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Long-term posterolateral spinal fusion in rabbits induced by rhBMP6 applied in autologous blood coagulum with synthetic ceramics. Sci Rep 2022; 12:11649. [PMID: 35803983 PMCID: PMC9270325 DOI: 10.1038/s41598-022-14931-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 06/15/2022] [Indexed: 11/21/2022] Open
Abstract
Autologous bone graft substitute (ABGS) containing rhBMP6 in autologous blood coagulum (Osteogrow) is a novel therapeutic solution for bone regeneration. This study is aimed to investigate the long-term outcome of ABGS with synthetic ceramics (Osteogrow-C) in rabbit posterolateral spinal fusion (PLF) model. Osteogrow-C implants were implanted bilaterally between rabbit lumbar transverse processes. We compared the outcome following implantation of ABGS with ceramic particles of different chemical composition (TCP and biphasic ceramics containing both TCP and HA) and size (500–1700 µm and 74–420 µm). Outcome was analyzed after 14 and 27 weeks by microCT, histology, and biomechanical analyses. Successful bilateral spinal fusion was observed in all animals at the end of observation period. Chemical composition of ceramic particles has impact on the PLF outcome via resorption of TCP ceramics, while ceramics containing HA were only partially resorbed. Moreover, persistence of ceramic particles subsequently resulted with an increased bone volume in implants with small particles containing high proportion of HA. ABGS (rhBMP6/ABC) with various synthetic ceramic particles promoted spinal fusion in rabbits. This is the first presentation of BMP-mediated ectopic bone formation in rabbit PLF model with radiological, histological, and biomechanical features over a time course of up to 27 weeks.
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Bone Morphogenetic Proteins, Carriers, and Animal Models in the Development of Novel Bone Regenerative Therapies. MATERIALS 2021; 14:ma14133513. [PMID: 34202501 PMCID: PMC8269575 DOI: 10.3390/ma14133513] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/26/2022]
Abstract
Bone morphogenetic proteins (BMPs) possess a unique ability to induce new bone formation. Numerous preclinical studies have been conducted to develop novel, BMP-based osteoinductive devices for the management of segmental bone defects and posterolateral spinal fusion (PLF). In these studies, BMPs were combined with a broad range of carriers (natural and synthetic polymers, inorganic materials, and their combinations) and tested in various models in mice, rats, rabbits, dogs, sheep, and non-human primates. In this review, we summarized bone regeneration strategies and animal models used for the initial, intermediate, and advanced evaluation of promising therapeutical solutions for new bone formation and repair. Moreover, in this review, we discuss basic aspects to be considered when planning animal experiments, including anatomical characteristics of the species used, appropriate BMP dosing, duration of the observation period, and sample size.
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Štoković N, Ivanjko N, Pećin M, Erjavec I, Karlović S, Smajlović A, Capak H, Milošević M, Bubić Špoljar J, Vnuk D, Matičić D, Oppermann H, Sampath TK, Vukičević S. Evaluation of synthetic ceramics as compression resistant matrix to promote osteogenesis of autologous blood coagulum containing recombinant human bone morphogenetic protein 6 in rabbit posterolateral lumbar fusion model. Bone 2020; 140:115544. [PMID: 32730919 DOI: 10.1016/j.bone.2020.115544] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/24/2022]
Abstract
Posterolateral lumbar fusion (PLF) is a commonly performed surgical procedure for the treatment of pathological conditions of the lumbosacral spine. In the present study, we evaluated an autologous bone graft substitute (ABGS) containing rhBMP6 in autologous blood coagulum (ABC) and synthetic ceramics used as compression resistant matrix (CRM) in the rabbit PLF model. In the pilot PLF rabbit experiment, we tested four different CRMs (BCP 500-1700 μm, BCP 1700-2500 μm and two different TCP in the form of slabs) which were selected based on achieving uniform ABC distribution. Next, ABGS implants composed of 2.5 mL ABC with 0.5 g ceramic particles (TCP or BCP (TCP/HA 80/20) of particle size 500-1700 μm) and 125 μg rhBMP6 (added to blood or lyophilized on ceramics) were placed bilaterally between transverse processes of the lumbar vertebrae (L5-L6) following exposition and decortication in 12 New Zealand White Rabbits observed for 7 weeks following surgery. Spinal fusion outcome was analysed by μCT, palpatory segmental mobility testing and selected specimens were either tested biomechanically (three-point bending test) and/or processed histologically. The total fusion success rate was 90.9% by both μCT analyses and by palpatory segmental mobility testing. The volume of newly formed bone between experimental groups with TCP or BCP ceramics and the different method of rhBMP6 application was comparable. The newly formed bone and ceramic particles integrated with the transverse processes on histological sections resulting in superior biomechanical properties. The results were retrospectively found superior to allograft devitalized mineralized bone as a CRM as reported previously in rabbit PLF. Overall, this novel ABGS containing rhBMP6, ABC and the specific 500-1700 μm synthetic ceramic particles supported new bone formation for the first time and successfully promoted posterolateral lumbar fusion in rabbits.
