scholarly journals Fracture Healing Assessment Based on Impact Testing: In Vitro Simulation and Monitoring of the Healing Process of a Tibial Fracture with External Fixator

2017 ◽  
Vol 09 (07) ◽  
pp. 1750098 ◽  
Author(s):  
Francesca Di Puccio ◽  
Lorenza Mattei ◽  
Antonia Longo ◽  
Stefano Marchetti
Keyword(s):  
Fracture Healing ◽  
Modal Analysis ◽  
External Fixator ◽  
Healing Process ◽  
Experimental Modal Analysis ◽  
Impact Testing ◽  
Resonant Frequencies ◽  
Bone Callus ◽  
Healing Assessment

In clinical practice, bone healing is monitored with X-rays and manipulation. Its assessment is thus subjective, depending on the skills of the operator. Alternative and quantitative approaches have been proposed, generally based on the estimation of bone stiffness, which is known to increase with the healing process. The present study investigates the application of experimental modal analysis to fracture healing assessment focusing on fractures treated with an external fixator. The aim is to ascertain the capability of this approach to detect changes in the bone-callus stiffness as variations in the resonant frequencies despite the presence of the fixator, which might hide the bone response. In vitro tests were performed on a tibia phantom where the healing process was simulated creating three different types of callus surrogates, using glue and resin. The resonant frequencies of the phantom with screwed pins and of the phantom with the complete fixator were estimated. Results confirm an increase in the frequencies as the simulated bone-callus stiffness increases, encouraging the application of experimental modal analysis to fracture healing monitoring. This approach can offer remarkable advantages with respect to the actual standards: being non-invasive and quantitative, it would allow a more frequent healing monitoring.

scholarly journals In vivo impact testing on a lengthened femur with external fixation: a future option for the non-invasive monitoring of fracture healing?

2018 ◽  
Vol 15 (142) ◽  
pp. 20180068 ◽  
Author(s):  
Lorenza Mattei ◽  
Francesca Di Puccio ◽  
Stefano Marchetti
Keyword(s):  
Fracture Healing ◽  
Soft Tissues ◽  
Healing Process ◽  
Impact Testing ◽  
Resonant Frequencies ◽  
Soft Phase ◽  
Non Invasive ◽  
Woven Bone ◽  
Healing Assessment ◽  
The Impact

Non-invasive methods for assessing fracture healing are crucial for biomedical engineers. An approach based on mechanical vibrations was tried out in the 1990s, but was soon abandoned due to insufficiently advanced technologies. The same approach is re-proposed in the present study in order to monitor the healing process of a lengthened femur with an external fixator. The pins screwed into the bone were exploited for the impact testing (IT) to excite the bone and capture its response. Transmission through the soft tissues was thus prevented, and the quality of the signals was improved. Impact tests were performed every three to four weeks for five months. Unfortunately, after seven weeks, some pins were removed due to infection, and thus, the system was modified. Two different configurations were considered: before and after pin removal. An additional configuration was examined in the last two sessions, when the fixator body was removed, while four pins were left in the femur. The evolution of the frequency response function and of the resonant frequencies of the system were analysed for the duration of the monitoring period. The IT results were compared to the indications provided by X-ray images. During the evolution of the callus from the soft phase to the woven bone, the resonant frequencies of the system were found to increase by approximately 2–3% per week. The largest increase (approx. 22%) was observed for the first resonant frequency. After formation of the woven bone, the vibratory response remained almost the same, suggesting that the healing assessment could be related to the relative variation in the resonant frequencies. The results presented support the application of the IT approach for fracture healing assessment.

scholarly journals Short Wave Enhances Mesenchymal Stem Cell Recruitment through Hypoxia-Inducible Factor-1 Signaling in Fracture Healing

2020 ◽  
Author(s):  
Dongmei Ye ◽  
Chen Chen ◽  
Qiwen Wang ◽  
Qi Zhang ◽  
Sha Li ◽  
...  
Keyword(s):  
Stem Cell ◽  
Mesenchymal Stem Cell ◽  
Fracture Healing ◽  
Callus Formation ◽  
Healing Process ◽  
Short Wave ◽  
Fracture Site ◽  
Related Factors ◽  
Femur Fractures

