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Wähnert D, Miersbach M, Colcuc C, Brianza S, Vordemvenne T, Plecko M, Schwarz A. Promoting bone callus formation by taking advantage of the time-dependent fracture gap strain modulation. Front Surg 2024; 11:1376441. [PMID: 38756355 PMCID: PMC11096559 DOI: 10.3389/fsurg.2024.1376441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 04/23/2024] [Indexed: 05/18/2024] Open
Abstract
Delayed union and non-union of fractures continue to be a major problem in trauma and orthopedic surgery. These cases are challenging for the surgeon. In addition, these patients suffer from multiple surgeries, pain and disability. Furthermore, these cases are a major burden on healthcare systems. The scientific community widely agrees that the stability of fixation plays a crucial role in determining the outcome of osteosynthesis. The extent of stabilization affects factors like fracture gap strain and fluid flow, which, in turn, influence the regenerative processes positively or negatively. Nonetheless, a growing body of literature suggests that during the fracture healing process, there exists a critical time frame where intervention can stimulate the bone's return to its original form and function. This article provides a summary of existing evidence in the literature regarding the impact of different levels of fixation stability on the strain experienced by newly forming tissues. We will also discuss the timing and nature of this "window of opportunity" and explore how current knowledge is driving the development of new technologies with design enhancements rooted in mechanobiological principles.
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Affiliation(s)
- Dirk Wähnert
- Department of Trauma and Orthopedic Surgery, Protestant Hospital of Bethel Foundation, University Hospital OWL of Bielefeld University, Bielefeld, Germany
| | - Marco Miersbach
- Department of Trauma and Orthopedic Surgery, Protestant Hospital of Bethel Foundation, University Hospital OWL of Bielefeld University, Bielefeld, Germany
| | - Christian Colcuc
- Department of Trauma and Orthopedic Surgery, Protestant Hospital of Bethel Foundation, University Hospital OWL of Bielefeld University, Bielefeld, Germany
| | | | - Thomas Vordemvenne
- Department of Trauma and Orthopedic Surgery, Protestant Hospital of Bethel Foundation, University Hospital OWL of Bielefeld University, Bielefeld, Germany
| | - Michael Plecko
- Department of Orthopaedics and Traumatology, Trauma Hospital Graz (UKH), Graz, Austria
| | - Angelika Schwarz
- Department of Orthopaedics and Traumatology, Trauma Hospital Graz (UKH), Graz, Austria
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Abstract
Despite major research efforts to elucidate mechanisms of non-union formation, failed fracture healing remains a common complication in orthopedic surgery. Adequate vascularization has been recognized as a crucial factor for successful bone regeneration, as newly formed microvessels guarantee the supply of the callus tissue with vital oxygen, nutrients, and growth factors. Accordingly, a vast number of preclinical studies have focused on the development of vascularization strategies to stimulate fracture repair. However, recent evidence suggests that stimulation of blood vessel formation is an oversimplified approach to support bone regeneration. This review discusses the role of vascularization during bone regeneration and delineates a phenomenon, for which we coin the term “the vascularization paradox of non-union-formation”. This view is based on the results of a variety of experimental studies that suggest that the callus tissue of non-unions is indeed densely vascularized and that pro-angiogenic mediators, such as vascular endothelial growth factor, are sufficiently expressed at the facture site. By gaining further insights into the molecular and cellular basis of non-union vascularization, it may be possible to develop more optimized treatment approaches or even prevent the non-union formation in the future.
