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It is a controversial issue that the difference of the occurrence of heterotopic ossification (HO) concerning cervical prosthesis is still huge. In this study, in the two cervical disc prostheses the development of HO is independent on their architecture., Study Design. Retrospective analysis using data from randomized clinical trials. Objective. To compare the occurrence of heterotopic ossification (HO) between two cervical disc prostheses. Clinical outcome and range of motion (ROM) were also evaluated. Summary of Background Data. Cervical arthroplasty was reported to be able to maintain the segmental ROM. However, controversy exists since the difference of the occurrence of HO concerning cervical prosthesis is still huge. Methods. Patients who underwent anterior cervical discectomy with arthroplasty for a cervical radiculopathy due to a herniated disc from the The Netherlands Cervical Kinematics (NECK) trial (activC; metal endplates with a polyethylene inlay and a keel for primary stability) and the PROCON trial (Bryan; metal-on-polymer with titanium coated endplates without a keel) were analyzed for HO at 12 and 24 months postoperatively. HO was scored according to the McAfee–Mehren classification. Segmental ROM was defined by a custom developed image analysis tool, and global cervical ROM was measured by Cobb's angle. Clinical outcome was evaluated by means of the neck disability index (NDI) as well as physical-component summary (PCS) and mental-component summary (MCS). Results. At 2-year follow-up, the occurrence of HO was 68% in patients treated with the activC prosthesis (severe HO 55%), which was comparable with 85% (P = 0.12) in patients with the Bryan disc (severe HO 44%; P = 0.43). The HO progression was similar between groups. Clinically, the patients had comparable NDI, PCS, and MCS at 2-year follow-up, and comparable improvement of clinical outcomes. The global ROM in the Bryan group (56.4 ± 10.8°) was significantly higher than in the activC group (49.5 ± 14.0, P = 0.044) at 2-year follow-up. Conclusion. In comparison of two cervical disc prostheses the development of HO is independent on their architecture. Although global ROM was higher in the Bryan prosthesis group, this difference was not deemed clinically important, particularly because the clinical condition of patients with and without severe HO was comparable. Level of Evidence: 2

Purpose Cervical spine surgery may affect sagittal alignment parameters and induce accelerated degeneration of the cervical spine. Cervical sagittal alignment parameters of surgical patients will be correlated with radiological adjacent segment degeneration (ASD) and with clinical outcome parameters. Methods Patients were analysed from two randomized, double-blinded trials comparing anterior cervical discectomy with arthroplasty (ACDA), with intervertebral cage (ACDF) and without intervertebral cage (ACD). C2–C7 lordosis, T1 slope, C2–C7 sagittal vertical axis (SVA) and the occipito-cervical angle (OCI) were determined as cervical sagittal alignment parameters. Radiological ASD was scored by the combination of decrease in disc height and anterior osteophyte formation. Neck disability index (NDI), SF-36 PCS and MCS were evaluated as clinical outcomes. Results The cervical sagittal alignment parameters were comparable between the three treatment groups, both at baseline and at 2-year follow-up. Irrespective of surgical method, C2–C7 lordosis was found to increase from 11° to 13°, but the other parameters remained stable during follow-up. Only the OCI was demonstrated to be associated with the presence and positive progression of radiological ASD, both at baseline and at 2-year follow-up. NDI, SF-36 PCS and MCS were demonstrated not to be correlated with cervical sagittal alignment. Likewise, a correlation with the value or change of the OCI was absent. Conclusion OCI, an important factor to maintain horizontal gaze, was demonstrated to be associated with radiological ASD, suggesting that the occipito-cervical angle influences accelerated cervical degeneration. Since OCI did not change after surgery, degeneration of the cervical spine may be predicted by the value of OCI. NECK trial Dutch Trial Register Number NTR1289. PROCON trial Trial Register Number ISRCTN41681847. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

