Yang P, et al. – The objective of this study was to investigate an association between preoperative T1 slope and surgical and adjacent segment degeneration (SASD) after Bryan cervical disc arthroplasty (BCDA) in patients with cervical degenerative disc disease. Investigations revealed that high T1 slope and endplate coverage discrepancy were associated with SASD after BCDA. In addition, patients with a high preoperative T1 slope had a smaller functional spinal unit (FSU) angle and more neck pain after BCDA.