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Fu R, Liu Y, Song F, Fu J, Du T, Liu Y, Willie BM, Yang H. Effects of dynamization timing and degree on bone healing of different fracture types. J Orthop Res 2023; 41:2394-2404. [PMID: 37138390 DOI: 10.1002/jor.25583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 12/27/2022] [Accepted: 05/01/2023] [Indexed: 05/05/2023]
Abstract
Dynamization, that is, increasing interfragmentary movement (IFM) by reducing fixation stiffness from a rigid to a more flexible state, has been successfully used in clinical practice to promote fracture healing. However, it remains unclear how dynamization timing and degree affect bone healing of different fracture types. Finite element models of tibial fractures based on the OTA/AO classification (Simple: A1-Spiral, A2-Oblique, A3-Transverse; Wedge: B2-Spiral, B3-Fragmented; Complex: C2-Segment, C3-Irregular), in combination with fuzzy logic-based mechano-regulatory tissue differentiation algorithms, were used to simulate the healing process when dynamization of varied degrees (dynamization coefficient or DC = 0-0.9; 0.9 represents 90% reduction in the fixation stiffness relative to a rigid fixation) were applied at different time points after fracture. The fuzzy logic-based algorithms have been validated with a preclinical animal model. The results showed that the healing responses of type A fractures were more sensitive to the changes in dynamization degree and timing comparing with type B or C fractures. Additionally, the optimal dynamization regime for each fracture type was different. For type A fractures, a moderate dynamization degree (e.g., DC = 0.5) applied after Week 1 promoted the recovery of biomechanical integrity. For type B and C fractures, the effective dynamization included a greater dynamization degree (DC = 0.7) applied after Week 2. Our results further demonstrated that the fracture morphology affected interfragmentary strain environments within the callus, leading to varied healing results for different fracture types. These results suggest that the effects of dynamization are highly dependent of the fracture types. Therefore, specific dynamization strategies should be chosen for different fracture types to achieve optimal healing outcomes.
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Affiliation(s)
- Ruisen Fu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Yang Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Fei Song
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Jizhi Fu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Tianming Du
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Youjun Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Bettina M Willie
- Department of Dentistry, McGill University, Montreal, Canada
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
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Hu M, Zeng W, Zhang J, Feng Y, Ma L, Huang F, Cai Q. Fixators dynamization for delayed union and non-union of femur and tibial fractures: a review of techniques, timing and influence factors. J Orthop Surg Res 2023; 18:577. [PMID: 37550732 PMCID: PMC10405409 DOI: 10.1186/s13018-023-04054-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/27/2023] [Indexed: 08/09/2023] Open
Abstract
The optimal balance between mechanical environment and biological factors is crucial for successful bone healing, as they synergistically affect bone development. Any imbalance between these factors can lead to impaired bone healing, resulting in delayed union or non-union. To address this bone healing disorder, clinicians have adopted a technique known as "dynamization" which involves modifying the stiffness properties of the fixator. This technique facilitates the establishment of a favorable mechanical and biological environment by changing a rigid fixator to a more flexible one that promotes bone healing. However, the dynamization of fixators is selective for certain types of non-union and can result in complications or failure to heal if applied to inappropriate non-unions. This review aims to summarize the indications for dynamization, as well as introduce a novel dynamic locking plate and various techniques for dynamization of fixators (intramedullary nails, steel plates, external fixators) in femur and tibial fractures. Additionally, Factors associated with the effectiveness of dynamization are explored in response to the variation in dynamization success rates seen in clinical studies.
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Affiliation(s)
- Minhua Hu
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenxing Zeng
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jingtao Zhang
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yuanlan Feng
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Luyao Ma
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Feng Huang
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China.
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
| | - Qunbin Cai
- The First Clinical College, Guangzhou University of Chinese Medicine, Guangzhou, China.
