Bone maintenance theory considers that the external load is the direct stimulating source of the bone remodeling. In this article, the method of experimental observation of self-repairing process of the bone defect and related results are introduced. Firstly, a hole was drilled in the rabbit thighbone so that the continuity of the bone was changed. Then bone defect model was established, and the thighbone data were obtained by using CT scanning, and the self-repairing process of bone defects caused by growth factor were observed and analyzed by MIMICS software. Finally, the relationship between volume changes of sclerotin was established, and scientific bases were provided for introducing the bionic topology optimization method to the remodeling process. The experimental results showed that the self-repairing of the each layer sclerotin of the young rabbits was faster than that of the adult ones under the same condition. In addition, the volume always changes contrarily between the spongy bone and enamel bone during the self-repairing process of bone defect.
Animals ; Bone Regeneration ; physiology ; Female ; Femoral Fractures ; physiopathology ; Femur ; injuries ; Fracture Healing ; physiology ; Male ; Osteogenesis ; physiology ; Rabbits

BACKGROUNDThere are few researches for the healing of metaphyseal fractures; moreover, the animal models to study the metaphyseal fractures are usually made by the oscillating saw osteotomy without reliable fixation, which is not in accordance with our current clinical practice. In this study, we established a new model to observe the healing process of metaphyseal fractures.

METHODSEighteen New Zealand rabbits were used in the study. The fracture model was created by splitting the medial tibial plateau in rabbits, then reset, and fixed with compression screws. At 1, 2, 3, 4, 6, and 8 weeks postoperatively, the tibial specimens were collected; firstly, a general observation and an X-ray examination of the specimens was done, and then they were embedded in methylmethacrylate and cut into sections with hard tissue slicer. The sections were stained with Giemsa reagent and examined under light microscopy.

RESULTSThere was no fracture displacement in the tibial specimens of all time points, except for one showing a collapse. No external callus formation could be observed by X-ray and general examination. After 1 week of the operation, the fracture gap was filled by mesenchymal tissue; 2 weeks postoperatively, a large number of woven bones were formed; from the third week onwards, the woven bone began to turn into lamellar bone, and new trabecular structure began to form. In all of the slices, no obvious chondrocytes formed in fracture areas; thus, there was no endochondral ossification.

CONCLUSIONSThis model was an ideal fracture animal model and suitable for the study of metaphyseal fracture healing. The X-ray and histological images demonstrated that metaphyseal fracture healing was a process of direct bone healing through intramembranous bone formation under the conditions of minor trauma, good reduction, and firm fixation.

Animals ; Fracture Healing ; physiology ; Fractures, Bone ; diagnostic imaging ; pathology ; Rabbits ; Radiography

OBJECTIVETo validate the hypothesis that there exists an optimal axial compression stress range to enhance tibial fracture healing.

METHODSRabbits with a surgically induced V-shaped tibial fracture were separated into 2 main groups: the control group (C Group, n equal to 6) without application of any axial compression stress stimulation postoperatively and the stimulation group (S Group, n equal to 90). The S Group was further divided into 20 subgroups (S11 to S54) in terms of 5 axial compression stress stimulation levels (112.8 kPa, 289.8 kPa, 396.5 kPa, 472.7 kPa, and 602.3 kPa) and 4 experimental endpoints (1, 3, 5 and 8 weeks after operation). A custom made circular external fixator was used to provide the axial compression stress of the fracture sites. Based on X-ray observation, a fracture healing scoring system was created to evaluate the fracture healing process.

RESULTSAt 8 weeks after operation, there existed a "arch shape" relationship between healing score and axial compression stress stimulation level of fracture site. The optimal axial compression stress stimulation ranged from 289.8 kPa to 472.7 kPa, accompanying the best fracture healing, i.e. the fracture line became indistinct or almost disappeared, and a lot of callus jointed the two fracture ends. Meanwhile, at 5 weeks after operation, corresponding to the relatively low healing scores, there was a fracture healing performance similar to that at 8 weeks. Besides, at 1 or 3 weeks after operation, for all the axial compression stress levels (0-602.3 kPa), no obvious healing effect was found.

CONCLUSIONSIt is implied from the stated X-ray observation results in this study that the potential optimal axial compression stress stimulation and optimal fracture healing time are available. The axial compression stress level of 289.8-472.7 kPa and fracture healing time of more than 8 weeks jointly comprise the optimal axial compression stress stimulation conditions to enhance tibial fracture healing.

Animals ; Disease Models, Animal ; Fracture Healing ; physiology ; Rabbits ; Radiography ; Stress, Mechanical ; Tibial Fractures ; diagnostic imaging ; physiopathology

A first order system model is proposed for simulating the influence of stress stimulation on fracture strength during fracture healing. To validate the model, the diaphyses of bilateral tibiae in 70 New Zealand rabbits were osteotomized and fixed with rigid plates and stress-relaxation plates, respectively. Stress shielding rate and ultimate bending strength of the healing bone were measured at 2 to 48 weeks postoperatively. Ratios of stress stimulation and fracture strength of the healing bone to those of intact bone were taken as the system input and output. The assumed first order system model can approximate the experimental data on fracture strength from the input of stress stimulation over time, both for the rigid plate group and the stress-relaxation plate group, with different system parameters of time constant and gain. The fitting curve indicates that the effect of mechanical stimulus occurs mainly in late stages of healing. First order system can model the stress adaptation process of fracture healing. This approach presents a simple bio-mathematical model of the relationship between stress stimulation and fracture strength, and has the potential to optimize planning of functional exercises and conduct parametric studies.
Animals ; Biomechanical Phenomena ; Fracture Healing ; physiology ; Mathematics ; Models, Animal ; Models, Biological ; Rabbits

