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Pet Article
DOG BONES
Ruptured Cranial Cruciate Ligament (RCCL) is a common and painful knee injury suffered by
many human athletes, but did you know that your dog could also be susceptible to this problem?
In dogs, this is a long term progressive disease which can lead to arthritis as well as other
permanent degenerative changes of the joint.
To be able to understand this condition, it is important to understand the anatomy of bones
in the hind leg of your dog. The femur is the large bone of the hind leg which is attached
to the pelvis. This rests on the tibia and the joint is stabilized by the joint capsule,
surrounding musculature and ligaments, one of which is the cranial cruciate ligament. This
ligament prevents the joint from bending too far the wrong way. It also prevents rotation of
the joint and prevents the tibia from sliding forward. If this ligament ruptures, the
joint becomes unstable and the femur is allowed to move freely over the tibia, pulling and
tearing the joint capsule of the knee.
This instability is very painful and can cause joint swelling and hemorrhage. It can also
cause abnormal wear of the bony cartilaginous structures found in the knee, leading to long
term problems such as degenerative jonit disease. Animals who suffer from this problem may
be lame for a few weeks or months and then may seem to get better, but may go onto develop a
more chronic progressive lameness that never resolves and could worsen with exercise.
Veterinarians will diagnose this problem by examining the gait or walk of your dog, by
feeling the joint and by checking for abnormal mobility of the joint, this is called
cranial drawer sign or cranial tibial thrust. By using this test the joint can be
manipulated either forwards or backwards, a movement normally prevented by the cranial
cruciate ligament. After diagnosis, x rays are usually taken to determine the extent of
the damage within the joint and to make sure there are no other underlying problems such as
a tumor or other erosive diseases.
In the past, treatment for this condition has consisted of stabilization of the joint
either by implanting a false replacement for the torn ligament or by placing an
external strut on the outside of the bone to stabilize the joint. The problem with
these techniques is that, they don't perfectly replace the ligament that Mother
Nature put there, so arthritis usually progresses and mobility of the knee can be
affected to a certain extent. A new procedure called a Tibial Plateau Leveling Osteotomy
(TPLO) has the potential to be much more effective in treating the problem and preventing
future degenerative changes in the joint.
TPLO changes the mechanics of the knee and is based on the theory that dogs with this
problem are predisposed to it because of abnormal sloping of the head of the tibia.
This sloping causes the femur, which rests on the plateau, to slip backwards and off the tibia,
thereby putting constant force on the cruciate ligament and making rupture more likely.
In TPLO procedure, the angle of the tibial plateau is altered by making a circular
cut in the top of the tibia and then rotating the piece so that the load bearing
surface of the bone is flat. A plate is then attached to hold the piece of bone in
this new position as it heals.
This type of surgery keeps the femur on a flat plane, eliminating the need for the knee to
be stabilized and removing the need for the cruciate ligament altogether. While performing
the TPLO procedure, the surgeon usually clears the joint of debris and dead tissue to reduce
further progression of arthritis. While this procedure will not eliminate all signs of
degenerative changes in the joint such as arthritis, it does minimize the problem and gives
your dog almost complete functionality of the joint. Because TPLO requires cutting the tibia,
the procedure can take upto 16 weeks to heal, but patients are able to bear weight on the joint
almost immediately after surgery.
Post operatively these patients seem to do very well and show improvement almost immediately.
Mark Woodcock
1 Flea Control
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