· TTA neutralizes cranial tibial thrust in cranial cruciate ligament deficient stifles
· Stability is achieved without compromising joint congruency
• TTA decreases internal joint reactions including retropatellar pressure
· TTA is less invasive than other geometry modifying techniques
•TTA reduces morbidity and post surgical complications while accelerating recovery
• Sound biomechanical rationale
• Unique implants designed specifically for TTA
• Superb biocompatibility of titanium
• Broad range of sizes available
Tibia Tuberosity Advancement Surgery
Cranial cruciate ligament deficiency in dogs has taken the center stage in small animal orthopedic surgery for both, the high incidence of the problem and clinical success of both TPLO and TTA surgeries. The highest incidence occurs in large middle to older age dogs. Both procedures modify the geometry of the stifle rather than attempt to repair the deficient function of the ligament. The tibiofemoral shear forces appear to be responsible for excessive loading of the cranial cruciate ligament (CCL) during weightbearing, leading to its partial or complete rupture.
The TTA procedure was developed by Dr. Sobodan Tepic and the first clinical trials were conducted beginning in 2001. The results of the clinical trials were very good and lead to a clinical release of the TTA system in early 2004. To date many thousand of successful TTA procedures have been completed with excellent results and minimum complication as compared to other procedures.
When the paw is loaded on weightbearing, a force is created through the foot to the metatarsus that causes the calcanean (Achilles) tendon to react with a second force to maintain the stability of the tarsus at its weightbearing angle. A vector force (sum of the resulting forces of weightbearing) occurs in the tarsus, creating a simultaneous force through the patella ligament necessary to stabilize the stifle. A combination of forces in the stifle results in a vector force in a plane almost parallel to the patella ligament at the standing weightbearing angle of the stifle. This is the tibiofemoral force across the stifle at weightbearing. If the slope of the tibial plateau is not anatomically oriented perpendicular to the patella ligament on weightbearing (the case in normal dog), then the vector force does not superimpose the normal compressive tibiofemoral force of weightbearing on the stifle joint. A tibiofemoral shear force (in the direction o cranial drawer of tibial translation) results and is accommodated for in the normal animal by the CCL which constrains the stifle for normal function. Constant loading (overloading) over time leads to its cyclical failure.
TTA positions the patellar ligament perpendicular to the slope of the tibial plateau by advancing its insertion on the tibial tuberosity in a cranial direction eliminating the tibiofemoral shear force with weight bearing and relieving the function of the CCL. The TPLO procedure accomplishes essentially the same redirection of vector force by rotating the tibial plateau (to a slope parallel to the patellar ligament) to neutralize the tibiofemoral shear force. However, TPLO increases the tension on the patellar ligament whereas TTA relieves patellar ligament tension since the tibial crest moves several millimeters proximal when it is also advanced cranially. This dual shift of the crest is an integral part of the technique.
Tibial Tuberosity Advancement for cranial cruciate deficiency.
THE TTA RESTORES STABILITY IN STIFLES WITH RUPTURED CRANIAL CRUCIATE LIGAMENTS USING A RATIONALLY BASED SURGICAL INTERVENTION REDUCING MORBIDITY IN COMPARISON TO OTHER GEOMETRY CHANGING APPROACHES
• Stability of the stifle is restored by adjusting the joint force vector to make it perpendicular to the condyles of the tibia with the stifle extended
• TTA achieves stability without effecting congruency of the joint and allows for an unimpeded full range of motion
• TTA does not disrupt the primary loading axis of the tibia
• TTA increases the lever arm of the quadriceps force thus reducing all internal joint reactions.
Tibia Tuberosity Advancement: Surgical Correction of ACL Damage
The most common cause of lameness in the canine stifle (knee) is damage to the anterior cruciate ligament (ACL). Stabilization of the stifle is the function of the ACL. Damage to the ACL can occur in two different ways. In larger animals (40lb. and above), the ACL breaks down over many months due to excess strain on the ACL, while in smaller animals the ACL damage is due to a traumatic injury. When a chronic break down of the ACL occurs, the lameness begins as a subtle off and on lameness over many months before the ACL finally tears and a more acute lameness occurs. Early recognition of this condition is important because degenerative changes or arthritis develops and these changes are permanent. When a traumatic injury occurs, the animal is completely pain free one minute and the next minute very painful and many times none weight bearing on the affected leg.
Surgical correction of ACL injuries is the best therapy. While there are many different surgical correction techniques, the most recent and promising surgical procedure, especially in larger animals, is the Tibia Tuberosity Advancement (TTA) technique. In this procedure the attachment of the patella ligament (knee cap ligament) on the tibia (lower leg bone) is moved forward and secured with a titanium plate. The stabilization of the knee is transferred from the ACL. In smaller animals, a different surgical technique called the Lateral Suture Technique using a nylon suture to stabilize the knee is sometimes used. The nylon suture secures the knee while the surrounding tissues heal. This procedure does not give the needed protection in larger dog and the recovery period is 2-3 times longer.
Prognosis and Aftercare:
The recovery rate for the TTA surgery is very good. Exercise restraint after the TTA procedure is 6-8 weeks and 12-14 weeks after lateral capsule technique is required.
Surgery patients are admitted between the morning of surgery and can go home the same afternoon or in some cases the next day. No food should be given after the night before surgery, but water can be given. Pain medication is given before, during and after the surgery to ensure that the patient is as comfortable as possible and without pain. For this reason the animal may be sleepy the night and next day after the surgery. Food and water can be given anytime after surgery. After TTA surgery the animal generally starts bearing weight on the leg in the first few days after surgery while after the lateral suture technique use of the leg generally requires more time. No bandages are applied. Sutures are removed in 2 weeks. In 6 weeks post surgery a radiograph is taken. In some cases the patient may need sedation to take the radiograph. There will be additional charges for the radiograph and the sedation. All referral patients can have the radiographs taken by their regular Veterinarian at their normal fee. If the radiograph reveals good healing, exercise can gradually be increased. After lateral suture surgery, rechecks are done at 6 and 10 weeks and exercise can slowly increase over the next 2-3 weeks. The most common complication after surgery is a meniscus tear. The meniscus is the cartilage sheet between the upper and lower bones in the stifle. This occurs in approximately 10% of animals after surgery and treatment of the meniscal tear is surgically removing the damaged portion of the meniscus.
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