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Autogenous Arteriovenous Bundle Implantation Maintains Viability Without Increased Immune Response in Large Porcine Bone Allotransplants. Transplant Proc 2020; 53:417-426. [PMID: 32958221 DOI: 10.1016/j.transproceed.2020.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/11/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Transplantation of living allogeneic bone segments may permit reconstruction of large defects, particularly if viability is maintained without immunosuppression. Development of a new autogenous osseous blood supply accomplishes this goal in rodent experimental models. This study evaluates potential systemic and local inflammatory responses to this angiogenesis in a large-animal model. METHODS Vascularized allogeneic tibia segments were transplanted orthotopically into matched tibial defects in Yucatan minipigs. Microvascular anastomoses of bone nutrient artery and vein were supplemented by intramedullary placement of an autogenous arteriovenous (AV) bundle in group 1. Group 2 served as a no-angiogenesis control. A 3-drug immunosuppression regimen was withdrawn after 2 weeks. During the 20-week survival period, periodic leukocyte counts and inflammatory cytokine levels were measured. Thereafter, osteocyte survival was quantified and transplant rejection graded by histologic examination and quantitative real-time polymerase chain reaction of immunologic markers. RESULTS Both groups developed an initial systemic response, which resolved after 4 to 6 weeks. No differences were seen in blood cytokine levels. Interleukin 2 expression was diminished in group 1 tibiae. As expected, nutrient pedicles had thrombosed without sustained immunosuppression, occluded by intimal hyperplasia. In group 1, angiogenesis from the autogenous AV bundle resulted in significantly less osteonecrosis (P = .04) and fibrosis (P = .02) than group 2 allotransplants. CONCLUSIONS Systemic immune responses to large-bone allotransplants were not increased by generation of an autogenous osseous blood supply within porcine tibial bone allotransplants. Implanted AV bundles diminished inflammation and fibrosis and improved bone viability when compared to no-angiogenesis controls.
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Struckmann V, Schmidmaier G, Ferbert T, Kneser U, Kremer T. Reconstruction of Extended Bone Defects Using Massive Allografts Combined with Surgical Angiogenesis: A Case Report. JBJS Case Connect 2018; 7:e10. [PMID: 29244692 DOI: 10.2106/jbjs.cc.16.00098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CASE A 20-year-old patient presented with an extended composite knee defect with destruction of the medial femoral condyle, including the medial collateral ligament. Treatment included using an anterolateral thigh flap for soft-tissue reconstruction, tensor fasciae latae muscle for ligament repair, and a massive allogenic bone graft of the medial femoral condyle that was revascularized with an osteocutaneous composite free flap from the contralateral femur. At 17 months postoperatively, the outcome was evaluated with scores on several established scales and radiographic assessment. CONCLUSION The combination of vascularized soft-tissue reconstruction and osseous reconstruction using allogenic bone along with surgical angiogenesis proved to be effective. Complex extremity reconstruction should be discussed with interdisciplinary specialists.
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Affiliation(s)
- Victoria Struckmann
- Department of Hand, Plastic and Reconstructive Surgery, Hand and Plastic Surgery, BG Trauma Center Ludwigshafen, Burn Center, Ludwigshafen, Rheinland-Pfalz, Germany
| | - Gerhard Schmidmaier
- Department of Orthopaedics and Traumatology, University of Heidelberg, Heidelberg, Germany
| | - Thomas Ferbert
- Department of Orthopaedics and Traumatology, University of Heidelberg, Heidelberg, Germany
| | - Ulrich Kneser
- Department of Hand, Plastic and Reconstructive Surgery, Hand and Plastic Surgery, BG Trauma Center Ludwigshafen, Burn Center, Ludwigshafen, Rheinland-Pfalz, Germany
| | - Thomas Kremer
- Department of Hand, Plastic and Reconstructive Surgery, Hand and Plastic Surgery, BG Trauma Center Ludwigshafen, Burn Center, Ludwigshafen, Rheinland-Pfalz, Germany
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Bigham-Sadegh A, Oryan A. Selection of animal models for pre-clinical strategies in evaluating the fracture healing, bone graft substitutes and bone tissue regeneration and engineering. Connect Tissue Res 2015; 56:175-94. [PMID: 25803622 DOI: 10.3109/03008207.2015.1027341] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In vitro assays can be useful in determining biological mechanism and optimizing scaffold parameters, however translation of the in vitro results to clinics is generally hard. Animal experimentation is a better approximation than in vitro tests, and usage of animal models is often essential in extrapolating the experimental results and translating the information in a human clinical setting. In addition, usage of animal models to study fracture healing is useful to answer questions related to the most effective method to treat humans. There are several factors that should be considered when selecting an animal model. These include availability of the animal, cost, ease of handling and care, size of the animal, acceptability to society, resistance to surgery, infection and disease, biological properties analogous to humans, bone structure and composition, as well as bone modeling and remodeling characteristics. Animal experiments on bone healing have been conducted on small and large animals, including mice, rats, rabbits, dogs, pigs, goats and sheep. This review also describes the molecular events during various steps of fracture healing and explains different means of fracture healing evaluation including biomechanical, histopathological and radiological assessments.
