Chronic grade 4 patellar luxation, both medial and lateral, or failed trochleoplasty can progress to severe joint degeneration with condromalacia, condyle deformation and massive osteophytosis. In such circumstances traditional trochleoplasty cannot provide a satisfying trochlear surface and the only conventional, but highly demanding solution is a total knee replacement. Moreover comminuted fractures of the trochlear ridge could not be repaired to provide adequate patellar support. Kyon AG, Zurich developed a trochlear prosthesis to replace the damaged condylar trochlea that could solve the problem with a less invasive surgical technique. A titanium aluminium vanadium alloy prosthesis shaped like the natural trochlea with a deep recess is fixed to the condyle via a perforated c.p. grade 4 titanium base plate. The surface of the trochlear pro- sthesis is treated with hard, low fric- tion amorphous diamond-like coating (ADLC). The base plate to be fixed with titanium screws to the condyle is treated with Biocer process to promote osteointegration. Ten sizes are available, suitable for all dogs from toy to giant breeds. The size is selected with the aid of a template superimposed on medio-lateral and caudo-cranial view radiographs and with intra-operative evaluation.The patellar groove prosthesis is fixed to the femoral condyle in the direction of the quadriceps mechanism, allowing compensation to a certain degree for coronal and axial limb deformities. Description of the technique and the outcome in 271 cases is presented.