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Affiliation(s)
- Nikola Štoković
- Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia; Scientific Center of Excellence for Reproductive and Regenerative Medicine, Zagreb, Croatia
| | - Natalia Ivanjko
- Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia; Scientific Center of Excellence for Reproductive and Regenerative Medicine, Zagreb, Croatia
| | - Marko Pećin
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Igor Erjavec
- Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia; Scientific Center of Excellence for Reproductive and Regenerative Medicine, Zagreb, Croatia
| | - Sven Karlović
- Faculty of Food Technology and Biotechnology, University of Zagreb, Zagreb, Croatia
| | - Ana Smajlović
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Hrvoje Capak
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Milan Milošević
- Department for Environmental Health, Occupational and Sports Medicine, Andrija Štampar School of Public Health, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Jadranka Bubić Špoljar
- Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia; Scientific Center of Excellence for Reproductive and Regenerative Medicine, Zagreb, Croatia
| | - Dražen Vnuk
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | - Dražen Matičić
- Clinics for Surgery, Orthopedics and Ophthalmology, School of Veterinary Medicine, University of Zagreb, Zagreb, Croatia
| | | | | | - Slobodan Vukičević
- Laboratory for Mineralized Tissues, School of Medicine, University of Zagreb, Zagreb, Croatia; Scientific Center of Excellence for Reproductive and Regenerative Medicine, Zagreb, Croatia.
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Holmes CA, Ishida W, Elder BD, Lo SFL, Chen YA, Kim E, Locke J, Taylor M, Witham TF. The Effects of High-Dose Parathyroid Hormone Treatment on Fusion Outcomes in a Rabbit Model of Posterolateral Lumbar Spinal Fusion Alone and in Combination with Bone Morphogenetic Protein 2 Treatment. World Neurosurg 2018; 115:e366-e374. [DOI: 10.1016/j.wneu.2018.04.058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 04/07/2018] [Accepted: 04/09/2018] [Indexed: 01/21/2023]
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Liu Z, Zhu Y, Zhu H, He X, Liu X. Enhancement of posterolateral lumbar spine fusion using recombinant human bone morphogenetic protein-2 and mesenchymal stem cells delivered in fibrin glue. J Biomater Appl 2016; 31:477-487. [PMID: 27059496 DOI: 10.1177/0885328216643854] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mesenchymal stem cells have shown great potential for accelerating bone healing. In the present study, we evaluate the efficacy of fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 composite for posterolateral spinal fusion in a rabbit model. Forty adult rabbits underwent posterolateral intertransverse fusion at the L5–L6 level. The animals were randomly divided into four groups based on the implant material: fibrin glue, fibrin glue/mesenchymal stem cells composite, fibrin glue-recombinant human bone morphogenetic protein-2 (fibrin glue/recombinant human bone morphogenetic protein-2) composite, and fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 composite. After six weeks, the rabbits were euthanized for manual palpation, radiographic examination, biomechanical testing, and histology. Manual palpation results showed that the fusion rate for fibrin glue, fibrin glue/mesenchymal stem cells, fibrin glue/recombinant human bone morphogenetic protein-2, and fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 was 0, 0, 40%, and 70%, respectively. Moreover, fusion rate determined by radiographic examination for fibrin glue, fibrin glue/mesenchymal stem cells, fibrin glue/recombinant human bone morphogenetic protein-2, and fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 was 0, 0, 40%, and 80%, respectively. Gray analysis showed that fibrin glue/recombinant human bone morphogenetic protein-2 group had higher ossification area and density than fibrin glue group; and fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 group had higher ossification area and density than fibrin glue/recombinant human bone morphogenetic protein-2 group. Formation of continuous bone masses between L5 and L6 level in mesenchymal stem cells/recombinant human bone morphogenetic protein-2/fibrin glue group was further confirmed by computed tomography scanning and three-dimensional reconstruction. Biomechanical testing demonstrated that the fusion strength (flexion, extension, lateral bending, and axial rotation) in fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 group is significantly higher than that in fibrin glue/recombinant human bone morphogenetic protein-2 group. The formation of mature bone tissues between transverse processes of the fused specimens from both fibrin glue/recombinant human bone morphogenetic protein-2, and fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 groups was confirmed by HE staining, and quantitative real-time polymerase chain reaction results showed the upregulation of CD31, type I collagen, osteocalcin, and osteonectin in the fibrin glue/mesenchymal stem cells/recombinant human bone morphogenetic protein-2 group. In conclusion, our findings show that mesenchymal stem cells delivered with recombinant human bone morphogenetic protein-2 using fibrin glue as carrier are more effective in enhancing spine fusion than recombinant human bone morphogenetic protein-2 without mesenchymal stem cells in the rabbit model.
