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Emerzian SR, Wu T, Vaidya R, Tang SY, Abergel RJ, Keaveny TM. Relative Effects of Radiation-Induced Changes in Bone Mass, Structure, and Tissue Material on Vertebral Strength in a Rat Model. J Bone Miner Res 2023; 38:1032-1042. [PMID: 37191221 PMCID: PMC10524463 DOI: 10.1002/jbmr.4828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/06/2023] [Accepted: 05/07/2023] [Indexed: 05/17/2023]
Abstract
The observed increased risk of fracture after cancer radiation therapy is presumably due to a radiation-induced reduction in whole-bone strength. However, the mechanisms for impaired strength remain unclear, as the increased fracture risk is not fully explained by changes in bone mass. To provide insight, a small animal model was used to determine how much of this whole-bone weakening effect for the spine is attributable to changes in bone mass, structure, and material properties of the bone tissue and their relative effects. Further, because women have a greater risk of fracture after radiation therapy than men, we investigated if sex had a significant influence on bone's response to irradiation. Fractionated in vivo irradiation (10 × 3 Gy) or sham irradiation (0 Gy) was administered daily to the lumbar spine in twenty-seven 17-week-old Sprague-Dawley rats (n = 6-7/sex/group). Twelve weeks after final treatment, animals were euthanized, and lumbar vertebrae (L4 and L5 ) were isolated. Using a combination of biomechanical testing, micro-CT-based finite element analysis, and statistical regression analysis, we separated out the effect of mass, structural, and tissue material changes on vertebral strength. Compared with the sham group (mean ± SD strength = 420 ± 88 N), the mean strength of the irradiated group was lower by 28% (117 N/420 N, p < 0.0001). Overall, the response of treatment did not differ with sex. By combining results from both general linear regression and finite element analyses, we calculated that mean changes in bone mass, structure, and material properties of the bone tissue accounted for 56% (66 N/117 N), 20% (23 N/117 N), and 24% (28 N/117 N), respectively, of the overall change in strength. As such, these results provide insight into why an elevated clinical fracture risk for patients undergoing radiation therapy is not well explained by changes in bone mass alone. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Shannon R. Emerzian
- Department of Mechanical Engineering, University of
California, Berkeley, California, USA
| | - Tongge Wu
- Department of Mechanical Engineering, University of
California, Berkeley, California, USA
| | - Rachana Vaidya
- Department of Orthopaedic Surgery, Washington University,
St. Louis, Missouri, USA
| | - Simon Y. Tang
- Department of Orthopaedic Surgery, Washington University,
St. Louis, Missouri, USA
- Department of Biomedical Engineering, Washington
University, St. Louis, Missouri, USA
- Department of Material Science & Mechanical
Engineering, Washington University, St. Louis, Missouri, USA
| | - Rebecca J. Abergel
- Department of Nuclear Engineering, University of
California, Berkeley, California, USA
| | - Tony M. Keaveny
- Department of Mechanical Engineering, University of
California, Berkeley, California, USA
- Department of Bioengineering, University of California,
Berkeley, California, USA
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Graf-Alexiou L, Qiu Y, Aalto D, Westover L. An Investigation of the Effect of Irradiation on the Biomechanical Properties of Fibular Grafts. J Oral Maxillofac Surg 2021; 80:784.e1-784.e5. [PMID: 34942151 DOI: 10.1016/j.joms.2021.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 11/05/2021] [Accepted: 11/23/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE Irradiation of fibular grafts for jaw reconstruction following mandibulectomy can be associated with increased graft failure and implant instability. The objective of this study is to investigate the effect of isolated irradiation on the biomechanical properties of ex-vivo porcine fibula grafts. It was hypothesized that the isolated irradiation (without biological response) will not significantly influence the biomechanical properties of the fibular grafts. METHODS Forty porcine fibular grafts (n = 20 irradiated and n = 20 nonirradiated) were obtained. The irradiated group was subjected to a single dose of 60 Gy of irradiation with cesium 137. Both groups underwent 3-point bending tests with cyclic loading for 1500 cycles (50 to 500 N at 2 Hz) followed by push to failure. Rate of damage (mm/s), stiffness (N/mm), modulus of elasticity (MPa), maximum load (N), maximum displacement (mm), and maximum stress (MPa) were compared between the 2 groups using independent t tests (P < .05). RESULTS No significant differences were found between the irradiated and nonirradiated groups for any of the biomechanical parameters (all P values > 0.05). CONCLUSIONS The results of this study support our hypothesis that even high levels of isolated irradiation do not significantly affect the biomechanical properties of fibular bone grafts. This work allows us to exclude acute structural changes in the bone due to irradiation as a possible factor leading to bone/implant instability following jaw reconstruction with fibular grafts. Further studies need to be conducted to better understand the range of factors that may lead to implant instability, including the biological response after radiation therapy.
