Clinical and Radiological Outcomes of Skip-Level Cervical Disk Arthroplasty

The skipped, in-between indexed, level theoretically has higher chances of adjacent segment disease (ASD), especially in between 2 anterior cervical diskectomy and fusion (ACDF) constructs. However, this inference remains unclear. The objective was to compare cervical disk arthroplasty (CDA) with ACDF for noncontiguous cervical disk problems.

Consecutive patients who underwent skip-level anterior cervical diskectomies for symptomatic disk herniations or spondylosis involving noncontiguous pathologies of the subaxial cervical spine were retrospectively analyzed and divided into 2 groups: CDA and ACDF. Clinical and radiological outcomes were analyzed, including comparison of the range of motion (ROM), cervical lordosis, C2-7 Cobb angle, sagittal vertical axis, and T1 slopes.

A total of 70 patients, 33 CDA vs 37 ACDF, completed at least 2 years of follow-up. Patients of the CDA group were younger (54.9 ± 8.6 vs 62.3 ± 9.9 years, P-value < .01) than ACDF. The incidences of radiological ASD were lower in the CDA than ACDF (18.2% vs 40.5%, P = .04) groups. One patient in the ACDF group had worsened symptoms caused by ASD of the initially skipped level that required a secondary surgery, whereas there were no reoperations for CDA. The ROM of both the skipped level and overall cervical spine (C2-7) were higher in the CDA group than those of the ACDF group (P-values = .04 and .01, respectively) at 2-year postoperation. The complication rates were no different between the 2 groups.

Both skip-level CDA and ACDF can restore cervical lordosis, while the overall cervical ROM was well preserved in the CDA group but almost eliminated in the ACDF group. Skip-level CDA not only preserves motion at the indexed but also at the in-between skipped level, with lower incidences of ASD and higher ROM than ACDF. Therefore, to avoid a three-level fusion in the long run, CDA is the superior option for noncontiguous disk herniations or spondylosis that require surgery.