Modified Stabilization Method of the Tibial Tuberosity Advancement Technique. An In vitro Study
The aim scope of this study was to evaluate, a modification of the stabilization method of the tibial tuberosity advancement (TTA) in vitro, using a titanium spacing cage inserted at the osteotomy site and one stainless steel cancellous screw placed in craniocaudal direction after transaction of the cranial cruciate ligament. Ten crossbreed dog cadavers aged from 1.8 to 4.2 years and weighting 20 to 30kg were used. The dogs were euthanatized for humanitarian reasons and the hind limbs were grouped into two groups: G1--operated (n=10) and G2--not operated control (n=10), represented by the opposite limb. Radiopaque markers were inserted and the operated hind limbs were orthopedically, goniometrically and radiographically evaluated. Evaluation was performed sequentially with the cranial cruciate ligament intact, and after cranial cruciate desmotomy, surgical stabilization of the stifle joint using modified TTA and caudal cruciate ligament desmotomy. Afterwards, in both groups the maximal load until failure of the stifle joints and the mechanical resistance of implants used in stabilization of tibial tuberosity in G1 were determined. Repositioning of the patellar tendon 90° in relation to the tibial plateau provided neutralization of the cranial tibial thrust, despite cranial drawer motion maintenance in all dogs. Fixation of the tibial tuberosity with a neutral cancellous screw and titanium cage resulted in resistance compatible with the normal physiologic forces applied to the pelvic limbs during locomotion. The biomechanical tests confirmed the viability of the method performed for tibial tuberosity fixation and support future clinical trials to validate the technique.