Since almost 60 years ago, anterior cervical discectomy and fusion (ACDF) has been a well-accepted surgical approach for cervical spondylotic myelopathy (CSM) caused by disc herniations. In the past 15 years, the emerging technology of cervical disc arthroplasty (CDA) has become a popular surgical option to treat herniation of disc or cervical spondylosis. The published reports of several prospective, multi-center, randomized control studies of the U.S. Food and Drug Administration on CDA versus ACDF have demonstrated the viability and safety for CDA for up to 7–10 years follow-up [1-6]. These clinical trials included patients with medical refractory cervical radiculopathy, myelopathy, or both, caused by 1- or 2-level cervical disc herniation or spondylosis [6-10]. However, none of these trials has specifically addressed patients with myelopathy, although none of the trials excluded these patients. From the reports, it remains elusive as to whether or not CDA is equally effective as ACDF in management of patients with only cervical myelopathy [6,11,12].
There are a few reports on retrospective series of CDA applied to patients with myelopathy [13-15]. They unanimously demonstrated the improvement of neurological function after CDA [16-18]. However, there has not been a randomized trial to evaluate the efficacy of CDA on CSM. The differences between CDA and ACDF in the management of CSM would likely be more evident in multiple levels of disease, in which cases more segmental mobility is maintained by CDA [19-21]. Although segmental instability, abnormal segmental motion, could also contribute to the pathophysiology of CSM, there has not been evidence as to whether the fixation or fusion is mandatory after decompression for cervical myelopathy. This could be corroborated by the wide acceptance of cervical laminoplasty for the management of severe CSM.
In this report, entitled: Effect of myelopathy on early clinical improvement after cervical disc replacement: A study of a local patient cohort and a large national cohort, the author demonstrated that the perioperative complication rates were indifferent between CDA and ACDF. There are limitations of the study, including the small number of patients with myelopathy treated in the institutional cohort, heterogeneity among the myelopathy patients, and lack of quantified measurement of neurological improvement in neurological function among patients with CSM. However, the authors should be commended for the attempt to address such a topic of potentials for a paradigm-shift. The balancing among decompression, preservation of motion rather than elimination like that which has been done for decades, and maintaining appropriate alignment with stability, would likely advance the treatment strategy of CSM. The introduction of CDA might allow earlier intervention and supposedly improved outcomes of surgical management for CSM [14,22].
References
1. Chang CC, Huang WC, Wu JC, et al. The option of motion preservation in cervical spondylosis: cervical disc arthroplasty update. Neurospine 2018;15:296–305.
2. Coric D, Mummaneni PV, Traynelis V, et al. Introduction: cervical arthroplasty. Neurosurg Focus 2017;42:E1.
3. Miller J, Sasso R, Anderson P, et al. Adjacent level degeneration: bryan total disc arthroplasty versus anterior cervical discectomy and fusion. Clin Spine Surg 2018;31:E98–101.
4. Sasso WR, Smucker JD, Sasso MP, et al. Long-term clinical outcomes of cervical disc arthroplasty: a prospective, randomized, controlled trial. Spine (Phila Pa 1976) 2017;42:209–16.
5. Upadhyaya CD, Wu JC, Trost G, et al. Analysis of the three United States Food and Drug Administration investigational device exemption cervical arthroplasty trials. J Neurosurg Spine 2012;16:216–28.
6. Wu JC, Chang HK, Huang WC, et al. Radiological and clinical outcomes of cervical disc arthroplasty for the elderly: a comparison with young patients. BMC Musculoskelet Disord 2019;20:115.
7. Coric D, Guyer RD, Nunley PD, et al. Prospective, randomized multicenter study of cervical arthroplasty versus anterior cervical discectomy and fusion: 5-year results with a metal-on-metal artificial disc. J Neurosurg Spine 2018;28:252–61.
8. Fay LY, Huang WC, Tsai TY, et al. Differences between arthroplasty and anterior cervical fusion in two-level cervical degenerative disc disease. Eur Spine J 2014;23:627–34.
9. Radcliff K, Davis RJ, Hisey MS, et al. Long-term evaluation of cervical disc arthroplasty with the Mobi-C© cervical disc: a randomized, prospective, multicenter clinical trial with seven-year follow-up. Int J Spine Surg 2017;11:31.
10. Tu TH, Kuo CH, Huang WC, et al. Effects of smoking on cervical disc arthroplasty. J Neurosurg Spine 2019;30:168–74.
11. Wu JC, Huang WC, Tsai HW, et al. Differences between 1- and 2-level cervical arthroplasty: more heterotopic ossification in 2-level disc replacement: Clinical article. J Neurosurg Spine 2012;16:594–600.
12. Wu JC, Huang WC, Tu TH, et al. Differences between softdisc herniation and spondylosis in cervical arthroplasty: CT-documented heterotopic ossification with minimum 2 years of follow-up. J Neurosurg Spine 2012;16:163–71.
13. Chang HC, Tu TH, Chang HK, et al. Hybrid corpectomy and disc arthroplasty for cervical spondylotic myelopathy caused by ossification of posterior longitudinal ligament and disc herniation. World Neurosurg 2016;95:22–30.
14. Chen YC, Kuo CH, Cheng CM, et al. Recent advances in the management of cervical spondylotic myelopathy: bibliometric analysis and surgical perspectives. J Neurosurg Spine 2019;31:299–309.
15. Fay LY, Huang WC, Wu JC, et al. Arthroplasty for cervical spondylotic myelopathy: similar results to patients with only radiculopathy at 3 years’ follow-up. J Neurosurg Spine 2014;21:400–10.
16. Chang HK, Huang WC, Wu JC, et al. Should cervical disc arthroplasty be done on patients with increased intramedullary signal intensity on magnetic resonance imaging? World Neurosurg 2016;89:489–96.
17. Riew KD, Buchowski JM, Sasso R, et al. Cervical disc arthroplasty compared with arthrodesis for the treatment of myelopathy. J Bone Joint Surg Am 2008;90:2354–64.
18. Sekhon LH. Cervical arthroplasty in the management of spondylotic myelopathy. J Spinal Disord Tech 2003;16:307–13.
19. Chang HK, Chang CC, Tu TH, et al. Can segmental mobility be increased by cervical arthroplasty? Neurosurg Focus 2017;42>E3.
20. Chang HK, Huang WC, Wu JC, et al. Cervical arthroplasty for traumatic disc herniation: an age- and sex-matched comparison with anterior cervical discectomy and fusion. BMC Musculoskelet Disord 2015;16:228.
21. Tu TH, Wu JC, Cheng H, et al. Hybrid cervical disc arthroplasty. Neurosurg Focus 2017;42(VideoSuppl1):V5.
22. Chang PY, Chang HK, Wu JC, et al. Is cervical disc arthroplasty good for congenital cervical stenosis? J Neurosurg Spine 2017;26:577–85.
