Five-Year Trends in Center of Rotation After Single-Level Cervical Arthroplasty with the Prestige-LP Disc

Abstract

To assess the invivo longitudinal kinematic performance of the Prestige-LP Disc and describe the 5-year trends in the center of rotation (COR) at the instrumented level. Forty-two patients with single-level cervical disc arthroplasty (CDA) were reviewed retrospectively. Lateral static and dynamic cervical radiographs were obtained preoperatively and postoperatively at 1, 3, and 5 years. Kinematic parameters collected included range of motion (ROM), COR, intervertebral disc height (IDH), functional spinal unit (FSU) angle. Japanese Orthopedic Association (JOA), visual analog scale (VAS), and Neck Disability Index (NDI) scores were used to evaluate clinical outcomes. The JOA score was increased significantly and VAS and NDI scores were decreased significantly after CDA. The ROM was preserved, stabilizing at 7.8° at the final follow-up. The mean IDH increased significantly from 4.4 ± 2.6 mm to 7.3 ± 1.9 mm after surgery, and remained unchanged thereafter. The mean FSU increased by nearly 4° from the preoperative value to 3.6° ± 4.4° at the 1-year follow-up but failed to maintain lordosis, decreasing to 0.4° ± 4.7° at the last follow-up. The mean COR-x was calculated as 38.9% preoperatively and remained unchanged throughout the follow-up period. The mean COR-y showed a significant cranial shift after surgery, and an upward trend continued in the subsequent measurements (12.7% at 1 year, 15.4% at 3 years, 19.2% at 5 years); however, there was no significant difference between the 1-year and 5-year measurements. Single-level CDA with the Prestige-LP Disc achieved favorable clinical outcomes and provided a durable solution for spinal motion at the instrumented level. The COR showed a significant cranial shift after surgery and remained relatively stable during the 5-year follow-up period.