Several studies have investigated the mechanical behavior of the thoracolumbar spine. However, an accurate reference for normal functional local alignment and segmental motion at the thoracolumbar junction is still illusive. Therefore, we conducted a cross-sectional cohort study with a balanced distribution of age and sex of healthy subjects to examine the normal alignment and segmental motion at the thoracolumbar junction using dynamic plain radiography. This study aimed to provide data that can be used when planning surgery or performing rehabilitation in pathological situations.

Inclusion Criteria:

• A total of 120 asymptomatic healthy volunteer subjects aged 20 to 79 without back pain complaints were included if they successfully met the study's exclusion criteria

Exclusion Criteria:

• (1) coronal deformity (Cobb angle > 10°); (2) a history of prior spine surgery; (3) a history of hip or knee arthroplasty or any other realignment surgery of the lower extremities (osteotomy, trauma, etc.); (4) complaints of back or neck pain that resulted in missed work, affected daily living activities, participation in recreational activities or required narcotic pain medication; (5) degenerative or pathologic conditions of the spine that necessitated physician intervention (i.e., physician appointment or epidural steroid injections); (6) non-ambulatory patients; (7) a history of neuromuscular disorders, inflammatory arthritis, or congenital anomalies; and (8) pregnancy

A total of 120 asymptomatic healthy volunteer subjects aged 20 to 79 without back pain complaints