BACKGROUND Motion preservation prostheses were introduced to prevent adjacent disc degeneration (ASD) and to diminish neck disability in the postsurgical follow-up. However, it is still a controversial issue, and the relationship between range of motion (ROM) and ASD has not been studied. PURPOSE To compare the correlation between ROM of the cervical spine and the presence of radiological ASD after anterior discectomy. Clinical outcome was also correlated to ROM and ASD. STUDY DESIGN Retrospective cohort study. METHODS In all, 253 patients who underwent anterior discectomy for cervical radiculopathy due to a herniated disc were analyzed for segmental and global cervical ROM and the presence of ASD both preoperatively, and 12 and 24 months postoperatively. Patients who were included in two randomized, double-blinded trials comparing anterior cervical discectomy with arthroplasty, anterior cervical discectomy with intervertebral cage, or anterior cervical discectomy without intervertebral cage for one level disc herniation were analyzed. ROM was defined by a custom-developed image analysis tool. ASD was defined by decrease in disc height and anterior osteophyte formation on X-rays. Clinical outcome was evaluated by means of the Neck Disability Index (NDI). RESULTS Two years postoperatively, no correlation was demonstrated between ROM and ASD. The incidence of ASD was comparable in the three groups, being 34% at baseline, and 58% at 2-year follow-up. Likewise, ASD progression was comparable in the three treatment arms. No correlation was demonstrated between ROM and NDI or ASD and NDI. CONCLUSIONS Since ROM is not correlated to ASD, and clinical outcome is not correlated to ROM either, the relevance of continued ROM at the target level seems absent. ispartof: The Spine Journal vol:19 issue:11 pages:1816-1823 ispartof: location:United States status: published

It is still a controversial issue that whether cervical disc prostheses can prevent adjacent segment degeneration. In this study, current data tend to indicate that the advantage of cervical prosthesis in preventing radiological adjacent segment degeneration is absent., Study Design. Retrospective analysis using data from RCTs. Objective. This study aimed to report on the incidence of radiological adjacent segment degeneration (ASD) in patients with cervical radiculopathy due to a herniated disc that were randomized to receive cervical arthroplasty or arthrodesis. Summary of Background Data. Cervical disc prostheses were introduced to prevent ASD in the postsurgical follow-up. However, it is still a controversial issue. Methods. Two hundred fifty-three patients were included in two randomized, double-blinded trials comparing anterior cervical discectomy with arthroplasty (ACDA), with intervertebral cage (ACDF), or without intervertebral cage (ACD) for one-level disc herniation. Neutral lateral radiographs were obtained preoperatively, at 1- and 2-year follow-up after surgery. Radiological ASD was evaluated on X-ray and defined by a decrease in disc height and the presence of anterior osteophyte formation on both the superior and the inferior level in relation to the target level. Results. Radiological ASD was present in 34% of patients at baseline and increased to 59% at 2-year follow-up in the arthrodesis groups (ACD and ACDF combined), and to 56% in the arthroplasty group. Progression of radiological ASD was present in 29% of patients in the arthrodesis group and in 31% of patients in the arthroplasty group for 2-year follow-up. Conclusions. Radiological ASD occurs in a similar manner in patients who were subjected to arthrodesis in cervical radiculopathy and in patients who received arthroplasty to maintain motion. Current data tend to indicate that the advantage of cervical prosthesis in preventing radiological ASD is absent. Level of Evidence: 2

Background Meta-analyses on the comparison between fusion and prosthesis in the treatment of cervical radiculopathy mainly analyse studies including mixed patient populations: patients with radiculopathy with and without myelopathy. The outcome for patients with myelopathy is different compared to those without. Furthermore, apart from decompression of the spinal cord, restriction of motion is one of the cornerstones of the surgical treatment of spondylotic myelopathy. From this point of view, the results for arthroplasty might be suboptimal for this category of patients. Comparing clinical outcome in patients exclusively suffering from radiculopathy is therefore a more valid method to compare the true clinical effect of the prosthesis to that of fusion surgery. Aim The objective of this study was to compare clinical outcome of cervical arthroplasty (ACDA) to the clinical outcome of fusion (ACDF) after anterior cervical discectomy in patients exclusively suffering from radiculopathy, and to evaluate differences with mixed patient populations. Methods A literature search was completed in PubMed, EMBASE, Web of Science, COCHRANE, CENTRAL and CINAHL using a sensitive search strategy. Studies were selected by predefined selection criteria (i.a.) patients exclusively suffering from cervical radiculopathy), and risk of bias was assessed using a validated Cochrane Checklist adjusted for this purpose. An additional overview of results was added from articles considering a mix of patients suffering from myelopathy with or without radiculopathy. Results Eight studies were included that exclusively compared intervertebral devices in radiculopathy patients. Additionally, 29 articles concerning patients with myelopathy with or without radiculopathy were studied in a separate results table. All articles showed intermediate to high risk of bias. There was neither a difference in decrease in mean NDI score between the prosthesis (20.6 points) and the fusion (20.3 points) group, nor was there a clinically important difference in neck pain (VAS). Comparing these data to the mixed population data demonstrated comparable mean values, except for the 2-year follow-up NDI values in the prosthesis group: mixed group patients that received a prosthesis reported a mean NDI score of 15.6, indicating better clinical outcome than the radiculopathy patients that received a prosthesis though not reaching clinical importance. Conclusions ACDF and ACDA are comparably effective in treating cervical radiculopathy due to a herniated disc in radiculopathy patients. Comparing the 8 radiculopathy with the 29 mixed population studies demonstrated that no clinically relevant differences were present in clinical outcome between the two types of patients. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Objective To report on the incidence of Modic changes (MCs) in patients with cervical radiculopathy due to a herniated disc. Presence of MCs was correlated to clinical outcomes and the presence of radiological degeneration. Methods Patients that underwent anterior discectomy for a cervical radiculopathy due to a herniating disc were analyzed for the presence of MCs at baseline and at 1-year follow-up after surgery. Neck Disability Index, physical component summary, mental component summary, and visual analog scale for neck pain and for arm pain were evaluated as clinical outcomes. The presence of radiological degeneration was defined by the method of Goffin. Results The prevalence of MCs was found at 18% at baseline and increased to 28% one year after surgery. Both at baseline and at 1-year follow-up, the percentage of patients with and without MCs reporting neck pain was comparable. Likewise, both at baseline and at 1-year follow-up, the percentage of patients with and without MCs reporting disabling arm pain was comparable. At baseline, the patients with MC demonstrated more radiologic degeneration than those without MC (OR 0.42), but this difference disappeared at 1 year after surgery. Conclusions MCs were not associated with neck pain, nor with arm pain. Furthermore, there was a tendency for a correlation between the presence of MCs and radiological degeneration.