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Affiliation(s)
- Zunpeng Liu
- Department of Orthopedics, First Affiliated Hospital, China Medical University, Shenyang, China
- Department of Orthopedics, Fourth Affiliated Hospital, China Medical University, Shenyang, China
| | - Yue Zhu
- Department of Orthopedics, First Affiliated Hospital, China Medical University, Shenyang, China
| | - Haitao Zhu
- Department of Orthopedics, First Affiliated Hospital, China Medical University, Shenyang, China
| | - Xiaoning He
- Department of Stomatology, Fourth Affiliated Hospital, China Medical University, Shenyang, China
| | - Xinchun Liu
- Department of Orthopedics, First Affiliated Hospital, China Medical University, Shenyang, China
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Fu TS, Chang YH, Wong CB, Wang IC, Tsai TT, Lai PL, Chen LH, Chen WJ. Mesenchymal stem cells expressing baculovirus-engineered BMP-2 and VEGF enhance posterolateral spine fusion in a rabbit model. Spine J 2015; 15:2036-44. [PMID: 25463976 DOI: 10.1016/j.spinee.2014.11.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 10/11/2014] [Accepted: 11/05/2014] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Mesenchymal stem cell (MSC)-based cell therapy and gene transfer have converged and show great potential for accelerating bone healing. Gene therapy can provide more sustained expression of osteogenic factors such as bone morphogenetic protein-2 (BMP-2). We previously demonstrated that low-dose BMP-2 enhanced spinal posterolateral fusion by MSCs in a rabbit model. Herein, we genetically modified rabbit MSCs with a recombinant baculovirus encoding BMP-2 (Bac-CB) and vascular endothelial growth factor (Bac-VEGF) seeded into porous scaffolds to enhance spinal fusion. PURPOSE This study evaluates the success rate of the MSC-based cell therapy and gene transfer approach for single-level posterolateral spine fusion. We hypothesize that combining three-dimensional tricalcium phosphate (TCP) scaffolds and genetically modified allogeneic MSCs with baculovirus-mediated growth factor expression would increase the success rate of spinal fusion. STUDY DESIGN The study design was based on an animal model (approved by the Institutional Animal Care and Use Committee) using 18 adult male New Zealand rabbits. METHODS This study included 18 male New Zealand rabbits, weighing 3.5 to 4 kg. Allogeneic bone marrow-derived MSCs were isolated and genetically modified with Bac-CB and Bac-CV seeded onto TCP scaffolds (MSC/Bac/TCP). The animals were divided into three groups according to the material implanted into the bilateral L4-L5 intertransverse space: TCP scaffold (n=6), MSC/TCP (n=6), and MSC/Bac/TCP (n=6). After 12 weeks, the rabbits were euthanized for radiographic examination, manual palpation, and histologic study. RESULTS Bilateral fusion areas in each animal were evaluated independently. The radiographic fusion rates at 12 sites were 0 of 12 in the TCP scaffold group, 4 of 12 in the MSC/TCP group, and 10 of 12 in the MSC/Bac/TCP group. By manual palpation, there were zero solid fusions in the TCP scaffold group, two solid fusions in the MSC/TCP group, and five solid fusions in the MSC/Bac/TCP group. Fusion rates were significantly greater in the MSC/Bac/TCP group. CONCLUSIONS The results indicate the potential of using baculovirus as a vector for gene/cell therapy approaches to improve bone healing and support the feasibility of using allogeneic MSCs for inducing bone formation and intertransverse process fusion.
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Affiliation(s)
- Tsai-Sheng Fu
- Department of Orthopaedic Surgery, Keelung Chang Gung Memorial Hospital, Chang Gung University, 7F, No. 222, Maijin Rd, Keelung 20401, Taiwan.
| | - Yu-Han Chang
- Department of Orthopaedic Surgery, Linkou Chang Gung Memorial Hospital, Chang Gung University, No. 5, Fusing St., Gueishan, Taoyuan 333, Taiwan
| | - Chak-Bor Wong
- Department of Orthopaedic Surgery, Keelung Chang Gung Memorial Hospital, Chang Gung University, 7F, No. 222, Maijin Rd, Keelung 20401, Taiwan
| | - I-Chun Wang
- Department of Orthopaedic Surgery, Keelung Chang Gung Memorial Hospital, Chang Gung University, 7F, No. 222, Maijin Rd, Keelung 20401, Taiwan
| | - Tsung-Ting Tsai
- Department of Orthopaedic Surgery, Linkou Chang Gung Memorial Hospital, Chang Gung University, No. 5, Fusing St., Gueishan, Taoyuan 333, Taiwan
| | - Po-Liang Lai
- Department of Orthopaedic Surgery, Linkou Chang Gung Memorial Hospital, Chang Gung University, No. 5, Fusing St., Gueishan, Taoyuan 333, Taiwan
| | - Lih-Huei Chen
- Department of Orthopaedic Surgery, Linkou Chang Gung Memorial Hospital, Chang Gung University, No. 5, Fusing St., Gueishan, Taoyuan 333, Taiwan
| | - Wen-Jer Chen
- Department of Orthopaedic Surgery, Linkou Chang Gung Memorial Hospital, Chang Gung University, No. 5, Fusing St., Gueishan, Taoyuan 333, Taiwan
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Sardar Z, Alexander D, Oxner W, du Plessis S, Yee A, Wai EK, Anderson DG, Jarzem P. Twelve-month results of a multicenter, blinded, pilot study of a novel peptide (B2A) in promoting lumbar spine fusion. J Neurosurg Spine 2015; 22:358-66. [PMID: 25615629 DOI: 10.3171/2013.11.spine121106] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Failure of fusion after a transforaminal lumbar interbody fusion (TLIF) procedure is a challenging problem that can lead to ongoing low-back pain, dependence on pain medication, and inability to return to work. B2A is a synthetic peptide that has proven efficacy in achieving fusion in animal models and may have a better safety profile than bone morphogenetic protein. The authors undertook this study to evaluate the safety and efficacy of B2A peptide-enhanced ceramic granules (Prefix) in comparison with autogenous iliac crest bone graft (ICBG, control) in patients undergoing single-level TLIF. METHODS Twenty-four patients with single-level degenerative disorders of the lumbar spine at L2-S1 requiring TLIF were enrolled between 2009 and 2010. They were randomly assigned to 3 groups: a control group (treated with ICBG, n = 9), a Prefix 150 group (treated with Prefix 150 μg/cm(3) granules, n = 8), and a Prefix 750 group (treated with Prefix 750 μg/cm(3) granules, n = 7). Outcome measures included the Oswestry Disability Index (ODI), visual analog pain scale, and radiographic fusion as assessed by CT and dynamic flexion/extension lumbar plain radiographs. RESULTS At 12 months after surgery, the radiographic fusion rate was 100% in the Prefix 750 group, 78% in the control group, and 50% in the Prefix 150 group, although the difference was not statistically significant (p = 0.08). At 6 weeks the mean ODI score was 41.0 for the control group, 27.7 for the Prefix 750 group, and 32.2 for the Prefix 150 group, whereas at 12 months the mean ODI was 24.4 for control, 31.1 for Prefix 750, and 29.7 for Prefix 150 groups. Complications were evenly distributed among the groups. CONCLUSIONS Prefix appears to provide a safe alternative to autogenous ICBG. Prefix 750 appears to show superior radiographic fusion when compared with autograft at 12 months after TLIF, although no statistically significant difference was demonstrated in this small study. Prefix and control groups both appeared to demonstrate comparable improvements to ODI at 12 months.
