The importance of preoperative T1 slope for determining proper postoperative C2-7 Cobb's angle in patients undergoing cervical reconstruction.

ABSTRACT

BACKGROUND: This study aimed to explore the relationship among different cervical sagittal parameters in asymptomatic volunteers and the correlation between surgical efficacy and difference of presumed and actual postoperative C2-7 Cobbs's angle (C2-7COBB), which was calculated based on preoperative T1 slope (T1S) in patients undergoing cervical reconstruction. METHODS: In total, 158 inpatients with cervical spondylosis and 274 asymptomatic volunteers were retrospectively reviewed. Cervical sagittal parameters, such as C2-7COBB, T1S, thoracic inlet angle (TIA), and neck tilt (NT), were compared. Then, the correlation among these parameters was analyzed in asymptomatic volunteers, and a regression equation between T1S and C2-7COBB was established and used to analyze the correlation among the Japanese Orthopaedic Association (JOA) score improvement, the sagittal parameters, and the difference between presumed and actual postoperative C2-7COBB in patients after cervical reconstruction. RESULTS: The mean T1S, C2-7COBB, and TIA were significantly decreased in patients (P < 0.01). T1S and NT had a strong correlation with TIA (P < 0.01). T1S demonstrated a moderate correlation with C2-7COBB in asymptomatic volunteers (r = 0.569, P < 0.01). A regression equation had been established as C2-7COBB = 0.742 × T1S - 0.866. The mean C2-7COBB and JOA score improved significantly (P < 0.05) postoperatively. Moreover, the JOA improvement rate showed a significant negative correlation with the difference in the presumed and actual postoperative C2-7COBB (r = - 0.696, P < 0.01). CONCLUSION: Our study successfully established a regression equation for calculating postsurgical C2-7COBB based on the correlation between T1S and C2-7COBB in asymptomatic volunteers. The regression equation could be used for guiding surgeons to accomplish an ideal postsurgical C2-7COBB for patients with cervical spondylosis.