Editorial Commentary: The Best Index to Determine Whether to Medialize the Tibial Tubercle In Patients With Patellar Instability May Be Tibial Tubercle to Trochlear Groove Distance/Trochlear Width, But Check the Intraoperative Patellar Tracking as Well.

An excessively lateral tibial tubercle is a well-accepted risk factor for recurrent patellar dislocation. Generally, it is measured on magnetic resonance imaging as the TT-TG distance (tibial tubercle-trochlear groove distance), and recent meta-analyses have suggested that a value as low as 12.5 mm can be used as the threshold for deciding when to medialize the tibial tubercle. However, a problem with using the TT-TG distance is that it is influenced by the size of the knee. An individualized index helps overcomes this problem, and dividing the TT-TG distance by the trochlear width may be the most promising method. The suggested cut-off value of (TT-TG)/trochlear width is 0.572.