by Dr. Margret Puccio, DVM, Diplomate ACVS
Cranial Curuciate Ligament Instability: Introducing the Tibial Tuberosity Advancement
Cranial cruciate ligament injuries are one of the most common causes of acute and chronic lameness in dogs and are also seen as a cause of lameness in cats. Unstabilized cranial cruciate ligament tears place the patient at risk of meniscal damage and osteoarthritis of the stifle joint. It has been reported that up to 80% of patients will have concurrent meniscal tears and 40% of patients will rupture the contralateral cranial cruciate ligament within one to two years. Reported success rates for surgical repair have been greater than 90%. Many surgical techniques for repair have been described to stabilize the cranial cruciate ligament deficient stifle. Currently, the most common surgical techniques performed include the Extracapsular Lateral Suture Technique, the Tibial Plateau Leveling Osteotomy, and the Tibial Tuberosity Advancement.
The Extracapsular Lateral Suture Technique is an effective and economical procedure and is technically the least challenging of the three fore-mentioned surgical techniques. This technique mimics the constraints and stability of the cranial cruciate ligament by placing a non-absorbable suture in an extracapsular, isometric position. The Extracapsular Lateral Suture technique can be performed in all sized dogs and cats.
More recently developed surgical techniques for reduced morbidity and greater stability in patients, particularly in active and larger sized dogs are the Tibial Plateau Leveling Osteotomyand the Tibial Tuberosity Advancement. Both techniques achieve stifle joint stability by neutralizing the tibiofemoral shear forces (cranial tibial thrust) dynamically in the cranial cruciate ligament deficient stifle. Both techniques involve an osteotomy of the proximal tibia for repositioning and are stabilized with specialized implants. Implants are rarely removed after bone healing is achieved.
The Tibial Plateau Leveling Osteotomy was developed by Dr. Barkley Slocum in the early 1990’s. With this technique cranial tibial thrust is stabilized by reduction of the tibial plateau angle. This is accomplished by a radial osteotomy of the proximal tibia and rotation of the segment in a caudal direction. The new position is maintained with a specialized left or right tibial plateau leveling osteotomy plate and screws until bone healing occurs. See Figure 1.
The Tibial Tuberosity Advancement was developed by Dr. Slobodan Tepic and Professor Pierre Montavon in the late 1990’s. The Tibial Tuberosity Advancement neutralizes tibial thrust by positioning the patella tendon perpendicular to the tibial plateau slope at the normal weight-bearing angle of 135 degrees. This is accomplished by an osteotomy of the tibial tuberosity and advancing the bone segment cranially in the frontal plane. The new position is maintained with specialized tibial tuberosity implants until bone healing occurs. See Figure 2.
Both the Tibial Plateau Leveling Osteotomy and the Tibial Tuberosity Advancement can be applied in small to large sized patients with the appropriately sized implants. Reports have demonstrated the techniques performed in dogs from 5 kg to 92 kg. Both techniques are comparable in cost. The Extracapsular Lateral Suture Technique is significantly less than both in cost. The advantages the Tibial Tuberosity Advancement offers over the Tibial Plateau Leveling Osteotomy are decreased morbidity immediately post-operatively; stability that is achieved without compromising joint congruity; and it is technically less invasive as the procedure does not alter the primary loading axis of the tibia.
Cranial cruciate ligament instability remains a commonly treated condition with many surgical technique options. Factors such as the patient’s health status, economics, activity, size, and age influence the decision making process for surgical repair. When deciding between the newer dynamic stabilization repair techniques, other considerations are bone confirmation and concurrent patella luxation.
Please feel free to contact me with any questions or concerns you may have in order that we may make the best recommendations and decisions for surgical treatment of your patients.