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Tibial Tuberosity
Advancement (TTA)
Tibial Tuberosity
Advancement is an orthopedic procedure to repair deficient cranial
cruciate ligaments in dogs. It has also been used in cats. This
procedure was developed by Dr. Slobodan Tepic and Professor Pierre
Montavon at the School of Veterinary Medicine, University of Zurich,
in Zurich, Switzerland beginning in the late 1990s.
The Anterior cruciate ligament in dogs, provides the same function
as the anterior cruciate ligament in humans. It stabilizes the knee
joint, called the stifle in dogs, and limits the tibia from sliding
forward in relation to the femur. It is attached to the cranial
(anterior) side of the intercondylar of the tibia at one end and the
caudal (posterior) side of the femoral condyle at the other end.
Damage to the CrCL is one of the most common injuries in dogs and
can cause severe lameness. 20 to 40% of dogs with CrCL rupture of
one limb subsequently have rupture of the other limb. Uncorrected
CrCL deficiencies have been associated with meniscal damage and
degenerative joint diseases such as severe osteoarthritis.
TTA is a surgical procedure designed to correct ACL deficient
stifles. The objective of the TTA is to advance the tibial
tuberosity, which changes the angle of the patellar tendon to
neutralize the tibiofemoral shear force during weight bearing. By
neutralizing the shear forces in the stifle caused by a ruptured or
weakened CrCL, the joint becomes more stable without compromising
joint congruency.
TTA appears to be a less invasive procedure than some other
techniques for stabilizing the deficient cranial cruciate ligament
such as TPLO (Tibial Plateau Leveling Osteotomy) and TWO (Tibial
Wedge Osteotomy), as TTA does not disrupt the primary loading axis
of the tibia.
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The Normal Knee
The normal Knee Joint (also know as the Stifle joint), has multiple
structures which are important to its function. This drawing shows a view
from the front with the muscles removed. It is important to note that the
Patellar Tendon, a vital structure in the joint has been removed, so that
you can see “behind” it. The Patellar Tendon is a thick, tough band that
runs from the Patella (green dot) to the Tibial Tuberosity (red dot). |
Tibial
Tuberosity Advancement ( TTA SURGERY )
Possibly the BEST
Surgery for your dog’s Knee
The most common knee injury in the dog is rupture of the Cranial Cruciate
Ligament (CCL), also frequently called the Anterior Cruciate Ligament
(ACL). This injury can occur at any age and in any breed, but most
frequently occurs in middle aged, overweight, medium to large breed dogs.
This ligament frequently can suffer a partial tear, leading to slight
instability of the knee. If this damage goes untreated, it most commonly
leads to complete rupture and possibly damage to the medial meniscus of the
knee. The meniscus acts as a cushion in the knee. Complete rupture results
in front-to-back instability, commonly called Tibial Thrust, and internal
rotation of the lower leg, commonly called Pivot Shift. Untreated legs
usually become very arthritic and painful from the instability.
An injured Cruciate Ligament can only be corrected by
surgery. There are numerous surgical corrections currently being performed.
The most common are 1) External Capsular Repair, 2) Tibial Plateau Leveling
Operation (TPLO), and 3) Tibial Tuberosity Advancement (TTA). Here at
the Angel Animal Hospital we are are performing surgeries on the TTA, which is the newest procedure, and probably the best
repair for most dogs. The forces within the knee are very complicated and
change as the knee is rotated through its range of motion. In a normal
standing position there is a tendency for the lower end of the Femur to
slide backwards on the tilted Tibial Plateau, this is called Tibial Thrust.
This force can be corrected by either cutting the Tibial Plateau and
rotating it into a more flat position (TPLO) or by counteracting this force
by changing the angle of pull of the very strong Patellar Tendon by
advancing the Tibial Tuberosity (TTA). It has been shown that the TPLO
procedure can still allow rotational instability (Pivot Shift) and this may
lead to the progression of arthritis as the dog ages. This Pivot Shift does
not seem to be a problem with the TTA procedure because it results in more
control of rotation by the large quadriceps muscle which pulls on the
Patellar Tendon.
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FAQs
About TTA
 How
long will it take for my dog to be back to normal?
That depends on the dogs age, length of
injury, any pre-existing arthritis or other orthopedic issues, and
type of activity your dog enjoys. 95% of dogs are back to normal in 3
months. The first 6-8 weeks they are on NO running, NO jumping, NO
stairs restrictions, but a walking program and early rehab can
preserve and speed up the recovery of the muscle strength. Most dogs
are walking 70-85% or better by 8 weeks. Dogs that have significant
arthritis in thier knee or hip/spinal problems may have residual
stiffness permanently and a less than optimum outcome, but they will
always still do much better with surgery than they would have without.
Which surgery is better, the TTA or TPLO?
We are certified to do both. TPLO is able to correct some of the
torsion and patellar issues at the same time as the cruciate repair.
TTA provides a slightly quicker return to full walking so in most
cases we are recommending the TTA as our first choice. Each case is
evaluated individually and the recommendation is based on exam and
radiographs.
Links:--http://www.slocumenterprises.com/TPLO%20International/tplo_veterinarians_canada.htm
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1.
The bone just below the knee or stifle joint is the tibia and the bone
above is the femur. The top of the tibia is the tibial plateau. The
patellar tendon attaches the kneecap (patella) to the tibial
tuberosity.
2.
During weight bearing, the femur slides down the tibial plateau. The
ACL stops this downward slope, therefore, is under constant tension
during weight bearing. This biomechanical problem results in ACL
rupture and is directly related to the angle between the tibial
plateau slope and the patellar tendon. A more perpendicular angle
results in a more stable joint.
3.
The TTA involves an osteotomy in the non-weight bearing portion of the
tibia, just behind the tibial tuberosity. The tibial tuberosity is
advanced to achieve a perpendicular relationship between the tibial
plateau slope and patellar tendon. This relationship results in a
stable joint.
4.
The advanced tibial tuberosity is secured using titanium implants. A
bone graft is packed in the open area of the osteotomy. Healing takes
about 8 weeks. Implants do not require removal.