Animals ; Biomechanical Phenomena ; Bone Development ; Bone Remodeling ; Bone and Bones ; injuries ; Fracture Healing ; physiology ; Fractures, Bone ; pathology

OBJECTIVE: To summarize the research progress on the mechanism related to traumatic brain injury (TBI) to promote fracture healing, and to provide theoretical basis for clinical treatment of fracture non-union. METHODS: The research literature on TBI to promote fracture healing at home and abroad was reviewed, the role of TBI in fracture healing was summarized from three aspects of nerves, body fluids, and immunity, to explore new ideas for the treatment of fracture non-union. RESULTS: Numerous studies have shown that fracture healing is faster in patients with fracture combined with TBI than in patients with simple fracture. It is found that the expression of various cytokines and hormones in the body fluids of patients with fracture and TBI is significantly higher than that of patients with simple fracture, and the neurofactors released by the nervous system reaches the fracture site through the damaged blood-brain barrier, and the chemotaxis and aggregation of inflammatory cells and inflammatory factors at the fracture end of patients with combined TBI also differs significantly from those of patients with simple fracture. A complex network of humoral, neural, and immunomodulatory networks together promote regeneration of blood vessels at the fracture site, osteoblasts differentiation, and inhibition of osteoclasts activity. CONCLUSION TBI promotes fracture healing through a complex network of neural, humoral, and immunomodulatory, and can treat fracture non-union by intervening in the perifracture microenvironment.
Humans ; Fracture Healing/physiology* ; Brain Injuries/metabolism* ; Brain Injuries, Traumatic ; Fractures, Bone ; Osteogenesis

External Fixators ; Female ; Femoral Fractures - diagnostic imaging Femoral Fractures - surgery ; Femoral Fractures - therapy ; Fracture Fixation, Internal - methods ; Fracture Fixation, Intramedullary - methods ; Fracture Healing - physiology

Biomechanical Phenomena ; Bone Substitutes ; therapeutic use ; Child ; Facial Bones ; physiology ; Fracture Fixation, Internal ; Fracture Healing ; Humans ; Skull ; physiology ; Skull Fractures ; therapy ; Stress, Mechanical

BACKGROUNDIntramedullary nails had been widely used in the treatment of long-bone fractures because of less interference of fractures and center bearing biomechanical advantage. However, it had been also found many shortcomings such as broken nails, delayed healing and was modified in order to achieve better efficacy and reduce complications. The aim of the present study is to compare the efficacy of rotary self-locking intramedullary nails (RSIN) with that of interlocking intramedullary nails (IIN) in the treatment of long-bone fractures.

METHODSA retrospective study investigated 129 cases with long-bone fractures (36 with femoral fracture, 81 with tibial fracture, and 12 with humeral fracture). The fractures were fixed using either an RSIN or IIN. All patients underwent followup for 12-30 months.

RESULTSAll patients in both groups achieved a clinical fracture healing standard and the postoperative affected limb muscle strength and joint function were well restored. The RSIN group required a shorter operative time and the fracture healed faster. There was no significant difference in the hospital stay, intraoperative blood loss or postoperative complications between the two groups.

CONCLUSIONSRSIN is used to treat long-bone fractures. Its healing efficacy is equivalent to the IIN. Moreover, the RSIN method is simpler and causes less tissue damage than the IIN, therefore having the advantage of accelerated healing.

Bone Nails ; Female ; Femoral Fractures ; surgery ; Fracture Healing ; physiology ; Humans ; Humeral Fractures ; surgery ; Male ; Retrospective Studies ; Tibial Fractures ; surgery

OBJECTIVETo investigate the effect of recombinant human basic fibroblast growth factor (rhbFGF) on angiogenesis during mandible fracture healing in rabbit.

METHODSFifty adult white rabbits were used for animal model and randomly divided into a control group (25 rabbits) and an experimental group (25 rabbits). The membranous complex of rhbFGF and bovine type I collagen was prepared and implanted into the rabbit mandible fracture site under periosteum. The animals were sacrificed on 7, 14, 28, 56 and 84 days respectively after operation and the whole mandibles were harvested. The expression of factor VIII related antigen (F8-RA) in callus was examined with immunohistochemical staining.

RESULTSThe amounts of microvascular formation in calluses in the rhbFGF-treating group on days 7, 14, 28 and 56 were more than those of the control group (P<0.01).

CONCLUSIONSThe results indicated that rhbFGF could stimulate microvascular formation during mandible fracture healing in rabbits.

Animals ; Fibroblast Growth Factor 2 ; pharmacology ; Fracture Healing ; physiology ; Mandibular Fractures ; physiopathology ; Neovascularization, Physiologic ; drug effects ; Rabbits ; Recombinant Proteins ; pharmacology