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Affiliation(s)
- Zeeshan Sardar
- McGill University Health Centre, McGill University, Montreal, Quebec
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Koo KH, Ahn JM, Lee JM, Kim BS, Kim CS, Im GI. Apatite-coated collagen sponge for the delivery of bone morphogenetic protein-2 in rabbit posterolateral lumbar fusion. Artif Organs 2014; 38:893-9. [PMID: 24404859 DOI: 10.1111/aor.12249] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bone morphogenetic proteins (BMPs) need an effective delivery system for efficient bone regeneration. In this study, we evaluated the efficiency of an apatite-coated collagen sponge for the long-term delivery of BMP-2 in a rabbit model of lumbar posterolateral fusion. A total of 15 rabbits, divided into three groups, underwent posterolateral lumbar fusion. The first group (control group) received uncoated collagen sponges without BMP-2. The second group (uncoated group) received uncoated collagen sponges with BMP-2 (40 μg each side). The third group (apatite-coated group) received apatite-coated collagen sponges with the same level of BMPs (40 μg each side). All rabbits were euthanized 6 weeks after operation, and the fusion status was assessed by radiographic study, micro-CT, manual palpation, biomechanical study, and histological examination. Fusion rates as determined by radiographic study, micro-CT, and manual palpation showed that the apatite-coated group had a significantly higher rate of fusion than the control group (P = 0.024), while the uncoated group did not (P = 0.083). Biomechanical study showed significantly higher tensile strength in the apatite-coated group than the uncoated group (P = 0.032). Denser trabeculations were found in the apatite-coated group compared with the uncoated group. It is concluded that the use of apatite-coated collagen sponges for BMP-2 delivery enhanced bone regeneration.
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Affiliation(s)
- Ki Hyoung Koo
- Department of Orthopedic Surgery, Dongguk University Ilsan Hospital, Goyang, Korea
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Ghodasra JH, Daley EL, Hsu EL, Hsu WK. Factors influencing arthrodesis rates in a rabbit posterolateral spine model with iliac crest autograft. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2013; 23:426-34. [PMID: 24166021 DOI: 10.1007/s00586-013-3074-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 10/12/2013] [Accepted: 10/13/2013] [Indexed: 12/01/2022]
Abstract
PURPOSE The rabbit posterolateral intertransverse spine arthrodesis model has been widely used to evaluate spinal biologics. However, to date, the validity and reproducibility of performance of iliac crest bone graft, the most common and critical control group, has not been firmly established. We evaluated original research publications that utilized this model, identified which experimental conditions affected fusion rates, and developed an algorithm to predict fusion rates for future study designs. METHODS A MEDLINE search was performed for publications through December, 2011 that utilized this model to evaluate fusion rates elicited by iliac crest autograft. All study parameters were recorded, and logistic regression analyses were performed to determine the effects of these variables on fusion rates as determined by either manual palpation or radiographs. RESULTS Seventy studies with 959 rabbits in 102 groups met the inclusion criteria. Excluding studies that measured fusion at 4 or fewer weeks or intentionally tried to decrease the fusion rate, the overall fusion rate for autograft was 58.3 ± 16.3 % (mean ± SD) as determined by manual palpation and 66.4 ± 17.8 % by plain radiographs. Regression analysis demonstrated a difference between these outcome measures with a trend towards significance (p = 0.09). Longer time points and larger volumes of autograft resulted in significantly greater reported fusion rates (p < 0.0001 and p < 0.05, respectively). Neither strain, age, weight, nor vertebral level significantly affected fusion rates. CONCLUSIONS Although experimental conditions varied across studies, time point evaluation and autograft volume significantly affected fusion rates. Despite some variability demonstrated across certain studies, we demonstrated that when the time point and volume of autograft were controlled for, the iliac crest control group of the rabbit posterolateral spinal arthrodesis model is both reliable and predictably affected by different experimental conditions.