Abstract Background: As a type of high-frequency electrotherapy, a short wave can promote the fracture healing process; yet, its underlying therapeutic mechanisms still remain unclear.Purpose: To observe the effect of short wave on mesenchymal stem cell (MSC) homing and its mechanisms associated with fracture healing.Materials and Methods: The effect of short wave on a fracture healing was examined in 40 rats. Stabilized femur fractures were established by intramedullary fixation; radiography was used to analyze the morphology and micro-architecture of the callus. Additionally, fluorescence assays were used to analyze the MSC migration after treatment in 20 nude mice with a femoral fracture. For in vitro study, osteoblast simulated fracture site was first irradiated by the short wave; siRNA targeting HIF-1 was used to investigate the role of HIF-1. Osteoblast cultured supernatant was then collected as chemotaxis content of MSC, and the migration of MSC was evaluated using wound healing assay and trans-well chamber test. The expression of HIF-1 and its related factors were quantified by qRT-PCR, ELISA, and Western blot.Results: Our in vivo experiment indicated that short wave could promote MSC migration, increase local and serum HIF-1 levels, induce changes in callus formation, and improve callus microarchitecture and mechanical properties, thus speeding up the healing process of the fracture site. Moreover, the in vitro results further indicated that short waves upregulated HIF-1 expression in osteoblast and increased HIF-1, SDF-1 protein levels in the supernatant, as well as the expression of CXCR-4, β-catenin, F-actin and phosphorylation levels of FAK in MSC. On the other hand, the inhibition of HIF-1α was significantly restrained by the inhibition of HIF-1α in osteoblast and it partially inhibited the migration of MSC.Conclusions: These results suggested that short wave could increase HIF-1 in callus, which is one of the crucial mechanisms of chemotaxis MSC homing in fracture healing.

scholarly journals Experimental modal analysis in research

2017 ◽  
Vol 16 (3) ◽  
pp. 005-012 ◽  
Author(s):  
Mariusz Żółtowski ◽  
Krzysztof Napieraj
Keyword(s):  
Parameter Estimation ◽  
Modal Analysis ◽  
Civil Engineering ◽  
Experimental Modal Analysis ◽  
Impact Testing ◽  
Engineering Industry ◽  
Vibration Modes ◽  
Modal Parameter ◽  
Excitation Techniques ◽  
Modal Parameter Estimation

Experimental modal analysis has grown steadily in popularity since the advent of the digital FFT spectrum analyser in the 1970’s. This days impact testing has become widespread as a fast and economical means of finding the vibration modes of a machine or structure. Its significantly use ascending roles can be seen also in the civil engineering industry [6]. This paper reviews the main topics associated with experimental modal analysis including making FRF measurements, modal excitation techniques, and modal parameter estimation from a set of FRFs.

Experimental Modal Analysis of Compressor Vibration Isolating System Based on LMS Test.Lab

2011 ◽  
Vol 121-126 ◽  
pp. 3283-3288
Author(s):  
Li Zhang ◽  
Hao Chen ◽  
Yan Jue Gong ◽  
Jing Wang
Keyword(s):  
Resonance Frequency ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Single Layer ◽  
Experimental Modal Analysis ◽  
Impact Testing ◽  
Modal Parameters ◽  
Isolation System ◽  
Refrigeration Unit ◽  
Comparison Results

In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experimental modal analysis based on LMS Test. Lab Impact Testing software. The comparison results of modal parameters of four different vibration isolating systems show that the natural frequency of single-layer vibration isolating system is higher than that of non-isolation system and effectively avoids the second order resonance frequency. Furthermore the natural frequency of double-layer vibration isolating system has reduced due to the additional middle-mass. And the system's natural frequency decreases obviously with the increase of middle-mass which is far from resonance frequency and significantly improve the effect of vibration isolating system.

scholarly journals Histological Analysis of Bone Callus in Delayed Union Model Fracture Healing Stimulated with Pulsed Electromagnetic Fields (PEMF)

Scientifica ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
U. Umiatin ◽  
Ismail Hadisoebroto Dilogo ◽  
Puji Sari ◽  
Sastra Kusuma Wijaya
Keyword(s):  
Fracture Healing ◽  
Histological Analysis ◽  
Healing Process ◽  
Fibrous Tissue ◽  
Delayed Union ◽  
Control Group ◽  
Left Femur ◽  
Physical Methods ◽  
Bone Callus ◽  
Pulsed Electromagnetic

Delayed union and nonunion fractures are clinical challenges for orthopedic surgeons. The development of fracture complications, such as delayed union and nonunion fractures, is still difficult to predict. Various methods are being investigated to improve fracture healing and prevent complications in patients. There are various methods to promote fracture healing, broadly divided into biological, chemical, and physical methods. One of the most widely used physical methods to promote fracture healing is the pulsed electromagnetic field (PEMF). This study aimed to evaluate the healing process of delayed union fracture after being stimulated by PEMF. Twenty-four rats were randomly divided into two groups: the control group (n = 12) and the PEMF group (n = 12). Delayed union fracture was performed on the left femur of all rats. Subsequently, the PEMF group was given PEMF stimulus with a magnetic field intensity of 1.6 mT and a frequency of 50 Hz for 4 hours/day and 7 days/week. The fracture healing process was evaluated on days 5, 10, 18, and 28 based on the bone callus histology using safranin O fast green (SOFG) staining. The results of the histological analysis showed that bone cartilage was higher in the PEMF group than in the control group throughout the observation period. In addition, the PEMF group had less fibrous tissue at the beginning of the healing. This finding indicates PEMF stimulation has an effect on inducing osteogenesis on fracture healing and reducing the risk of delayed union.

scholarly journals Short-wave enhances mesenchymal stem cell recruitment in fracture healing by increasing HIF-1 in callus

