The Roof Technique in the Treatment of Bone Tumors of the Spine. A Ten Years’ Experience

The Roof Technique in the Treatment of Bone Tumors of the Spine. 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A Ten Years’ Experience Alessandro Gasbarrini, Chiara Cini, Stefano Bandiera, Giovanni Barbanti Brodano, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6868012/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Introduction: Besides appropriate oncological principles for resection, spine tumors require complex reconstructive techniques in a setting of biologic compromise. Fusion outcomes in this cohort are influenced by several variables. Most previous studies focused more on the oncology related prognosis and only briefly reported on fusion rates and instrumentation failure. The aim of our study was to evaluate the efficacy of using bone graft for fusion across long posterior column defects after en bloc resection. Material and Methods: This retrospective observational study analyzed 30 patients with primary spinal tumors who underwent posterior column reconstruction after en bloc resections. In all cases, the resected anterior column was reconstructed with 3D-printed custom-made prosthesis, titanium mesh cages (TMC) or Polyetheretherketone/Carbon fiber (PEEK/CF) Vertebral Body Replacement (VBR). In regions where the posterior elements were completely resected, a structural fresh-frozen allograft or autologous bone graft was placed to span the defect and cover spinal cord. Fashioned bone graft was prepared with saddle cuts on its proximal and distal end to sit on the surface of the extremities of the spinous processes anchored to posterior instrumentation with sublaminar bands. Posterior fusion graft assessment was performed using CT scans with multiplanar reconstruction (MPRs) at 6 months, 12 months, and at the last follow-up. Fusion status was recorded according to four grades: complete fusion (cortical union of the structural allograft with central trabecular continuity), partial fusion (cortical union with partial trabecular incorporation), unipolar pseudarthrosis and bipolar pseudarthrosis (central trabecular discontinuity with superior or inferior cortical non-union, or both, along with a complete lack of central trabecular continuity, respectively). Results: Complete posterior graft fusion was achieved in 11 patients (36.67%, p=0.32) at six months of follow-up while 16 patients (53.33%, p=0.25) achieved partial fusion at the first follow-up. 28 patients achieved grade I graft fusion at the final follow-up (mean 56.38 ± 23.40 months, p=0.18). A rod fracture, without evidence of graft dislodgment, occurred only in one patient who underwent revision surgery at 20 months of follow-up. 3 (3%) patients experienced wound infections treated with DAIR without affecting the final degree of fusion. The last clinical and radiographic follow-up with a mean of months (±) showed no evidence of graft dislodgment or increased axial pain. In 4 patients there was evidence of local recurrence (LR) within 12 ± 3.4 months of followup. In one case a revision surgery for decompression was required at 11 months of follow-up. Conclusion: This innovative technique of fashioning the graft posteriorly allows for both early and long-term stability with solid fusion. Additionally, in case of revision surgery for local recurrence, it avoids direct exposure of the spinal cord. primary spinal tumors en bloc resection bone defects posterior column reconstruction bone graft Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 INTRODUCTION Enbloc resection is a validated procedure in the treatment of benign aggressive and malignant bone tumor of the spine [ 1 ]. This procedure was popularised by RoyCamille [ 2 ] and Tomita [ 3 ]. Later on, the literature was progressively populated by many single case reports [ 4 – 6 ] and cohort studies (7, 8), summarised in systematic reviews [ 9 ]. The Weinstein-Boriani-Biagini (WBB) surgical system was introduced in 1997 [ 10 ] to classify the extension of spine tumors and supported the surgical planning of en bloc resection. Recently a staging system was proposed to standardise the technique according to tumor extension [ 11 ]. But the pioneer of this procedure was Bertil Stener [ 12 ], who many years before applied to the spine the concepts of the treatment of malignant tumor of other systems. From his design, reported in his papers, we can understand how huge the soft tissue sacrifice is required for a tumor-free margin enbloc resection. For these reasons, besides appropriate oncological principles for resection, these procedures require complex reconstructive techniques. During the last years the advances of surgical techniques have been accompanied by the development of adjuvant cancer therapies and radiotherapy, in particular charged-particle therapy (proton beam therapy and carbon ion therapy), allowing improved survival rates for patients undergoing spinal tumor resection. With the increase of survival, the efficacy of reconstruction is relevant in order to avoid complications and instrumentation failures. For the anterior column reconstruction different techniques are reported, including vascularized or nonvascularized graft strut, titanium cage systems (also 3D-printed custom-made prosthesis), stackable carbon cage system and PMMA [ 13 ]. However, the unique regional and morphological characteristics of each primary spine tumor prevent a generic approach to anterior and posterior column reconstruction and what are the best reconstructive options is still debated: most previous studies focused more on the oncology related prognosis and only briefly reported structural outcomes and fusion rates [ 14 – 16 ]. Few reports analyzed the use of iliac crest autograft, morcelized allograft or bone graft substitutes for posterior fusion: Lewis et al. [ 17 ] described one case of vascularized and three cases of nonvascularized rib autograft struts for posterior reconstruction. Literature data have been summarized in a recent review reporting consensus expert opinion about reconstructive techniques [ 18 ]. The aim of the present study is to evaluate the efficacy of using a bone graft for posterior column defects after en bloc resection for primary tumors. MATERIALS AND METHODS This retrospective observational study was approved by the local Ethics Committee on November 2024 (PG nr. 0017319, 29/11/2024). About 300 patients with primary spinal tumors were treated with en bloc resection from January 2009 to January 2024 at our referral center. We included in our analysis 30 patients who underwent posterior column reconstruction after en bloc resection at our Institution from 2015 to 2024 according to these inclusion criteria: age > 18 years, mobile spine lesions (C1-L5), diagnosis of primary tumor confirmed preoperatively by CT-guided trocar biopsy, en bloc resection according to Enneking appropriateness and a minimum of 1 year of outpatient follow-up. Patients who underwent previous surgery including incisional biopsy were excluded. In all cases, whole-spine MRI, CT scan and total-body FDG- PET were performed to define oncological assessment. All patients were classified according to Weinstein-Boriani-Biagini score [ 9 ] before undergoing en bloc resection. Surgical resection was defined as en bloc (wide or marginal, R0 margins) when the tumor was removed in a single piece encased by healthy tissue. The pathologists’ assessments of the overall margin were documented as marginal margin referring to dissection within the pseudocapsule or reactive zone, while as wide margin referring to a plane of resection within normal tissue. Intralesional margin (R1 margins) implied that the plane of dissection has transgressed into the lesion involving residual macroscopic tumor. Furthermore, the number of surgical stages (categorized as 1 or ≥ 2) and surgical approach (anterior, posterior, or simultaneous) of each procedure were collected for each patient. In all cases, the resected anterior column was reconstructed with 3D-printed custom-made prosthesis, titanium mesh cages (TMC) or Polyetheretherketone/Carbon fiber (PEEK/CF) Vertebral Body Replacement (VBR). Posterior fixation was realized with Titanium implant or with Carbon Fiber reinforced PEEK instrumentation. In regions where the posterior elements were completely resected, a structural fresh-frozen autologous bone graft was placed to span the defect and cover spinal cord, as shown in Fig. 1 . The length of the defect created posteriorly on the side of the resection was measured and an oversized length of a fresh frozen autograft was harvested in the field of surgery. In particular, fashioned bone graft was prepared with saddle cuts on its proximal and distal end to sit on the surface of the corresponding extremities of the spinous process delimiting the posterior resection above and below the posterior column defect. As we previously described [ 19 ], the “roof” was anchored to posterior instrumentation with