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Some Background:
Tibial Tuberosity Advancement (TTA), a new surgical method for treating dogs with deficient cranial cruciate ligament, was developed at the University of Zurich, by Dr. Slobodan Tepic and Prof. Pierre Montavon, where most of the first 150 cases were treated during 02/'03. By mid 2003 it was also adopted by the surgical team at Alameda East, Denver, Drs. Preston Stubbs, Nathan Miller and Robert Taylor. Early in 2004 the system was released into a controlled clinical use by additional 20 surgeons in the US and as many in Europe and Asia. TTA is currently practiced by 130 surgeons.
Dr. Freedman was trained in this procedure by the doctors who developed TTA. These doctors come to the states once a month to teach this procedure. Dr. Freedman has been to Florida and Virginia Tech to learn this procedure.
TTA advancing tibial insertion of the patellar ligament cranially by a predetermined amount so as to place the ligament at 90 degrees to the tibial plateau with the knee extended - leads to only a slight modification of the geometry of the knee, yet it renders it stable throughout its functional range. Morbidity of the method is low, facilitating a fast recovery to function.
The surgery to correct a ruptured cruciate ligament is the latest advancement in canine orthopedic surgery, and is a less invasive alternative to the traditional tplo.
Currently there are approximately 300 veterinarians WORLDWIDE that perform the TTA Procedure. To date, 18,000 TTA surgeries have been performed worldwide.
Clinical Experience
Over the course of 2 years, starting in December 2001, some 150 clinical procedures were performed mostly at the University of Zurich, in the process of refining the surgical approach and the implants for TTA.
While the biochemical arguments for TTA were immediately verified dogs did rapidly regain near normal use of the affected limb, with their stifles functionally stable the technical issues turned out to be much more of a challenge than anticipated. Trial and error of the first year was followed by more focused development phase of the second year, leading to a controlled clinical release of the TTA system in early 2004.
Clinical experience with several hundred cases performed since, by about 50 surgeons, in the USA, Europe and Japan, has met our expectations. Reduced complexity and morbidity of the procedure, in comparison to tplo, has been generally appreciated. The method has also been reported to be reproducible, with most of the ambiguity still present related to the method of measuring the required advancement.
Early complication rates of a few percent seem to have caused no alarm. In most cases, complications were related to technical errors, such as placement of the implants and location/orientation of the osteotomy. While these positive reports on the technique and short-term clinical outcomes are welcome and encouraging, the most important benefits and advantages of TTA are expected in long-term performance.
Advancement of the patellar ligament insertion point on the tibia increases the lever arm of the dominant active force at the stifle, leading to a general reduction of all reaction forces, including those between the patella and the femur and the femur and the tibia.
Professor montavon and his colleagues were the first to propose that the summation of the external and internal forces acting around the weight-bearing stifle result in a total force that is approximately perpendicular to the patellar ligament. If the tibial plateau is not perpendicular to the patellar ligament a shear force, termed cranial thrust', results when the animal bears weight. Cranial thrust is normally apposed by the intact cranial cruciate ligament.
By advancing the tibial tuberosity in a cruciate deficient stifle, the patellar ligament can be positioned perpendicular to the tibial plateau and this eliminates cranial tibial thrust and any tensile load on the deficient cranial cruciate ligament. This technique preserves the normal range of motion of the joint, in-creases the lever-arm of the quadriceps group, and reduces retropatellar forces, thereby reducing the risk of osteoarthritis.
The tibial tuberosity is osteotomised and advanced using a specially designed titanium cage, which acts as a bone expander. The construct is stabilized using a space age titanium plate, which is secured to the tibial tuberosity with specially designed titanium hooks. The plate is then secured to the tibia with self-tapping titanium screws.
All of the equipment used in the TTA surgery is ordered from one company and is made from the highest quality materials. Our equipment is ordered and shipped from Switzerland. If you would like to learn more about the equipment we use in the TTA procedure, please visit www.kyon.ch/. This site will educate you on the type of equipment, as well as the quality, used and the surgical technique itself.
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