Guided Bone Regeneration of Femoral Segmental Defects using Equine Bone Graft: An In-Vivo Micro-Computed Tomographic Study in Rats
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Background and objectives: Guided bone regeneration (GBR) is commonly used for osseous defect reconstruction. The objective of this study was to evaluate in real-time (in-vivo) the efficacy of equine bone graft for GBR in segmental critical-size defects (CSD) of the femur in a rat model. Materials and methods: Following ethical approval, 30 male Wistar-Albino rats (age 12-14 months/weight 450-500 grams) were included. Under general-anesthesia, a mid-diaphyseal segmental CSD (5 mm) was created in the femur and stabilized using titanium Miniplate(4 holes,1.0 mm thickness). Depending upon material used for GBR, animals were randomly divided into three groups(n = 10/per group). Negative control-Defect covered with resorbable collagen membrane(RCM); Positive control-Defect filled with autologous bone and covered by RCM; Equine bone-Defect filled with equine bone and covered by RCM. Real-time in-vivo Micro-CT was performed at baseline, 2, 4, 6 and 8 weeks to determine volume and mineral density of newly formed bone (NFB) and remaining bone graft particles (BGP). Results: In-vivo micro-CT revealed increase in volume and mineral density of NFB within defects from baseline to 8-weeks in all groups. At 8-weeks NFB-volume in the equine bone group(53.24 ± 13.83 mm3; p < 0.01) was significantly higher than the negative control(5.6 ± 1.06 mm3) and positive control(26.07 ± 5.44 mm3) groups. Similarly, NFB-mineral density in the equine bone group(3.33 ± 0.48 g/mm3; p < 0.01) was higher than the other (negative control-0.27 ± 0.02 g/mm3; positive control-2.55 ± 0.6 g/mm3). A gradual decrease in the BGP-volume and BGP-mineral density was observed. Conclusion: The use of equine bone for GBR in femoral segmental defects in rats, results in predictable new bone formation as early as 2-weeks after bone graft placement.Keywords:
X-ray microtomography
Animal study
Purpose To study the application of computed tomographic dacryocystography in endoscopic intranasal dacryocystorhinostomy.Methods Twenty three patients with dacryocystitis were undergone the computed tomographic dacryocystography.Results In 26 dacryocysts of 23 cases,there were 11 large size,13 middle size and 2 small size. Computed tomographic dacryocystography can reveal clearly the size of dacryocyst and its relation with adjoining structures. Conclusion Computed tomographic dacryocystomography can provide significant clinical information for the endoscopic transnasal dacryocystorhinostomy.
Dacryocystitis
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Endochondral ossification
Primary bone
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Computed tomographic angiography
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Periosteum
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The authors prospectively followed the natural evolution of lumbar disc herniation in 48 patients treated by conservative measures. The initial computed tomographic scan was obtained during the acute phase of the disc herniation and the second was performed 1-48 months after healing. The initial computed tomographic scan allowed classification of the herniations according to size: 13 were considered small, 20 medium and 15 large. Comparison with follow-up computed tomographic scans showed that 9 of the herniations decreased by at least 25%, 8 decreased between 50 and 75% and 31 decreased between 75 and 100%. In the later group, a few had disappeared even though the second computed tomographic scan was performed as early as the month immediately after successful treatment. The largest herniations were those which had the greatest tendency to decrease in size. It is postulated that this could be secondary to the herniation breaking through the outer fibers of the anulus and entering the epidural space.
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Although most recent research efforts have focused on understanding and grasping the role of growth factors and their importance in fracture healing, understanding fracture healing patterns and sequences remains of vital importance because they allow us to further comprehend the mechanism and correlation between growth factors. We review the biology of fracture healing including the bone structure, cells involved in bone formation, fracture healing responses, sequence of fracture healing, and the effect of growth factors in fracture healing. We believe that even with the advent of new research into growth factors, understanding the basic principles of fracture healing may lead to more effective treatments for patients with fractures.