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Affiliation(s)
- Jason H Ghodasra
- Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave., 76-143 CHS, Los Angeles, CA, 90095, USA,
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Koo KH, Lee JM, Ahn JM, Kim BS, La WG, Kim CS, Im GI. Controlled Delivery of Low-Dose Bone Morphogenetic Protein-2 Using Heparin-Conjugated Fibrin in the Posterolateral Lumbar Fusion of Rabbits. Artif Organs 2013; 37:487-94. [DOI: 10.1111/j.1525-1594.2012.01578.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ki-Hyoung Koo
- Department of Orthopaedic Surgery; Dongguk University Ilsan Hospital; Goyang
| | - Jong-Min Lee
- Department of Orthopaedic Surgery; Dongguk University Ilsan Hospital; Goyang
| | - Jung-Min Ahn
- Department of Orthopaedic Surgery; Dongguk University Ilsan Hospital; Goyang
| | | | | | - Chang-Sung Kim
- Department of Periodontology; College of Dentistry; Yonsei University; Seoul; Korea
| | - Gun-Il Im
- Department of Orthopaedic Surgery; Dongguk University Ilsan Hospital; Goyang
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Odri GA, Revert R, Deschamps C, Romih M, Maugars Y, Heymann D, Delecrin J. Effect of adding bone marrow to ceramic graft materials with different interconnectivities in lumbar arthrodesis : quantification of bone formation. J Orthop Sci 2013. [PMID: 23203844 DOI: 10.1007/s00776-012-0336-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Combining bone marrow (BM) with graft materials can stimulate bone healing. However, bone growth is not quantified in most studies, and the influence of the rate of interconnectivity of ceramics loaded with bone marrow has not yet been quantified. Here, a rabbit model of posterolateral intertransverse arthrodesis was used to quantify the effect of adding BM to partially (PIC) or totally (TIC) interconnected ceramics. MATERIALS AND METHODS A single lumbar level was grafted on two sides with TIC (n = 12) or PIC (n = 18). The ceramic was loaded with 1.5 ml of BM on one side (chosen at random). The fusion rate was assessed by manual palpation test. Bone formation was quantified on scanning electron microscopy images and by dual-energy X-ray absorptiometry. RESULTS At week 6, bone formation with TIC was twice as high as that with PIC. When BM was added, 35.1 and 87.8 % more bone formation was observed in the TIC and PIC, respectively. In ceramics loaded with BM, the bone mineral density was significantly higher than that in ceramics alone. CONCLUSIONS Differences in interconnectivity within the family of biphasic ceramics should be taken into account when applying them clinically. BM increased bone formation regardless of the type of ceramic employed.
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Affiliation(s)
- Guillaume-A Odri
- Clinique Chirurgicale Orthopédique et Traumatologique, CHU Hôtel Dieu, 1 Place Alexis Ricordeau, 44093 Nantes Cedex 1, France.
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Dohzono S, Imai Y, Nakamura H, Wakitani S, Takaoka K. Successful spinal fusion by E. coli-derived BMP-2-adsorbed porous beta-TCP granules: a pilot study. Clin Orthop Relat Res 2009; 467:3206-12. [PMID: 19582526 PMCID: PMC2772941 DOI: 10.1007/s11999-009-0960-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 06/15/2009] [Indexed: 01/31/2023]
Abstract
Bone morphogenetic proteins (BMPs) were originally identified as osteoinductive proteins. With cloning of BMP genes, studies of BMPs and their clinical application have advanced. However, with increasing clinical applications, drug delivery systems and production costs have become more important issues. To address these issues, we asked whether E. coli-derived rhBMP-2 (E-BMP-2)-adsorbed porous beta-TCP granules could achieve posterolateral lumbar fusion in a rabbit model similar to autogenous bone grafts. Lumbar spinal fusion masses were evaluated by 3-D computed tomography, mechanical testing, and histological analyses 8 weeks after surgery. By these measures E-BMP-2-adsorbed beta-TCP granules achieved lumbar spinal fusion in dose-dependent fashion in a rabbit model as well as autogenous bone graft. Our preliminary findings suggest E-BMP-2-adsorbed porous beta-TCP could be a novel, effective alternative to autogenous bone grafting for generating new bone and promoting regenerative repair of bone, and potentially utilizable in the clinical setting for treating spinal disorders.
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Affiliation(s)
- Sho Dohzono
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, Osaka, 545-8585 Japan
| | - Yuuki Imai
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, Osaka, 545-8585 Japan
| | - Hiroaki Nakamura
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, Osaka, 545-8585 Japan
| | - Shigeyuki Wakitani
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, Osaka, 545-8585 Japan
| | - Kunio Takaoka
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, Osaka, 545-8585 Japan
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Seo HS, Jung JK, Lim MH, Hyun DK, Oh NS, Yoon SH. Evaluation of Spinal Fusion Using Bone Marrow Derived Mesenchymal Stem Cells with or without Fibroblast Growth Factor-4. J Korean Neurosurg Soc 2009; 46:397-402. [PMID: 19893733 DOI: 10.3340/jkns.2009.46.4.397] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 06/24/2009] [Accepted: 10/15/2009] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE In this study, the authors assessed the ability of rat bone marrow derived mesenchymal stem cells (BMDMSCs), in the presence of a growth factor, fibroblast growth factor-4 (FGF-4) and hydroxyapatite, to act as a scaffold for posterolateral spinal fusion in a rat model. METHODS Using a rat posterolateral spine fusion model, the experimental study comprised 3 groups. Group 1 was composed of 6 animals that were implanted with 0.08 gram hydroxyapatite only. Group 2 was composed of 6 animals that were implanted with 0.08 gram hydroxyapatite containing 1 x 10(6)/ 60 microL rat of BMDMSCs. Group 3 was composed of 6 animals that were implanted with 0.08 gram hydroxyapatite containing 1 x 10(6)/ 60 microL of rat BMDMSCs and FGF-4 1 microG to induce the bony differentiation of the BMDMSCs. Rats were assessed using radiographs obtained at 4, 6, and 8 weeks postoperatively. After sacrifice, spines were explanted and assessed by manual palpation, high-resolution microcomputerized tomography, and histological analysis. RESULTS Radiographic, high-resolution microcomputerized tomographic, and manual palpation revealed spinal fusion in five rats (83%) in Group 2 at 8 weeks. However, in Group 1, three (60%) rats developed fusion at L4-L5 by radiography and two (40%) by manual palpation in radiographic examination. In addition, in Group 3, bone fusion was observed in only 50% of rats by manual palpation and radiographic examination at this time. CONCLUSION The present study demonstrates that 0.08 gram of hydroxyapatite with 1 x 10(6)/ 60 microL rat of BMDMSCs induced bone fusion. FGF-4, added to differentiate primitive 1 x 10(6)/ 60 microL rat of BMDMSCs did not induce fusion. Based on histologic data, FGF-4 appears to induce fibrotic change rather than differentiation to bone by 1 x 10(6)/ 60 microL rat of BMDMSCs.
