What are the associative factors of adjacent segment degeneration after anterior cervical spine surgery? Comparative study between anterior cervical fusion and arthroplasty with 5-year follow-up MRI and CT

Abstract

Purpose It is well known that arthrodesis is associated with adjacent segment degeneration (ASD). However, previous studies were performed with simple radiography or CT. MRI is most sensitive in assessing the degenerative change of a disc, and this is the first study about ASD by radiography, CT and MRI. We sought to factors related to ASD at cervical spine by an MRI and CT, after anterior cervical spine surgery. Materials and methods This is a retrospective crosssectional study of cervical disc herniation. Patients of cervical disc herniation with only radiculopathy were treated with either arthroplasty (22 patients) or ACDF with cage alone (21 patients). These patients were required to undergo MRI, CT and radiography preoperatively, as well as radiography follow-up for 3 months and 1 year, and we conducted a cross-sectional study by MRI, CT and radiography including clinical evaluations 5 years after. Clinical outcomes were assessed using VAS and NDI. The fusion rate and ASD rate, and radiologic parameters (cervical lordosis, operated segmental height, C2-7 ROM, operated segmental ROM, upper segmental ROM and lower segmental ROM) were measured. Results The study groups were demographically similar, and substantial improvements in VAS (for arm) and NDI (for neck) scores were noted, and there were no significant differences between groups. Fusion rates were 95.2 % in the fusion group and 4.5 % in the arthroplasty group. ASD rates of the fusion and arthroplasty groups were 42.9 and 50 %, respectively. Among the radiologic parameters, operated segmental height and operated segmental ROM significantly decreased, while the upper segmental ROM significantly increased in the fusion group. In a comparative study between patients with ASD and without ASD, the clinical results were found to be similar, although preexisting ASD and other segment degeneration were significantly higher in the ASD group. C2-7 ROM was significantly decreased in ASD group, and other radiologic parameters have no significant differences between groups. Conclusion The ASD rate of 46.5 % after ACDF or arthroplasty, and arthroplasty did not significantly lower the rate of ASD. ASD occurred in patients who had preexisting ASD and in patients who also had other segment degeneration. ASD may be associated with a natural history of cervical spondylosis rather than arthrodesis.

Adjacent segment degeneration after single-level anterior cervical decompression and fusion: Disc space distraction and its impact on clinical outcomes

“…The reported rates of ASD following ACDF using radiographic criteria range from 25% to 92% in the literature. [4,5,11] The ASD rate in the present study was similar to related studies. Katsuura et al [15] reported that sagittal alignment was related to the development of ASD, with the loss of lordotic curvature resulting in the condition.…”

“…Several studies have reported that ASD is not in excess of the normal degenerative process and not a consequence of spinal fusion [10][11][12]. However, many biomechanical and clinical studies have reported that surgical arthrodesis influences the mechanical properties of intervertebral discs at adjacent levels.…”

Can an Endplate‐conformed Cervical Cage Provide a Better Biomechanical Environment than a Typical Non‐conformed Cage?

“…Finally, though ASD is one of the primary complications after anterior cervical discectomy and fusion, a positive correlation between segmental stiffness and ASD is not yet definite. Indeed, it is generally agreed that a stiff segment contributes to hypermobility and increased intra‐disc stress in the adjacent segments; however, many studies have reported opposite conclusions. Therefore, the impact on adjacent segments of endplate‐conformed cages also requires evaluation.…”

Costs of Cervical Disc Replacement Versus Anterior Cervical Discectomy and Fusion for Treatment of Single-Level Cervical Disc Disease

“…[1][2][3][4][5][6][7] Biomechanical models have shown that CDA maintains normal cervical range of motion and kinematics at adjacent levels as compared with ACDF. Both anterior cervical decompression and fusion (ACDF) and cervical disc arthroplasty (CDA) have been demonstrated by many level I studies to achieve clinical success, relieve symptoms of neural compression, and improve health-related quality of life.…”