Editorial Commentary: Sagittal Tibial Tuberosity to Trochlear Groove Distance Measurements May Reflect Patellofemoral Contact Pressures

Tibial tubercle to trochlear groove (TTTG) distance is a commonly utilized measurement in the assessment of knees with patellar instability, representing malalignment in the form of tuberosity lateralization relative to the trochlear groove. More recently, the concept of the anteroposterior TTTG, renamed the sagittal TTTG (sTTTG), has been studied as a measurement to assess the relationship between the 2 structures in the anteroposterior plane, potentially representing patellofemoral contact pressures. How this relates to knee flexion angles is critical to understanding the context of these variables and, in addition, as we attempt to characterize the relationship of sTTTG to trochlear dysplasia that occurs via relative anteriorization of the trochlear floor and posteriorization of the tibial tuberosity. As we incorporate this measurement to capture how our surgical procedures can offload the joint and “correct” the sTTTG distance, the utility of this measurement as a proxy for patellofemoral contact pressures will continue to grow, allowing us to better consider joint preservation in addition to stability in the management of patellar instability.