sublaminar bands and reinforced with Fiber Wires to ensure more stability (Fig. 2 ). Generally, a gentle compression to posterior instrumentation was applied to improve correspondence. Posterior fusion graft assessment was performed using CT scans with multiplanar reconstruction (MPRs) at 6 months, 12 months, and at the last follow-up. Considering that the Creeping substi- tution begins at the graft-host junction and then moves along the axis of the cortical graft, fusion status at the two extremities of the graft in contact with the spinous processes was recorded according to four grades: complete fusion -Grade IV (cortical union of the strutgraft with spinous process central trabecular continuity), partial fusion -Grade III (cortical union with partial trabecular incorporation), unipolar pseudarthrosis, and bipolar pseudarthrosis -Grade II and I respectively (central trabecular discontinuity with superior or inferior cortical non-union, or both, along with a complete lack of central trabecular continuity, respectively) (Fig. 3 ). Data on additional hadron therapy were recorded during outpatient’s follow-up. At every follow-up information regarding mechanical complication and surgical infection was collected. Oncological status at the final follow-up was registered for every patient. The primary endpoint of our study was to demonstrate that the “roof” technique protects the spinal cord and avoid creation of adherent scar. The second end point was to demonstrate that the structural graft allows immediate and long-term stabilization of the posterior column defect created by the en bloc tumor resection and enhances the fusion bed with the adjacent spinous processes in a setting of biological compromise due to the large bone and soft tissue voids after surgery. Statistical Analysis The statistical analysis was conducted using Microsoft Excel for database creation and management, while RStudio (version 2025.05.0 Build 496) was employed for data processing and statistical tests. The dataset includes a total of 29 patients (15 women and 14 men) with 77 clinical variables, encompassing parameters related to bone fusion across different follow-ups. To assess the normality of the analyzed distributions, the Shapiro-Wilk test was applied. In cases where normality was not met, non-parametric tests were chosen to ensure the robustness of the analyses. For the comparison of bone fusion progression over time, the Fisher’s exact test was used. This test is especially effective for small sample sizes, allowing comparisons between categorical groups without the constraints imposed by the Chi-square test. The statistical significance threshold was set at p < 0.05. All analyses were performed following principles of methodological rigor and statistical reproducibility. Marginally significant results were interpreted with caution, considering the limited number of observations available. RESULTS A total of 30 patients were included in our analysis. The median age in our population was 48.55 ± 17.04 and the majority of patients were female (15 [53.33%]). The most common histological diagnosis was cordoma (36.67%). No patients had metastasis at the time of index surgery. The most common location of primary tumor was the lumbar spine (43.33%). All patients underwent preoperative CT guided trocar biopsy and received preoperative arterial selective embolization (SAE). 12 patients (40%) underwent a single-stage posterior procedure while 18 (60%) patients underwent surgery in two stages. For those who underwent multistage surgery, the anterior approach was most commonly performed as the first stage (16 [88.89%] patients), followed by posterior approach as first stage (2 [11.11%]). Overall, marginal or wide margins were attained in 21 (70.0%) patients, in 9 (30.0%) cases the final anatomopathological analysis demonstrated focal transgression with intralesional margins. Descriptive analysis of our population and tumor characteristics are shown in Table 1 . The mean length of the graft was 11.47 ± 4.03 cm, and the mean construct spanned 6.7 ± 3.0 vertebral levels. Graft characteristics in our population are shown in Table 2 . Table 1 Tumor characteristics and Treatments. Primary tumor Level Involved > 1 Adjuvant Hadron-Therapy Cordoma Chondrosarcoma Gigant Cell Tumor Osteoblastoma Osteosarcoma Ewing sarcoma Epitheliod Hemangioma Hemangioendothelioma Aneurismatic Bone Cyst Desmoplastic Fibroma 11 4 3 3 3 2 1 1 1 1 Cervical 4 Lumbar 2 Thoracic 2 Tumor Location Cervical 6 Lumbar 13 Thoracic 9 No Hadron Therapy 11 Proton Beam Therapy (PBT) 9 Anterior Column Reconstruction Titanium mesh cage 13 PEEK/CF VBR 14 3D-printed custom-made Prosthesis 1 Table 2 Bone graft details Mean length of the graft 11.47 ± 4.03 cm Mean length of resected vertebrae 4.32 ± 2.55 cm Length of spinal shortening 2.2 ± 1.8 cm Mean construct span (vertebral levels) 6.7 ± 3.0 Cutting line of resection Disc Vertebra 20 (66.6%) 10 (33.3%) Complete posterior graft fusion was achieved in 11 patients (36.67%, p = 0.32) at six months of follow-up while 16 patients (53.33%, p = 0.25) achieved partial fusion at the first follow-up. 28 patients achieved grade I graft fusion at the final follow-up (mean 56.38 ± 23.40 months, p = 0.18) (Fig. 4 ). Among the 9 patients who were treated with PBT with a mean prescription dose of 50–54 Gy (RBE) in 25–27 fractions within 25 weeks from index surgery, complete fusion was observed in all cases at the last follow-up and was already achieved at six months intermediate follow-up. No difference in time to final fusion was found compared to patients who did not undergo radiation therapy (9 [100%] vs 19 [90.48%], p = 1.00) (Fig. 5 ). All patients with PEEK/CF instrumentation achieved bone fusion at the last follow-up and no difference was observed between PEEK/CF instrumentation and Titanium instrumentation at each time of follow-up (12 [100%] vs 15 [88.24%] respectively, p = 1.00) (Fig. 6 ). Moreover, no statistically significant difference was observed in fusion grade at the last follow-up according to the length of the posterior graft, as shown in Fig. 7 . Grade III and Grade IV graft fusions assessed by CT scan are shown in Figs. 8 and 9 . A rod fracture, without evidence of graft dislodgment, occurred only in one patient who underwent revision surgery at 20 months of follow-up. 3 (3%) patients experienced wound infections treated with DAIR without affecting the final degree of fusion. The last clinical and radiographic follow-up with a mean of months (±) showed no evidence of graft dislodgment or increased axial pain. In 4 patients there was evidence of local recurrence (LR) within 12 ± 3.4 months of followup. In one case a revision surgery for decompression was required at 11 months of follow-up (Fig. 10 ). DISCUSSION In the reconstruction of the spine after total spondylectomy, allogenic strutgraft are frequently used to restore the continuity of the anterior column [ 20 , 21 ]. In a systematic literature review combined with consensus expert opinion, to provide recommendations on reconstructive constructs after complete vertebrectomy [ 18 ] no mention is reported on the role of posterior allograft. Apparently, no significant mechanical advantage can be expected by a posteriorly located strutgraft, as Wolff’s law (published in 1892 and still unchallenged) [ 22 ] declares that bone growth is enhanced under pressure and reabsorbed under tension. As it is known that 80% of load is supported anteriorly and 20% posteriorly [ 23 ], it is justified to position a strut graft anteriorly and implant a posterior fixation system posteriorly in compression: as a consequence the posterior tensile stresses are expected to be converted into anterior compressive stresses, in order to facilitate osteointegration of anterior graft, either strutgraft or cancellous bone inside cage, preventing stress shielding. The technique here reported is apparently in contradiction to other validated experiences. It is proposed to include in the 360 degrees reconstruction -after total spondylectomy- a posterior strut graft, in addition to posterior fixation (at least two levels above and two levels below) and to anterior reconstruction according to the surgeon’s preferences (cage and graft, instrumented strut graft, 3D printed prosthesis). The posterior allograft is a specifically shaped semi-circular segment of frozen femoral shaft and the rationale of this technique is based on the experience of a single team performing enbloc resection for bone tumors of the spine. Complete spondylectomy -performed for enbloc tumor resection- includes not only bone, joints, discs, but also extensive sacrifice of soft tissues (notably muscles, and fasciae). The result is not only a full instability, but also a complete disruption of anatomical compartments which leaves a huge empty cavity around the thecal sac, frequently uncovered under the skin. Plastic surgery is frequently required for safe soft tissue reconstruction, even by muscle flaps [ 24 ]. A critical review of complications related to lack of protection of posterior dura and residual scar tissue suggested to look for a solution [ 25 ]. In 2015 the first “roof technique” was used as a possible solution to implant a semicircular femoral shaft graft interposed between the residual spinous processes, like a roof over the theca sac. This technique was named roof technique and till now only proposed during meeting discussion, waiting for middle-long term results before submission for publication on a scientific paper. The results here reported show that there was no evidence of graft dislodgment at the final follow-up in our population. Moreover, the majority of patients achieved complete fusion at the final follow-up and this result is in line with Lewis et al. [ 17 ] who demonstrated that serial CT scans at a minimum of 6 months showed fusion of the posterolateral autologous rib graft in all 11 surviving cases. We did not find any difference in time to fusion between patients who were treated with adjuvant PBT and patients who did not receive adjunctive therapies at the final follow-up and this is in contrast with the current literature. Infact, Elder et al. [ 26 ] demonstrated in their systematic review that the average time to fusion of patients who received RT were longer than those who did not receive adjunctive treatments (RT: 6.1 months vs 4.3 months, p < 0.001, p = 0.02) [ 26 ]. No additional imaging procedures were performed on patients to evaluate the graft fusion because the first aim of our study was to evaluate the advantages of recreating the tridimensionality of a virtual vertebral canal and to avoid the creation of the scar close to the dura after surgery. Therefore, it is impossible to draw any more precise judgments about the grafts' incorporation time into the spinous processes. Our study is the first description of a posterior reconstructive technique after en bloc resection inclusive of a complete posterior frozen allograft. Further studies are necessary to evaluate the role of the roof for posterior reconstruction in relation to anterior subsidence and proximal junctional failure. CONCLUSION The “roof technique” consists on implanting a semicircular femoral shaft strutgraft (frozen allograft) between the residual spinous process above and below the resected vertebrae. The graft is shaped to be stuck under the longitudinal pressure applied by the posterior instrumentation. The main porpuses are: Protection of the dura; Avoiding adherent scar (in case of revision the most severe cause of dural tear); Creating a safe zone around the sac useful for radiotherapists in planning high dose radiotherapy close to the dura. Surprisingly, in the middle term follow-up evident fusion was found between the extremity of the graft and the spinous processes. This innovative technique of fashioning the graft posteriorly allows for both early and long-term stability. Additionally, in case of local recurrence, it avoids direct exposure of the spinal cord if revision surgery is needed. Declarations The authors declare they have no financial and non-financial interests that are directly or indirectly related to the work submitted for publication. No funding was received for this research. Author Contribution Conceptualization: Alessandro Gasbarrini, Chiara Cini. Methodology: Gasbarrini Alessandro, Cini Chiara, Valerio Pipola Validation Stefano Bandiera, Riccardo Ghermandi. Formal Analysis Gabriele Bilancia, Loredana Mavilla. Investigation Alessandro Gasbarrini, Chiara Cini, Silvia Terzi, Gisberto Evangelisti, Cristiana Griffoni, Giovanni Barbanti Brodano, Giuseppe Tedesco. Resources Alessandro Gasbarrini, Chiara Cini, Stefano Bandiera Writing original draft Alessandro Gasbarrini, Chiara Cini. Writing- Review & Editing Cristiana Griffoni, Loredana Mavilla. Visualization: Alessandro Gasbarrini, Giuseppe Tedesco. Supervision: Alessandro Gasbarrini, Chiara Cini, Riccardo Ghermandi, Stefano Bandiera References Enneking WF (1983) Muscoloskeletal Tumor Surgery. New York: Churchill Livingstone, :69–122 Roy-Camille R, Saillant G, Mazel CH, Monpierre H (1990) Total vertebrectomy as treatment of malignant tumors of the spine. Chir Organi Mov 75(1 Suppl):94–96 PMID: 2249570 Murakami H, Kawahara N, Abdel-Wanis ME, Tomita K (2001) Total en bloc spondylectomy. Semin Musculoskelet Radiol. ;5(2):189 – 94. 10.1055/s-2001-15679 . PMID: 11500165 Hardes J, Gosheger G, Halm H, Winkelmann W, Liljenqvist U (2003) Three-level en bloc spondylectomy for desmoplastic fibroma of the thoracic spine: a case report. Spine (Phila Pa 1976). ;28(9):E169-72. 10.1097/01.BRS.0000058730.55078.5E . PMID: 12942020 Samartzis D, Marco RA, Benjamin R, Vaporciyan A, Rhines LD (2005) Multilevel en bloc spondylectomy and chest wall excision via a simultaneous anterior and posterior approach for Ewing sarcoma. Spine (Phila Pa 1976). ;30(7):831-7. 10.1097/01.brs.0000158226.49729.6c . PMID: 15803089 Biagini R, Casadei R, Boriani S, Erba F, Sturale C, Mascari C, Bortolotti C, Mercuri M (2003) En bloc vertebrectomy and dural resection for chordoma: a case report. Spine (Phila Pa 1976). ;28(18):E368-72. 10.1097/01.BRS.0000084644.84095.10 . PMID: 14501938 Hasegawa K, Homma T, Hirano T, Ogose A, Hotta T, Yajiri Y, Nagano J, Inoue Y (2007) Margin-free spondylectomy for extended malignant spine tumors: surgical technique and outcome of 13 cases. Spine (Phila Pa 1976). ;32(1):142-8. 10.1097/01.brs.0000251045.79708.7a . PMID: 17202906 Teng H, Xinghai Y, Wei H, Huang Q, Xiao J, Zhang C (2011) Malignant fibrous histiocytoma of the spine: a series of 13 clinical case reports and review of 17 published cases. Spine (Phila Pa 1976) 36(22):E1453–E1462. 10.1097/BRS.0b013e318203e292 PMID: 21343863 Yamazaki T, McLoughlin GS, Patel S, Rhines LD, Fourney DR, the Spine Oncology Study Group (2009) Feasibility and safety of en bloc resection for primary spine tumors: a systematic review by. Spine (Phila Pa 1976). ;34(22 Suppl):S31-8. 10.1097/BRS.0b013e3181b8b796 . PMID: 19829275 Boriani S, Weinstein JN, Biagini R (1997) Primary bone tumors of the spine. Terminology and surgical staging. Spine (Phila Pa 1976) 22:1036–1044 Boriani S (2018) En bloc resection in the spine: a procedure of surgical oncology. J Spine Surg 4(3):668–676 Stener B (1989) Complete removal of vertebrae for extirpation of tumors. A 20-year experience. Clin Orthop Relat Res. ;(245):72–82. PMID: 2752635. Chen J, Zhai S, Zhou H, Hu P, Liu X, Liu Z, Liu X, Li Y, Li Z, Wei F (2023) Implant Materials for Anterior Column Reconstruction of Cervical Spine Tumor. Orthop Surg 15(5):1219–1227 Fidler MW (1994) Radical resection of vertebral body tumours. A surgical technique used in ten cases. J Bone Joint Surg Br 76:765–772 Huang L, Chen K, Ye JC et al (2013) Modified total en bloc spondylectomy for thoracolumbar spinal tumors via a single posterior approach. Eur Spine J 22:556–564 Fourney DR, Abi-Said D, Rhines LD et al (2001) Simultaneous anterior- posterior approach to the thoracic and lumbar spine for the radical resection of tumors followed by reconstruction and stabilization. J Neurosurg 94(2 suppl):232–244 Lewis SJ, Kulkarni AG, Rampersaud YR et al (2012) Posterior column reconstruction with autologous rib graft after en bloc tumor excision. Spine (Phila Pa 1976) 37:346–350 Glennie RA, Rampersaud YR, Boriani S, Reynolds JJ, Williams R, Gokaslan ZL, Schmidt MH, Varga PP, Fisher CG (2016) A Systematic Review With Consensus Expert Opinion of Best Reconstructive Techniques After Osseous En Bloc Spinal Column Tumor Resection. Spine (Phila Pa 1976) 41(Suppl 20):S205–S211 de Ruiter GCW, Pipola V, Griffoni C, Gasbarrini A (2021) Sublaminar bands in oncological spine surgery: illustrative cases. J Neurosurg Case Lessons 1(21):CASE21111. 10.3171/CASE21111 PMID: 35854866; PMCID: PMC9245747 Lewandrowski KU, Hecht AC, DeLaney TF, Chapman PA, Hornicek FJ, Pedlow FX (2004) Anterior spinal arthrodesis with structural cortical allografts and instrumentation for spine tumor surgery. Spine (Phila Pa 1976). ;29(10):1150-8; discussion 1159. 10.1097/00007632-200405150-00019 . PMID: 15131446 Elder BD, Ishida W, Goodwin CR, Bydon A, Gokaslan ZL, Sciubba DM, Wolinsky JP, Witham TF (2017) Bone graft options for spinal fusion following resection of spinal column tumors: systematic review and meta-analysis. Neurosurg Focus. ;42(1):E16. 10.3171/2016.8.FOCUS16112 . PMID: 28041327 Wolff Julius Das Gesetz der Transformation der Knochen. 1892 Hirschwald (Berlin) Aulisa L, Pitta L, Padua R, Ceccarelli E, Aulisa A, Leone A (2000 Jan-Mar) Biomechanics of the spine. Rays 25(1):11–18 English, Italian. PMID: 10967631 Boriani S, Bandiera S, Donthineni R, Amendola L, Cappuccio M, De Iure F, Gasbarrini A (2010) Morbidity of en bloc resections in the spine. Eur Spine J. ;19(2):231 – 41. doi: 10.1007/s00586-009-1137-z. Epub 2009 Aug 19. PMID: 19690899; PMCID: PMC2899819 Li Z, Guo L, Zhang P, Wang J, Wang X, Yao W (2023) A Systematic Review of Perioperative Complications in en Bloc Resection for Spinal Tumors. Global Spine J 13(3):812–822. 