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Tolgyesi A, Huang C, Akens M, Kiss A, Hardisty M, Whyne CM. Treatment affects load to failure and microdamage accumulation in healthy and osteolytic rat vertebrae. J Mech Behav Biomed Mater 2024; 151:106382. [PMID: 38211499 DOI: 10.1016/j.jmbbm.2024.106382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 12/22/2023] [Accepted: 01/03/2024] [Indexed: 01/13/2024]
Abstract
Bone turnover and microdamage are impacted by the presence of skeletal metastases which can contribute to increased fracture risk. Treatments for metastatic disease may further impact bone quality. This exploratory study aimed to establish an initial understanding of microdamage accumulation and load to failure in healthy and osteolytic rat vertebrae following focal and systemic cancer treatment (docetaxel (DTX), stereotactic body radiotherapy (SBRT), or zoledronic acid (ZA)). Osteolytic spine metastases were developed in 6-week-old athymic female rats via intracardiac injection of HeLa human cervical cancer cells (day 0). Additional rats served as healthy controls. Rats were either untreated, received SBRT to the T10-L6 vertebrae on day 14 (15 Gy, two fractions), DTX on day 7 or 14, or ZA on day 7. Rats were euthanized on day 21. Tumor burden was assessed with bioluminescence images acquired on day 14 and 21, histology of the excised T11 and L5 vertebrae, and ex-vivo μCT images of the T13-L4. Microstructural parameters (bone volume/total volume, trabecular number, spacing, thickness, and bone mineral density) were measured from L2 vertebrae. Load to failure was measured with axial compressive loading of the L1-L3 motion segments. Microdamage accumulation was labeled in T13 vertebrae with BaSO4 staining and was visualized with high resolution μCT imaging. Microdamage volume fraction was defined as the ratio of BaSO4 to bone volume. DTX administered on day 7 reduced tumor growth significantly (p < 0.05). Microdamage accumulation was found to be increased by the presence of metastases but was reduced by all treatments with ZA showing the largest improvement in HeLa cell injected rats. Load to failure was decreased in untreated and SBRT HeLa cell injected rats compared to healthy controls (p < 0.01). There was a moderate negative correlation between load to failure and microdamage volume fraction in vertebrae from rats injected with HeLa cells (R = -0.35, p = 0.031). Strong correlations were also found between microstructural parameters and load to failure and microdamage accumulation. Several factors, including the presence of osteolytic lesions and use of cancer therapies, influence microdamage accumulation and load to failure in rat vertebrae. Understanding the impact of these treatments on fracture risk of metastatic vertebrae is important to improve management of patients with spinal metastases.
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Affiliation(s)
- Allison Tolgyesi
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada; Institute of Biomedical Engineering, Faculty of Engineering, University of Toronto, 164 College Street, Toronto, ON, M5S 3G9, Canada.
| | - Christine Huang
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada; Division of Engineering Science, Faculty of Engineering, University of Toronto, 42 St George Street, Toronto, ON, M5S 2E4, Canada
| | - Margarete Akens
- Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, ON, M5T 1P5, Canada; Techna Institute, University Health Network, 190 Elizabeth Street, Toronto, ON, M5G 2C4, Canada; Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto, ON, M5G 1L7, Canada
| | - Alex Kiss
- Department of Research Design and Biostatistics, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada
| | - Michael Hardisty
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada; Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, ON, M5T 1P5, Canada
| | - Cari M Whyne
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada; Institute of Biomedical Engineering, Faculty of Engineering, University of Toronto, 164 College Street, Toronto, ON, M5S 3G9, Canada; Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, ON, M5T 1P5, Canada
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Anderson DE, Groff MW, Flood TF, Allaire BT, Davis RB, Stadelmann MA, Zysset PK, Alkalay RN. Evaluation of Load-To-Strength Ratios in Metastatic Vertebrae and Comparison With Age- and Sex-Matched Healthy Individuals. Front Bioeng Biotechnol 2022; 10:866970. [PMID: 35992350 PMCID: PMC9388746 DOI: 10.3389/fbioe.2022.866970] [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: 01/31/2022] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
