Background: The apex of tibial tuberosity (TT) is traditionally used to represent the insertion of patellar tendon (PT) in various clinical applications. However, whether the TT is located at the PT center and can represent the PT in all studies has not been verified before. Purpose: The purpose of this retrospective study is to verify such a doubt, and consequently using the TT in clinical application might be wider and believable. Methods: The locations of the apex of TT and the PT center in magnetic resonance imaging were investigated in 100 consecutive young adult patients (50 men and 50 women; average, 27 years). The tibial width (TW), the distance from the apex of TT and the PT center to the lateral end of TW, and the PT width were measured. The ratios of the TT distance and the PT center distance to the TW were compared statistically. Results: The TW was on average 64 mm (62-66 mm). The apex of TT was on average 38% (37%-39%) from the lateral end of TW. The PT center was on average 37% (36%-38%) from the lateral end of TW. Except the TW and the PT width (both, p ＜ 0.001), there was no statistical significance in all other comparisons between sexes (p ＞ 0.05). The correlation between the TT distance and PT center distance in 100 patients was 0.84. There was statistical difference between the two parameters (p = 0.02). Conclusion: Although the PT center is lateral to the apex of TT, the discrepancy is minimal (on average 1% of TW, about 0.6 mm; or 3% of PT width). Clinically, using the apex of TT to represent the insertion of PT may be reasonable.