10.1177/21925682221120644 Epub 2022 Aug 24. PMID: 36000332; PMCID: PMC10240596 Elder BD, Ishida W, Goodwin CR, Bydon A, Gokaslan ZL, Sciubba DM, Wolinsky JP, Witham TF (2017) Bone graft options for spinal fusion following resection of spinal column tumors: systematic review and meta-analysis. Neurosurg Focus. ;42(1):E16. 10.3171/2016.8.FOCUS16112 . PMID: 28041327 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 08 Jan, 2026 Reviews received at journal 07 Jan, 2026 Reviewers agreed at journal 07 Jan, 2026 Reviews received at journal 14 Jun, 2025 Reviewers agreed at journal 13 Jun, 2025 Reviewers invited by journal 13 Jun, 2025 Editor assigned by journal 11 Jun, 2025 Submission checks completed at journal 11 Jun, 2025 First submitted to journal 11 Jun, 2025 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. 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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-6868012","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":471281686,"identity":"e8aa4566-1a2a-4200-a0d2-71972a4d4faf","order_by":0,"name":"Alessandro Gasbarrini","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Alessandro","middleName":"","lastName":"Gasbarrini","suffix":""},{"id":471281687,"identity":"e99a25bf-b99d-462e-bd33-e49d3f1925d0","order_by":1,"name":"Chiara Cini","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvklEQVRIiWNgGAWjYDACCcYGMM3GwNj4IAHMIEFLswFYC0E9EggmmwRUM37AP7u58XNFDYM8n3RzW8WDinsMfPINBCy5c7BZ8swxBsM2mYNtNxLOFBN2mIFEYoNkAxtDAptEYtuNxLYEorQ0/2z4B9FSQKyWNsnGNogWBqK0SAAdY9nYJ2HYBrROIuFMAg8bWwJ+Lfwz0h/fbPhmIy8/I/3hxx8VCXLyzQcIWAO1DM7iIUr9KBgFo2AUjAL8AABGZThTYjNZTwAAAABJRU5ErkJggg==","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":true,"prefix":"","firstName":"Chiara","middleName":"","lastName":"Cini","suffix":""},{"id":471281688,"identity":"ce38199b-2dc5-4280-824d-74b5649f325b","order_by":2,"name":"Stefano Bandiera","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Stefano","middleName":"","lastName":"Bandiera","suffix":""},{"id":471281689,"identity":"b6d0d358-b2a1-409c-8451-100c3bb65494","order_by":3,"name":"Giovanni Barbanti 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Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Silvia","middleName":"","lastName":"Terzi","suffix":""},{"id":471281694,"identity":"37a596b5-424c-48ef-992e-b039da2c7035","order_by":7,"name":"Cristiana Griffoni","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Cristiana","middleName":"","lastName":"Griffoni","suffix":""},{"id":471281696,"identity":"1729d59e-d31a-467d-ab5b-a720e3ffd5f1","order_by":8,"name":"Gabriele Bilancia","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Gabriele","middleName":"","lastName":"Bilancia","suffix":""},{"id":471281699,"identity":"99a3275d-bebe-48bd-b2cb-3c793235260d","order_by":9,"name":"Loredana Mavilla","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Loredana","middleName":"","lastName":"Mavilla","suffix":""},{"id":471281700,"identity":"aaf4e248-9bd5-4c10-9498-6de4677b75b4","order_by":10,"name":"Giuseppe Tedesco","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Giuseppe","middleName":"","lastName":"Tedesco","suffix":""},{"id":471281701,"identity":"b3ab5f7e-cd93-4b28-b8a4-c99ff3c9df92","order_by":11,"name":"Riccardo Ghermandi","email":"","orcid":"","institution":"Istituto Ortopedico Rizzoli","correspondingAuthor":false,"prefix":"","firstName":"Riccardo","middleName":"","lastName":"Ghermandi","suffix":""}],"badges":[],"createdAt":"2025-06-11 05:23:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6868012/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6868012/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84858268,"identity":"51962e85-2bdc-4e41-a067-145d8139f910","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":141457,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(A,B,C). \u003c/strong\u003eHandling technique for preparation of graft material and surgical positioning.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/47d61b29e3a57cf5d94e919f.png"},{"id":84858267,"identity":"2a48c52f-96c5-474f-b87c-5b8b02b38a4d","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":121837,"visible":true,"origin":"","legend":"\u003cp\u003eReinforcement with Fiber Wires to the posterior instrumentation after positioning\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/c1f270f3171a9a2a493700a4.jpg"},{"id":84858271,"identity":"6c10aebb-f067-41f9-a265-0921839dae30","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":251177,"visible":true,"origin":"","legend":"\u003cp\u003eStage fusion between graft extremities and spinous processes above and below the posterior defect, according to the presence of cortical union and trabecular continuity\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/b171e429a8e1de4eb0b2ace7.png"},{"id":84859360,"identity":"524a6a32-6513-4517-bd89-5e755cb9554d","added_by":"auto","created_at":"2025-06-18 06:40:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":58833,"visible":true,"origin":"","legend":"\u003cp\u003eFusion assessment in the study population at different time of follow-up\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/e02d55082bd424f9d1adfb32.png"},{"id":84858270,"identity":"d5de1ca2-f841-4265-9064-58b41624eef6","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":120793,"visible":true,"origin":"","legend":"\u003cp\u003eFusion assessment according to adjuvant PBT (0= no PBT; 1= PBT).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/ee9b2e6a73cca7ece3c44f22.png"},{"id":84859363,"identity":"2fd6e443-7a4e-4cee-97ed-e6003fa46e9d","added_by":"auto","created_at":"2025-06-18 06:40:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":108605,"visible":true,"origin":"","legend":"\u003cp\u003eFusion assessment according to the type of posterior instrumentation (0=titanium; 1=CRF/PEEK).\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/9bbdc134d5938cc316c0c025.png"},{"id":84858278,"identity":"83d21db9-ee89-40d5-8fa0-c1b69e49d883","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":126138,"visible":true,"origin":"","legend":"\u003cp\u003ePosterior graft fusion assessment according to graft length (subdivided into three groups).\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/533ae3eb5e4de56e0faf1e14.png"},{"id":84858275,"identity":"82e8b220-a3d0-420f-9ef0-fe4ec3736eda","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":17744,"visible":true,"origin":"","legend":"\u003cp\u003eGrade III graft fusion at 6 months of follow-up\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/a1d5dad5e03071e8180beedc.jpg"},{"id":84859365,"identity":"51bf3cfc-4a3a-478c-aa9d-354d12492aa8","added_by":"auto","created_at":"2025-06-18 06:40:12","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":197636,"visible":true,"origin":"","legend":"\u003cp\u003eGrade IV graft fusion after 12 months of follow-up.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/3cc94d20b7ab33c9f18ac12b.png"},{"id":84858282,"identity":"86b610a4-0992-4029-8de5-b46a498f8483","added_by":"auto","created_at":"2025-06-18 06:32:12","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":3186380,"visible":true,"origin":"","legend":"\u003cp\u003eRevision surgery for local recurrence.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/4e8c671f0c2f2ab0c69dcd05.png"},{"id":84861051,"identity":"96229fa6-55cb-4f09-b2b0-2cd59cfb6a00","added_by":"auto","created_at":"2025-06-18 06:56:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4686441,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6868012/v1/8bbcb923-a780-4bc4-8c7e-6d6401b8e93b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eThe Roof Technique in the Treatment of Bone Tumors of the Spine. A Ten Years’ Experience\u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eEnbloc resection is a validated procedure in the treatment of benign aggressive and malignant bone tumor of the spine [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. This procedure was popularised by RoyCamille [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and Tomita [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Later on, the literature was progressively populated by many single case reports [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] and cohort studies (7, 8), summarised in systematic reviews [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe Weinstein-Boriani-Biagini (WBB) surgical system was introduced in 1997 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] to classify the extension of spine tumors and supported the surgical planning of en bloc resection. Recently a staging system was proposed to standardise the technique according to tumor extension [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBut the pioneer of this procedure was Bertil Stener [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], who many years before applied to the spine the concepts of the treatment of malignant tumor of other systems. From his design, reported in his papers, we can understand how huge the soft tissue sacrifice is required for a tumor-free margin enbloc resection. For these reasons, besides appropriate oncological principles for resection, these procedures require complex reconstructive techniques.