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
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Jin L, Zhang S, Zhang Y, Lin X, Feng D, Hu K. Management algorithm of external fixation in lower leg arterial injury for limb salvages. BMC Surg 2022; 22:79. [PMID: 35241049 PMCID: PMC8895514 DOI: 10.1186/s12893-022-01486-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 01/17/2022] [Indexed: 11/10/2022] Open
Abstract
Purpose The aim of this study is to investigate the outcome of these limb-threatening injuries through external fixation treatment and to discuss the case of patients’ functional recovery after external fixation. Methods Demographics, surgical treatment and outcomes in 88 patients with lower leg arterial injuries treated by external fixation at two trauma centers from 2009 to 2018 were reviewed. The primary outcome was the rate of successful lower leg salvage, while secondary outcomes were complications and functional recovery. Results Eighty-eight patients were identified and 80 patients (90 legs) maintained a successful lower leg salvage. The mean age was 32.7 ± 10.8 years, and 81.8% were male. The primary outcomes included the following complications: pin-tract infection (8 legs), pins loosening (4 pins), wound superficial infection (7 legs), deep infection developed osteomyelitis (3 legs), bone nonunion or bone defect (17 legs) and amputation (8 legs). The average healing time of fracture was 5.6 ± 4.3 months. The maintain of external fixation average time was 5.8 ± 3.6 months. The improvement of scores of the pain, function and quality of life in our follow-up was statistically significant. Conclusion For the lower extremity fracture patients with vascular injuries, using external fixation correctly can improve clinical outcomes and produce the improvement of pain, function and the quality of life. Level of evidence Retrospective cohort, level IV. The success rate of the lower leg salvage is high, reach the percentage of 91.8% (90/98). External fixation is less invasive, with achieving adequate stability to repair the arterial injury timely, can lower the ischemic time, and beneficial for the following bone or soft tissue repair. Treating the patients with external fixators timely is beneficial to the following vascular anticoagulation, bone defect and vein graft, as a result, the protection of lower limb can be improved.
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Affiliation(s)
- Lei Jin
- Department of Orthopedics, Wuxi Hongqiao Hospital, Jiangnan University School of Medicine, Wuxi, 214026, China.,Department of Orthopedics, Wuxi Orthopedics Hospital, Soochow University, Wuxi, 214062, China
| | - Song Zhang
- School of Basic Medicine, Naval Medical University, Shanghai, 200433, China
| | - Yuxuan Zhang
- Department of Orthopedics, Wuxi Orthopedics Hospital, Soochow University, Wuxi, 214062, China
| | - Xin Lin
- Department of Orthopedics, Wuxi Hongqiao Hospital, Jiangnan University School of Medicine, Wuxi, 214026, China
| | - Dehong Feng
- Department of Orthopedics, Wuxi People's Hospital, Nanjing Medical University, Wuxi, 214023, China. .,Laboratory of Digital Medicine, Wuxi People's Hospital, Nanjing Medical University, Wuxi, 214023, China.
| | - Kejia Hu
- Laboratory of Digital Medicine, Wuxi People's Hospital, Nanjing Medical University, Wuxi, 214023, China. .,Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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Fu R, Feng Y, Liu Y, Willie BM, Yang H. The combined effects of dynamization time and degree on bone healing. J Orthop Res 2022; 40:634-643. [PMID: 33913530 DOI: 10.1002/jor.25060] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 03/08/2021] [Accepted: 04/19/2021] [Indexed: 02/04/2023]
Abstract
Dynamization, increasing the interfragmentary movement (IFM) by reducing the fixation stiffness from a rigid to a more flexible condition, is widely used clinically to promote fracture healing. However, it remains unknown how dynamization degree (relative change in fixation stiffness/IFM from a rigid to a flexible fixation) affects bone healing at various stages. To address this issue, we used a fuzzy logic-based mechano-regulated tissue differentiation algorithm on published experimental data from a sheep osteotomy healing model. We applied a varied degree of dynamization, from 0 (fully rigid fixation) to 0.9 (90% reduction in stiffness relative to the rigid fixation) after 1, 2, 3, and 4 weeks of osteotomy (R1wF, R2wF, R3wF, and R4wF) and computationally evaluated bone regeneration and biomechanical integrity over the healing process of 8 weeks. Compared with the constant rigid fixation, early dynamization (R1wF and R2wF) led to delays in bone bridging and biomechanical recovery of the osteotomized bone. However, the effect of early dynamization on healing was dependent of the degree of dynamization. Specifically, a higher dynamization degree (e.g., 0.9 for R1wF) led to a prolonged delay in bone bridging and largely unrecovered bending stiffness (48% relative to the intact bone), whereas a moderate degree of dynamization (e.g., 0.5 or 0.7) significantly enhanced bone formation and biomechanical properties of the osteotomized bone. These results suggest that dynamization degree and timing interactively affect the healing process. A combination of early dynamization with a moderate degree could enhance the ultimate biomechanical recovery of the fractured bone.