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Affiliation(s)
- Hyun Sung Seo
- Department of Neurosurgery, School of Medicine, Inha University, Incheon, Korea
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Hoshino M, Egi T, Terai H, Namikawa T, Kato M, Hashimoto Y, Takaoka K. Repair of long intercalated rib defects in dogs using recombinant human bone morphogenetic protein-2 delivered by a synthetic polymer and beta-tricalcium phosphate. J Biomed Mater Res A 2009; 90:514-21. [DOI: 10.1002/jbm.a.32123] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Walsh WR, Vizesi F, Cornwall GB, Bell D, Oliver R, Yu Y. Posterolateral spinal fusion in a rabbit model using a collagen-mineral composite bone graft substitute. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2009; 18:1610-20. [PMID: 19475437 DOI: 10.1007/s00586-009-1034-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 04/03/2009] [Accepted: 05/10/2009] [Indexed: 11/26/2022]
Abstract
Choosing the appropriate graft material to participate in the healing process in posterolateral spinal fusion continues to be a challenge. Combining synthetic graft materials with bone marrow aspirate (BMA) and autograft is a reasonable treatment option for surgeons to potentially reduce or replace the need for autograft. FormaGraft, a bone graft material comprising 12% bovine-derived collagen and 88% ceramic in the form of hydroxyapatite (HAp) and beta tricalcium phosphate (beta-TCP) was evaluated in three possible treatment modalities for posterior spinal fusion in a standard rabbit model. These three treatment groups were FormaGraft alone, FormaGraft soaked in autogenous BMA, and FormaGraft with BMA and iliac crest autograft. No statistically demonstrable benefits or adverse effects of the addition of BMA were found in the current study based on macroscopic, radiology or mechanical data. This may reflect, in part, the good to excellent results of the collagen HA/TCP composite material alone in a well healing bony bed. Histology did, however, reveal a benefit with the use of BMA. Combining FormaGraft with autograft and BMA achieved results equivalent to autograft alone. The mineral and organic nature of the material provided a material that facilitated fusion between the transverse processes in a standard preclinical posterolateral fusion model.
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Affiliation(s)
- William Robert Walsh
- Surgical and Orthopaedic Research Laboratories (SORL), Prince of Wales Hospital, University of New South Wales, Level 1 Clinical Sciences Bldg, Sydney, NSW 2031, Australia.
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Fu TS, Chen WJ, Chen LH, Lin SS, Liu SJ, Ueng SWN. Enhancement of posterolateral lumbar spine fusion using low-dose rhBMP-2 and cultured marrow stromal cells. J Orthop Res 2009; 27:380-4. [PMID: 18853429 DOI: 10.1002/jor.20644] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We tested the hypothesis that the dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) required to induce spine fusion can be reduced by combination with mesenchymal stem cells (MSCs). Twenty-four adult rabbits underwent posterolateral intertransverse fusion at the L4-L5 level. The animals were divided into four groups based on the implant material: autologous iliac graft, Alginate-MSCs composite, Alginate-BMP-2-MSCs composite, and Alginate-BMP-2 composite. After 16 weeks, the rabbits were euthanized for radiographic examination, manual palpation, biomechanical testing, and histology. Radiographic union of 12 intertransverse fusion areas for the autogenous iliac graft, Alginate-MSCs, Alginate-BMP-2-MSCs, and Alginate-BMP-2 groups was 11, 8, 11, and 0, respectively. Moreover, manual palpation of six fusion segments in each subgroup found solid union to be 6, 1, 5, and 0, respectively. The average torques at failure of the first three groups were 2278 +/- 135, 1943 +/- 140, and 2334 +/- 187 N-mm, respectively. The failure torque did not differ significantly between the autograft and Alginate-BMP-2-MSCs groups; both groups were significantly higher than the Alginate-MSCs group. The results indicate that MSCs delivered with in vitro cellular doses of rhBMP-2 are more osteoinductive than MSCs without rhBMP-2. In combination with MSCs, a low dose (2.5 microg) of rh-BMP-2 could enhance bone formation and posterolateral spine fusion success in the rabbit model.