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Affiliation(s)
- Amin Bigham-Sadegh
- Faculty of Veterinary Medicine, Department of Veterinary Surgery and Radiology, Shahrekord University , Shahrekord , Iran and
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Krishnan L, Willett NJ, Guldberg RE. Vascularization strategies for bone regeneration. Ann Biomed Eng 2014; 42:432-44. [PMID: 24468975 DOI: 10.1007/s10439-014-0969-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/02/2014] [Indexed: 12/31/2022]
Abstract
The functional regeneration of thick vascularized tissues such as bone and muscle is complicated by the large volume of lost tissue, challenging biomechanical environment, and the need to reproduce the highly organized structure of both the native tissue extracellular matrix and its vascular support system. Stem cell or progenitor cell delivery approaches, for example, continue to be plagued by low viability and engraftment in part due to the initial absence of a vascular supply. Recognition of diffusion limitations in thick tissues has prompted regenerative strategies that seek to accelerate establishment of a functional vasculature. The successful design of robust regeneration strategies for these challenging clinical scenarios will rely on a thorough understanding of interactions between construct design parameters and host biological and biomechanical factors. Here, we discuss the critical role of vascularization in normal bone tissue homeostasis and repair, vascular network adaptation to the local biomechanical environment, and the future directions of revascularization approaches being developed and integrated with bone regeneration strategies.
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Affiliation(s)
- Laxminarayanan Krishnan
- Parker H. Petit Institute for Bioengineering and Bioscience, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, GA, 30332-0363, USA
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Willems WF, Kremer T, Friedrich P, Bishop AT. Surgical revascularization induces angiogenesis in orthotopic bone allograft. Clin Orthop Relat Res 2012; 470:2496-502. [PMID: 22723247 PMCID: PMC3830091 DOI: 10.1007/s11999-012-2442-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Remodeling of structural bone allografts relies on adequate revascularization, which can theoretically be induced by surgical revascularization. We developed a new orthotopic animal model to determine the technical feasibility of axial arteriovenous bundle implantation and resultant angiogenesis. QUESTIONS/PURPOSES We asked whether arteriovenous bundles implanted in segmental allografts would increase cortical blood flow and angiogenesis compared to nonrevascularized frozen bone allografts and contralateral femoral controls. METHODS We performed segmental femoral allotransplantation orthotopically from 10 Brown Norway rats to 20 Lewis rats. Ten rats each received either bone allograft reconstruction alone (Group I) or allograft combined with an intramedullary saphenous arteriovenous flap (Group II). At 16 weeks, we measured cortical blood flow with the hydrogen washout method. We then quantified angiogenesis using capillary density and micro-CT vessel volume measurements. RESULTS All arteriovenous bundles were patent. Group II had higher mean blood flow (0.12 mL/minute/100 g versus 0.05 mL/minute/100 g), mean capillary density (23.6% versus 2.8%), and micro-CT vessel volume (0.37 mm(3) versus 0.07 mm(3)) than Group I. Revascularized allografts had higher capillary density than untreated contralateral femora, while vessel volume did not differ and blood flow was lower. CONCLUSIONS Axial surgical revascularization in orthotopic allotransplants can achieve strong angiogenesis and increases cortical bone blood flow.
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Affiliation(s)
- Wouter F. Willems
- Microvascular Research Laboratory, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905 USA
| | - Thomas Kremer
- Microvascular Research Laboratory, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905 USA
| | - Patricia Friedrich
- Microvascular Research Laboratory, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905 USA
| | - Allen T. Bishop
- Microvascular Research Laboratory, Mayo Clinic, 200 First Street, SW, Rochester, MN 55905 USA
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Schneider MKJ, Seebach JD. Xenotransplantation literature update: February-March, 2010. Xenotransplantation 2010; 17:256-60. [DOI: 10.1111/j.1399-3089.2010.00593.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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