament. The lameness may be acute but have features of more chronic joint disease or the lameness may simply be a more gradual/chronic problem.

Larger overweight dogs that rupture one cruciate ligament may rupture the other one. An owner should be prepared for another surgery in this time frame.

What Happens if the Cruciate Rupture is Not Surgically Repaired?

Without an intact cruciate ligament, the knee is unstable. Wear between the bones and meniscal cartilage becomes abnormal, and the joint begins to develop degenerative changes. Bone spurs called osteophytes develop, resulting in chronic pain and loss of joint motion. This process can be arrested by surgery but cannot be reversed.

Osteophytes are evident as soon as 1 to 3 weeks after the rupture in some patients. This kind of joint disease is substantially more difficult for a large breed dog to bear though all dogs will ultimately show degenerative changes. Typically, after several weeks from the time of the acute injury, the dog may appear to get better but is not likely to become permanently normal.

In one study, a group of dogs was studied for 6 months after cruciate rupture. At the end of 6 months, 85% of dogs under 30 lbs of body weight had regained near normal or improved function, while only 19% of dogs over 30 lbs had regained near normal function. Both groups of dogs required at least 4 months to show maximum improvement.

Options for surgical repair will be discussed in the next post.