Tibial tuberosity advancement (TTA) is a new surgical procedure developed at the School of Veterinary Medicine, University of Zurich, Schwitzerland by Dr's Slobodan Tepic and Pierre Montavon. The procedure was developed over a 2 year period starting in December 2001 and was first taught to surgeons in the US in October of 2004. As of July 2005, TTA has been performed on approximately 4,500 dogs.
TTA and tibial plateau leveling osteotomy (TPLO) both stabilize the knee by altering forces across the knee so that the stifle is stable during weight bearing, eliminating the need for an intact cranial cruciate ligament. TTA achieves stability by moving the patellar tendon,, whereas TPLO achieves stability by rotating the tibial plateau. In contrast to TPLO, TTA is simpler to perform and less invasive, so operating time is less and complications are fewer and less serious. Most complications that occur with TTA resolve over time without surgical intervention, whereas many complications require additional surgery. TTA is expected to have similar or potentially better long term results than TPLO because it increases the lever arm of the active force across the stifle, thus reducing forces between the patella and the femur and between the femur and the tibia. Reduction of these forces may slow the progression of degenerative joint disease more than TPLO. By decreasing retropatellar pressure, TTA should be beneficial in cronic cases of cranial cruciate ligament rupture where chondromalacia is present.
Extracapsular methods of repair stabilize the stifle with heavy monofilament nylon sutures. Intracaptular methods of repair stabilize the stifle joint with or autografts of fascia, with or without part of the patellar tendon. Extracapsular sutures break over time and rely on periarticular fibrosis to maintain stability. Autografts of patellar tendon or fascia lata may stretch prematurely resulting in return of instability to the knee.
GENERAL INFO:
TTA - simpler procedure and less invasive than the TPLO
TPLO-Tecnically more complex, more potential for error
Extracapsular/Intracapsular Stabilization (E/I Stabilization) - Less invasive
COST:
TTA - higher than E/I stabilization due to specialized instrumentation and implants. Implants cost more than the TPLO
TPLO - Higher than the E/I stabilization due to specialized instrumentations and implants.
E/I stabilization- Least expensive since specialized instruments and implants are not required.
Complication rate:
TTA-low, since procedure is straight forward
TPLO-Varies with skill and experience of surgeon. Catastrophic failure may occur.
E/I stabilization- Low, since relative simple procedure
Post Operative meniscal injury:
TTA-less likely than after a TPLO because TTA does not change the stifle range of motion
TPLO-TPLO result in increased stifle flexion which may injure the medial meniscus
E/I stabilization-Meniscal injury may occur if the stifle becomes unstable from inadequate periarticular fibrosis of stretching of autografts
Progression of degeneratine joint disease:
TTA-TTA decreases forces between the patella and femur and between the femur and tibia which may minimize progression of DJD
TPLO- TPLO increases forces between the femur and patella and between the femur and the tibia resulting in patellar tendonitis and potential pregression of DJD
E/I stabilization- DJD progresses
Creation of postoperative limb malalignment:
TTA- no unintended geometry changes
TPLO-can correct preoperative limb malalignment but also have the potential of creating unintended deformity
E/I stabilization- No unintended geometry changes
Implant material:
TTA- titanium, which is more biocompatible than stainless steel
TPLO-Stainless steel
E/I stabilization-Stainless steel, if suture anchors, crimb clamps or bone staples are used
Treatment of concurrent medial patellar luxation:
TTA- allows lateral transposition of the tibial tuberosity
TPLO-Tibial tuberosity is not readily transposed
E/I stabilization-can transpose tibial tuberosity