Bone regrowth after cervical corpectomy: long-term follow-up in a series of 34 patients

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Lioi, Sergio Paolini, Angela Ambrosone, Daniele Marruzzo, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4991930/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Cervical corpectomy and fusion is widely performed for relieving spinal cord compression due to vertebral body spondylosis. Bone regrowth in the empty space should occur, but there are not long-term follow-up studies demonstrating the timeline and the steps of this process. Methods Patients with spondylotic myelopathy that underwent single or multilevel cervical corpectomy and fusion, with or without posterior longitudinal ligament removal were submitted to long term CT follow-up to ascertain how and how much the resected bone reacts in the empty corpectomy space. Results Bone regrows and fills the empty space in a stepwise and time dependent fashion. Starting from the lateral edges of the corpectomy, new bone grips develop and progressively envelope the titanium implant. At the final stage the bone regrowth reaches the posterior ligament or the extradural space, and a smooth plane results in the posterior corpectomy space. The posterior longitudinal ligament does not appear play a role in the bone regrowth since no morphological differences occur between patients jointly submitted or not to its removal. Conclusion After cervical corpectomy the empty space undergoes a stepwise and time-dependent bone regrowth without redo mielo-radicular compression in the long-term. bone cervical fusion spine surgery vertebra Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction In studies evaluating bone fusion after spinal arthrodesis, plain X-rays are a very simple and low-cost diagnostic tool, but may underestimate or overestimate the degree of fusion [ 20 ]. Bone bridging the interspace anterior to the cage on a lateral view (anterior sentinel sign) should demonstrate that fusion has occurred [ 25 ]. According to others, this sign is the result of bone remodeling due to mechanical loads (Wolff’s law)[ 28 , 21 ]. Patients submitted to anterior cervical corpectomy and fusion (ACCF) are almost always monitored using X-rays to evaluate spine stability and bony fusion, since artifacts from the metallic implant may hamper good imaging in postoperative control CT scan[ 2 , 13 , 27 , 17 , 14 , 24 , 11 , 31 , 8 , 7 , 29 , 18 , 34 , 38 , 33 , 37 ]. However Computed Tomography has been demonstrated a reliable imaging technique in comparison to digital radiography to assess bone healing [ 20 , 35 , 4 , 30 , 15 ]. Some postoperative CT scans of patients submitted to ACCF with autologous bone strut graft demonstrate the amount of bone removal and the resulting empty space [ 36 , 16 , 19 , 32 , 23 , 12 , 9 ]. In a single patient after ACCF and titanium implantation 1 year control CT scan shows bone regrowth around the mesh cage without artifacts [ 8 ]. The literature lacks any long term study demonstrating how bone reacts around the titanium implant after a cervical corpectomy and what changes develop in the empty space. The widespread use of metallic implants for ACCF prompt us to present our series of patients submitted to ACCF for cervical spondylotic myelopathy to determine the behavior of the resected bone in the long term. Materials and Methods For this retrospective study, we identified patients with cervical spondylotic myelopathy, without ossification of the posterior longitudinal ligament (PLL), that underwent single or multilevel ACCF between January 2000 and June 2014 in a single institution from six neurosurgeons. None of these patients was affected by diseases that could impair bone metabolism as diffuse idiopathic skeletal hyperostosis (DISH), rheumatoid arthritis (RA), or sarcopenia (SA). Surgical treatment was performed conforming to the standard technique[ 9 ] and the removal of the posterior longitudinal ligament was jointly considered. Patients were divided into two groups, according to the type of arthrodesis performed. The first group ( group A ) include patients with a titanium cylinder mesh cage (DePuy Spine, New Brunswick, New Jersey; Zimmer Spine, Inc., Indiana) filled with autologous cancellous bone or hydroxyapatite chips, and an anterior plate (DePuy Synthes, Raynham, MA) fixed with screws into the vertebral bodies above and below the CC site. The second group ( group B ) collects patients with a Titanium Expandable Cage (Tecorp, Scient'x, France; Ulrich, Ulm, Germany). Early postoperative control CT scan were searched and a comparative imaging was sieved in the long-term follow-up. The surface of the removed vertebral bone was obtained on the scanner table from the axial CT scan (Toshiba®). A closed surface area (in square millimeters) over the edges of the corpectomy empty space was drawn in every axial slice (Fig. 1 ). A corresponding axial level slice available in the long-term follow-up was determined and measured. Two observers (one neuroradiologist, one neurosurgeon) calculated the measure in the axial scans. Agreement between observers was evaluated using kappa statistics. We