Vertebrae containing osteolytic and osteosclerotic bone metastases undergo pathologic vertebral fracture (PVF) when the lesioned vertebrae fail to carry daily loads. We hypothesize that task-specific spinal loading patterns amplify the risk of PVF, with a higher degree of risk in osteolytic than in osteosclerotic vertebrae. To test this hypothesis, we obtained clinical CT images of 11 cadaveric spines with bone metastases, estimated the individual vertebral strength from the CT data, and created spine-specific musculoskeletal models from the CT data. We established a musculoskeletal model for each spine to compute vertebral loading for natural standing, natural standing + weights, forward flexion + weights, and lateral bending + weights and derived the individual vertebral load-to-strength ratio (LSR). For each activity, we compared the metastatic spines' predicted LSRs with the normative LSRs generated from a population-based sample of 250 men and women of comparable ages. Bone metastases classification significantly affected the CT-estimated vertebral strength (Kruskal-Wallis, p < 0.0001). Post-test analysis showed that the estimated vertebral strength of osteosclerotic and mixed metastases vertebrae was significantly higher than that of osteolytic vertebrae (p = 0.0016 and p = 0.0003) or vertebrae without radiographic evidence of bone metastasis (p = 0.0010 and p = 0.0003). Compared with the median (50%) LSRs of the normative dataset, osteolytic vertebrae had higher median (50%) LSRs under natural standing (p = 0.0375), natural standing + weights (p = 0.0118), and lateral bending + weights (p = 0.0111). Surprisingly, vertebrae showing minimal radiographic evidence of bone metastasis presented significantly higher median (50%) LSRs under natural standing (p < 0.0001) and lateral bending + weights (p = 0.0009) than the normative dataset. Osteosclerotic vertebrae had lower median (50%) LSRs under natural standing (p < 0.0001), natural standing + weights (p = 0.0005), forward flexion + weights (p < 0.0001), and lateral bending + weights (p = 0.0002), a trend shared by vertebrae with mixed lesions. This study is the first to apply musculoskeletal modeling to estimate individual vertebral loading in pathologic spines and highlights the role of task-specific loading in augmenting PVF risk associated with specific bone metastatic types. Our finding of high LSRs in vertebrae without radiologically observed bone metastasis highlights that patients with metastatic spine disease could be at an increased risk of vertebral fractures even at levels where lesions have not been identified radiologically.
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Affiliation(s)
- Dennis E. Anderson
- Department of Orthopedic Surgery, Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States
| | - Michael W. Groff
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA, United States
| | - Thomas F. Flood
- Department of Radiology, Brigham and Women’s Hospital, Boston, MA, United States
| | - Brett T. Allaire
- Department of Orthopedic Surgery, Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States
| | - Roger B. Davis
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States
| | - Marc A. Stadelmann
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Philippe K. Zysset
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Ron N. Alkalay
- Department of Orthopedic Surgery, Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States
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Sun J, Xing F, Braun J, Traub F, Rommens PM, Xiang Z, Ritz U. Progress of Phototherapy Applications in the Treatment of Bone Cancer. Int J Mol Sci 2021; 22:ijms222111354. [PMID: 34768789 PMCID: PMC8584114 DOI: 10.3390/ijms222111354] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 02/05/2023] Open
Abstract
Bone cancer including primary bone cancer and metastatic bone cancer, remains a challenge claiming millions of lives and affecting the life quality of survivors. Conventional treatments of bone cancer include wide surgical resection, radiotherapy, and chemotherapy. However, some bone cancer cells may remain or recur in the local area after resection, some are highly resistant to chemotherapy, and some are insensitive to radiotherapy. Phototherapy (PT) including photodynamic therapy (PDT) and photothermal therapy (PTT), is a clinically approved, minimally invasive, and highly selective treatment, and has been widely reported for cancer therapy. Under the irradiation of light of a specific wavelength, the photosensitizer (PS) in PDT can cause the increase of intracellular ROS and the photothermal agent (PTA) in PTT can induce photothermal conversion, leading to the tumoricidal effects. In this review, the progress of PT applications in the treatment of bone cancer has been outlined and summarized, and some envisioned challenges and future perspectives have been mentioned. This review provides the current state of the art regarding PDT and PTT in bone cancer and inspiration for future studies on PT.
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Affiliation(s)
- Jiachen Sun
- Biomatics Group, Department of Orthopaedics and Traumatology, University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz, Germany; (J.S.); (J.B.); (F.T.); (P.M.R.)
