Since 2001 (or so), I've been using the IMEX® Interface® mini (toy breeds) or regular Interface® (medium to large dogs) pins, with positive-profile threads, in every surgical repair of medial patellar luxation with tibial tuberosity transposition (TTT). The historical standard for affixing the tibial tuberosity into position after the TTT is performed, involves the use of K-wires and a tension band. After experiencing a couple of cases where the K-wires loosened and then migrated, I tried the suggestion below.

This technique replaces the need for K-wires and a tension band. Use the appropriate sized Interface® pin to transfix the repositioned tuberosity into its optimal location. I usually will place two pins at slightly varying angles to insure good purchase of the bone. In some larger dogs, I may use three, depending on how much tuberosity surface area is available for purchase. The technique is far easier than K-wire and tension band technique, with a result that is cosmetically far better. It also results in a much lower implant profile due to the fact the pins are cut flush with their insertion into the osteotomized tuberosity. In over 100 cases, I have never had a pin fail or migrate, even slightly and have never had to remove an implant for any reason. The threads seem to provide exceptional hold (and also provide an easy measuring guide intraoperatively, using second pin of same size as comparison). I've used this technique in dogs from 2 to 80 pounds, and have had excellent short and long term results. As an aside, prior to placement of the Interface® end, the smooth end of the pin can be used (miniature versions) for temporarily holding the tuberosity in a lateralized position (assuming medial luxation) while joint range of motion and patella reduction are assessed. The pin can be flipped around, the threaded end placed as described above, and cut once the optimal tuberosity position is established. This technique successfully simplifies the tibial tuberosity transposition technique and provides excellent surgical results.

Tip submitted by Kevin Brumfield, DVM – Northwood Animal Hospital