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Hedman T, Rogers A, Beall D. A Self-Polymerizing Mesh of Nano-Tethers for the Mechanical Constraint of Degraded Intervertebral Discs-A Review of 25 Years of Pre-Clinical and Early Clinical Research. Bioengineering (Basel) 2024; 11:535. [PMID: 38927771 PMCID: PMC11200395 DOI: 10.3390/bioengineering11060535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/08/2024] [Accepted: 05/22/2024] [Indexed: 06/28/2024] Open
Abstract
Genipin polymers are self-forming tensile-load-carrying oligomers, derived from the gardenia fruit, that covalently bond to amines on collagen. The potential therapeutic mechanical benefits of a non-discrete in situ forming mesh of genipin oligomers for degraded spinal discs were first conceived in 1998. Over more than two decades, numerous studies have demonstrated the immediate mechanical effects of this injectable, intra-annular polymeric mesh including an early demonstration of an effect on clinical outcomes for chronic or recurrent discogenic low back pain. This literature review focused on articles investigating mechanical effects in cadaveric animal and human spinal discs, biochemical mechanism of action studies, articles describing the role of mechanical degradation in the pathogenesis of degenerative disc disease, initial clinical outcomes and articles describing current discogenic low back pain treatment algorithms. On the basis of these results, clinical indications that align with the capabilities of this novel injectable polymer-based treatment strategy are discussed. It is intended that this review of a novel nano-scale material-based solution for mechanical deficiencies in biologically limited tissues may provide a helpful example for other innovations in spinal diseases and similarly challenging musculoskeletal disorders.
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Affiliation(s)
- Thomas Hedman
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40513, USA
- Spinal Simplicity LLC, Overland Park, KS 66211, USA
| | - Adam Rogers
- Spinal Simplicity LLC, Overland Park, KS 66211, USA
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Hedman T, Yu J, Singh H, Deer T. Early Clinical Results of Intervertebral Joint Stabilization by Injectable Load-Sharing Polymers. J Pain Res 2023; 16:2777-2789. [PMID: 37583391 PMCID: PMC10424685 DOI: 10.2147/jpr.s413104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/25/2023] [Indexed: 08/17/2023] Open
Abstract
Background Genipin is a polymer-forming collagen bonding substance that can be dissolved in a buffered carrier and injected into disc annulus tissues. Therapeutic benefit is derived from the mechanical support provided by a large number of genipin polymers attached to collagen fibers in a degraded disc. Study Design/Setting IRB-approved prospective, multi-site, single-arm, 12-month feasibility studies were undertaken in two countries to evaluate the safety and efficacy of the genipin-based implant for treating discogenic chronic low back pain (CLBP). Patient Sample Twenty CLBP patients with symptomatic discs at one or two levels were enrolled in the study. Outcome Measures The primary safety endpoint was serious adverse events at 1 month, and the primary efficacy endpoint was reduction of pain and disability at 3 months. Secondary efficacy endpoints included reduction of pain and disability at 2 weeks, 1 month, 6 months, and 12 months; reduction of flexion-extension instability; increase in segmental lordosis and rotation; and patient satisfaction. Methods Fluoroscopic image-guidance was used to deliver two posterolateral injections of buffered genipin to each symptomatic disc. Flexion-extension radiographs were used to quantify joint kinematics at three time-points. Results Clinically meaningful improvements in pain and disability scores were reported in 80% or more of patients from 2 weeks to 1 year post-treatment. For the more severely unstable joints, treatment significantly reduced the instability score from a pre-treatment level of 2.4 standard deviations above the mean for an asymptomatic population to the asymptomatic mean at the 3-month follow-up. Conclusion These initial clinical data demonstrate the safety and efficacy of a genipin-based collagen tethering device capable of improving spinal joint stability while successfully addressing CLBP. This work merits additional randomized clinical studies.