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Dongmei Ye ◽  
Chen Chen ◽  
Qiwen Wang ◽  
Qi Zhang ◽  
Sha Li ◽  
...  
Keyword(s):  
Stem Cell ◽  
Mesenchymal Stem Cell ◽  
Fracture Healing ◽  
Callus Formation ◽  
Healing Process ◽  
Short Wave ◽  
Fracture Site ◽  
Related Factors

Abstract Background As a type of high-frequency electrotherapy, a short-wave can promote the fracture healing process; yet, its underlying therapeutic mechanisms remain unclear. Purpose To observe the effect of Short-Wave therapy on mesenchymal stem cell (MSC) homing and relative mechanisms associated with fracture healing. Materials and methods For in vivo study, the effect of Short-Wave therapy to fracture healing was examined in a stabilized femur fracture model of 40 SD rats. Radiography was used to analyze the morphology and microarchitecture of the callus. Additionally, fluorescence assays were used to analyze the GFP-labeled MSC homing after treatment in 20 nude mice with a femoral fracture. For in vitro study, osteoblast from newborn rats simulated fracture site was first irradiated by the Short-Wave; siRNA targeting HIF-1 was used to investigate the role of HIF-1. Osteoblast culture medium was then collected as chemotaxis content of MSC, and the migration of MSC from rats was evaluated using wound healing assay and trans-well chamber test. The expression of HIF-1 and its related factors were quantified by q RT-PCR, ELISA, and Western blot. Results Our in vivo experiment indicated that Short-Wave therapy could promote MSC migration, increase local and serum HIF-1 and SDF-1 levels, induce changes in callus formation, and improve callus microarchitecture and mechanical properties, thus speeding up the healing process of the fracture site. Moreover, the in vitro results further indicated that Short-Wave therapy upregulated HIF-1 and SDF-1 expression in osteoblast and its cultured medium, as well as the expression of CXCR-4, β-catenin, F-actin, and phosphorylation levels of FAK in MSC. On the other hand, the inhibition of HIF-1α was significantly restrained by the inhibition of HIF-1α in osteoblast, and it partially inhibited the migration of MSC. Conclusions These results suggested that Short-Wave therapy could increase HIF-1 in callus, which is one of the crucial mechanisms of chemotaxis MSC homing in fracture healing.

scholarly journals The Effect of External Fixator Configurations on the Dynamic Compression Load: An Experimental and Numerical Study

2019 ◽  
Vol 10 (1) ◽  
pp. 3
Author(s):  
Ana Martins Amaro ◽  
Maria Fátima Paulino ◽  
Luis Manuel Roseiro ◽  
Maria Augusta Neto
Keyword(s):  
External Fixator ◽  
Bone Fractures ◽  
Numerical Study ◽  
Dynamic Compression ◽  
Healing Process ◽  
Laminated Composite ◽  
Composite Plates ◽  
External Fixators ◽  
Compression Load ◽  
Bone Callus

(1) Objective: External fixation systems are commonly used by surgeons to ensure stabilization and consolidation of bone fractures, especially in patients who are at high risk for systematic complications. Both rigid and elastic external fixations are important in the fracture healing process. This study aims to evaluate the behavior of the Orthofix Limb Reconstruction System (LRS)® in the dynamic compression mode. (2) Methods: Experimental and numerical setups were developed using a simplified model of a human tibia which consisted of a nylon bar with a diameter of 30 mm. The bone callus was included in both setups by means of a load cell-based system, which consisted of two carbon epoxy laminated composite plates with a final stiffness of 220 N/mm. The system was evaluated experimentally and numerically, considering different numbers of pins and comparing distances between the external fixator frame and the bone, achieving a good correlation between experimental and numerical results. (3) Results: The results identified and quantified the percental load transferred to the fracture and its sensibility to the distance between the external fixator and bone. Additionally, LRS locking stiffness was evaluated which resulted from the clamp-rail clearances. The results show that the blocking effects of the free clamp movement are directly related to the fixator configuration and are responsible for changes in the amount of load that crosses the bone callus. (4) Conclusions: From the biomechanical point of view, the results suggest that the average bending span of Schanz pins and the weights of the patients should be included into clinical studies of external fixators comparisons purpose.

Experimental Modal Analysis of a Suspension Assembly Loaded on a Rotating Disk

1994 ◽  
Vol 116 (1) ◽  
pp. 85-92 ◽  
Author(s):  
C. J. Wilson ◽  
D. B. Bogy
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Rotating Disk ◽  
Disk Drive ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Resonant Frequencies ◽  
Analysis System ◽  
Computer Disk

An experimental modal analysis system, which has been shown to be effective in the study of small structures, is utilized to analyze the interaction of the disk and the suspension assembly in a computer disk drive. A thorough understanding of the interaction of these structures is obtained by determining the modal parameters for each of the components in an uncoupled state and in a coupled state with the disk both stationary and rotating. It is shown that when a natural frequency of the suspension is close to that of the disk, two system resonant frequencies are created when the components are coupled together.

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