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Bone fracture healing is sensitive to the fixation stability. However, it is unclear which phases of healing are mechano-sensitive and if mechanical stimulation is required throughout repair. In this study, a novel bone defect model, which isolates an experimental fracture from functional loading, was applied in sheep to investigate if stimulation limited to the early proliferative phase is sufficient for bone healing. An active fixator controlled motion in the fracture. Animals of the control group were unstimulated. In the physiological-like group, 1 mm axial compressive movements were applied between day 5 and 21, thereafter the movements were decreased in weekly increments and stopped after 6 weeks. In the early stimulatory group, the movements were stopped after 3 weeks. The experimental fractures were evaluated with mechanical and micro-computed tomography methods after 9 weeks healing. The callus strength of the stimulated fractures (physiological-like and early stimulatory) was greater than the unstimulated control group. The control group was characterized by minimal external callus formation and a lack of bone bridging at 9 weeks. In contrast, the stimulated groups exhibited advanced healing with solid bone formation across the defect. This was confirmed quantitatively by a lower bone volume in the control group compared to the stimulated groups.The novel experimental model permits the application of a well-defined load history to an experimental bone fracture. The poor healing observed in the control group is consistent with under-stimulation. This study has shown early mechanical stimulation only is sufficient for a timely healing outcome. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1790-1796, 2018.
Bone Formation
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It is quite important to understand the histological aspect of fracture healing. It is helpful in the clinical practice to recognize how fracture management induces biological reaction. Repair process is classified into primary and secondary fracture healing. Primary healing is direct bone repair without endochondral ossification, which includes cartilaginous callus formation. This pattern does not usually happen in the natural process of fracture healing. Bone remodeling initially occurs under the stable condition of fracture with rigid fixation and no gap formation. The key of this process is Haversian canal remodeling and reestablishment of blood vessels. Secondary healing is typically characterized by three overlapping stages: the initial inflammatory response, callus formation (soft and hard callus), initial bony union and bone remodeling. Most of fracture repair in the clinic follow this process, and callus formation is confirmed with X-ray. The key of this process is the appropriate stability of the fracture site to maintain biological healing response.
Endochondral ossification
Intramembranous ossification
Primary bone
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Repeated x-rays are required to confirm healing of fractures. Clinical assessment is also difficult in patients treated with Ilizaro rings. Electrical stimulation was earlier tried to speed the fracture union whereas it has not been tried as a method to diagnose healing of fracture. In this study we have tried electric stimulation as a method to monitor fracture healing. There is a comparative group followed with traditional method of xrays and clinical assessment only.
Non union
Delayed union
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The effects of mechanical stress stimulation on bone fracture healing have been documented clinically over many years, and it has been known for some time that appropriate mechanical stimulation facilitates bone fracture healing. However, several studies have reported that certain types of stimulation can prevent bone union. Although many experiments have been conducted to determine the effects of mechanical stress stimulation on bone fracture healing, no conclusive findings have been made on the relationship between stimulation type and bone fracture healing. In this paper, the optimal mechanical stress stimulation for bone fracture healing was investigated. A total of 108 healthy rabbits were used to establish the V-shape tibial fracture models and determine the fracture healing effects at six(6) mechanical stress levels (s = 0, 1.13, 2.90, 3.97, 4.73, 6.02 kgf/ cm2) and four(4) fracture healing time points (t = 1, 3, 5, 8 weeks). The fracture healing was monitored by X-ray radiography. The radiographic findings were compared for each postoperative period. The experimental results were as follows: At 1 or 3 weeks after operations, no obvious healing effects could be found. At 5 weeks after operations, there existed a -shape relationship between healing score and mechanical stress of bone fracture. The optimal stress stimulation levels ranged from 2.90 to 4.73 kgf/cm2. These were the following fracture healing effects. When s= 2.90, 3.97, 4.73 kgf/cm2, the bone fracture line became indistinct or almost disappeared, and a great amount of callus had been able to joint two fracture ends. When s = 6.02 kgf/ cm2, bone fracture line was still clearly or partly visible, although a great amount of internal callus had been able to joint the related bone fracture ends. When s = 0, 1.13 kgf/cm2,bone fracture lines were very clearly visible and only little callus between two fracture ends was seen. At 8 weeks after operation, there also existed a -shape relationship between healing score and mechanical stress of bone fracture. It was similar to the healing effects at 8 weeks after operation. However, when s= 2.90, 3.97, 4.73 kgf/cm2, the bone fracture healing effect was better at 8 weeks than at 5 weeks after operation. In conclusion, the authors had described an open tibial fracture model of the midshaft tibia that showed distinctive patterns of bone fracture healing. Furthermore, it was implied from the stated x-ray observation results that the potential optimal mechanical stress stimulation and optimal fracture healing time were available. In detail, the mechanical stress level of 2.90-4.73 kgf/cm2 and fracture healing time of more than five(5) weeks comprised the optimal mechanical stress stimulation conditions to enhance tibial fracture healing.
Stress Fractures
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