investigated the presence of differences in ossification between the execution of single versus multilevel corpectomy, between the use of Mesh versus expandable cages and between the removal or not of the PLL. Finally, we analyzed the bony regrowth dynamic and the stepwise sequence of the process during the long-term follow-up. Data were imported into JASP (Version 0.18.3 Computer software, JASP Team, 2024) statistical software for analysis. We used Mann-Whitney U-test to compare variables and and p-values < 0.05 were considered as significant. Informed consent was obtained from all patients or their next of kin prior to their inclusion in the study. This study was approved by the local ethics committee (Rif. 3275/26.06.2014). Results Thirty-four adult patients who underwent ACCF in a single-institution between January 2000 and June 2014 were enrolled in this retrospective study. The study population is composed of 18 males (53%) and 16 females (47%), which performed an early and one long-term CT scan. Mean age of the whole group was 54.3 ± 11 years old, with a mean age 52.9 ± 11 for males and 53.8 ± 11 for females. Twenty patients (59%) were submitted to single level corpectomy, fourteen (41%) to multiple levels corpectomy, of which 13 two level and one three level corpectomy. In 25 (73.5%) patients a titanium cylinder mesh cage was placed (group A) while in 9 (26.5%) patients an expandable cage was used (group B). PLL removal was performed in 11 (32.3%) patients, of which 4 during single level procedures and the remaining 7 in multiple level corpectomies. In 25 (73%) patients a titanium cylinder mesh cage was placed and in 9 (26%) was preferred an expandable cage. Titanium mesh was used in 15 single-level and 10 multi-level procedures, whereas the use of the expandable cage has been used in 5 single-level and 4 multi-level interventions. Radiological evaluation shows that bone regrowth progressed in a time dependent step fashion. Starting from the lateral edges of the corpectomy the resected cancellous bone showed early restore and growth toward the titanium mesh (Fig. 2). The metallic implant was progressively gripped (Fig. 3). In the late phase the mesh was incorporated and the extra-ligamentous or extra-dural space was progressively replenished (Fig. 4). Bone regrowth never exceeded the posterior vertebral line, resulting a smooth posterior ligament or extradural interface. In patients with an expandable cage bone regrowth around the implant was less plentiful and in one case asymptomatic break of the cage was demonstrated (Fig. 5). Male or female sex does not seem to affect the process of ossification at a distance in our population. (p=0.67). There were no significant differences in the extent of bony regrowth between patients who underwent single versus multiple corpectomy (p=0.25). Similarly, the use of a cylinder mesh cage rather than an expandable cage does not lead to significant differences in terms of ossification in follow-up (p=0.15). Finally, nor the choice of removing PLL or not had significant repercussions in terms of bone regrowth (p=0.42). The mean average radiological follow-up of all patients was 4.8 ± 4.1 years. There was a positive linear correlation between bone regrowth and months of follow-up (p<0.023), so that a longer follow-up period is associated with greater osseointegration (Fig. 6). Asymptomatic subsidence of the implant in the inferior endplate (Fig. 5), never exceeding 3 millimeters, was observed in 3 patients with a cylindrical mesh cage (12%) and in one expandable cage (11%). Discussion Although a variable evolution was detected among patients, bone regrowth progressed in a stepwise and time-dependent pattern. In the long term follow-up of patients submitted to cervical corpectomy bone tissue progressively regrows in the empty space, without formation of new osteophytes projecting into the vertebral canal, squeezing the spinal nerves or spinal cord. The cancellous bone from the resected lateral edges of the corpectomy shows the most active regrowth and the titanium implant is progressively wrapped without any adverse reaction on the bone-metallic interface. The compact bone from the endplate of the superior adjacent vertebral body does not show signs of reaction. No differences were detected in bony regrowth among patients with single, double or three level corpectomies as well between mesh replenished with autogenous bone or hydroxyapatite chips. The implant in some cases shows a small amount of subsidence in the inferior vertebral body. A risk of subsidence in the cervical spine is well known in patients with an associated cylinder mesh or an expandable cage [ 6 , 10 ]. In our series this result may be due to endcaps lacking in the mesh’ edges which telescoped inside the inferior vertebral body endplate, without clinical drawbacks in the short and long term follow-up. A small subsidence of a cylinder mesh in the inferior vertebral body can contribute to stabilize the implant. The bone growth heppens even in the anterior vertebral body, variably grabbing the anterior plate without overrun the prevertebral (deep cervical) fascia and retro-esophageal space. The