Impact of T1 Pelvic Angle Improvement on Cervical Lordosis: A Retrospective Analysis of Postoperative Outcomes in Patients Undergoing Deformity Correction

Introduction: Investigate the change in cervical lordosis (CL) after significant TPA improvement (≥10°) and to assess the impact of demographic factors (age, sex), preop TPA, and CL on postop CL outcomes. We also aim to establish if a threshold TPA improvement leads to clinically significant CL changes.

Methods: This retrospective cohort study analyzed data from patients who underwent deformity spinal surgery with preop and postop measurements of TPA and CL.

Results: The study included 167 patients, of which 65.3% were females. The average age of patients was 67 years, with an age range of 59 to 74 years. The preop CL was more negative in females (-24.6°) than in males (1.47°), suggesting greater preop cervical kyphosis in females. At 6 months postop, patients with a TPA improvement of 10° or more experienced a significant improvement in CL, with an average change of 7.17° (p-value = 0.004). In contrast, patients with less than 10° TPA improvement exhibited a worsening in CL by an average of -3.61°. Subgroup analysis revealed that sex and age had minor effects on CL improvement. Females showed a greater improvement (7.70°) compared to males (4.37°), though this difference was not statistically significant (p-value = 0.591). Age-wise, patients over 65 years exhibited a greater improvement in CL (8.86°) compared to younger age groups, though the age-related differences were also not statistically significant (p-value = 0.206). A linear regression model demonstrated a weak but statistically significant relationship between TPA improvement and CL change (R² = 0.094, p-value = 0.004).

Conclusion : Patients with a TPA improvement of 10° or more demonstrated a significant improvement in cervical lordosis, confirming the importance of achieving optimal sagittal alignment. Moderate TPA improvement (5-10°) had the most significant effect on CL improvement, while larger improvements (>15°) had a reduced impact. Age and sex had minor influences on CL improvement, but these factors were not statistically significant. These findings underscore the importance of TPA correction in clinical practice to improve postoperative cervical alignment.