\u003c/p\u003e \u003cp\u003eDuring the last years the advances of surgical techniques have been accompanied by the development of adjuvant cancer therapies and radiotherapy, in particular charged-particle therapy (proton beam therapy and carbon ion therapy), allowing improved survival rates for patients undergoing spinal tumor resection. With the increase of survival, the efficacy of reconstruction is relevant in order to avoid complications and instrumentation failures. For the anterior column reconstruction different techniques are reported, including vascularized or nonvascularized graft strut, titanium cage systems (also 3D-printed custom-made prosthesis), stackable carbon cage system and PMMA [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, the unique regional and morphological characteristics of each primary spine tumor prevent a generic approach to anterior and posterior column reconstruction and what are the best reconstructive options is still debated: most previous studies focused more on the oncology related prognosis and only briefly reported structural outcomes and fusion rates [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Few reports analyzed the use of iliac crest autograft, morcelized allograft or bone graft substitutes for posterior fusion: Lewis et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] described one case of vascularized and three cases of nonvascularized rib autograft struts for posterior reconstruction. Literature data have been summarized in a recent review reporting consensus expert opinion about reconstructive techniques [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of the present study is to evaluate the efficacy of using a bone graft for posterior column defects after en bloc resection for primary tumors.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eThis retrospective observational study was approved by the local Ethics Committee on November 2024 (PG nr. 0017319, 29/11/2024). About 300 patients with primary spinal tumors were treated with en bloc resection from January 2009 to January 2024 at our referral center. We included in our analysis 30 patients who underwent posterior column reconstruction after en bloc resection at our Institution from 2015 to 2024 according to these inclusion criteria: age\u0026thinsp;\u0026gt;\u0026thinsp;18 years, mobile spine lesions (C1-L5), diagnosis of primary tumor confirmed preoperatively by CT-guided trocar biopsy, en bloc resection according to Enneking appropriateness and a minimum of 1 year of outpatient follow-up. Patients who underwent previous surgery including incisional biopsy were excluded. In all cases, whole-spine MRI, CT scan and total-body FDG- PET were performed to define oncological assessment. All patients were classified according to Weinstein-Boriani-Biagini score [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] before undergoing en bloc resection. Surgical resection was defined as en bloc (wide or marginal, R0 margins) when the tumor was removed in a single piece encased by healthy tissue. The pathologists\u0026rsquo; assessments of the overall margin were documented as marginal margin referring to dissection within the pseudocapsule or reactive zone, while as wide margin referring to a plane of resection within normal tissue. Intralesional margin (R1 margins) implied that the plane of dissection has transgressed into the lesion involving residual macroscopic tumor. Furthermore, the number of surgical stages (categorized as 1 or \u0026ge;\u0026thinsp;2) and surgical approach (anterior, posterior, or simultaneous) of each procedure were collected for each patient.\u003c/p\u003e \u003cp\u003eIn all cases, the resected anterior column was reconstructed with 3D-printed custom-made prosthesis, titanium mesh cages (TMC) or Polyetheretherketone/Carbon fiber (PEEK/CF) Vertebral Body Replacement (VBR). Posterior fixation was realized with Titanium implant or with Carbon Fiber reinforced PEEK instrumentation.\u003c/p\u003e \u003cp\u003eIn regions where the posterior elements were completely resected, a structural fresh-frozen autologous bone graft was placed to span the defect and cover spinal cord, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The length of the defect created posteriorly on the side of the resection was measured and an oversized length of a fresh frozen autograft was harvested in the field of surgery. In particular, fashioned bone graft was prepared with saddle cuts on its proximal and distal end to sit on the surface of the corresponding extremities of the spinous process delimiting the posterior resection above and below the posterior column defect. As we previously described [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], the \u0026ldquo;roof\u0026rdquo; was anchored to posterior instrumentation with sublaminar bands and reinforced with Fiber Wires to ensure more stability (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Generally, a gentle compression to posterior instrumentation was applied to improve correspondence.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePosterior fusion graft assessment was performed using CT scans with multiplanar reconstruction (MPRs) at 6 months, 12 months, and at the last follow-up. Considering that the Creeping substi- tution begins at the graft-host junction and then moves along the axis of the cortical graft, fusion status at the two extremities of the graft in contact with the spinous processes was recorded according to four grades: complete fusion -Grade IV (cortical union of the strutgraft with spinous process central trabecular continuity), partial fusion -Grade III (cortical union with partial trabecular incorporation), unipolar pseudarthrosis, and bipolar pseudarthrosis -Grade II and I respectively (central trabecular discontinuity with superior or inferior cortical non-union, or both, along with a complete lack of central trabecular continuity, respectively) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eData on additional hadron therapy were recorded during outpatient\u0026rsquo;s follow-up. At every follow-up information regarding mechanical complication and surgical infection was collected. Oncological status at the final follow-up was registered for every patient.\u003c/p\u003e \u003cp\u003eThe primary endpoint of our study was to demonstrate that the \u0026ldquo;roof\u0026rdquo; technique protects the spinal cord and avoid creation of adherent scar. The second end point was to demonstrate that the structural graft allows immediate and long-term stabilization of the posterior column defect created by the en bloc tumor resection and enhances the fusion bed with the adjacent spinous processes in a setting of biological compromise due to the large bone and soft tissue voids after surgery.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eThe statistical analysis was conducted using Microsoft Excel for database creation and management, while RStudio (version 2025.05.0 Build 496) was employed for data processing and statistical tests. The dataset includes a total of 29 patients (15 women and 14 men) with 77 clinical variables, encompassing parameters related to bone fusion across different follow-ups.\u003c/p\u003e \u003cp\u003eTo assess the normality of the analyzed distributions, the Shapiro-Wilk test was applied. In cases where normality was not met, non-parametric tests were chosen to ensure the robustness of the analyses.\u003c/p\u003e \u003cp\u003eFor the comparison of bone fusion progression over time, the Fisher\u0026rsquo;s exact test was used. This test is especially effective for small sample sizes, allowing comparisons between categorical groups without the constraints imposed by the Chi-square test. The statistical significance threshold was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eAll analyses were performed following principles of methodological rigor and statistical reproducibility. Marginally significant results were interpreted with caution, considering the limited number of observations available.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 30 patients were included in our analysis. The median age in our population was 48.55\u0026thinsp;\u0026plusmn;\u0026thinsp;17.04 and the majority of patients were female (15 [53.33%]). The most common histological diagnosis was cordoma (36.67%). No patients had metastasis at the time of index surgery. The most common location of primary tumor was the lumbar spine (43.33%). All patients underwent preoperative CT guided trocar biopsy and received preoperative arterial selective embolization (SAE). 