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Affiliation(s)
- Thomas Hedman
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - James Yu
- Sydney Spine and Pain, Waratah Private Hospital, Hurstville, New South Wales, Australia
| | - Harwant Singh
- Spine and Joint Centre, Pantai Hospital, Kuala Lumpur, Malaysia
| | - Timothy Deer
- The Spine and Nerve Center of the Virginias, Charleston, WV, USA
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Warren MR, Vedadghavami A, Bhagavatula S, Bajpayee AG. Effects of polycationic drug carriers on the electromechanical and swelling properties of cartilage. Biophys J 2022; 121:3542-3561. [PMID: 35765244 PMCID: PMC9515003 DOI: 10.1016/j.bpj.2022.06.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/07/2022] [Accepted: 06/23/2022] [Indexed: 11/15/2022] Open
Abstract
Cationic nanocarriers offer a promising solution to challenges in delivering drugs to negatively charged connective tissues, such as to articular cartilage for the treatment of osteoarthritis (OA). However, little is known about the effects that cationic macromolecules may have on the mechanical properties of cartilage at high interstitial concentrations. We utilized arginine-rich cationic peptide carriers (CPCs) with varying net charge (from +8 to +20) to investigate the biophysical mechanisms of nanocarrier-induced alterations to cartilage biomechanical properties. We observed that CPCs increased the compressive modulus of healthy bovine cartilage explants by up to 70% and decreased the stiffness of glycosaminoglycan-depleted tissues (modeling OA) by 69%; in both cases, the magnitude of the change in stiffness correlated with the uptake of CPC charge variants. Next, we directly measured CPC-induced osmotic deswelling in cartilage tissue due to shielding of charge repulsions between anionic extracellular matrix constituents, with magnitudes of reductions between 36 and 64 kPa. We then demonstrated that electrostatic interactions were required for CPC-induced stiffening to occur, evidenced by no observed increase in tissue stiffness when measured in hypertonic bathing salinity. We applied a non-ideal Donnan osmotic model (under triphasic theory) to separate bulk modulus measurements into Donnan and non-Donnan components, which further demonstrated the conflicting charge-shielding and matrix-stiffening effects of CPCs. These results show that cationic drug carriers can alter tissue mechanical properties via multiple mechanisms, including the expected charge shielding as well as a novel stiffening phenomenon mediated by physical linkages. We introduce a model for how the magnitudes of these mechanical changes depend on tunable physical properties of the drug carrier, including net charge, size, and spatial charge distribution. We envision that the results and theory presented herein will inform the design of future cationic drug-delivery systems intended to treat diseases in a wide range of connective tissues.
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Affiliation(s)
- Matthew R Warren
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Armin Vedadghavami
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Sanjana Bhagavatula
- Department of Bioengineering, Northeastern University, Boston, Massachusetts
| | - Ambika G Bajpayee
- Department of Bioengineering, Northeastern University, Boston, Massachusetts; Department of Mechanical Engineering, Northeastern University, Boston, Massachusetts.
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Che YJ, Guo JB, Hao YF, Luo ZP. Regenerating and repairing degenerative intervertebral discs by regulating the micro/nano environment of degenerative bony endplates based on low-tension mechanics. BMC Musculoskelet Disord 2022; 23:462. [PMID: 35578221 PMCID: PMC9112526 DOI: 10.1186/s12891-022-05422-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 05/05/2022] [Indexed: 11/10/2022] Open
Abstract
Background Conservative treatment is the recommended first-line treatment for degenerative disc diseases. Traction therapy has historically been one of the most common clinical methods to address this, but the clinical effect remains controversial. Methods Forty-two six-month-old male Sprague-Dawley rats were randomly divided into six groups: the model group (Group A, four coccyx vertebrae (Co7-Co10) were fixed with customized external fixators, and the vertebral disc degeneration model was constructed by axial compression of the target segment Co8 - Co9 for 4 weeks), the experimental control group (Group B, after successful modeling, the external fixation device was removed and self-rehabilitation was performed) and four intervention groups (Groups C to F): Groups C and E: Co8 - Co9 vertebrae compressed for 4 weeks followed by two or 4 weeks of high tension traction (HTT), respectively, and Groups D and F: vertebrae compressed for 4 weeks followed by two or 4 weeks of low-tension traction (LTT), respectively. Imaging tests (X-ray and MRI) were performed to assess disc height and T2 signal intensity at each time point. After the experiment, the animals were euthanized, and the caudal vertebrae were collected for analysis of intervertebral disc histopathology, proteoglycan content, and micronanostructure of the annulus fibrosus, nucleus pulposus and bony endplate. Results Signs of tissue regeneration were apparent in all four intervention groups. After two to 4 weeks of intervention (HTT and LTT), the morphology of pores in the bony endplate, their number, and diameter had recovered significantly compared with those in Group A. The LTT group was superior to the HTT group, and the 4w in situ group was significantly superior to the 2w group. Meanwhile, the histological scores of discs, the mean fibril diameter and modulus of annulus fibrosus were significantly improved compared with the control groups, and the LTT group was superior to HTT group. Conclusions Low-tension traction better promotes active reconstruction of bony endplates and improves the elastic modulus and micro/nanostructure of the disc. Thus, it further promotes the regeneration and repair of intervertebral discs.