intrasomatic screws placed in the adjacent vertebral bodies do not show any loosening or foreign body reaction. Definite solid fusion of all the implant with the adjacent vertebral bodies usually appear after the fourth year. We have not been able to assess the degree of participation of the material graft placed inside the mesh cages, but the density values detected on the CT scans within the cylinder, let us presume that it concur likewise in the fusion process. In patients with preserved PLL, the ligament do not show play a role in the bone regrowth and the extra-ligament space is the last slot to be filled by new osseous tissue. In the long-term CT scan don’t demonstrate quantitative or morphological differences in bone regrowth between patients with or without PLL removal. Osseointegration of titanium implants has been demonstrated microscopically in rats, dogs and humans up to 14 months[ 3 , 22 ]. They also demonstrate that the surface of the titanium implant does not have to be porous or rough to become osseointegrated [ 1 , 22 ]. A large literature has subsequently confirmed the validity of titanium as a prosthetic implant and the absence of any adverse effect of the implant. In our patients submitted to ACCF, after many years the titanium implant, as previously demonstrated, has “zero reaction” to bone regrowth [ 22 ]. But the most satisfactory result is the strong adherence of the titanium to the bone, favouring a near natural complete osseointegration. Vertebral bone regrowth after surgery has been reported exclusively in patients submitted to lumbar spine surgery. In patients evaluated with plain radiographs or CT after laminectomy for stenosis, after an average follow-up of 8 years bone regrowth averaged 11%, only 20% of the patients the regrowth rate was more than 20%[ 15 ]. In a multivariate analysis with a follow-up period of more than 5 years, moderate or marked bone re-growth was observed in 44% of patients after decompression at more than three spinal levels and age under 60 years[ 5 ]. Moreover when bone regrowth is analyzed as an outside variable, female patients show a positive value suggesting mild or no significant bone regrowth compared with male. This gender related bone regrowth is not demonstrated in our study. In one other study the majority of patients (88%) had bone re-growth, which occurred at any border on the surgical defect, at increased follow-up period in some it ceased or was very slow, in others it developed continuously or very rapidly[ 26 ]. For this result the authors conjectured that initial bone re-growth was stimulated from direct surgical resection, whereas the progression of bone re-growth should be influenced by an undetermined factor. In our experience, the titanium implant seems to favour bone regrowth, and the entity of surgical resection don’t show a relation with the subsequent filling of the bony gap. Conclusions After an ACCF the empty space undergoes a stepwise and time-dependent bony regrowth process without any mielo-radicular compression in the long-term. The amount of bony regrowth is time-dependent and is not influenced by the extent of the initial surgical decompression, by the use of a cylindrical mesh rather than an expandable cage nor by the removal of the PLL. Abbreviations ACCF: anterior cervical corpectomy and fusion DISH: diffuse idiopathic skeletal hyperostosis PLL: posterior longitudinal ligament RA: rheumatoid arthritis SA: sarcopenia Declarations Ethical Approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Informed consent was obtained from all patients or their next of kin prior to their inclusion in the study. This study was approved by the local ethics committee (Rif. 3275/26.06.2014). Competing interests The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Authors' contributions CRediT author statement: Author: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing – original Draft, Writing – review and editing, Visualisation, Supervision, Project administration, Funding acquisition. Francesco M.C. Lioi : Methodology, Software, Validation, Formal analysis, Investigation,Data Curation, Writing – original Draft, Writing – review and editing, Visualisation Sergio Paolini: Conceptualization, Resources, Writing – original Draft, Writing – review and editing, Visualisation, Supervision Angela Ambrosone: Writing – original Draft, Writing – review and editing, Visualisation Daniele Marruzzo: Writing – original Draft, Writing – review and editing, Visualisation, Simone Peschillo: Writing – original Draft, Writing – review and editing, Visualisation, Supervision Paolo Missori: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing – original Draft, Writing – review and editing, Visualisation, Supervision, Project administration Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. 