The ruptured cruciate ligament is the most common knee injury of 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 suddenly so sore that the dog can hardly bear weight on it. If left alone, it 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 often seen by the veterinarian in either the acute stage shortly after the injury or in the chronic stage weeks or months
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.
Although most cruciates rupture
suddenly, they can rupture in small tears which cause pain but not the drawer sign. This makes diagnosis long and complicated.
Picture 1 shows the normal structure of
the stifle joint when viewed from the side. When the anterior cruciate ruptures the tibia can move forward in relation to the femur resulting in instability and pain. This has to be repaired in all
cases even when the rupture has been present for a long time.
There are four main ways of repairing
this ligament and if you ask four vets you will get four answers as to which is best.
The longest standing method, which is
still used today, is the Fabellar suture. It is the
quickest and cheapest to do but is has,
in the opinion of most orthopedic surgeons been superseded by the other three methods. It still gets done in light pets under 5kg and in uninsured pets where cost is a driving factor. In this
operation a large, strong suture is passed around the fabella behind the knee and through a hole drilled in the front of the tibia. This tightens the joint to prevent the drawer motion, effectively
taking over the job of the cruciate ligament.
Over the Top
Intracapsular repair intuitively seems
like it should do better as it uses living tissue (rather than an artificial material) to essentially make a new ligament. This takes more time surgically. As with the extracapsular repair, the knee joint is opened, fragments of the ligament are removed, as is
damaged meniscus. After this a strip of connective tissue is dissected locally and passed through the middle of the joint exactly where the cruciate ligament used to be. The new ligament is attached
at the opposite end to an implant or simply sewn into place. This has been the method of choice at Anrich for the last 20 years.
TPLO (Tibia Plateau Leveling
This is the most complex and most
expensive of the options and is preferred by many referral centres. However, it requires “breaking” the tibia and plating it together again which lends itself to complications. This method has recently been superseded by the
TTA (Tibial Tuberosity
Here at Anrich we have embraced the new methods as they have developed. Whilst TPLO’s were within our ability, we found it difficult to justify the cost of this complex operation. However, the TTA on the other hand is an excellent
addition to our skill set and we have had excellent results with it. In this case the tibial crest is cut off and advanced by 3mm to 14mm depending on the size of the dog and the geometric
calculations as seen in figures 2 and 3. The space in the advancement is filled with a titanium cage and held in place by a plate. The return to function is very rapid in less than 2 weeks in most
cases. Most vets refer ths type of surgery to specialist centers but here at Anrich we have learnt the skills so that pets do not need referring.