Role of T1 Pelvic Angle in Assessing Sagittal Balance in Outpatients With Unspecific Low Back Pain

The aim of the study was to explore the significance of T1 pelvic angle (TPA) for assessment of sagittal balance in a cohort of Chinese patients with unspecific low back pain. TPA has been commonly used to assess sagittal balance in adult spinal deformity. However, whether TPA could be used to assess sagittal balance in patients with unspecific low back pain effectively remains unanswered. Medical records of outpatients with unspecific low back pain who received treatment in our outpatient clinic between September 2013 and November 2014 were reviewed. Demographic data and radiographic data were collected. Correlation coefficients between TPA and other sagittal parameters were analyzed, and the intraclass correlation coefficient (ICC) analysis was performed to assess the inter- and intra-observer reliability of TPA. Patients were divided into 2 groups according to whether they were well-aligned (TPA ≤ 20°) or poorly aligned (TPA > 20°), and then demographic and sagittal parameters were compared between the 2 groups of patients. A total of 97 patients with unspecific low back pain were included in this study. The inter- and intraobserver reliability of the TPA measure had excellent agreement (ICC = 0.985 and 0.919, respectively). There were significant correlations between TPA and age, LL, PT, PI, T1SPI, SVA, and NRS (all P < 0.05). Of the 38 well-aligned patients in Group A, SVA was ≤5 cm in 33 (86.84%) patients and >5 cm in the other 5 (13.16%) patients, and of the 59 poorly aligned patients in Group B, SVA was >5 cm in 42 (71.19%) patients and ≤5 cm in the other 17 (28.81%) patients. There were significant differences in age, LL, SS, PT, PI, T1SPI, SVA, and NRS between the 2 groups of patients, but no significant difference was observed in TK and TL. TPA could be used to assess sagittal balance in outpatients with unspecific low back pain effectively.