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Affiliation(s)
- Yan-Jun Che
- Orthopedics and Sports Medicine Center, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, 215008, Jiangsu Province, China.
| | - Jiang-Bo Guo
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital of SooChow University, 708 Renmin Rd, SuZhou, Jiangsu, 215007, People's Republic of China
| | - Yue Feng Hao
- Orthopedics and Sports Medicine Center, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, 215008, Jiangsu Province, China
| | - Zong-Ping Luo
- Department of Orthopaedics, Orthopaedic Institute, The First Affiliated Hospital of SooChow University, 708 Renmin Rd, SuZhou, Jiangsu, 215007, People's Republic of China
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Yang M, Xiang D, Wang S, Liu W. In Vitro Studies for Investigating Creep of Intervertebral Discs under Axial Compression: A Review of Testing Environment and Results. MATERIALS 2022; 15:ma15072500. [PMID: 35407833 PMCID: PMC9000064 DOI: 10.3390/ma15072500] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/14/2022] [Accepted: 03/22/2022] [Indexed: 01/06/2023]
Abstract
Creep responses of intervertebral discs (IVDs) are essential for spinal biomechanics clarification. Yet, there still lacks a well-recognized investigation protocol for this phenomenon. Current work aims at providing researchers with an overview of the in vitro creep tests reported by previous studies, specifically specimen species, testing environment, loading regimes and major results, based on which a preliminary consensus that may guide future creep studies is proposed. Specimens used in creep studies can be simplified as a “bone–disc–bone” structure where three mathematical models can be adopted for describing IVDs’ responses. The preload of 10–50 N for 30 min or three cycles followed by 4 h-creep under constant compression is recommended for ex vivo simulation of physiological condition of long-time sitting or lying. It is worth noticing that species of specimens, environment temperature and humidity all have influences on biomechanical behaviors, and thus are summarized and compared through the literature review. All factors should be carefully set according to a guideline before tests are conducted to urge comparable results across studies. To this end, this review also provides a guideline, as mentioned before, and specific steps that might facilitate the community of biomechanics to obtain more repeatable and comparable results from both natural specimens and novel biomaterials.
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Affiliation(s)
- Mengying Yang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China;
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
| | - Dingding Xiang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China;
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China
| | - Song Wang
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
- Correspondence: (S.W.); (W.L.)
| | - Weiqiang Liu
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
- Correspondence: (S.W.); (W.L.)