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Affiliation(s)
- Ruisen Fu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Yili Feng
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Youjun Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
| | - Bettina M Willie
- Department of Pediatric Surgery, Research Centre, Shriners Hospital for Children-Canada, McGill University, Montreal, Quebec, Canada
| | - Haisheng Yang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, China
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Abstract
Background: Traumatic fracture is a common orthopaedic disease, and application of 3D printing technology in fracture treatment, which entails utilisation of pre-operative printed anatomic fracture model, is increasingly gaining popularity. However, effectiveness of 3D printing-assisted surgery lacks evidence-based findings to support its application. Materials and Methods: Embase, PubMed and Cochrane Library databases were systematically searched until October, 2020 to identify relevant studies. All randomised controlled trials (RCTs) comparing efficacy of 3D printing-assisted surgery vs. conventional surgery for traumatic fractures were reviewed. RevMan V.5.3 software was used to conduct meta-analysis. Results: A total of 12 RCTs involving 641 patients were included. Pooled findings showed that 3D printing-assisted surgery had shorter operation duration [standardised mean difference (SMD) = −1.52, 95% confidence interval (CI) – 1.70 ~ −1.34, P < 0.00001], less intraoperative blood loss (SMD = 1.34, 95% CI 1.74 ~ 0.94, P < 0.00001), fewer intraoperative fluoroscopies (SMD = 1.25, 95% CI 1.64 ~ 0.87, P < 0.00001), shorter fracture union time (SMD = −0.15, 95% CI −0.25 ~ −0.05, P = 0.003), and higher rate of excellent outcomes (OR = 2.40, 95% CI 1.07 ~ 5.37, P = 0.03) compared with conventional surgery. No significant differences in complication rates were observed between the two types of surgery (OR = 0.69, 95% CI 0.69 ~ 1.42, P = 0.32). Conclusions: Indicators including operation duration, intraoperative blood loss, number of intraoperative fluoroscopies, fracture union time, and rates of excellent outcomes showed that 3D printing-assisted surgery is a superior alternative in treatment of traumatic fractures compared with conventional surgery. Moreover, the current study did not report significant differences in incidence of complications between the two approaches. Systematic Review Registration: CRD42021239507.
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Affiliation(s)
- Sha Yang
- Department of Orthopaedics, Children's Hospital of Chongqing Medical University, Chongqing, China.,Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Engineering Research Center of Stem Cell Therapy, National Clinical Research Center for Child Health and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Huapeng Lin
- Department of Intensive Care Unit, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Cong Luo
- Department of Orthopaedics, Children's Hospital of Chongqing Medical University, Chongqing, China.,Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Engineering Research Center of Stem Cell Therapy, National Clinical Research Center for Child Health and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
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Claes L. Improvement of clinical fracture healing - What can be learned from mechano-biological research? J Biomech 2020; 115:110148. [PMID: 33341439 DOI: 10.1016/j.jbiomech.2020.110148] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/12/2020] [Accepted: 11/21/2020] [Indexed: 10/22/2022]
Abstract
The most significant predictors of reoperation following operative management of fractures are the presence of a third degree open fracture, remaining fracture gaps and a transverse fracture. However clinical studies provide no information regarding the involvement of various soft tissues or how the mechanical environment affects revascularisation and bone healing. Here the results of experimental and numerical mechano-biological studies on fracture healing are summarized to provide guidance toward clinical treatment of fractures. In experimental studies, isolated muscle crush appeared to only temporarily impair fracture healing, with no significant effect to the final bone healing, whereas a more severe muscle trauma significantly reduced callus formation and biomechanical properties of the healed bones. An intraoperative trauma can furthermore impede vascularization. Surgical removal of the haematoma or periosteum disturbs fracture healing. While reaming for intramedullary nailing reduced blood flow in the bone during the early phase of bone healing, it did not affect the stiffness or strength of the final bone healing. The optimal conditions for rapid vascularization and bone healing result from fracture fixation that minimizes shearing movements in the healing zone while allowing moderate compressive movements. Bone healing is increasingly delayed with increasing fracture gap size and critical-size defects do not heal sufficiently independent of the mechanical environment. The stiffness of fracture fixation systems like nails and external fixators applied in clinical treatments frequently display a too low stiffness, whereas plate systems often cause a too stiff fixation that suppresses bone healing.
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Affiliation(s)
- Lutz Claes
- Institute for Orthopaedic Research and Biomechanics, Center for Trauma Research, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.
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