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Medicine (Baltimore) 97:e9724. doi:10.1097/md.0000000000009724 Zhang Y, Quan Z, Zhao Z, Luo X, Tang K, Li J, Zhou X, Jiang D (2014) Evaluation of anterior cervical reconstruction with titanium mesh cages versus nano-hydroxyapatite/polyamide66 cages after 1- or 2-level corpectomy for multilevel cervical spondylotic myelopathy: a retrospective study of 117 patients. PLoS One 9:e96265. doi:10.1371/journal.pone.0096265 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4991930","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":360072968,"identity":"d9bb94be-51c2-44a5-8a3d-8b29a1e34615","order_by":0,"name":"Francesco M.C. Lioi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA60lEQVRIiWNgGAWjYBACPmYGhgMVcC6IxczcgFcLG0jLGTgXxGJmJKAFphAMGNvAJAEt7MwHDxzcY5fH397+8MPHebXR/O1ALT8qtuFxGFvCgQPPkoslzpwxlpy57XjujMOMDYw9Z27j0cJjcPjDAebEDRI5bMy8247lNgC1MDO24ddy4MCB+sQN8s+fMfPOOZY7n0gth4G2MJgx8zbU5G4grAXklwPHE2ecyTGWnHHsQO5GoJaD+PzCz38Y6JUD1Yn97ccffvhQU5c77/zhgw9+VODWgg4Og8kDRKsHgjpSFI+CUTAKRsEIAQDRyF4ftWcZvAAAAABJRU5ErkJggg==","orcid":"","institution":"“Sapienza” University of Rome","correspondingAuthor":true,"prefix":"","firstName":"Francesco","middleName":"M.C.","lastName":"Lioi","suffix":""},{"id":360072969,"identity":"1ec00326-e974-4944-a6e2-f5136d5c5d43","order_by":1,"name":"Sergio Paolini","email":"","orcid":"","institution":"Istituto Neurologico Mediterraneo","correspondingAuthor":false,"prefix":"","firstName":"Sergio","middleName":"","lastName":"Paolini","suffix":""},{"id":360072970,"identity":"d4e23746-6f4e-4943-bd5e-be7b5f3960a9","order_by":2,"name":"Angela Ambrosone","email":"","orcid":"","institution":"Azienda Ospedaliera S.Giuseppe Moscati","correspondingAuthor":false,"prefix":"","firstName":"Angela","middleName":"","lastName":"Ambrosone","suffix":""},{"id":360072971,"identity":"13405710-6b3b-4113-8020-219989093dd4","order_by":3,"name":"Daniele Marruzzo","email":"","orcid":"","institution":"Belcolle Hospital, ASL of Viterbo","correspondingAuthor":false,"prefix":"","firstName":"Daniele","middleName":"","lastName":"Marruzzo","suffix":""},{"id":360072972,"identity":"5db522f4-8d96-44fe-aaba-a9b1c18de70e","order_by":4,"name":"Simone Peschillo","email":"","orcid":"","institution":"Unicamillus International University of Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Simone","middleName":"","lastName":"Peschillo","suffix":""},{"id":360072973,"identity":"c44a7f76-0771-4acb-9541-0203e69edd9b","order_by":5,"name":"Paolo Missori","email":"","orcid":"","institution":"“Sapienza” University of Rome","correspondingAuthor":false,"prefix":"","firstName":"Paolo","middleName":"","lastName":"Missori","suffix":""}],"badges":[],"createdAt":"2024-08-28 14:41:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4991930/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4991930/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":65707678,"identity":"5b8b1bee-f891-4ab9-b2a6-8b00435b3835","added_by":"auto","created_at":"2024-10-01 13:46:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":138436,"visible":true,"origin":"","legend":"\u003cp\u003eOn the CT scanner table a closed surface area (mm\u003csup\u003e2\u003c/sup\u003e) was drawn in every axial slice and the largest surface was chosen.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/72d5074462160fe081df801f.png"},{"id":65707676,"identity":"839c7ee4-f859-43b6-bfb1-1137982f6410","added_by":"auto","created_at":"2024-10-01 13:46:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":333421,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Early postoperative control CT scan in a fifty-six year old female after C4-C6 corpectomy. (B) \u003cstrong\u003eTwenty-six months later\u003c/strong\u003e bone regrowth start from the corpectomy’s lateral edges to join the titanium mesh.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/bbc8a7277cb50ea614964c90.png"},{"id":65708527,"identity":"a625b755-d8be-4a96-a222-6c6fb792ca59","added_by":"auto","created_at":"2024-10-01 13:54:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":299806,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Early postoperative control CT scan in a fifty-two year old male after C6 corpectomy.(B) \u003cstrong\u003eThirty-six months later\u003c/strong\u003e bone regrowth embrace the titanium mesh, extending from anterior, to posterior titanium contour.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/eb47c2930e08288493324949.png"},{"id":65707681,"identity":"6b4a5b0a-b17c-4cc7-9b06-4df8e0360e59","added_by":"auto","created_at":"2024-10-01 13:46:16","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":303036,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Early postoperative control CT scan in a fifty-four year old male after C5-C6 corpectomy. (B) \u003cstrong\u003eFifty-six months later\u003c/strong\u003e bone encircles the titanium mesh, without exceeding the posterior vertebral line.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/f305f42a2e56b10308b9e4a8.png"},{"id":65707680,"identity":"28476cfa-ccd3-43e7-a48f-45874b2ee0cb","added_by":"auto","created_at":"2024-10-01 13:46:16","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":145238,"visible":true,"origin":"","legend":"\u003cp\u003eFifty-three year old female with a C5 corpectomy and titanium expandable cage. (A) Ninety-eight months after surgical treatment the bone encircles the titanium mesh without extending in the extra-ligamentous space. (B) The implant shows a broken left screw at C4 level and intrasomatic retention of the apex, and breakage the upper tool of the expandable cage. Slight subsidence of the inferior posterior implant in the C7 vertebral boby.