Comparison of Recruitment Method on Clinical Outcomes Following Cervical Disk Arthroplasty

Study Design. Retrospective cohort. Objective. To compare the clinical outcomes of trial versus standard clinical practice (SCP) patients following cervical disk arthroplasty (CDA). Background. CDA is hypothesized to reduce the shear strain and related complications resulting from fusion procedures. CDA has gained significant traction in recent decades. The typical nontrial patient undergoing CDA does not undergo the same level of preoperative scrutiny as those treated in formal clinical trials. Concerns exist about diverging clinical outcomes between these groups. Methods. This investigation retrospectively reviews prospectively collected data on one and two-level CDA patients from C3-T1. Patients were recruited into randomized, controlled trials or SCP practice beginning in 2002 or 2018, respectively. One-year minimum follow-up was required. Hybrid constructs and prior cervical spine surgical history have been excluded. Clinical assessments included reoperation history and the patient-reported outcome measures of Visual Analog Scale (VAS) neck, VAS arm, and Neck Disability Index (NDI). Data were collected at the preoperative, postoperative, one-year, two-year, three-year, five-year, and 10-year time points. Results. One hundred sixty-eight patients underwent CDA at 193 cervical levels, including 104 trial patients and 64 SCP patients. The mean follow-up for the entire cohort was 6.1 years (0.9–20.4 yr). Eight unique disk designs were utilized. Trial patients had a greater proportion of females and longer follow-up duration ( P <0.05). Trial patients had significantly worse preoperative clinical scores with greater improvements at each follow-up time point. SCP patients had significantly higher index-level reoperation rates at five years. Conclusions. Trial patients have lower rates of reoperation and improved clinical performance which could be in part due to more stringent selection criteria. This study is limited by long-term SCP response rates. Additional studies with larger cohorts are needed to improve our understanding of disk implant performance.