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Affiliation(s)
- Tsai-Sheng Fu
- Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chang Gung University, 5, Fu-Hsing Street, 333, Kweishan, Taoyuan, Taiwan
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Namikawa T, Terai H, Hoshino M, Kato M, Toyoda H, Yano K, Nakamura H, Takaoka K. Enhancing effects of a prostaglandin EP4 receptor agonist on recombinant human bone morphogenetic protein-2 mediated spine fusion in a rabbit model. Spine (Phila Pa 1976) 2007; 32:2294-9. [PMID: 17906568 DOI: 10.1097/brs.0b013e318154c5b6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN An experimental animal study aimed at achieving posterolateral intertransverse process fusion with rhBMP-2 in combination with the local delivery of an EP4 receptor agonist. OBJECTIVE To determine whether an EP4 receptor agonist (EP4A) can reduce the amount of BMP required to achieve posterolateral spinal fusion in rabbits. SUMMARY OF BACKGROUND DATA In the clinic, BMP retaining implants are used for spinal fusion and the treatment of pseudarthrosis after long bone fracture. However, the requirement of high doses of BMP-2 for bone formation in humans makes the implants expensive and limits their use in the clinic. Previous studies in our laboratory using a new delivery system involving a synthetic polymer/beta-TCP powder composite had shown it was possible to reduce the total BMP-2 amount to 30 microg per fusion in a rabbit model. To further reduce the dose of BMP required for a successful fusion, we explored the use of a chemical compound to enhance the bone-inducing action of BMP-2. METHODS In order to prepare 1 implant to bridge the unilateral L5 and L6 transverse processes, 300 mg of polymer gel (PLA-DX-PEG block copolymer), 300 mg of beta-TCP powder, rhBMP-2 (7.5, 3.75, or 0 microg), with or without EP4A (45 microg) were mixed and manually shaped to resemble a rod. Through a posterolateral approach, 2 implants were placed on both sides (1 per side) by surgery in order to bridge the transverse processes of adult New Zealand white rabbits (n = 48). The lumbar vertebrae were recovered 6 weeks after surgery. The posterolateral fusion was examined by manual palpation, radiography, biomechanical testing, and histology. RESULTS All of 8 rabbits that received 7.5 microg of BMP-2 and EP4A consistently showed fusion by significant amount of new bone formation. However, solid fusion was seen in only 3 of 8 rabbits that received 7.5 microg of BMP-2 without the EP4 receptor agonist. CONCLUSION Local administration of an EP4 receptor agonist enhanced the bone-inducing activity of BMP-2 in a rabbit posterolateral lumbar spinal fusion model and as a result, the dose of BMP-2 required for this outcome was reduced by 50% compared with our previous report. The coadministration of this compound via a local delivery system may help to reduce the costs of spine fusion with use of BMP-2 in the clinic.
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Affiliation(s)
- Takashi Namikawa
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan.
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Weiner AA, Shuck DM, Bush JR, Prasad Shastri V. In vitro degradation characteristics of photocrosslinked anhydride systems for bone augmentation applications. Biomaterials 2007; 28:5259-70. [PMID: 17825904 DOI: 10.1016/j.biomaterials.2007.08.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 08/14/2007] [Indexed: 11/20/2022]
Abstract
In the past decade, injectable biomaterials that are capable of in situ formation have garnered increased interest for use in restorative orthopedic procedures. In this study, the in vitro degradation of photocrosslinked polyanhydride matrices, derived from methacrylic anhydrides of 1,6-bis(p-carboxyphenoxy)hexane (MCPH) and sebacic acid (MSA) were evaluated over a 6-week period under physiological conditions. These matrices were augmented with two additives--the reactive diluent poly(ethylene glycol) diacrylate (PEGDA) and the buffering agent calcium carbonate (CaCO3). Disk shaped specimens were produced by crosslinking the components using both chemical and photoinitiators and exposure to visible light. The experimental variables studied included: MCPH:MSA ratio, PEGDA molecular weight and weight fraction, and incorporation of CaCO3. The effects of these variables on local pH, water uptake, mass loss, and mechanical properties were explored. Increasing the MCPH:MSA ratio decreased the mass loss and water uptake at predetermined endpoints, and decreased buffer acidity during degradation. Both PEGDA and CaCO3 were found to decrease acidity and to reduce water uptake during degradation. Incorporation of CaCO3 enabled maintenance of compressive modulus during degradation. These results demonstrate that incorporation of reactive diluents and nonreactive additives into networks of photocrosslinked anhydrides can improve system properties as a material for bone replacement.