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/9a00953d5bfbc1dd9b7b9722.png"},{"id":65708528,"identity":"dd441fcf-9d33-4f58-bd84-aaaa8bbd2d9e","added_by":"auto","created_at":"2024-10-01 13:54:16","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":36540,"visible":true,"origin":"","legend":"\u003cp\u003eMarginal effect plot showing the relationship between follow-up months (FU months) and percentage of bony regrowth.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/fd89b8e56fc9c615ac987a2e.png"},{"id":65708529,"identity":"27844b2b-2b4a-4c9c-8f81-c19270814811","added_by":"auto","created_at":"2024-10-01 13:54:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1590308,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4991930/v1/58782ebd-8d45-4fb5-a88f-216088da7b0c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Bone regrowth after cervical corpectomy: long-term follow-up in a series of 34 patients","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn studies evaluating bone fusion after spinal arthrodesis, plain X-rays are a very simple and low-cost diagnostic tool, but may underestimate or overestimate the degree of fusion [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Bone bridging the interspace anterior to the cage on a lateral view (anterior sentinel sign) should demonstrate that fusion has occurred [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. According to others, this sign is the result of bone remodeling due to mechanical loads (Wolff\u0026rsquo;s law)[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Patients submitted to anterior cervical corpectomy and fusion (ACCF) are almost always monitored using X-rays to evaluate spine stability and bony fusion, since artifacts from the metallic implant may hamper good imaging in postoperative control CT scan[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. However Computed Tomography has been demonstrated a reliable imaging technique in comparison to digital radiography to assess bone healing [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Some postoperative CT scans of patients submitted to ACCF with autologous bone strut graft demonstrate the amount of bone removal and the resulting empty space [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In a single patient after ACCF and titanium implantation 1 year control CT scan shows bone regrowth around the mesh cage without artifacts [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The literature lacks any long term study demonstrating how bone reacts around the titanium implant after a cervical corpectomy and what changes develop in the empty space. The widespread use of metallic implants for ACCF prompt us to present our series of patients submitted to ACCF for cervical spondylotic myelopathy to determine the behavior of the resected bone in the long term.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eFor this retrospective study, we identified patients with cervical spondylotic myelopathy, without ossification of the posterior longitudinal ligament (PLL), that underwent single or multilevel ACCF between January 2000 and June 2014 in a single institution from six neurosurgeons. None of these patients was affected by diseases that could impair bone metabolism as diffuse idiopathic skeletal hyperostosis (DISH), rheumatoid arthritis (RA), or sarcopenia (SA). Surgical treatment was performed conforming to the standard technique[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] and the removal of the posterior longitudinal ligament was jointly considered. Patients were divided into two groups, according to the type of arthrodesis performed. The first group (\u003cb\u003egroup A\u003c/b\u003e) include patients with a titanium cylinder mesh cage (DePuy Spine, New Brunswick, New Jersey; Zimmer Spine, Inc., Indiana) filled with autologous cancellous bone or hydroxyapatite chips, and an anterior plate (DePuy Synthes, Raynham, MA) fixed with screws into the vertebral bodies above and below the CC site. The second group (\u003cb\u003egroup B\u003c/b\u003e) collects patients with a Titanium Expandable Cage (Tecorp, Scient'x, France; Ulrich, Ulm, Germany). Early postoperative control CT scan were searched and a comparative imaging was sieved in the long-term follow-up. The surface of the removed vertebral bone was obtained on the scanner table from the axial CT scan (Toshiba\u0026reg;). A closed surface area (in square millimeters) over the edges of the corpectomy empty space was drawn in every axial slice (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). A corresponding axial level slice available in the long-term follow-up was determined and measured. Two observers (one neuroradiologist, one neurosurgeon) calculated the measure in the axial scans. Agreement between observers was evaluated using kappa statistics. We investigated the presence of differences in ossification between the execution of single versus multilevel corpectomy, between the use of Mesh versus expandable cages and between the removal or not of the PLL. Finally, we analyzed the bony regrowth dynamic and the stepwise sequence of the process during the long-term follow-up. Data were imported into JASP (Version 0.18.3 Computer software, JASP Team, 2024) statistical software for analysis. We used Mann-Whitney U-test to compare variables and and p-values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered as significant. Informed consent was obtained from all patients or their next of kin prior to their inclusion in the study. This study was approved by the local ethics committee (Rif. 3275/26.06.2014).