Effects of endplate coverage and intervertebral height change on heterotopic ossification following cervical disc replacement

Abstract

Background Heterotopic ossification (HO) is a common complication after cervical disc replacement (CDR). Biomechanical factors including endplate coverage and intervertebral disc height change may be related to HO formation. However, there is a dearth of quantitative analysis for endplate coverage, intervertebral height change and their combined effects on HO. Methods Patients who underwent single-level or two-level CDR with Prestige-LP were retrospectively reviewed. Clinical outcomes were evaluated through Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI) score, and visual analogue scale (VAS) score. Radiological data, including the prosthesis-endplate depth ratio, intervertebral height change, posterior heterotopic ossification (PHO) and angular parameters, were collected. Logistic regression analysis was used to identify the potential risk factors. Receiver operating characteristic curves were plotted and the cut-off values of each potential factors were calculated. Results A total of 138 patients with 174 surgical segments were evaluated. Both the prosthesis-endplate depth ratio (P < 0.001) and post-operative disc height change (P < 0.001) were predictive factors for PHO formation. The area under the curve (AUC) of the prosthesis-endplate depth ratio, disc height change and their combined effects represented by the combined parameter (CP) were 0.728, 0.712 and 0.793, respectively. The risk of PHO significantly increased when the prosthesis-endplate depth ratio < 93.77% (P < 0.001, OR = 6.909, 95% CI 3.521–13.557), the intervertebral height change ≥ 1.8 mm (P < 0.001, OR = 5.303, 95% CI 2.592–10.849), or the CP representing the combined effect < 84.88 (P < 0.001, OR = 10.879, 95% CI 5.142–23.019). Conclusions Inadequate endplate coverage and excessive change of intervertebral height are both potential risk factors for the PHO after CDR. Endplate coverage less than 93.8% or intervertebral height change more than 1.8 mm would increase the risk of PHO. The combination of these two factors may exacerbate the non-uniform distribution of stress in the bone-implant interface and promote HO development.

Finite element analysis of optimized novel additively manufactured non-articulating prostheses for cervical total disc replacement

“…Due to the load-bearing capabilities and complexity of motion exposure to daily activities, the importance of evaluating the material characteristics of the prosthesis intended to replace the disc cannot be underestimated. Furthermore, current failures associated with existing implants, such as heterotopic ossification, insufficient stiffness, dislocation, wear and improper ICR further buttress the need for assessing the mechanical behavior of a material proposed to replace the disc ( Virk et al, 2021 ; Shen et al, 2021 ; Shen et al, 2022 ; Cao et al, 1976 ; Parish et al, 2020 ). Thus, an appropriate material attribute design using a PE core and PCU fiber jacket with adequate native geometry could represent a suitable candidate for replacing the disc.…”

“…The preservation of physiologic motion at the treated level leads to longevity of the facet joints and decreases the adjacent segment degeneration rate, which would otherwise lead to additional revision surgery ( Bhattacharya et al, 2019 ; Rajakumar et al, 2017 ; Yang et al, 2017 ). Ball-and-socket TDR have been more popular than other designs in recent years, but their potential disadvantages include polyethylene (PE) wear, heterotrophic ossification, increased contact forces, and disc subsidence and migration ( Virk et al, 2021 ; Shen et al, 2021 ; Shen et al, 2022 ; Cao et al, 1976 ; Parish et al, 2020 ). A new-generation prosthesis with a compressible central core allows for six kinematic degrees of freedom and mimics normal biomechanics has been developed and used ( Patwardhan et al, 2012 ; Phillips et al, 2021 ; Oltulu et al, 2019 ).…”

Atypical Heterotopic Bone Formation Rear to the Functioning Cervical Artificial Disc Prosthesis Causing Cervical Spondylotic Myelopathy

“…Hu et al 4) have iterated that a more than 5° increase in immediate post-operative disc space angle and less segmental ROM have conferred a negative effect on HO formation. Meanwhile, Shen et al 10) have previously concluded that endplate coverage of less than 93.8% or intervertebral height change of more than 1.8 mm would exacerbate the non-uniform distribution of stress in the bone-implant interface and promote posterior HO development after cervical disc replacement. Further investigations are warranted to corroborate these risk factors, including multilevel calcified disc herniation, severe spondylosis, and suboptimal placement of the device during primary cervical disc replacement surgery.…”

Preservation of Motion in Spine Surgery

“…18 Possible solutions to decrease the risk of HO is to attempt to restore physiologic disk height and to ensure the implant covers more than 93% of the end plate. 19…”

“…18 Possible solutions to decrease the risk of HO is to attempt to restore physiologic disk height and to ensure the implant covers more than 93% of the end plate. 19 Subsidence of cervical ADA devices has been reported to occur in zero to 33% of cases and at a time frame of up to 4 years after implantation. Subsidence can cause issues such as axial neck pain and recurrent radiculopathy because of loss of foraminal height.…”