X-ray observation on tibial fracture healing due to mechanical stress stimulation
0
Citation
0
Reference
20
Related Paper
Abstract:
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.Keywords:
Stress Fractures
Cite
In order to clarify the influence of interlocking condition on the fracture healing process, the following three studies were carried out. First, an axial loading test was done in which an interlocking nail was inserted into a osteotomised human femoral bone. As a callus substitute, several kinds of resin were packed into the osteotomy gap. Load-formation curves were detected with strain gauges. These experiments suggest that the strain of the fractured end and its substitutes increase as the stiffness of the substitutes increases. Next, three weeks after the fixation with an interlocking nail of the osteotomized rabbit femur, the half of the femora were dynamized. The other half were not. Four to 56 weeks after osteotomy, the femora were harvested for radiographical and histological examination. No significant differences were detected between the two groups. In the last study, static and dynamic condition models similar to the second experiment were made. At 12 weeks, femora were harvested and measured for maximum bending strength. There were no statistically significant differences. These studies suggest that a so-called static condition has no unfavorable effects on fracture healing.
Interlocking
Strain gauge
Cite
Citations (0)
Objective To study the rap force produced by stimulator of bone stress on fracture ends of lower limbs in different positions and fixation methods, and to examine changing relationship of rap force in vitro with the stress at fracture ends. Methods Ten complete fresh lower limb specimens of 5 cadavers were used to establish models of femur fracture, tibia fracture and tibiofibular fracture in sequence. The specimens with various fracture positions were all fixed with external fixators and plates successively. Ten specimens of each group under two fixation methods over various fracture positions were observed. Pressure sensor was located on transverse fracture over midshaft of specimens and fracture ends. Stimulator of bone stress was used to rap the heel of specimen. Rap force produced by stimulator and the compressive stress at the fracture ends under two fixation methods over various fracture positions were recorded, and their correlation was analyzed. Results A liner correlation was observed between rap force （50-350N） and fracture end stress （all r=1.000, P=0.000）. Under the same rap force, the fracture end stress under the same fixation method was as follows： tibiofibular group 〉 tibia group 〉 femur group （P〈0.05）. As to fracture ends stress on the same position, external fixator group is bigger than plate group （P〈0.05）. Conclusions Corresponding stress over fracture end appears when rap force was given after fracture fixation. It is advised to give corresponding rap force on individual fracture position and fixation method so as to promote healing.
Key words:
Pressure; Biomechanics; Fracture fixation; Femoral fractures; Tibial fractures
Biomechanics
Tibia Fracture
Cite
Citations (1)
Mechanical properties of healing fractures and growing, intact bones were studied in male rats aged 8 weeks at the beginning of the study period. A standardized, closed fracture was produced in the middle of the left femur. The fracture was not immobilized. At various intervals after the fracture, the healing fractured femora and the contralateral, intact femora were subjected to bending, torsional and tensile tests.The fractured femora regained the strength and the ultimate deformation of the contralateral, intact femora after about 8 weeks when tested in bending, and after about 13 weeks when tested in torsion. In the first phases of fracture repair, the healing fractures could resist more torsional than bending load, whereas the opposite was found for solidly consolidated fractures and intact bones.For intact bones, the ultimate bending and torsional moments increased with increase in age and weight of the animals, whereas the ultimate angular deformation remained constant. The ultimate bending and torsional stresses (bone material strength) increased to reach a plateau when the rats were about 14 weeks old. No significant differences were observed between the bending, torsional and tensile test methods. For the evaluation of fracture repair, each test has its particular application.
Biomechanics
Cite
Citations (106)
The use of a closed fracture model has become the preferred model to study the fracture healing process, given that the periosteum and the soft tissue surrounding the fracture site play an important role in the fracture healing process. Some techniques like osteotomy, drilling the long bones and the use of the guillotine-like apparatus to induce fracture are characterized by some undesirable effects and complications. The aim of this study is to optimize and evaluate an in vivo fracture model using three-point bending pliers that can be used to study secondary bone fracture healing in rats.Modified three-point bending pliers were used as a device to create the closed rat tibial bone fracture that was prefixed with an intramedullary pin (23 G × 11/2″) in rats. The exact location of the induced closed fracture was along the long bone. The presence of bone comminution, and the fracture bone alignment were immediately examined after the induction of the fracture until the 6th week.All fractures induced were transverse, located in the middle to proximal one third of the tibia, and they all healed without complications. Bone union as shown radiographically occurred within 2-3 weeks postoperative. The average angle of the fracture line with the axis of the tibia was 89.41 ± 2.11°. The lateral and anterio-posterior pin angulation views were 167.33 ± 3.67° and 161.60 ± 4.87° respectively. The average length of proximal end of the fractured bone in comparison with the whole length of intact bone was 41.02 ± 3.27%. There was a significant difference in percentage of the gross callus area and gross callus index, while there was no significant difference in X-ray callus index. There was no significant difference of the gross callus area between slight comminution (n = 4) and non comminution (n = 21).The optimized rat tibial fracture model resulted in mainly transverse tibial mid-shaft fractures with minimal bone comminution and absence of surrounding soft tissue damage. The size area of consequent soft callus formation and the extent to which the closed fracture model was reproducible are very good outcomes making it feasible for in vivo laboratory research use.