OBJECTIVE: To investigate the occurrence and progression of heterotopic ossification (HO) in patients treated by anterior cervical discectomy with arthroplasty. It was evaluated if HO affects clinical outcome and range of motion (ROM). Risk factors of HO was studied as well. METHODS: Patients who underwent anterior cervical discectomy with arthroplasty for a cervical radiculopathy because of a herniated disc from the NECK and PROCON trial were analyzed for HO at 12 and 24 months postoperatively. HO was scored according to the McAfee-Mehren classification. The index ROM was defined by a custom developed image analysis tool, and global cervical ROM was measured by Cobb's angle. Clinical outcome was evaluated by means of the Neck Disability Index and the 36-Item Short Form Health Survey. RESULTS: The occurrence of HO was 60% at 1 year, and it increased to 76% at 2-year follow-up. A total of 31% of patients were scored as high-grade HO at 1-year follow-up, and this percentage increased to 50% at 2-year follow-up. Clinical outcome does not correlate to HO grade, and no risk factor for high-grade HO could be identified. The ROM at the index level was significantly higher in low-grade HO group than those patients with high-grade HO, but in 15%-38% HO grade does not correspond to ROM. CONCLUSIONS: HO occurs in three fourths of the patients at 2 years after surgery, but does not necessarily correspond to clinical outcome, nor loss or preservation of ROM. The McAfee-Mehren classification should be combined with ROM evaluation to properly study HO. ispartof: WORLD NEUROSURGERY vol:131 pages:E408-E414 ispartof: location:United States status: published

Objective The objective of this study was to review current literature on the comparison of the radiological outcome of cervical arthroplasty with fusion after anterior discectomy for radiculopathy. Materials and Methods A literature search was performed in PubMed, Embase, Web of Science, Cochrane, CENTRAL, and CINAHL using a sensitive search string combination. Studies were selected by predefined selection criteria (patients exclusively suffering from cervical radiculopathy), and risk of bias was assessed using a validated Cochrane checklist adjusted for this purpose. Additionally, an overview of results of articles published in 21 meta-analyses was added, considering a group of patients with myelopathy with or without radiculopathy. Results Seven articles that compared intervertebral devices in patients with radiculopathy (excluding patients with myelopathy) were included in the study. Another 31 articles were studied as a mixed group, including patients with myelopathy and radiculopathy. Apart from three studies with low risk of bias, all other articles showed intermediate or high risk of bias. Heterotopic ossification was reported to be present in circa 10% of patients, seemingly predominant in patients with radiculopathy, with a very low level of evidence. Radiological signs of adjacent segment disease were present at baseline in 50% of patients, and there is a low level of evidence that this increased more (10%–20%) in the fusion group at long-term follow-up. However, this was only studied in the mixed study population, which is degenerative by diagnosis. Conclusion Although the cervical disc prosthesis was introduced to decrease adjacent level disease, convincing radiological evidence for this benefit is lacking. Heterotopic ossification as a complicating factor in the preservation of motion of the device is insufficiently studied. Regarding purely radiological outcomes, currently, no firm conclusion can be drawn for implanting cervical prosthesis versus performing fusion.