Pan C, et al. - Between April 2017 and May 2019, a cohort of 183 asymptomatic volunteers, older than 18 years, were recruited to test the association between the apex of lumbar lordosis (LLA) and pelvic incidence (PI), and to establish predictive formulae based on the PI to obtain the reference values of lumbar sagittal parameters. For each individual, a full-spine, standing x-ray was taken. In the sagittal plane, the following parameters were measured: the LLA, the distance between the plumb line of the lumbar apex (LAPL) and gravity plumb line, lumbar lordosis (LL), the upper arc of lumbar lordosis (LLUA), the lower arc of lumbar lordosis (LLLA) and the PI. According to findings, the PI has strong relationships with LLA, LAPL, LL, LLUA and LLLA, suggesting that pelvic morphology can influence the specific lumbar shape. In addition, predictive models have been developed for ideal PI-based lumbar sagittal parameters, helping to layout precise and individualized preoperative plans.