12 patients (40%) underwent a single-stage posterior procedure while 18 (60%) patients underwent surgery in two stages. For those who underwent multistage surgery, the anterior approach was most commonly performed as the first stage (16 [88.89%] patients), followed by posterior approach as first stage (2 [11.11%]). Overall, marginal or wide margins were attained in 21 (70.0%) patients, in 9 (30.0%) cases the final anatomopathological analysis demonstrated focal transgression with intralesional margins.\u003c/p\u003e\n\u003cp\u003eDescriptive analysis of our population and tumor characteristics are shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eThe mean length of the graft was 11.47\u0026thinsp;\u0026plusmn;\u0026thinsp;4.03 cm, and the mean construct spanned 6.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0 vertebral levels. Graft characteristics in our population are shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eTumor characteristics and Treatments.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePrimary tumor\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eLevel Involved\u0026thinsp;\u0026gt;\u0026thinsp;1\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eAdjuvant Hadron-Therapy\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eCordoma\u003c/p\u003e\n\u003cp\u003eChondrosarcoma\u003c/p\u003e\n\u003cp\u003eGigant Cell Tumor\u003c/p\u003e\n\u003cp\u003eOsteoblastoma\u003c/p\u003e\n\u003cp\u003eOsteosarcoma\u003c/p\u003e\n\u003cp\u003eEwing sarcoma\u003c/p\u003e\n\u003cp\u003eEpitheliod Hemangioma\u003c/p\u003e\n\u003cp\u003eHemangioendothelioma\u003c/p\u003e\n\u003cp\u003eAneurismatic Bone Cyst\u003c/p\u003e\n\u003cp\u003eDesmoplastic Fibroma\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11\u003c/p\u003e\n\u003cp\u003e4\u003c/p\u003e\n\u003cp\u003e3\u003c/p\u003e\n\u003cp\u003e3\u003c/p\u003e\n\u003cp\u003e3\u003c/p\u003e\n\u003cp\u003e2\u003c/p\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003cp\u003e1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eCervical 4\u003c/p\u003e\n\u003cp\u003eLumbar 2\u003c/p\u003e\n\u003cp\u003eThoracic 2\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTumor Location\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCervical 6\u003c/p\u003e\n\u003cp\u003eLumbar 13\u003c/p\u003e\n\u003cp\u003eThoracic 9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eNo Hadron Therapy 11\u003c/p\u003e\n\u003cp\u003eProton Beam Therapy (PBT) 9\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnterior Column Reconstruction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTitanium mesh cage 13\u003c/p\u003e\n\u003cp\u003ePEEK/CF VBR 14\u003c/p\u003e\n\u003cp\u003e3D-printed custom-made\u003c/p\u003e\n\u003cp\u003eProsthesis 1\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eBone graft details\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eMean length of the graft\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003e11.47\u0026thinsp;\u0026plusmn;\u0026thinsp;4.03 cm\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eMean length of resected vertebrae\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4.32\u0026thinsp;\u0026plusmn;\u0026thinsp;2.55 cm\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eLength of spinal shortening\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8 cm\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eMean construct span\u003c/strong\u003e (vertebral levels)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eCutting line of resection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDisc\u003c/p\u003e\n\u003cp\u003eVertebra\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e20 (66.6%)\u003c/p\u003e\n\u003cp\u003e10 (33.3%)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eComplete posterior graft fusion was achieved in 11 patients (36.67%, p\u0026thinsp;=\u0026thinsp;0.32) at six months of follow-up while 16 patients (53.33%, p\u0026thinsp;=\u0026thinsp;0.25) achieved partial fusion at the first follow-up. 28 patients achieved grade I graft fusion at the final follow-up (mean 56.38\u0026thinsp;\u0026plusmn;\u0026thinsp;23.40 months, p\u0026thinsp;=\u0026thinsp;0.18) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). Among the 9 patients who were treated with PBT with a mean prescription dose of 50\u0026ndash;54 Gy (RBE) in 25\u0026ndash;27 fractions within 25 weeks from index surgery, complete fusion was observed in all cases at the last follow-up and was already achieved at six months intermediate follow-up. No difference in time to final fusion was found compared to patients who did not undergo radiation therapy (9 [100%] vs 19 [90.48%], p\u0026thinsp;=\u0026thinsp;1.00) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e). All patients with PEEK/CF instrumentation achieved bone fusion at the last follow-up and no difference was observed between PEEK/CF instrumentation and Titanium instrumentation at each time of follow-up (12 [100%] vs 15 [88.24%] respectively, p\u0026thinsp;=\u0026thinsp;1.00) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e). Moreover, no statistically significant difference was observed in fusion grade at the last follow-up according to the length of the posterior graft, as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eGrade III and Grade IV graft fusions assessed by CT scan are shown in Figs.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eA rod fracture, without evidence of graft dislodgment, occurred only in one patient who underwent revision surgery at 20 months of follow-up. 3 (3%) patients experienced wound infections treated with DAIR without affecting the final degree of fusion. The last clinical and radiographic follow-up with a mean of months (\u0026plusmn;) showed no evidence of graft dislodgment or increased axial pain. In 4 patients there was evidence of local recurrence (LR) within 12\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4 months of followup. In one case a revision surgery for decompression was required at 11 months of follow-up (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eIn the reconstruction of the spine after total spondylectomy, allogenic strutgraft are frequently used to restore the continuity of the anterior column [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In a systematic literature review combined with consensus expert opinion, to provide recommendations on reconstructive constructs after complete vertebrectomy [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] no mention is reported on the role of posterior allograft. Apparently, no significant mechanical advantage can be expected by a posteriorly located strutgraft, as Wolff\u0026rsquo;s law (published in 1892 and still unchallenged) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] declares that bone growth is enhanced under pressure and reabsorbed under tension. As it is known that 80% of load is supported anteriorly and 20% posteriorly [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], it is justified to position a strut graft anteriorly and implant a posterior fixation system posteriorly in compression: as a consequence the posterior tensile stresses are expected to be converted into anterior compressive stresses, in order to facilitate osteointegration of anterior graft, either strutgraft or cancellous bone inside cage, preventing stress shielding. The technique here reported is apparently in contradiction to other validated experiences. It is proposed to include in the 360 degrees reconstruction -after total spondylectomy- a posterior strut graft, in addition to posterior fixation (at least two levels above and two levels below) and to anterior reconstruction according to the surgeon\u0026rsquo;s preferences (cage and graft, instrumented strut graft, 3D printed prosthesis).\u003c/p\u003e \u003cp\u003eThe posterior allograft is a specifically shaped semi-circular segment of frozen femoral shaft and the rationale of this technique is based on the experience of a single team performing enbloc resection for bone tumors of the spine. Complete spondylectomy -performed for enbloc tumor resection- includes not only bone, joints, discs, but also extensive sacrifice of soft tissues (notably muscles, and fasciae). The result is not only a full instability, but also a complete disruption of anatomical compartments which leaves a huge empty cavity around the thecal sac, frequently uncovered under the skin. Plastic surgery is frequently required for safe soft tissue reconstruction, even by muscle flaps [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. A critical review of complications related to lack of protection of posterior dura and residual scar tissue suggested to look for a solution [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. In 2015 the first \u0026ldquo;roof technique\u0026rdquo; was used as a possible solution to implant a semicircular femoral shaft graft interposed between the residual spinous processes, like a roof over the theca sac. This technique was named \u003cem\u003eroof technique\u003c/em\u003e and till now only proposed during meeting discussion, waiting for middle-long term results before submission for publication on a scientific paper.