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThirty-four adult patients who underwent ACCF in a single-institution between January 2000 and June 2014 were enrolled in this retrospective study. The study population is composed of 18 males (53%) and 16 females (47%), which performed an early and one long-term CT scan. Mean age of the whole group was 54.3 ± 11 years old, with a mean age 52.9 ± 11 for males and 53.8 ± 11 for females. Twenty patients (59%) were submitted to single level corpectomy, fourteen (41%) to multiple levels corpectomy, of which 13 two level and one three level corpectomy. In 25 (73.5%) patients a titanium cylinder mesh cage was placed (group A) while in 9 (26.5%) patients an expandable cage was used (group B). PLL removal was performed in 11 (32.3%) patients, of which 4 during single level procedures and the remaining 7 in multiple level corpectomies. In 25 (73%) patients a titanium cylinder mesh cage was placed and in 9 (26%) was preferred an expandable cage. Titanium mesh was used in 15 single-level and 10 multi-level procedures, whereas the use of the expandable cage has been used in 5 single-level and 4 multi-level interventions.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRadiological evaluation shows that bone regrowth progressed in a time dependent step fashion. Starting from the lateral edges of the corpectomy the resected cancellous bone showed early restore and growth toward the titanium mesh (Fig. 2). The metallic implant was progressively gripped (Fig. 3). In the late phase the mesh was incorporated and the extra-ligamentous or extra-dural space was progressively replenished (Fig. 4). Bone regrowth never exceeded the posterior vertebral line, resulting a smooth posterior ligament or extradural interface. In patients with an expandable cage bone regrowth around the implant was less plentiful and in one case asymptomatic break of the cage was demonstrated (Fig. 5).\u003c/p\u003e\n\u003cp\u003eMale or female sex does not seem to affect the process of ossification at a distance in our population. (p=0.67). There were no significant differences in the extent of bony regrowth between patients who underwent single versus multiple corpectomy (p=0.25). Similarly, the use of a cylinder mesh cage rather than an expandable cage does not lead to significant differences in terms of ossification in follow-up (p=0.15). Finally, nor the choice of removing PLL or not had significant repercussions in terms of bone regrowth (p=0.42). The mean average radiological follow-up of all patients was 4.8 ± 4.1 years. There was a positive linear correlation between bone regrowth and months of follow-up (p\u0026lt;0.023), so that a longer follow-up period is associated with greater osseointegration (Fig. 6). Asymptomatic subsidence of the implant in the inferior endplate (Fig. 5), never exceeding 3 millimeters, was observed in 3 patients with a cylindrical mesh cage (12%) and in one expandable cage (11%).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAlthough a variable evolution was detected among patients, bone regrowth progressed in a stepwise and time-dependent pattern. In the long term follow-up of patients submitted to cervical corpectomy bone tissue progressively regrows in the empty space, without formation of new osteophytes projecting into the vertebral canal, squeezing the spinal nerves or spinal cord. The cancellous bone from the resected lateral edges of the corpectomy shows the most active regrowth and the titanium implant is progressively wrapped without any adverse reaction on the bone-metallic interface. The compact bone from the endplate of the superior adjacent vertebral body does not show signs of reaction. No differences were detected in bony regrowth among patients with single, double or three level corpectomies as well between mesh replenished with autogenous bone or hydroxyapatite chips. The implant in some cases shows a small amount of subsidence in the inferior vertebral body. A risk of subsidence in the cervical spine is well known in patients with an associated cylinder mesh or an expandable cage [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In our series this result may be due to endcaps lacking in the mesh\u0026rsquo; edges which telescoped inside the inferior vertebral body endplate, without clinical drawbacks in the short and long term follow-up. A small subsidence of a cylinder mesh in the inferior vertebral body can contribute to stabilize the implant. The bone growth heppens even in the anterior vertebral