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Affiliation(s)
- Lucas Graf-Alexiou
- Student, Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
| | - Yuelin Qiu
- Student, Department of Civil Engineering, University of Alberta, Edmonton, Canada
| | - Daniel Aalto
- Assistant Professor, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada; Assistant Professor, Institute for Reconstructive Sciences in Medicine (iRSM), Edmonton, Canada
| | - Lindsey Westover
- Student, Department of Mechanical Engineering, University of Alberta, Edmonton, Canada.
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Pendleton MM, Emerzian SR, Sadoughi S, Li A, Liu JW, Tang SY, O'Connell GD, Sibonga JD, Alwood JS, Keaveny TM. Relations Between Bone Quantity, Microarchitecture, and Collagen Cross-links on Mechanics Following In Vivo Irradiation in Mice. JBMR Plus 2021; 5:e10545. [PMID: 34761148 PMCID: PMC8567491 DOI: 10.1002/jbm4.10545] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 08/20/2021] [Indexed: 01/22/2023] Open
Abstract
Humans are exposed to ionizing radiation via spaceflight or cancer radiotherapy, and exposure from radiotherapy is known to increase risk of skeletal fractures. Although irradiation can reduce trabecular bone mass, alter trabecular microarchitecture, and increase collagen cross‐linking, the relative contributions of these effects to any loss of mechanical integrity remain unclear. To provide insight, while addressing both the monotonic strength and cyclic‐loading fatigue life, we conducted total‐body, acute, gamma‐irradiation experiments on skeletally mature (17‐week‐old) C57BL/6J male mice (n = 84). Mice were administered doses of either 0 Gy (sham), 1 Gy (motivated by cumulative exposures from a Mars mission), or 5 Gy (motivated by clinical therapy regimens) with retrieval of the lumbar vertebrae at either a short‐term (11‐day) or long‐term (12‐week) time point after exposure. Micro‐computed tomography was used to assess trabecular and cortical quantity and architecture, biochemical composition assays were used to assess collagen quality, and mechanical testing was performed to evaluate vertebral compressive strength and fatigue life. At 11 days post‐exposure, 5 Gy irradiation significantly reduced trabecular mass (p < 0.001), altered microarchitecture (eg, connectivity density p < 0.001), and increased collagen cross‐links (p < 0.001). Despite these changes, vertebral strength (p = 0.745) and fatigue life (p = 0.332) remained unaltered. At 12 weeks after 5 Gy exposure, the trends in trabecular bone persisted; in addition, regardless of irradiation, cortical thickness (p < 0.01) and fatigue life (p < 0.01) decreased. These results demonstrate that the highly significant effects of 5 Gy total‐body irradiation on the trabecular bone morphology and collagen cross‐links did not translate into detectable effects on vertebral mechanics. The only mechanical deficits observed were associated with aging. Together, these vertebral results suggest that for spaceflight, irradiation alone will likely not alter failure properties, and for radiotherapy, more investigations that include post‐exposure time as a positive control and testing of both failure modalities are needed to determine the cause of increased fracture risk. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Megan M Pendleton
- Department of Mechanical Engineering University of California Berkeley CA USA
| | - Shannon R Emerzian
- Department of Mechanical Engineering University of California Berkeley CA USA
| | - Saghi Sadoughi
- Department of Mechanical Engineering University of California Berkeley CA USA
| | - Alfred Li
- Endocrine Research Unit University of California and Veteran Affairs Medical Center San Francisco CA USA
| | - Jennifer W Liu
- Department of Orthopaedic Surgery Washington University St. Louis MO USA
| | - Simon Y Tang
- Department of Orthopaedic Surgery Washington University St. Louis MO USA.,Department of Biomedical Engineering Washington University St. Louis MO USA.,Department of Mechanical Engineering and Materials Science Washington University St. Louis MO USA
| | - Grace D O'Connell
- Department of Mechanical Engineering University of California Berkeley CA USA.,Department of Orthopaedic Surgery University of California San Francisco CA USA