\u003c/p\u003e \u003cp\u003eThe results here reported show that there was no evidence of graft dislodgment at the final follow-up in our population.\u003c/p\u003e \u003cp\u003eMoreover, the majority of patients achieved complete fusion at the final follow-up and this result is in line with Lewis et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] who demonstrated that serial CT scans at a minimum of 6 months showed fusion of the posterolateral autologous rib graft in all 11 surviving cases. We did not find any difference in time to fusion between patients who were treated with adjuvant PBT and patients who did not receive adjunctive therapies at the final follow-up and this is in contrast with the current literature. Infact, Elder et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] demonstrated in their systematic review that the average time to fusion of patients who received RT were longer than those who did not receive adjunctive treatments (RT: 6.1 months vs 4.3 months, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, p\u0026thinsp;=\u0026thinsp;0.02) [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. No additional imaging procedures were performed on patients to evaluate the graft fusion because the first aim of our study was to evaluate the advantages of recreating the tridimensionality of a virtual vertebral canal and to avoid the creation of the scar close to the dura after surgery. Therefore, it is impossible to draw any more precise judgments about the grafts' incorporation time into the spinous processes.\u003c/p\u003e \u003cp\u003eOur study is the first description of a posterior reconstructive technique after en bloc resection inclusive of a complete posterior frozen allograft. Further studies are necessary to evaluate the role of the roof for posterior reconstruction in relation to anterior subsidence and proximal junctional failure.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe \u0026ldquo;roof technique\u0026rdquo; consists on implanting a semicircular femoral shaft strutgraft (frozen allograft) between the residual spinous process above and below the resected vertebrae. The graft is shaped to be stuck under the longitudinal pressure applied by the posterior instrumentation.\u003c/p\u003e \u003cp\u003eThe main porpuses are:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eProtection of the dura;\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAvoiding adherent scar (in case of revision the most severe cause of dural tear);\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eCreating a safe zone around the sac useful for radiotherapists in planning high dose radiotherapy close to the dura.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eSurprisingly, in the middle term follow-up evident fusion was found between the extremity of the graft and the spinous processes. This innovative technique of fashioning the graft posteriorly allows for both early and long-term stability. Additionally, in case of local recurrence, it avoids direct exposure of the spinal cord if revision surgery is needed.\u003c/p\u003e"},{"header":"Declarations","content":"\n\u003cp\u003eThe authors declare they have no financial and non-financial interests that are directly or indirectly related to the work submitted for publication. No funding was received for this research.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eConceptualization: Alessandro Gasbarrini, Chiara Cini. Methodology: Gasbarrini Alessandro, Cini Chiara, Valerio Pipola Validation Stefano Bandiera, Riccardo Ghermandi. Formal Analysis Gabriele Bilancia, Loredana Mavilla. Investigation Alessandro Gasbarrini, Chiara Cini, Silvia Terzi, Gisberto Evangelisti, Cristiana Griffoni, Giovanni Barbanti Brodano, Giuseppe Tedesco. Resources Alessandro Gasbarrini, Chiara Cini, Stefano Bandiera Writing original draft Alessandro Gasbarrini, Chiara Cini. Writing- Review \u0026amp; Editing Cristiana Griffoni, Loredana Mavilla. Visualization: Alessandro Gasbarrini, Giuseppe Tedesco. Supervision: Alessandro Gasbarrini, Chiara Cini, Riccardo Ghermandi, Stefano Bandiera\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eEnneking WF (1983) Muscoloskeletal Tumor Surgery. New York: Churchill Livingstone, :69\u0026ndash;122\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoy-Camille R, Saillant G, Mazel CH, Monpierre H (1990) Total vertebrectomy as treatment of malignant tumors of the spine. Chir Organi Mov 75(1 Suppl):94\u0026ndash;96 PMID: 2249570\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMurakami H, Kawahara N, Abdel-Wanis ME, Tomita K (2001) Total en bloc spondylectomy. Semin Musculoskelet Radiol. ;5(2):189\u0026thinsp;\u0026ndash;\u0026thinsp;94. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/s-2001-15679\u003c/span\u003e\u003cspan address=\"10.1055/s-2001-15679\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 11500165\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHardes J, Gosheger G, Halm H, Winkelmann W, Liljenqvist U (2003) Three-level en bloc spondylectomy for desmoplastic fibroma of the thoracic spine: a case report. Spine (Phila Pa 1976). ;28(9):E169-72. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.BRS.0000058730.55078.5E\u003c/span\u003e\u003cspan address=\"10.1097/01.BRS.0000058730.55078.5E\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 12942020\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSamartzis D, Marco RA, Benjamin R, Vaporciyan A, Rhines LD (2005) Multilevel en bloc spondylectomy and chest wall excision via a simultaneous anterior and posterior approach for Ewing sarcoma. Spine (Phila Pa 1976). ;30(7):831-7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.brs.0000158226.49729.6c\u003c/span\u003e\u003cspan address=\"10.1097/01.brs.0000158226.49729.6c\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 15803089\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBiagini R, Casadei R, Boriani S, Erba F, Sturale C, Mascari C, Bortolotti C, Mercuri M (2003) En bloc vertebrectomy and dural resection for chordoma: a case report. Spine (Phila Pa 1976). ;28(18):E368-72. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.BRS.0000084644.84095.10\u003c/span\u003e\u003cspan address=\"10.1097/01.BRS.0000084644.84095.10\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 14501938\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHasegawa K, Homma T, Hirano T, Ogose A, Hotta T, Yajiri Y, Nagano J, Inoue Y (2007) Margin-free spondylectomy for extended malignant spine tumors: surgical technique and outcome of 13 cases. Spine (Phila Pa 1976). ;32(1):142-8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.brs.0000251045.79708.7a\u003c/span\u003e\u003cspan address=\"10.1097/01.brs.0000251045.79708.7a\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 17202906\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTeng H, Xinghai Y, Wei H, Huang Q, Xiao J, Zhang C (2011) Malignant fibrous histiocytoma of the spine: a series of 13 clinical case reports and review of 17 published cases. Spine (Phila Pa 1976) 36(22):E1453\u0026ndash;E1462. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/BRS.0b013e318203e292\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e318203e292\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003ePMID: 21343863\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYamazaki T, McLoughlin GS, Patel S, Rhines LD, Fourney DR, the Spine Oncology Study Group (2009) Feasibility and safety of en bloc resection for primary spine tumors: a systematic review by. Spine (Phila Pa 1976). ;34(22 Suppl):S31-8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/BRS.0b013e3181b8b796\u003c/span\u003e\u003cspan address=\"10.1097/BRS.0b013e3181b8b796\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 19829275\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoriani S, Weinstein JN, Biagini R (1997) Primary bone tumors of the spine. Terminology and surgical staging. Spine (Phila Pa 1976) 22:1036\u0026ndash;1044\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoriani S (2018) En bloc resection in the spine: a procedure of surgical oncology. J Spine Surg 4(3):668\u0026ndash;676\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStener B (1989) Complete removal of vertebrae for extirpation of tumors. A 20-year experience. Clin Orthop Relat Res. ;(245):72\u0026ndash;82. PMID: 2752635.