Name
Cruciate Ligament Rupture, Canine
Short Description
Ruptured cranial cruciate ligament (CCL)
Affected Animals:
Commonly, dogs and humans; less commonly, cats. Obese animals are at
greater risk for suffering this injury. In addition, certain breeds
of dogs are more susceptible than others to developing a ruptured
cruciate ligament. Most commonly, these breeds include the
rottweiler and cocker spaniel. The Labrador retriever, German
shepherd, mastiff, golden retriever, miniature and toy poodle, Lhasa
apso, and bichon frise are likely to suffer from the problem as
well.
Overview:
A normal dog's knee joint
works like a hinge, keeping the animal's leg stable as it bends.
When the knee has a ruptured cruciate ligament, the "hinge" becomes
loose and no longer functions as effectively. This looseness
prevents the knee from maintaining stability of motion. As a result,
the dog suffers pain, inflammation, and eventually develops
arthritis. This is a very common orthopedic disease in dogs.
When a knee injury occurs suddenly -- as it usually does among
humans who suffer from injuries to the cruciate ligament due to a
skiing, football, or other sports-related accident -- the ligament
will tear rapidly. But usually with dogs, the tearing is partial and
occurs gradually, resulting in low-level lameness that may improve
initially over time. However, progressive injuries can be quite
damaging; because of the trauma to the ligament, the knee joint
becomes inflamed, leading to arthritis, which only grows worse with
continued weight bearing.
- Trochlea of femur
Tibia
Fibula
Cranial cruciate ligament
Caudal cruciate ligament
Lateral meniscus
Medial meniscus
|
 |
In more severe chronic cases, the
"shock absorbers" of the knee -- quarter-moon shaped sections of
cartilage called the medial and lateral menisci -- tear or become
crushed because of exposure to abnormal stress that occurs when the
knee is loose. Animals with this condition often are severely lame
and may not be able to put any weight on the affected leg.
Both surgical and non-surgical methods for treatment are available.
Generally, dogs have a good chance of recovering normal, or almost
normal, movement after surgery, but the arthritis that has occurred
already will not be reversible. Additionally, dogs that have
ruptured the cruciate ligament on one side are more likely to tear
the ligament in the other knee.
Obesity is a major risk factor for this injury and certain breeds of
dogs are more likely than others to rupture their ligaments.
Clinical Signs:
Clinical signs include acute non-weight bearing lameness; chronic
progressive lameness; crepitus; pain; decreased range of motion;
presence of medial buttress; presence of meniscal click; stifle
effusion; thickened joint capsule; positive cranial drawer test;
positive tibial compression test; reluctance to sit with normal
flexed stifle tucked under the body; and inability to rise or walk
if the condition is bilateral.
Symptoms:
Rear limb lameness, sudden onset lameness that either improves
slightly and remains chronic or worsens again. The affected knee may
feel thicker than the normal one. The dog may sit with its injured
leg held out to the side, rather than tucked up underneath. The
lameness should worsen with exercise. The knee may sound "crunchy"
when put through a range-of-motion test.
Description:
Found in every joint of the body, ligaments are bands of tough,
fibrous tissue that hold two or more bones in proper position. One
of the ligaments that stabilizes the knee joint when the leg bends
and moves is called the cranial cruciate ligament. When this
cruciate ligament becomes loose, it is no longer able to ensure
stable movement, and damage to the cartilage in the knee joint,
leading to arthritis.
Ligaments are very strong tissues, but once they are damaged, they
tend to heal slowly and incompletely. In people, cruciate ligament
tears are often the result of rapidly occurring trauma, such as
injuries resulting from skiing, football, soccer, and other sports
accidents. Although this type of injury can also occur in dogs --
jumping up to catch a Frisbee, for example, can cause rapid trauma
-- ruptured cranial cruciate ligament injury in the canine usually
occurs progressively, over a period of time. There is often a
partial tearing, which may show up as a low-level lameness and
appears to improve in days to weeks. This partial tearing sets up
inflammation within the knee joint, and the weakened ligament is
further damaged with continued weight bearing. Eventually, this
leads to complete rupture.
Due to a possible genetic component, some breeds, such as the
rottweiller and cocker spaniel, are very prone to this disease. They
may have some underlying genetic, conformational, or inflammatory
disorder that predisposes the ligament to rupture; their
susceptibility to the injury is a topic of research at many
veterinary institutions. Obese animals are also at increased risk
for this disease. However, dogs of all sizes and breeds can develop
ruptured cranial cruciate ligaments.
Dogs with a ruptured cranial cruciate ligament in one knee have a 20
to 40 percent chance of injuring the other side, making a full
recovery less likely.
|
|
Diagnosis:
The diagnosis of a ruptured cranial cruciate ligament usually can be
made upon physical examination. Two tests, the positive cranial
drawer test, and the positive tibial compression test, will confirm
the diagnosis. The positive cranial drawer test, in which the dog's
knee is bent slightly and pressure is applied to the bones
comprising it, is performed to check for instability within the
joint. A positive tibial compression test also assesses the
stability of the knee joint; this test may be more sensitive in
detecting looseness in heavily muscled dogs. It may be necessary to
sedate large dogs before performing the test. When the injury is
chronic, the cranial drawer and tibial compression tests may be less
effective assessments because their results will be more difficult
to evaluate, since the body will have built up scar tissue in the
joint capsule in an attempt to limit the abnormal motion.
