|
 We
are commonly presented with pets for suffering from lameness in the hind
limb. Frequently this lameness can be localized to the knee or stifle
joint. One of the most common injuries that occur to the stifle joint
is the rupture or tear of the anterior cruciate ligament. This ligament
is found inside the joint and it serves the purpose of limiting the
forward motion of the tibia or shinbone relative to the femur or
thighbone. When the cruciate ligament is torn, either partially or
fully, the knee becomes unstable and painful. Sometimes the ligament
may deteriorate slowly over time and the pets will develop chronic
arthritis. In other times, ligament ruptures suddenly and pet may be
unwilling and unable to their weight on the affected limb. (click on
the images to see the normal knee and the ruptured ligament)
The anterior cruciate tends to rupture
in dogs so often because of the relationship between the tibia and the
femur. The tibial plateau (the weight bearing surface of the tibia)
tends to be angled from front to back. This causes the Femur to slide
down the slope during weight bearing and the anterior cruciate ligament
is used to prevent this motion. Constant strain on this ligament leads
to its degeneration and ultimate collapse.
When the anterior cruciate ligament
ruptures, it is common to also damage a structure called the medial
meniscus. The structure acts as a glide plate between the tibia and the
femur, allowing them to move smoothly relative to one another.
How
do we diagnose ruptured cruciate ligaments?
Diagnosis of this problem relies on
physical examination, palpation of the joint in question as well as
radiographs of the affected limb. Frequently, pets must be sedated or
anesthetized to adequately evaluate the joint. When the pet is relaxed,
the doctor can elicit movement of the tibia relative to the femur, which
is known as the anterior drawer sign. Radiographs allow us to see if
there are any fractures of the bone for if there is chronic arthritis
associated with the ruptured ligament.
How can we treat
ruptured cruciate ligaments?
Once the
cruciate ligament and/or the medial meniscus are damaged, it cannot
repair itself and must be repaired surgically. There are many surgical
procedures that can be used to repair the cruciate ligament. All of the
techniques require the removal of the fragments of the cruciate ligament
as well as removal of the torn meniscus. This is accomplished by
surgically opening the joint and inspecting the structures therein. Any
damaged structures are removed to reduce the inflammation that their
presence causes in the joint. The joint is than thoroughly irrigated
and close surgically.
At this
point, we perform a surgical procedure which will alter the forces in
the knee so that the tibia does not slip out from under the femur.
The Tibial Tuberosity
Advancement (TTA) surgery is our technique of choice. In this
surgery, the tibial crest (front part of the bone) is cut and advanced
cranially to alter the angle of the patella ligament to the plane of the
tibial plateau. It turns out that if we can make this angle close to 90
degrees, the tendency for the tibia to slip out from under the femur is
minimized or eliminated. . A small plate is placed in the leg and a bone
graft is placed to fill in the gap between the bones. Recovery takes 6
to 8 weeks.
An
alternate surgical technique known as the Tibial Plateau Leveling
Operation (TPLO) can be performed as well, however, this procedure is
more technically challenging and may have slightly longer recovery
periods and slightly more complications.
What can we expect
from surgical intervention:
Most pets
that undergo surgical repair of the cruciate ligament will regain
seventy to one hundred percent usage of the leg. If the pet as existing
arthritis in the joint, surgery will slow the progression of the
arthritis and generally improve the pets function significantly. If the
meniscus is damaged from the ligament rupture, there is more potential
for post op pain.
It usually
takes six to eight weeks for the pet to return to function after
surgery. During the recovery period it is very important to restrict
activity of the pet. Frequently we'll ask the owners to keep the pet
confined in a crate or cage for two to four weeks post-operatively.
Typically pets are discharged from the hospital with anti-inflammatory
drugs as well as chondro-protectant drugs such as Dasequin to help
reduce inflammation in the joint and subsequent pain.
As many as
60 percent of dogs that suffer from anterior cruciate ligament rupture
of one limb, may experience rupture of the opposite knee within 2 years
from the first injury. Frequently this may occur during the recovery
phase from the first surgery as the pets relying on the other knee
support themselves. In order to protect the other knee, restricted
activity and weight control are essential. Many dogs that suffer from
cruciate ligament rupture are overweight or obese. Therefore we will
commonly recommend a strict diet to help bring the dog back to its ideal
weight.
Are there any
complications associated with this surgery?
As with any
orthopedic surgery, there is a small chance of infection during the
surgery. For this reason all pets are placed on antibiotics before
during and after surgery. In our experience, the likelihood of
infection from the surgery is less than two percent. I
In rare
cases, the surgical implants can break or fail. These materials are
made of pure titanium and with proper exercise restriction after
surgery, this should not occur.
Fracture of
the tibia is another rare, but possible complication from this surgery.
In
general, cruciate repair surgery is very rewarding and will give the
pets the best chance of continued use of their leg with the least amount
of pain. In recent studies of over 1000 dogs undergoing TTA procedure,
the incidence of complications was under 6%. Over 95% of the owners
reported good to excellent results from the surgery.
|