body, variably grabbing the anterior plate without overrun the prevertebral (deep cervical) fascia and retro-esophageal space. The intrasomatic screws placed in the adjacent vertebral bodies do not show any loosening or foreign body reaction. Definite solid fusion of all the implant with the adjacent vertebral bodies usually appear after the fourth year. We have not been able to assess the degree of participation of the material graft placed inside the mesh cages, but the density values detected on the CT scans within the cylinder, let us presume that it concur likewise in the fusion process. In patients with preserved PLL, the ligament do not show play a role in the bone regrowth and the extra-ligament space is the last slot to be filled by new osseous tissue. In the long-term CT scan don\u0026rsquo;t demonstrate quantitative or morphological differences in bone regrowth between patients with or without PLL removal. Osseointegration of titanium implants has been demonstrated microscopically in rats, dogs and humans up to 14 months[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. They also demonstrate that the surface of the titanium implant does not have to be porous or rough to become osseointegrated [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. A large literature has subsequently confirmed the validity of titanium as a prosthetic implant and the absence of any adverse effect of the implant. In our patients submitted to ACCF, after many years the titanium implant, as previously demonstrated, has \u0026ldquo;zero reaction\u0026rdquo; to bone regrowth [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. But the most satisfactory result is the strong adherence of the titanium to the bone, favouring a near natural complete osseointegration. Vertebral bone regrowth after surgery has been reported exclusively in patients submitted to lumbar spine surgery. In patients evaluated with plain radiographs or CT after laminectomy for stenosis, after an average follow-up of 8 years bone regrowth averaged 11%, only 20% of the patients the regrowth rate was more than 20%[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. In a multivariate analysis with a follow-up period of more than 5 years, moderate or marked bone re-growth was observed in 44% of patients after decompression at more than three spinal levels and age under 60 years[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Moreover when bone regrowth is analyzed as an outside variable, female patients show a positive value suggesting mild or no significant bone regrowth compared with male. This gender related bone regrowth is not demonstrated in our study. In one other study the majority of patients (88%) had bone re-growth, which occurred at any border on the surgical defect, at increased follow-up period in some it ceased or was very slow, in others it developed continuously or very rapidly[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. For this result the authors conjectured that initial bone re-growth was stimulated from direct surgical resection, whereas the progression of bone re-growth should be influenced by an undetermined factor. In our experience, the titanium implant seems to favour bone regrowth, and the entity of surgical resection don\u0026rsquo;t show a relation with the subsequent filling of the bony gap.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eAfter an ACCF the empty space undergoes a stepwise and time-dependent bony regrowth process without any mielo-radicular compression in the long-term. The amount of bony regrowth is time-dependent and is not influenced by the extent of the initial surgical decompression, by the use of a cylindrical mesh rather than an expandable cage nor by the removal of the PLL.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eACCF: anterior cervical corpectomy and fusion\u003c/p\u003e\n\u003cp\u003eDISH:\u0026nbsp;diffuse idiopathic skeletal hyperostosis\u003c/p\u003e\n\u003cp\u003ePLL: posterior longitudinal ligament\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eRA: rheumatoid arthritis\u003c/p\u003e\n\u003cp\u003eSA: sarcopenia\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp skip=\"true\"\u003eAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of\u0026nbsp;Helsinki\u0026nbsp;and its later amendments or comparable ethical standards. Informed consent was obtained from all patients or their next of kin prior to their inclusion in the study. This study was approved by the local ethics committee (Rif. 3275/26.06.2014).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCRediT author statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthor: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation, Supervision, Project administration, Funding acquisition.