By Tibial Tubercle Osteotomy (TTO) the insertion site of the ligamentum patella on the tibia is moved either inwards or down causing a more aligned traction of the patella.
If your Patella is placed to high in relation to the groove (Patella alta), the Tibia Tubercle Transposition can bring your Patella downwards into the groove. If the Tibial Tubercle is outward placed, your Patella tends to track outwards and by medialization (moving inwards), your patella will track more correctly. The surgery should only be performed if you are having either an increased TT-TG or an decreased cartilage overlap between the patella and the trochlea groove (less than 6 mm) - read more here. A little variation of this surgery is called Fulkerson osteotomy and this can be used for a special group of patients having anterior knee pain caused by osteoarthritis in the Patellofemoral joint.
As it appears from the picture at left, the Tibial Tubercle is chiseled off and moved inwards. The bone block is fixated again by 2 - 4 screws.
This demonstrates how a Patella Alta (meaning a high riding kneecap) is operated, by replacing the tibial tuberosity to a lower position. Four titanium screws inserted in different angles, fixate the tuberosity.
By distalization of the tibial tubercle the patella have been brought into the trochlear groove
A newer and more safe technique, with an oblique cut most distal
Medialisaton of the tibial tubercle has been very popular, however due to several clinical and biomechanical studies, the surgery tend to be replaced by de-rotational osteotomies of the tibial and/or trochleoplasty surgery.