We would like to thank the authors of the Letter to the Editor for their interest in our recent publication and comments on it. The authors raised two important issues that are worthy of discussion.
First, our results suggested that dysphagia was inversely associated with heterotopic ossification (HO) after adjustment for age and length of follow-up [1]. We agree with your assessment that HO shares many risk factors with postoperative dysphagia such as smoking, long operation time, inadequate hemostasis and retraction. As the authors of this letter pointed out, our theory that intact and undamaged peripheral nerve containing progenitor cells in the endoneurium may play a role in HO formation should be interpreted with caution. Such theory has not been proven, to our best knowledge, in any in vivo or in vitro studies.
Second, we have performed correlation analyses on the association between high-grade HO (McAfee or Mehren grade III and IV) and adjacent segment degeneration (ASDegeneration). In midterm follow-up (≥ 2 and < 5 years), high-grade HO was not associated with ASDegeneration (n = 6, p = 0.52, R2 = 0%). The insignificant result in midterm follow-up can be explained by the fact that four out of six studies reported zero rate of high-grade HO [2,3,4,5]. By contrast, high-grade HO was positively associated with ASDegeneration (n = 8, p = 0.0052, R2 = 58.9%), in studies with ≥ 5-year follow-up. As discussed in our original study, the positive association between HO and ASDegeneration could be due to altered biomechanics by HO formation or a natural degenerative process.
We would like to thank the authors of this letter again for their comments and suggestions and hope the above response could clarify their concerns.
References
Hui N, Phan K, Cheng HM, Lin YH, Mobbs RJ (2020) Complications of cervical total disc replacement and their associations with heterotopic ossification: a systematic review and meta-analysis. Eur Spine J 29:2688–2700
Li J, Liang L, Ye XF, Qi M, Chen HJ, Yuan W (2013) Cervical arthroplasty with discover prosthesis: clinical outcomes and analysis of factors that may influence postoperative range of motion. Eur Spine J 22:2303–2309
Wang Q, Cheng H, Mao Z, Qi X, Zhang M, Chen Y (2011) Clinical and radiographic results after treatment of cervical degenerative disc disease with the Bryan disc prosthesis: a prospective study with 2-year follow-up. Acta Orthop Belg 77:809–815
Sun Q, Sun L, Li P, Zhao H, Hu H, Chen J, Li J (2016) A comparison of zero-profile devices and artificial cervical disks in patients with 2 noncontiguous levels of cervical spondylosis. Clin Spine Surg 29:E61–E66
Liu S, Song Y, Liu L, Wang L, Zhou Z, Zhou C, Yang X (2016) Clinical and radiologic comparison of dynamic cervical implant arthroplasty and cervical total disc replacement for single-level cervical degenerative disc disease. J Clin Neurosci 27:102–109
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Mobbs, R.J. Answer to the Letter to the Editor of Shen YW, et al. concerning “Complications of cervical total disc replacement and their associations with heterotopic ossification: a systematic review and meta-analysis” by N. Hui, et al. [Eur Spine J; 2020; 29(11):2688–2700]. Eur Spine J 30, 1788 (2021). https://doi.org/10.1007/s00586-021-06821-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00586-021-06821-4