\u003c/p\u003e\n\u003cp\u003eFrancesco M.C. Lioi : Methodology, Software, Validation, Formal analysis, Investigation,Data Curation, Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation\u003c/p\u003e\n\u003cp\u003eSergio Paolini: Conceptualization, Resources, Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation, Supervision\u003c/p\u003e\n\u003cp\u003eAngela Ambrosone: Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation\u003c/p\u003e\n\u003cp\u003eDaniele Marruzzo: Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSimone Peschillo: Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation, Supervision\u003c/p\u003e\n\u003cp\u003ePaolo Missori: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing \u0026ndash; original Draft, Writing \u0026ndash; review and editing, Visualisation, Supervision, Project administration\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData are available upon reasonable request\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBobyn JD, Pilliar RM, Cameron HU, Weatherly GC (1981) Osteogenic phenomena across endosteal bone-implant spaces with porous surfaced intramedullary implants. 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Spine J 3:294-300. doi:10.1016/s1529-9430(02)00588-0\u003c/li\u003e\n\u003cli\u003eTominaga T, Koshu K, Mizoi K, Yoshimoto T (1994) Anterior cervical fixation with the titanium locking screw-plate: a preliminary report. Surg Neurol 42:408-413. doi:10.1016/0090-3019(94)90347-6\u003c/li\u003e\n\u003cli\u003eWu J, Luo D, Ye X, Luo X, Yan L, Qian H (2015) Anatomy-related risk factors for the subsidence of titanium mesh cage in cervical reconstruction after one-level corpectomy. Int J Clin Exp Med 8:7405-7411\u003c/li\u003e\n\u003cli\u003eYang X, Chen Q, Liu L, Song Y, Kong Q, Zeng J, Xue Y, Ren C (2013) Comparison of anterior cervical fusion by titanium mesh cage versus nano-hydroxyapatite/polyamide cage following single-level corpectomy. Int Orthop 37:2421-2427. doi:10.1007/s00264-013-2101-4\u003c/li\u003e\n\u003cli\u003eYee AJ, Bae HW, Friess D, Robbin M, Johnstone B, Yoo JU (2004) Accuracy and interobserver agreement for determinations of rabbit posterolateral spinal fusion. Spine (Phila Pa 1976) 29:1308-1313. doi:10.1097/01.brs.0000127184.43765.61\u003c/li\u003e\n\u003cli\u003eYonenobu K, Fuji T, Ono K, Okada K, Yamamoto T, Harada N (1985) Choice of surgical treatment for multisegmental cervical spondylotic myelopathy. Spine (Phila Pa 1976) 10:710-716. doi:10.1097/00007632-198510000-00004\u003c/li\u003e\n\u003cli\u003eZeng J, Duan Y, Yang Y, Wang B, Hong Y, Lou J, Ning N, Liu H (2018) Anterior corpectomy and reconstruction using dynamic cervical plate and titanium mesh cage for cervical spondylotic myelopathy: A minimum 5-year follow-up study. Medicine (Baltimore) 97:e9724. doi:10.1097/md.0000000000009724\u003c/li\u003e\n\u003cli\u003eZhang Y, Quan Z, Zhao Z, Luo X, Tang K, Li J, Zhou X, Jiang D (2014) Evaluation of anterior cervical reconstruction with titanium mesh cages versus nano-hydroxyapatite/polyamide66 cages after 1- or 2-level corpectomy for multilevel cervical spondylotic myelopathy: a retrospective study of 117 patients. PLoS One 9:e96265. doi:10.1371/journal.pone.0096265\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"bone, cervical, fusion, spine, surgery, vertebra","lastPublishedDoi":"10.21203/rs.3.rs-4991930/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4991930/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eCervical corpectomy and fusion is widely performed for relieving spinal cord compression due to vertebral body spondylosis. Bone regrowth in the empty space should occur, but there are not long-term follow-up studies demonstrating the timeline and the steps of this process.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003ePatients with spondylotic myelopathy that underwent single or multilevel cervical corpectomy and fusion, with or without posterior longitudinal ligament removal were submitted to long term CT follow-up to ascertain how and how much the resected bone reacts in the empty corpectomy space.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eBone regrows and fills the empty space in a stepwise and time dependent fashion. Starting from the lateral edges of the corpectomy, new bone grips develop and progressively envelope the titanium implant. At the final stage the bone regrowth reaches the posterior ligament or the extradural space, and a smooth plane results in the posterior corpectomy space. The posterior longitudinal ligament does not appear play a role in the bone regrowth since no morphological differences occur between patients jointly submitted or not to its removal.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eAfter cervical corpectomy the empty space undergoes a stepwise and time-dependent bone regrowth without redo mielo-radicular compression in the long-term.\u003c/p\u003e","manuscriptTitle":"Bone regrowth after cervical corpectomy: long-term follow-up in a series of 34 patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-01 13:46:11","doi":"10.21203/rs.3.rs-4991930/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"dcb66c61-4881-4507-9e93-6356bd2cba85","owner":[],"postedDate":"October 1st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-10-01T13:46:11+00:00","versionOfRecord":[],"versionCreatedAt":"2024-10-01 13:46:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4991930","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4991930","identity":"rs-4991930","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}