- Department of Orthopaedics, West China Hospital, Sichuan University, No. 37 Guoxue Lane, Chengdu 610041, China;
| | - Fei Xing
- Department of Orthopaedics, West China Hospital, Sichuan University, No. 37 Guoxue Lane, Chengdu 610041, China;
| | - Joy Braun
- Biomatics Group, Department of Orthopaedics and Traumatology, University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz, Germany; (J.S.); (J.B.); (F.T.); (P.M.R.)
| | - Frank Traub
- Biomatics Group, Department of Orthopaedics and Traumatology, University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz, Germany; (J.S.); (J.B.); (F.T.); (P.M.R.)
| | - Pol Maria Rommens
- Biomatics Group, Department of Orthopaedics and Traumatology, University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz, Germany; (J.S.); (J.B.); (F.T.); (P.M.R.)
| | - Zhou Xiang
- Department of Orthopaedics, West China Hospital, Sichuan University, No. 37 Guoxue Lane, Chengdu 610041, China;
- Correspondence: (Z.X.); (U.R.)
| | - Ulrike Ritz
- Biomatics Group, Department of Orthopaedics and Traumatology, University Medical Center of the Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz, Germany; (J.S.); (J.B.); (F.T.); (P.M.R.)
- Correspondence: (Z.X.); (U.R.)
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Elevated Microdamage Spatially Correlates with Stress in Metastatic Vertebrae. Ann Biomed Eng 2019; 47:980-989. [PMID: 30673956 DOI: 10.1007/s10439-018-02188-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 12/11/2018] [Indexed: 12/15/2022]
Abstract
Metastasis of cancer to the spine impacts bone quality. This study aims to characterize vertebral microdamage secondary to metastatic disease considering the pattern of damage and its relationship to stress and strain under load. Osteolytic and mixed osteolytic/osteoblastic vertebral metastases were produced in athymic rats via HeLa cervical or canine Ace-1 prostate cancer cell inoculation, respectively. After 21 days, excised motion segments (T12-L2) were µCT scanned, stained with BaSO4 and re-imaged. T13-L2 motion segments were loaded in axial compression to induce microdamage, re-stained and re-imaged. L1 (loaded) and T12 (unloaded) vertebrae were fixed, sample blocks cut, polished and BSE imaged. µFE models were generated of all L1 vertebrae with displacement boundary conditions applied based on the loaded µCT images. µCT stereological analysis, BSE analysis and µFE derived von Mises stress and principal strains were quantitatively compared (ANOVA), spatial correlations determined and patterns of microdamage assessed qualitatively. BaSO4 identified microdamage was found to be spatially correlated with regions of high stress in µFEA. Load-induced microdamage was shown to be elevated in the presence of osteolytic and mixed metastatic disease, with diffuse, crossed hatched areas of microdamage present in addition to linear microdamage and microfractures in metastatic tissue, suggesting diminished bone quality.
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Preparation of a chlorophyll derivative and investigation of its photodynamic activities against cholangiocarcinoma. Biomed Pharmacother 2018; 92:285-292. [PMID: 28551549 DOI: 10.1016/j.biopha.2017.05.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/09/2017] [Accepted: 05/09/2017] [Indexed: 11/24/2022] Open
Abstract
Photodynamic therapy (PDT) is emerging as a promising method for the treatment of various cancer diseases. However, the clinical application of PDT is limited due to the lack of effective photosensitizers. In this study, a novel chlorophyll derivative, N,N-bis(2-carboxyethyl)pyropheophorbide a (BPPA), had been synthesized and characterized. BPPA had a characteristic long wavelength absorption peak at 669nm and a singlet oxygen quantum yield of 0.54. To investigate the photodynamic ability of BPPA against cholangiocarcinoma (CCA), cellular uptake, subcellular location and bio-distribution, in vitro and in vivo PDT efficacy of BPPA were studied. The results showed that BPPA could rapidly accumulate in QBC-939 cells and localize in the cytoplasm. BPPA- PDT was effective in reducing the cell viability in a drug dose- and light dose-dependent manner in vitro. In CCA xenograft nude mouse model, the concentration of BPPA in the plasma lowered rapidly, and the fluorescence signal peaked at 0.5h and 2h after injection in the skin and tumor, respectively. Significant quantities could be observed in the tumor. BPPA followed by irradiation could significantly inhibit growth of tumors, and histological examination revealed necrotic damage in PDT-treated tumors. These results suggested that BPPA could be a promising drug candidate for photodynamic therapy in cholangiocarcinoma.
