A measurement derived from CT or MRI scans which gives an indication of the alignment of the patellar groove with the point at which the patellar tendon is attached to the tibia.

The TT-TG distance is normally about 9mm, and if it´s more than 15-20mm then it means that the alignment is poor, and there is increased stress upon the patella simply as a result of the person's anatomy.

TT-TG distance




How TT-TG Distance is measured, and what it means to the patient with patellar instability.

This is the Editor's interpretation of a paper published in the orthopaedic literature in 2016.



The TT-TG Index: a new knee size adjusted measure method to determine the TT-TG distance. Hingelbaum S, Best R, Huth J, Wagner D, Bauer G, Mauch F. Knee Surg Sports Traumatol Arthrosc. 2014 Oct;22(10):2388-95.

Factors contributing to an Unstable Patella - ebook