How is TTTG distance calculated?

How is TTTG distance calculated?

Draw a line along the posterior femoral condyles, and then draw the following lines perpendicular to this line:

1. bisecting the tibial tuberosity (TT)
2. bisecting the trochlear groove sulcus (TG)
3. measure the distance between TT and TG = TT-TG distance.

What is tibial tubercle Trochlear groove distance?

Tibial tubercle-trochlear groove (TT-TG) distance is a measurement generally made on CT scans that is commonly used to quantify the risk of patellofemoral instability (PFI); however, its interrater reliability and accuracy as an indicator of PFI in patients is poorly characterized.

How is Trochlear depth measured?

The trochlear depth is calculated by measuring the mean of the maximum anteroposterior (AP) distance of the medial and lateral femoral condyles minus the distance between the deepest point of the trochlear groove and the line paralleling the posterior femoral condyles surfaces (Fig. 1).

What is patellar translation?

Patellar translation is the distance between tibial tubercle and trochlear groove and is also called TT-TG distance. It is measured on CT or MRI by overlapping or superimposing axial images of the femoral condyles and tibial tuberosity. The measurements are used to quantify patellar instability.

What is a high riding patella?

Patella alta or high-riding patella refers to an abnormally high patella in relation to the femur. The patella sits high on the femur where the groove is very shallow.

What is TTTG in knee?

The TT-TG distance represents the radiographic measurement of the quadriceps vector, which represents a lateral force displacement on the patella during knee motion. It is > 20 mm in patients with recurrent patellar dislocations, as compared with 13 mm in control subjects.

What is a TTTG?

Tibial tuberosity-trochlear groove distance (TTTG) is very important in the assessment of patellofemoral joint instability.

How is trochlear dysplasia measured?

1. the ratio between medial versus lateral trochlear facet length calculated as (medial facet) / (lateral facet) is one way to calculate it 8
2. a ratio of <40%, in this case, indicates trochlear dysplasia.

What is Trochlear groove?

The trochlea is a groove in the femur bone underneath the kneecap (patella). The walls of the trochlea stabilize the patella and allow it to glide down the center of the trochlea as the knee bends.

What is normal patellar tilt?

The mean tilt angle of a group of patients with signs and symptoms suggesting patellofemoral malalignment was 12 degrees (+/- 6 degrees); in a similar group of control subjects it was 2 degrees (+/- 2 degrees) (p < 0.01). Tilting of 5 degrees was taken to be the limit of normal.

How do you measure patella?

PL is measured as an oblique line connecting the inner margin of the upper pole of the patella with the most inferior point of the lower pole. In the ISI normal is defined as 1.0 +/-20%. Thus Patella baja is defined as an ISI value of <0.8, patella alta as> 1.2 and the normal range is between . 8 and 1.2.