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Affiliation(s)
- Ashley A Weiner
- Department of Biomedical Engineering, Vanderbilt University, Station B Box 351631, 5824 Stevenson Center, Nashville, TN 37235, USA
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Wheeler DL, Jenis LG, Kovach ME, Marini J, Turner AS. Efficacy of silicated calcium phosphate graft in posterolateral lumbar fusion in sheep. Spine J 2007; 7:308-17. [PMID: 17482114 DOI: 10.1016/j.spinee.2006.01.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 01/03/2006] [Accepted: 01/12/2006] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Conditions requiring posterior lumbar spinal fusion remain a clinical challenge. Achieving arthrodesis using autogenous bone graft is inconsistent when rigid internal fixation such as transpedicular instrumentation is applied. Synthetic materials, particularly calcium phosphate-based ceramics, have shown promise for spine fusion applications, especially when combined with autograft. Silicate substitution has been shown to enhance the bioactivity of calcium phosphates and may obviate the need for autologous supplementation. PURPOSE Determine efficacy of silicated calcium phosphate (Si-CaP) compared with autograft to generate solid lumbar fusion. STUDY DESIGN Comparison of healing of instrumented posterolateral lumbar fusion in ewes at 2 and 6 months using Si-CaP or iliac crest autograft. METHODS Eighteen skeletally mature ewes underwent implantation of either autograft or Si-CaP in the space spanning the L4-L5 transverse process. In vivo quantitative computed tomography (CT) scans were made at 2-month intervals and after euthanasia. Harvested spine segments were radiographed and biomechanically tested in bending at 6 months. Histological assessments were made at 2 and 6 months. RESULTS Animals receiving Si-CaP graft were biomechanically and radiographically equivalent to those receiving autograft. Fusion mass density and volume were higher for the Si-CaP group throughout the healing period. Si-CaP regenerated normal bone tissue morphology, cellularity, and maturation with no inflammatory responses despite the fact that no autograft, bone marrow aspirate, or blood was mixed with the material. Histomorphometrically, fusion mass was higher for Si-CaP and bony bridging was equivalent when compared with autograft treatment. CONCLUSIONS Si-CaP was biomechanically, radiographically, and histologically equivalent to autograft in generating a solid, bony, intertransverse process fusion in an ovine model. Both treatment groups achieved 100% bridging fusion after 6 months of healing.
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Affiliation(s)
- Donna L Wheeler
- Department of Mechanical Engineering, College of Engineering, Orthopaedic Bioengineering Research Laboratory, Colorado State University, A101 Engineering Building, Fort Collins, CO 80523-1374, USA.
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Acosta FL, Aryan HE, Ames CP. Successful outcome of six-level cervicothoracic corpectomy and circumferential reconstruction: case report and review of literature on multilevel cervicothoracic corpectomy. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2006; 15 Suppl 5:670-4. [PMID: 16924551 PMCID: PMC1602202 DOI: 10.1007/s00586-006-0203-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 05/16/2006] [Accepted: 07/07/2006] [Indexed: 11/29/2022]
Abstract
The authors report the successful outcome of a six-level corpectomy across the cervico-thoracic spine with circumferential reconstruction in a patient with extensive osteomyelitis of the cervical and upper thoracic spine. To the authors’ knowledge, this is the first report of a corpectomy extending across six levels of the cervico-thoracic spine. Clinical relevance: the authors recommend anterior cage and plate-assisted reconstruction and additional posterior instrumentation using modern spinal surgical techniques and implants.
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Affiliation(s)
- Frank L Acosta
- Department of Neurological Surgery, University of California, 505 Parnassus Avenue, Moffitt Hospital M779, Box 0112, San Francisco, CA 94143, USA.
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Namikawa T, Terai H, Suzuki E, Hoshino M, Toyoda H, Nakamura H, Miyamoto S, Takahashi N, Ninomiya T, Takaoka K. Experimental spinal fusion with recombinant human bone morphogenetic protein-2 delivered by a synthetic polymer and beta-tricalcium phosphate in a rabbit model. Spine (Phila Pa 1976) 2005; 30:1717-22. [PMID: 16094272 DOI: 10.1097/01.brs.0000172155.17239.fa] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN An experimental animal study to achieve posterolateral intertransverse process spine fusion with recombinant bone morphogenetic protein in combination with a new delivery system. OBJECTIVE To evaluate the efficacy of a new synthetic biodegradable bone-inducing material containing recombinant human bone morphogenetic protein-2 (rhBMP-2) as a bone-graft substitute for posterolateral intertransverse process fusion in a rabbit model. SUMMARY OF BACKGROUND DATA rhBMP-2, a powerful bone-inducing cytokine, has been used as a bone graft substitute in combination with animal-derived collagen to achieve spinal fusion in animal models. However, the minimum dose of rhBMP-2 required to obtain solid posterolateral intertransverse process fusion was high on the basis of previous reports (>100 microg in rabbit models). To improve the efficacy, performance of rhBMP-2, and the safety of the delivery system for this protein, a more sophisticated system is required. METHODS To fabricate one implant for one-side L4-L5 intertransverse process fusion, beta-tricalcium phosphate (beta-TCP) powder (300 microg), a polymer gel (PLA-DX-PEG block copolymer; 300 microg) and rhBMP-2 (7.5, 15, or 30 microg) were mixed and manually shaped to resemble a rod. Through a posterolateral approach, two implants were placed on both sides (1 per side) by surgery so as to bridge the transverse processes of adult New Zealand white rabbits (n = 27). In control animals, implants without rhBMP or autogenous cortico-cancellous bone chips from the iliaccrest were placed in a similar location. The lumbar vertebrae were recovered 6 weeks after surgery. The posterolateral fusion was examined by manual palpation, radiography, biomechanical testing, and histology. RESULTS Rabbits that received 15 or 30 microg of rhBMP-2 showed consistent fusion. However, solid fusion was seen in 2 of 5 rabbits with autografting and rabbits that received 7.5 microg of rhBMP-2. Fusion was not observed in the rabbits that did not receive rhBMP-2. CONCLUSIONS Consistent spinal fusion was obtained by implanting a biodegradable bone-inducing implant composed of beta-TCP, PLA-DX-PEG, and rhBMP-2 within a period of 6 weeks. The rhBMP-2 doses required for the spinal fusion were significantly lower than those reported previously.
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Affiliation(s)
- Takashi Namikawa
- Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan
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