| | - Jean D Sibonga
- Biomedical Research and Environmental Sciences Division NASA Johnson Space Center Houston TX USA
| | - Joshua S Alwood
- Space Biosciences Division NASA Ames Research Center Moffett Field CA USA
| | - Tony M Keaveny
- Department of Mechanical Engineering University of California Berkeley CA USA.,Department of Bioengineering University of California Berkeley CA USA
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Rosen DB, Haseltine JM, Bartelstein M, Flynn JR, Zhang Z, Kohutek ZA, Yamada Y, Schmitt A, Higginson DS, Vaynrub M, Yang JT, Gillespie EF. Should Postoperative Radiation for Long Bone Metastases Cover Part or All of the Orthopedic Hardware? Results of a Large Retrospective Analysis. Adv Radiat Oncol 2021; 6:100756. [PMID: 34585024 PMCID: PMC8450200 DOI: 10.1016/j.adro.2021.100756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/12/2021] [Accepted: 07/04/2021] [Indexed: 11/25/2022] Open
Abstract
Purpose For patients with long bone metastases who undergo orthopedic stabilization surgery followed by radiotherapy (RT), it is unclear what extent of hardware coverage by the radiation field is needed for optimal tumor control. Methods and Materials Long bone metastases treated with surgical intervention followed by radiation between August 2011 to May 2019 from a single institution were reviewed. Local recurrence, defined as any in-bone recurrence, was identified by chart review. Accompanying demographic and treatment characteristics were recorded. Statistical analysis to evaluate factors associated with tumor recurrence included univariate analysis, multivariate analysis, and propensity score matching. Results Among 138 patients with 145 long bone metastases undergoing postoperative RT with a median follow-up of 29.5 months, 36 bone metastases experienced a local recurrence. Most patients (92%) were treated with conventional RT and the median delivered dose was 30 Gy (interquarile range, 20-30 Gy). On univariate analysis, whole hardware RT field coverage and higher dose (biologically effective dose 10 ≥39 Gy) were associated with reduced local recurrence (0.44 hazard ratio [HR]; 95% confidence interval [CI], 0.22%-0.86%; P = .017; 0.5 HR; 95% CI, 0.26%-0.96%; P = .038, respectively). Covariates of time from surgery to RT start, histology of primary tumor (categorized as resistant vs sensitive), intramedullary hardware placement, reaming procedure, and margin status did not reach statistical significance. To adjust for confounding effects, we also conducted a propensity score matched analysis which confirmed that whole hardware coverage was statistically associated with a decreased risk of recurrence on the matched dataset (0.24 HR; 95% CI, 0.07%-0.84%; P = .026). Conclusions In this analysis of mostly patients undergoing conventional radiation, coverage of the whole hardware was associated with reduced local recurrence for patients with long bone metastases, consistent with prior reports. Investigation of approaches to further reduce local recurrence, such as preoperative stereotactic radiation, may be warranted.
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Affiliation(s)
| | | | - Meredith Bartelstein
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jessica R Flynn
- Orthopaedic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Zhigang Zhang
- Orthopaedic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Zachary A Kohutek
- Department of Epidemiology & Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York
| | | | - Adam Schmitt
- Vanderbilt-Ingram Cancer Center, Nashville, Tennessee
| | | | - Maksim Vaynrub
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
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Butterworth KT, Williams JP. Animal Models for Radiotherapy Research: All (Animal) Models Are Wrong but Some Are Useful. Cancers (Basel) 2021; 13:cancers13061319. [PMID: 33809414 PMCID: PMC8001499 DOI: 10.3390/cancers13061319] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Affiliation(s)
- Karl T. Butterworth
- Patrick G. Johnston Centre for Cancer Research, Queen’s University Belfast, Belfast BT9 7AE, UK
- Correspondence:
| | - Jacqueline P. Williams
- University of Rochester Medical Centre, University of Rochester, Rochester, NY 14642, USA;
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