Background Bryan cervical disc arthroplasty can be used to restore and maintain the mobility and function of the involved cervical spinal segments.The efficiency of posterior longitudinal ligament (PLL) resection in anterior cervical decompression and fusion has been demonstrated.However,no clinical reports have compared PLL removal with preservation in Bryan cervical disc arthroplasty.This study aimed to assess the role of removal of PLL in Bryan cervical disc arthroplasty at an 18-month follow-up.Methods We performed a prospective investigation of clinical and radiological outcomes in patients after Bryan cervical disc arthroplasty.Sixty patients who underwent Bryan cervical disc arthroplasty were included.The PLL was removed in 35 patients (investigational group) and preserved in 25 patients (control group).All of the patients were followed up for more than 18 months.Clinical (Japanese Orthopedic Association score and Visual Analogue Scale pain score) and radiological (functional spinal unit (FSU) angle,range of movement (ROM),and diameter of the spinal cord) parameters were compared between the two groups before and after surgery (18 months).Results Clinical outcomes in the investigational group were significantly superior to those in the control group.There were no significant differences in the FSU angle and ROM (P=-0.41 and 0.16,respectively) between the two groups.However,the increase in diameter of the spinal cord in the investigational group was significantly greater than that in the control group (P ＜0.01).Conclusions Removal of the PLL can improve the clinical outcomes of Bryan cervical disc arthroplasty.This procedure does not have a large effect on imbalance and motion of the cervical spine.