If the dog's meniscal cartilage -- the knee's "shock absorbers" --
has been torn, the veterinarian may feel a "meniscal click." Thirty
to 50 percent of dogs that have knee joints with chronically
ruptured cruciate ligaments will experience damage to their
cartilage, resulting in arthritis. X-rays can help confirm the
diagnosis and give an indication of how much arthritis already is
present. This information may be important for determining
prognosis. X-rays can also rule out diseases such as rheumatoid
arthritis and fractures that may display similar symptoms.
Occasionally, the veterinarian will obtain and analyze a sample of
joint fluid in an attempt to rule out other types of arthritic
diseases. However, this procedure usually will not be performed
unless there is suspicion that an underlying disease is causing the
ruptured cruciate ligament.
Prognosis:
The prognosis depends on a number of factors. The longer the injury
has been present, the more arthritic the joint and the more guarded
the prognosis. If the meniscal cartilage is torn, the prognosis is
more guarded as well. Obese animals tend to recover more slowly than
animals in good shape. Animals with torn cruciate ligaments on both
sides take longer to recover than animals with an injury on only one
side. Dogs with underlying diseases such as rheumatoid arthritis,
lupus, or immune mediated polyarthritis have a decreased prospect
for a full recovery.
In general, animals stabilized with any surgical technique will
require three to six months of rehabilitation. After that time,
depending on how arthritic the joint was before surgery, they should
return to fairly normal activity levels, although they are unlikely
to regain 100 percent of their pre-injury function. These dogs may
be sore after heavy exercise and occasionally may require pain
medication. Athletic animals will have some decrease in function and
will be unlikely to return to competition. Hunting dogs may not be
able to hunt as frequently or for extended periods of time as they
did prior to injury. The TPLO- surgery is purported to be able to
return animals to performance levels; however, definitive objective
studies have not been published to date.
Transmission or Cause:
The cause can be traumatic, or can occur as a result of chronic
inflammation in the knee joint. There may be no known cause to the
inflammation. However, the ligament may rupture as a result of the
following diseases: medial patellar luxation, a disease in which the
kneecap pops in and out of joint; rheumatoid arthritis; lupus;
immune mediated polyarthritis; septic arthritis, an infection in the
joint; osteochondrosis, which is a cartilage development problem;
and problems related to the animal's build or body conformation.
Dogs that are obese are much more likely to develop this disease
than dogs that are of normal weight. In addition, certain breeds are
more prone to developing the disease, especially the rottweiller and
cocker spaniel.
Treatment:
The treatment for this disease can be surgical or non-surgical.
Non-surgical management consists of exercise restriction,
anti-inflammatory medications, physical therapy and weight loss.
These therapies can be effective in very small animals such as cats
and dogs weighing less than 15 pounds, although these animals will
develop some arthritis, they may regain almost normal function.
Most veterinarians will recommend surgery for treatment of a
ruptured cranial cruciate ligament. The many surgical procedures
that are available for treatment can be organized into three basic
categories: intracapsular stabilization, extracapsular
stabilization, and a patented procedure called the Tibial Plateau
Leveling Osteotomy® (TPLO).
Intracapsular ligament replacement involves either transplanting
tissue from other parts of the dog's body, such as the patellar
ligament or fascia lata, into the knee joint. Other options for
ligament replacement include a synthetic graft made from materials
such as Gore-Tex® or ligament from a tissue bank. The goal of
intracapsular ligament replacement is to position the replacement
ligament in an anatomically correct configuration.
Extracapsular stabilization stabilizes the knee joint, using
materials such as fascia lata, which is a strong fibrous sheet of
tissue surrounding the muscles in the outside of the leg,
monofilament nylon or other suture material, or stainless steel
wire. Fibular head transposition is an extracapsular technique that
allows another ligament in the knee joint, the lateral collateral
ligament, to replace the function of the cranial cruciate ligament.
These techniques are not performed inside the joint; rather, they
function to counteract the instability in the joint by acting in a
manner similar to an intact cranial cruciate ligament.
Tibial Plateau Leveling Osteotomy® (TPLO) is a technique that
utilizes a different approach to treating cranial cruciate ligament
injury. Rather than trying to oppose the forces acting on the
cranial cruciate ligament in the normal knee joint, a TPLO®
eliminates these forces -- and thus the need for a cranial cruciate
ligament -- by changing the anatomy of the knee joint. This
procedure requires that a bone cut be made in the tibia, which is
then stabilized with a specialized bone plate. Only veterinarians
that have been trained and licensed by the developer of the
technique are permitted to perform this surgery. In general, dogs
weighing less than 40 pounds are too small for this procedure.
There are advantages and disadvantages to each of these techniques.
The results of these procedures are generally very good; however,
some surgeries are more promising than others for complete return to
function. There also can be substantial differences in cost and
recovery time. A veterinarian can detail these surgical options and
further explain the various procedures. Although cruciate ligament
surgery can be very demanding, many veterinarians have a great deal
of experience and success with these procedures.
Rehabilitation regimens vary, but most veterinarians recommend
range-of-motion exercises, gradual return of activity, swimming,
weight reduction, and pain medication.
Prevention:
While prevention of injuries is difficult, there are some factors
that can decrease the likelihood of rupturing a cranial cruciate
ligament. First and foremost is avoiding obesity. A veterinarian can
assess the dog's body condition and provide guidelines for a healthy
diet and ideal body weight. Exercise is also important for dogs,
just as it is for people, since a daily exercise regimen will lessen
the likelihood of injury. Because animals with other orthopedic
diseases of the knee joint, such as a luxating patella, may be more
prone to cranial cruciate ligament rupture, early surgical
correction of such orthopedic problems is an important preventative
measure.
Back to Encyclopedia Listings |