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Choudhari C, Herblum R, Akens MK, Moore S, Hardisty M, Whyne CM. Post-euthanasia micro-computed tomography-based strain analysis is able to represent quasi-static in vivo behavior of whole vertebrae. Proc Inst Mech Eng H 2016; 230:900-904. [PMID: 27422827 DOI: 10.1177/0954411916658679] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Three-dimensional image-based strain measurement in whole bones allows representation of physiological, albeit quasi-static, loading conditions. However, such work to date has been limited to specimens postmortem. The main purpose of this study is to verify the efficacy of deformable image registration of post-euthanasia strain to characterize the in vivo mechanical behavior of rat vertebrae. A micro-computed tomography-compatible custom loading device was used to apply 75 N load to a three-level caudal motion segment of a healthy rat. Loaded and unloaded micro-computed tomography scans were acquired in vivo and post-sacrifice. A micro-computed tomography-based deformable image registration algorithm was used to calculate vertebral strains live and post-euthanasia. No significant difference was found in the in vivo strains (-0.011 ± 0.001) and ex vivo strains (-0.012 ± 0.001) obtained from the comparisons of loaded and unloaded images (p = 0.3). Comparisons between unloaded-unloaded and loaded-loaded scans yielded significantly lower axial strains, representing the error of the method. Qualitatively, high strains were observed adjacent to growth plate regions in evaluating the loaded-unloaded images. Strain patterns in the loaded-loaded and unloaded-unloaded scans were inconsistent as would be expected in representing noise. Overall, live and dead loaded to unloaded comparisons yielded similar strain patterns and magnitudes. Point-wise differences in axial strain fields also supported this observation. This study demonstrated a proof of concept, suggesting that post-euthanasia micro-computed tomography-based strain analysis is able to represent the in vivo quasi-static behavior of rat tail vertebrae.
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Affiliation(s)
- Chetan Choudhari
- 1 Orthopaedic Biomechanics Lab, Sunnybrook Research Institute, Toronto, ON, Canada
- 2 Institute of Biomaterials and Biomedical Engineering, Toronto, ON, Canada
| | - Ryan Herblum
- 1 Orthopaedic Biomechanics Lab, Sunnybrook Research Institute, Toronto, ON, Canada
- 2 Institute of Biomaterials and Biomedical Engineering, Toronto, ON, Canada
| | - Margarete K Akens
- 3 TECHNA Institute, University Health Network, Toronto, ON, Canada
- 4 Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Sara Moore
- 1 Orthopaedic Biomechanics Lab, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Michael Hardisty
- 1 Orthopaedic Biomechanics Lab, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Cari M Whyne
- 1 Orthopaedic Biomechanics Lab, Sunnybrook Research Institute, Toronto, ON, Canada
- 2 Institute of Biomaterials and Biomedical Engineering, Toronto, ON, Canada
- 4 Department of Surgery, University of Toronto, Toronto, ON, Canada
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7
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Horas K, Zheng Y, Zhou H, Seibel MJ. Animal Models for Breast Cancer Metastasis to Bone: Opportunities and Limitations. Cancer Invest 2015; 33:459-68. [DOI: 10.3109/07357907.2015.1065500] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Herblum R, Beek M, Whyne CM. μFEA successfully exhibits higher stresses and strains in microdamaged regions of whole vertebrae. J Orthop Res 2013; 31:1653-60. [PMID: 23737260 DOI: 10.1002/jor.22392] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 04/28/2013] [Indexed: 02/04/2023]
Abstract
Micro-finite element (μFE) modeling has shown promise in evaluating the structural integrity of trabecular bone. Histologic microcrack analyses have been compared to μFE models of trabecular bone cores to demonstrate the potential of this technique. To date this has not been achieved in whole bone structures, and comparisons of histologic microcrack and μFE results have been limited due to challenges in alignment of 2D sections with 3D data sets. The goal of this study was to ascertain if image registration can facilitate determination of a relationship between stresses and strains generated from μFE models of whole vertebrae and histologically identified microdamage. μFE models of three whole vertebrae, stained sequentially with calcein and fuchsin, were generated with accurate integration of element sets representing the histologic sections based on volumetric image registration. Displacement boundary conditions were applied to the μFE models based on registration of loaded and unloaded μCT images. Histologically labeled damaged regions were found to have significantly higher von Mises stresses and principle strains in the μFE models, as compared to undamaged regions. This work provides a new robust method for generating and histologically validating μFE models of whole bones that can represent trabecular damage resulting from complex physiologic loading.
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Affiliation(s)
- Ryan Herblum
- Orthopaedic Biomechanics Laboratory, Sunnybrook Research Institute, 2075 Bayview Avenue, S620, Toronto, ON, Canada, M4N3M5
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Hibberd C, Cossigny DAF, Quan GMY. Animal cancer models of skeletal metastasis. CANCER GROWTH AND METASTASIS 2013; 6:23-34. [PMID: 24665205 PMCID: PMC3941154 DOI: 10.4137/cgm.s11284] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The bony skeleton is one of the most common sites of metastatic spread of cancer and is a significant source of morbidity in cancer patients, causing pain and pathologic fracture, impaired ambulatory ability, and poorer quality of life. Animal cancer models of skeletal metastases are essential for better understanding of the molecular pathways behind metastatic spread and local growth and invasion of bone, to enable analysis of host-tumor cell interactions, identify barriers to the metastatic process, and to provide platforms to develop and test novel therapies prior to clinical application in human patients. Thus, the ideal model should be clinically relevant, reproducible and representative of the human condition. This review summarizes the current in vivo animal models used in the study of cancer metastases of the skeleton.
