Tibial tubercle-Roman arch (TT-RA) distance is superior to tibial tubercle-trochlear groove (TT-TG) distance when evaluating coronal malalignment in patients with knee osteoarthritis.

• The TT-RA distance is a reliable and repeatable alternative to the TT-TG distance in evaluating coronal malalignment, especially in patients with severe PFOA. • We validated the significant relationships between TT-TG distance or TT-RA distance and HKA angle in valgus knees, while the correlations among such parameters were not significant in varus knees. • Pathological lateralization of the tibial tubercle was prone to be traced in patients with valgus malalignment or severe PFOA, which could contribute to the patellofemoral malalignment.