Periosteum
Closed Fracture
Long bone
Tibia Fracture
Cite
Citations (24)
Since 1978, the author has applied Hoffmann external fixation to the treatment of open fractures and infected pseudoarthrosis of long bones in the lower limbs, but has some difficulties in determining when weight bearing should be started after operation, how much weight bearing should be and when the pin should be removed. As new method to mechanically analyze the callus strength, I tried to estimate the amount of strain at intervals of 2 to 3 weeks, beginning from the second week after operation, by bending or compressing the fracture site through the strain gauge glued to the middle of the external fixator's connecting rod. From a strength test by means of a model of fracture using a vinyl chloride pipe and also from a study of computer calculation using the model of plane beam structure for architectural design, it was found that the amount of the strain on the connecting rod decreased hyperbolically when the mechanical properties of the callus increased, and that it became constant when the mechanical properties of the callus reached 50% of the intact bone. The strength test using an cadaveric skin bone demonstrated that the callus volume was one of the most important and affecting factor. Twenty-three cases were treated by Hoffmann external fixation, and the bone healing was achieved in 20 of them. On the basis of the bone healing curve obtained by the serial strain gauge measurement in those cases, the bone healing process could be classified into 5 types: normal healing, slow healing, non-union, arrest in evolution and breakage of callus; and were employed as indexes in the post-operative rehabilitation program.
Strain gauge
Cadaveric spasm
Callus
Strain (injury)
Cite
Citations (2)
Femoral fracture
Weight-bearing
Cite
Citations (6)
Displaced fractures of patella often require open reduction surgery and internal fixation to restore the extensor continuity and articular congruity. Fracture fixation with biodegradable magnesium (Mg) pins enhanced fracture healing. We hypothesized that fixation with Mg pins and their degradation over time would enhance healing of patellar fracture radiologically, mechanically, and histologically. Transverse patellar fracture surgery was performed on thirty-two 18-weeks old female New Zealand White Rabbits. The fracture was fixed with a pin made of stainless steel or pure Mg, and a figure-of-eight stainless steel band wire. Samples were harvested at week 8 or 12, and assessed with microCT, tensile testing, microindentation, and histology. Microarchitectural analysis showed that Mg group showed 12% higher in the ratio of bone volume to tissue volume at week 8, and 38.4% higher of bone volume at week 12. Tensile testing showed that the failure load and stiffness of Mg group were 66.9% and 104% higher than the control group at week 8, respectively. At week 12, Mg group was 60.8% higher in ultimate strength than the control group. Microindentation showed that, compared to the Control group, Mg group showed 49.9% higher Vickers hardness and 31% higher elastic modulus at week 8 and 12, respectively. At week 12, the new bone of Mg group remodelled to laminar bone, but those of the control group remained woven bone-like. Fixation of transverse patellar fracture with Mg pins and its degradation enhanced new bone formation and mechanical properties of the repaired patella compared to the Control group.
Patella fracture
Cite
Citations (21)
In a fracture healing experiment using rabbit tibiae, apparatus was used to produce a constant measured compression at the site of surgically produced fractures. The apparatus did not hold the fracture rigidly immobilized, but permitted a degree of motion. Under these conditions, compression itself was not a uniformly beneficial factor in fracture healing. In excess, compression acted adversely on the healing process, resulting in slower healing and a bulkier, less mature callus. Excess compression was also related to an adverse response in the diaphysis manifested by resorption of bone along Haversian canals with resultant diminution of structural substance of the cortex.
Cite
Citations (7)
Abstract To characterize the site‐specific mechanical and histological properties in fracture repair and to relate these properties to the initial mechanical situation, an experimental fracture model was used in the metatarsus of 42 sheep. the mechanical situation of a transverse osteotomy was described by three gap sizes (1,2, or 6 mm) and two amounts of strain (7 or 31 %). An external fixator that allowed a defined axial movement provided control of these settings. Nine weeks following surgery, the healing area was dissected and tensile and compressive properties were measured in subregions of the fracture gap and the periosteal callus. The central, sagittal section was used for quantitative histology. We found the quality of the tissue along the osteotomy line to be most important for regaining mechanical stability. Increasing the size of osteotomy gaps resulted in poorer mechanical and histological qualities, and the repair process was less complete. Interfragmentary strain did not significantly influence the repair process. The smaller strain levels had already stimulated the secondary repair process, and this stimulatory effect could not be further enhanced by increasing the amount of strain. Our finding that large gaps between bone segments were not as well healed as were smaller gaps suggests that it is advantageous to avoid large gaps in fracture treatment.
Cite
Citations (199)
A considerable proportion of bone fractures show signs of delayed or impaired healing. A novel device that applies interfragmentary compressive forces to the fracture site was developed and evaluated for its effect on fracture healing. The midshafts of the right tibias of 16 rabbits were osteotomized, leaving a 2-mm gap. A 4-pin, double-bar external fixator was fixed to the tibias. Interfragmental compressive displacement of 0.5 mm with a frequency of 1 Hz was applied 15 minutes per day. Mechanical stimulation began 1 week postoperatively and continued for 2 and 3 weeks. Control animals received no stimulation. Callus quality and area were assessed by radiographs. Maximum force and total energy absorbed up to failure of the healed bones were determined using a standard 3-point bending test. Postmortem radiographic examinations showed that mean radiographic measures in both anteroposterior and mediolateral views was significantly larger in experimental groups than controls ( P =.029). Mechanical measures of the healed bones demonstrated that mean values of maximum force and absorbed energy were significantly higher in the experimental groups than in the control groups ( P =.029). Both radiographic and mechanical measures were significantly higher after 3 weeks compared to 2 weeks of receiving stimulation ( P <.05).
Cite
Citations (6)