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Affiliation(s)
- Catherine Hibberd
- Spinal Biology Research Laboratory, University of Melbourne, Department of Surgery, Austin Health, Heidelberg Victoria 3084, Australia. ; Department of Spinal Surgery, Austin Health, Heidelberg Victoria 3084, Australia
| | - Davina A F Cossigny
- Spinal Biology Research Laboratory, University of Melbourne, Department of Surgery, Austin Health, Heidelberg Victoria 3084, Australia
| | - Gerald M Y Quan
- Spinal Biology Research Laboratory, University of Melbourne, Department of Surgery, Austin Health, Heidelberg Victoria 3084, Australia. ; Department of Spinal Surgery, Austin Health, Heidelberg Victoria 3084, Australia
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Hanson K, Ashford DL, Concepcion JJ, Binstead RA, Habibi S, Luo H, Glasson CRK, Templeton JL, Meyer TJ. Sensitized Photodecomposition of Organic Bisphosphonates By Singlet Oxygen. J Am Chem Soc 2012; 134:16975-8. [DOI: 10.1021/ja307987g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Kenneth Hanson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Dennis L. Ashford
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Javier J. Concepcion
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Robert A. Binstead
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Sohrab Habibi
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Hanlin Luo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Christopher R. K. Glasson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Joseph L. Templeton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
| | - Thomas J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599, United States
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Current World Literature. Curr Opin Support Palliat Care 2012; 6:402-16. [DOI: 10.1097/spc.0b013e3283573126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Can micro-imaging based analysis methods quantify structural integrity of rat vertebrae with and without metastatic involvement? J Biomech 2012; 45:2342-8. [PMID: 22858318 DOI: 10.1016/j.jbiomech.2012.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 06/15/2012] [Accepted: 07/08/2012] [Indexed: 11/20/2022]
Abstract
This study compares the ability of μCT image-based registration, 2D structural rigidity analyses and multimodal continuum-level finite element (FE) modeling in evaluating the mechanical stability of healthy, osteolytic, and mixed osteolytic/osteoblastic metastatically involved rat vertebrae. μMR and μCT images (loaded and unloaded) were acquired of lumbar spinal motion segments from 15rnu/rnu rats (five per group). Strains were calculated based on image registration of the loaded and unloaded μCT images and via analysis of FE models created from the μCT and μMR data. Predicted yield load was also calculated through 2D structural rigidity analysis of the axial unloaded μCT slices. Measures from the three techniques were compared to experimental yield loads. The ability of these methods to predict experimental yield loads were evaluated and image registration and FE calculated strains were directly compared. Quantitatively for all samples, only limited weak correlations were found between the image-based measures and experimental yield load. In comparison to the experimental yield load, we observed a trend toward a weak negative correlation with median strain calculated using the image-based strain measurement algorithm (r=-0.405, p=0.067), weak significant correlations (p<0.05) with FE based median and 10th percentile strain values (r=-0.454, -0.637, respectively), and a trend toward a weak significant correlation with FE based mean strain (r=-0.366, p=0.09). Individual group analyses, however, yielded more and stronger correlations with experimental results. Considering the image-based strain measurement algorithm we observed moderate significant correlations with experimental yield load (p<0.05) in the osteolytic group for mean and median strain values (r=-0.840, -0.832, respectively), and in the healthy group for median strain values (r=-0.809). Considering the rigidity-based predicted yield load, we observed a strong significant correlation with the experimental yield load in the mixed osteolytic/osteoblastic group (r=0.946) and trend toward a moderate correlation with the experimental yield load in the osteolytic group (r=0.788). Qualitatively, strain patterns in the vertebral bodies generated using image registration and FEA were well matched, yet quantitatively a significant correlation was found only between mean strains in the healthy group (r=0.934). Large structural differences in metastatic vertebrae and the complexity of motion segment loading may have led to varied modes of failure. Improvements in load characterization, material properties assignments and resolution are necessary to yield a more generalized ability for image-based registration, structural rigidity and FE methods to accurately represent stability in healthy and pathologic scenarios.
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