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Vasilikos I, Teixeira GQ, Seitz A, Nothelfer J, Haas J, Wilke HJ, Mizaikoff B, Beck J, Hubbe U, Neidlinger-Wilke C. Can UVA-light-activated riboflavin-induced collagen crosslinking be transferred from ophthalmology to spine surgery? A feasibility study on bovine intervertebral disc. PLoS One 2021; 16:e0252672. [PMID: 34081754 PMCID: PMC8174733 DOI: 10.1371/journal.pone.0252672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/19/2021] [Indexed: 11/19/2022] Open
Abstract
Background Collagen cross-links contribute to the mechanical resilience of the intervertebral disc (IVD). UVA-light-activated riboflavin-induced collagen crosslinking (UVA-CXL) is a well-established and effective ophthalmological intervention that increases the mechanical rigidity of the collagen-rich corneal matrix in Keratoconus. This study explores the feasibility, safety and efficacy of translating this intervention in reinforcing the IVD. Methods Annulus fibrosus (AF) cells were isolated from bovine IVDs and treated with different combinations of riboflavin (RF) concentrations (0.05–8 mM) and UVA light intensities (0.3–4 mW/cm2). Metabolic activity (resazurin assay), cell viability (TUNEL assay), and gene expression of apoptosis regulators C-FOS and PT5 were assessed immediately and 24 hours after treatment. Biomechanical effects of UVA-CXL on IVDs were measured by indentation analysis of changes in the instantaneous modulus and by peel-force delamination strength analysis of the AF prior and after treatment. Results Different intensities of UVA did not impair the metabolic activity of AF cells. However, RF affected metabolic activity (p < 0.001). PT53 expression was similar in all RF conditions tested while C-FOS expression decreased 24 hours after treatment. Twenty-four hours after treatment, no apoptotic cells were observed in any condition tested. Biomechanical characterizations showed a significant increase in the annular peel strength of the UVA-CXL group, when compared to controls of UVA and RF alone (p < 0.05). UVA-CXL treated IVDs showed up to 152% higher (p < 0.001) instantaneous modulus values compared to the untreated control. Conclusion This is the first study on UVA-CXL treatment of IVD. It induced significantly increased delamination strength and instantaneous modulus indentation values in intact IVD samples in a structure–function relationship. RF concentrations and UVA intensities utilized in ophthalmological clinical protocols were well tolerated by the AF cells. Our findings suggest that UVA-CXL may be a promising tool to reinforce the IVD matrix.
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Affiliation(s)
- Ioannis Vasilikos
- Department of Neurosurgery, Faculty of Medicine, Medical Center—University of Freiburg, University of Freiburg, Freiburg, Germany
- Laboratory of Experimental Neurosurgery (LENS), Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- * E-mail:
| | - Graciosa Q. Teixeira
- Institute of Orthopaedic Research and Biomechanics, Trauma Research Center, University of Ulm, Ulm, Germany
| | - Andreas Seitz
- Institute of Orthopaedic Research and Biomechanics, Trauma Research Center, University of Ulm, Ulm, Germany
| | - Julia Nothelfer
- Institute of Orthopaedic Research and Biomechanics, Trauma Research Center, University of Ulm, Ulm, Germany
| | - Julian Haas
- Institute of Analytical and Bioanalytical Chemistry, University of Ulm, Ulm, Germany
| | - Hans-Joachim Wilke
- Institute of Orthopaedic Research and Biomechanics, Trauma Research Center, University of Ulm, Ulm, Germany
| | - Boris Mizaikoff
- Institute of Analytical and Bioanalytical Chemistry, University of Ulm, Ulm, Germany
| | - Jürgen Beck
- Department of Neurosurgery, Faculty of Medicine, Medical Center—University of Freiburg, University of Freiburg, Freiburg, Germany
- Laboratory of Experimental Neurosurgery (LENS), Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ulrich Hubbe
- Department of Neurosurgery, Faculty of Medicine, Medical Center—University of Freiburg, University of Freiburg, Freiburg, Germany
- Laboratory of Experimental Neurosurgery (LENS), Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Cornelia Neidlinger-Wilke
- Institute of Orthopaedic Research and Biomechanics, Trauma Research Center, University of Ulm, Ulm, Germany
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McMorran JG, Gregory DE. The Influence of Axial Compression on the Cellular and Mechanical Function of Spinal Tissues; Emphasis on the Nucleus Pulposus and Annulus Fibrosus: A Review. J Biomech Eng 2021; 143:050802. [PMID: 33454730 DOI: 10.1115/1.4049749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Indexed: 11/08/2022]
Abstract
In light of the correlation between chronic back pain and intervertebral disc (IVD) degeneration, this literature review seeks to illustrate the importance of the hydraulic response across the nucleus pulposus (NP)-annulus fibrosus (AF) interface, by synthesizing current information regarding injurious biomechanics of the spine, stemming from axial compression. Damage to vertebrae, endplates (EPs), the NP, and the AF, can all arise from axial compression, depending on the segment's posture, the manner in which it is loaded, and the physiological state of tissue. Therefore, this movement pattern was selected to illustrate the importance of the bracing effect of a pressurized NP on the AF, and how injuries interrupting support to the AF may contribute to IVD degeneration.
