Impact of pelvic anteversion on spinopelvic alignment in an asymptomatic population: a dynamic perspective of standing and sitting

•The evaluation and restoration of sagittal balance is important for accurate spinal surgery.•People with pelvic anteversion was focused due to their relatively large lumbar lordosis and sacral slope based on relatively small pelvic incidence.•In movement from standing to sitting, different patterns of spine and pelvis motion can be observed in asymptomatic people with pelvic anteversion and in people without it.•Considering the special characteristics of anteverted-pelvis subgroup would help to improve the accuracy of predictive formulas based on pelvic incidence for determining lumbar lordosis. A subgroup of patients with pelvic anteversion can present with an unusually large degree of lumbar lordosis (LL), a highly sloped sacrum, and a relatively small pelvic incidence (PI). Prior to lumbar surgery, it can be important to consider such unique sagittal alignment. However, until now, there has been a lack of a predictive model considering different pelvic alignments. Furthermore, the dynamic characteristics of an anteverted pelvis (AP) subgroup have also been unclear. To build linear predictive formulas for LL that take pelvic anteversion into consideration and to explore the dynamic characteristics of an AP subgroup. Monocentric, cross-sectional study. Five hundred sixty-five asymptomatic Chinese men and women between the ages of 18 and 80 years. Sagittal parameters including LL, lumbar lordosis minus thoracic kyphosis (LL-TK), PI, pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), sacral slope (SS), sacral slope divided by pelvic incidence (SS/PI), sagittal vertical axis (SVA), thoracic kyphosis (TK), and T1 (first thoracic vertebra) pelvic angle (TPA) were measured on whole spine radiographs obtained with participants in standing and sitting positions. All participants underwent radiography in the standing position; 235 of them underwent additional radiography in the sitting position to allow measurement of sagittal parameters. The participants with pelvic anteversion were placed in an AP (anteverted pelvis) group. Sagittal parameters were compared between the AP group and the non-AP group, and predictive formulas for LL based on PI were created in both groups. In addition, changes in sagittal parameters from standing to sitting were compared in the AP group and a PI-matched control group. Of the 565 participants, 171 (30.3%) had pelvic anteversion. In comparison with the non-AP group, the AP group presented with larger LL, a larger SS,