Final answer:
The TT-TG distance is a measurement used in orthopedics to assess the stability of the patella within the trochlear groove of the femur.
Step-by-step explanation:
The abbreviation TT-TG stands for Tibial Tubercle-Trochlear Groove distance, which is a measurement used in orthopedics to assess the stability of the patella (kneecap) within the trochlear groove of the femur. It is used to evaluate cases of patellar instability or malalignment. When the TT-TG distance is abnormal, it can indicate a higher risk of patellar instability and may require surgical intervention to correct.