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Affiliation(s)
- John G McMorran
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON N2 L 3C5
| | - Diane E Gregory
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON N2 L 3C5; Department of Health Sciences, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON N2 L 3C5
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Vasilikos I, Haas J, Teixeira GQ, Nothelfer J, Neidlinger-Wilke C, Wilke HJ, Seitz A, Vavvas DG, Zentner J, Beck J, Hubbe U, Mizaikoff B. Infrared attenuated total reflection spectroscopic surface analysis of bovine-tail intervertebral discs after UV-light-activated riboflavin-induced collagen cross-linking. JOURNAL OF BIOPHOTONICS 2020; 13:e202000110. [PMID: 32589779 DOI: 10.1002/jbio.202000110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/31/2020] [Accepted: 06/10/2020] [Indexed: 06/11/2023]
Abstract
The tensile strength of the intervertebral disc (IVD) is mainly maintained by collagen cross-links. Loss of collagen cross-linking combined with other age-related degenerative processes contributes to tissue weakening, biomechanical failure, disc herniation and pain. Exogenous collagen cross-linking has been identified as an effective therapeutic approach for restoring IVD tensile strength. The current state-of-the-art method to assess the extent of collagen cross-linking in tissues requires destructive procedures and high-performance liquid chromatography. In this study, we investigated the utility of infrared attenuated total reflection (IR-ATR) spectroscopy as a nondestructive analytical strategy to rapidly evaluate the extent of UV-light-activated riboflavin (B2)-induced collagen cross-linking in bovine IVD samples. Thirty-five fresh bovine-tail IVD samples were equally divided into five treatment groups: (a) untreated, (b) cell culture medium Dulbecco's Modified Eagle's Medium only, (c) B2 only, (d) UV-light only and (e) UV-light-B2. A total of 674 measurements have been acquired, and were analyzed via partial least squares discriminant analysis. This classification scheme unambiguously identified individual classes with a sensitivity >91% and specificity >92%. The obtained results demonstrate that IR-ATR spectroscopy reliably differentiates between different treatment categories, and promises an excellent tool for potential in vivo, nondestructive and real-time assessment of exogenous IVD cross-linking.
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Affiliation(s)
- Ioannis Vasilikos
- Department of Neurosurgery, University Medical Center Freiburg, Faculty of Medicine University of Freiburg, Freiburg, Germany
| | - Julian Haas
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany
| | - Graciosa Q Teixeira
- Institute of Orthopedic Research and Biomechanics, Centre for Trauma Research Ulm (ZTF Ulm), Ulm University, Ulm, Germany
| | - Julia Nothelfer
- Institute of Orthopedic Research and Biomechanics, Centre for Trauma Research Ulm (ZTF Ulm), Ulm University, Ulm, Germany
| | - Cornelia Neidlinger-Wilke
- Institute of Orthopedic Research and Biomechanics, Centre for Trauma Research Ulm (ZTF Ulm), Ulm University, Ulm, Germany
| | - Hans-Joachim Wilke
- Institute of Orthopedic Research and Biomechanics, Centre for Trauma Research Ulm (ZTF Ulm), Ulm University, Ulm, Germany
| | - Andreas Seitz
- Institute of Orthopedic Research and Biomechanics, Centre for Trauma Research Ulm (ZTF Ulm), Ulm University, Ulm, Germany
| | - Demetrios G Vavvas
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, USA
| | - Josef Zentner
- Department of Neurosurgery, University Medical Center Freiburg, Faculty of Medicine University of Freiburg, Freiburg, Germany
| | - Jürgen Beck
- Department of Neurosurgery, University Medical Center Freiburg, Faculty of Medicine University of Freiburg, Freiburg, Germany
| | - Ulrich Hubbe
- Department of Neurosurgery, University Medical Center Freiburg, Faculty of Medicine University of Freiburg, Freiburg, Germany
| | - Boris Mizaikoff
- Institute of Analytical and Bioanalytical Chemistry, Ulm University, Ulm, Germany
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