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen J, Zhai S, Zhou H, Hu P, Liu X, Liu Z, Liu X, Li Y, Li Z, Wei F (2023) Implant Materials for Anterior Column Reconstruction of Cervical Spine Tumor. Orthop Surg 15(5):1219\u0026ndash;1227\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFidler MW (1994) Radical resection of vertebral body tumours. A surgical technique used in ten cases. J Bone Joint Surg Br 76:765\u0026ndash;772\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang L, Chen K, Ye JC et al (2013) Modified total en bloc spondylectomy for thoracolumbar spinal tumors via a single posterior approach. Eur Spine J 22:556\u0026ndash;564\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFourney DR, Abi-Said D, Rhines LD et al (2001) Simultaneous anterior- posterior approach to the thoracic and lumbar spine for the radical resection of tumors followed by reconstruction and stabilization. J Neurosurg 94(2 suppl):232\u0026ndash;244\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLewis SJ, Kulkarni AG, Rampersaud YR et al (2012) Posterior column reconstruction with autologous rib graft after en bloc tumor excision. Spine (Phila Pa 1976) 37:346\u0026ndash;350\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGlennie RA, Rampersaud YR, Boriani S, Reynolds JJ, Williams R, Gokaslan ZL, Schmidt MH, Varga PP, Fisher CG (2016) A Systematic Review With Consensus Expert Opinion of Best Reconstructive Techniques After Osseous En Bloc Spinal Column Tumor Resection. Spine (Phila Pa 1976) 41(Suppl 20):S205\u0026ndash;S211\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Ruiter GCW, Pipola V, Griffoni C, Gasbarrini A (2021) Sublaminar bands in oncological spine surgery: illustrative cases. J Neurosurg Case Lessons 1(21):CASE21111. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/CASE21111\u003c/span\u003e\u003cspan address=\"10.3171/CASE21111\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003ePMID: 35854866; PMCID: PMC9245747\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLewandrowski KU, Hecht AC, DeLaney TF, Chapman PA, Hornicek FJ, Pedlow FX (2004) Anterior spinal arthrodesis with structural cortical allografts and instrumentation for spine tumor surgery. Spine (Phila Pa 1976). ;29(10):1150-8; discussion 1159. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/00007632-200405150-00019\u003c/span\u003e\u003cspan address=\"10.1097/00007632-200405150-00019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 15131446\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElder BD, Ishida W, Goodwin CR, Bydon A, Gokaslan ZL, Sciubba DM, Wolinsky JP, Witham TF (2017) Bone graft options for spinal fusion following resection of spinal column tumors: systematic review and meta-analysis. Neurosurg Focus. ;42(1):E16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2016.8.FOCUS16112\u003c/span\u003e\u003cspan address=\"10.3171/2016.8.FOCUS16112\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 28041327\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWolff Julius Das Gesetz der Transformation der Knochen. 1892 Hirschwald (Berlin)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAulisa L, Pitta L, Padua R, Ceccarelli E, Aulisa A, Leone A (2000 Jan-Mar) Biomechanics of the spine. Rays 25(1):11\u0026ndash;18 English, Italian. PMID: 10967631\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoriani S, Bandiera S, Donthineni R, Amendola L, Cappuccio M, De Iure F, Gasbarrini A (2010) Morbidity of en bloc resections in the spine. Eur Spine J. ;19(2):231\u0026thinsp;\u0026ndash;\u0026thinsp;41. doi: 10.1007/s00586-009-1137-z. Epub 2009 Aug 19. PMID: 19690899; PMCID: PMC2899819\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Z, Guo L, Zhang P, Wang J, Wang X, Yao W (2023) A Systematic Review of Perioperative Complications in en Bloc Resection for Spinal Tumors. Global Spine J 13(3):812\u0026ndash;822. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1177/21925682221120644\u003c/span\u003e\u003cspan address=\"10.1177/21925682221120644\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003eEpub 2022 Aug 24. PMID: 36000332; PMCID: PMC10240596\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElder BD, Ishida W, Goodwin CR, Bydon A, Gokaslan ZL, Sciubba DM, Wolinsky JP, Witham TF (2017) Bone graft options for spinal fusion following resection of spinal column tumors: systematic review and meta-analysis. Neurosurg Focus. ;42(1):E16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2016.8.FOCUS16112\u003c/span\u003e\u003cspan address=\"10.3171/2016.8.FOCUS16112\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID: 28041327\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"primary spinal tumors, en bloc resection, bone defects, posterior column reconstruction, bone graft","lastPublishedDoi":"10.21203/rs.3.rs-6868012/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6868012/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eIntroduction: \u003c/strong\u003eBesides appropriate oncological principles for resection, spine tumors require complex reconstructive techniques in a setting of biologic compromise. Fusion outcomes in this cohort are influenced by several variables. Most previous studies focused more on the oncology related prognosis and only briefly reported on fusion rates and instrumentation failure. The aim of our study was to evaluate the efficacy of using bone graft for fusion across long posterior column defects after en bloc resection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterial and Methods: \u003c/strong\u003eThis retrospective observational study analyzed 30 patients with primary spinal tumors who underwent posterior column reconstruction after en bloc resections. In all cases, the resected anterior column was reconstructed with 3D-printed custom-made prosthesis, titanium mesh cages (TMC) or Polyetheretherketone/Carbon fiber (PEEK/CF) Vertebral Body Replacement (VBR). In regions where the posterior elements were completely resected, a structural fresh-frozen allograft or autologous bone graft was placed to span the defect and cover spinal cord. Fashioned bone graft was prepared with saddle cuts on its proximal and distal end to sit on the surface of the extremities of the spinous processes anchored to posterior instrumentation with sublaminar bands. Posterior fusion graft assessment was performed using CT scans with multiplanar reconstruction (MPRs) at 6 months, 12 months, and at the last follow-up. Fusion status was recorded according to four grades: complete fusion (cortical union of the structural allograft with central trabecular continuity), partial fusion (cortical union with partial trabecular incorporation), unipolar pseudarthrosis and bipolar pseudarthrosis (central trabecular discontinuity with superior or inferior cortical non-union, or both, along with a complete lack of central trabecular continuity, respectively).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eComplete posterior graft fusion was achieved in 11 patients (36.67%, p=0.32) at six months of follow-up while 16 patients (53.33%, p=0.25) achieved partial fusion at the first follow-up. 28 patients achieved grade I graft fusion at the final follow-up (mean 56.38 ± 23.40 months, p=0.18). A rod fracture, without evidence of graft dislodgment, occurred only in one patient who underwent revision surgery at 20 months of follow-up. 3 (3%) patients experienced wound infections treated with DAIR without affecting the final degree of fusion. The last clinical and radiographic follow-up with a mean of months (±) showed no evidence of graft dislodgment or increased axial pain. In 4 patients there was evidence of local recurrence (LR) within 12 ± 3.4 months of followup. In one case a revision surgery for decompression was required at 11 months of follow-up.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e This innovative technique of fashioning the graft posteriorly allows for both early and long-term stability with solid fusion. Additionally, in case of revision surgery for local recurrence, it avoids direct exposure of the spinal cord.\u003c/p\u003e","manuscriptTitle":"The Roof Technique in the Treatment of Bone Tumors of the Spine. A Ten Years’ Experience","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-18 06:32:07","doi":"10.21203/rs.3.rs-6868012/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-08T17:17:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-07T14:00:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"330372951927017349603875187465250691646","date":"2026-01-07T13:48:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-14T13:47:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"319749084879714248857282632395798908989","date":"2025-06-13T14:06:18+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-13T12:08:20+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-11T11:27:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-11T11:26:02+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Spine Journal","date":"2025-06-11T05:12:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ad67a7f9-83b6-4807-9956-ecf0f890365b","owner":[],"postedDate":"June 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-19T18:08:32+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-18 06:32:07","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6868012","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6868012","identity":"rs-6868012","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}