No abstract available.
External Fixators

No abstract available.
External Fixators

No abstract available.
External Fixators*

The mechanical stiffness of Unilateral-Ring Hybrid External Fixation(URHEF) was analyzed and compared with conventional Ilizarov circular external fixation system and unilateral fixation with DynaExtor(R). Our URHEF is basically a unilateral external fixation system which affords easier incorporation and removal of the Ilizarov rings(200mm in diameter) coupled with connecting clamps at anytime, if needed. It allows controlled axial micromotion in due time. For mechanical test, URHEF system was constructed using a DynaExtor(R) fixed with two or three half pins(6 mm in diameter) attached with two proximal and distal Ilizarov rings fixed with an olive pin and a half pin on each ring. Unilateral fixation system was constructed with a DynaExtor(R) fixed with 2 or 3 half pins. Ring fixation system was constructed with four Ilizarov rings(140mm in diameter). Ilizarov system were assembled into 90degrees-90degrees and 45degrees-13 5degrees configurations with 2 olive pins, respectively. The distance between the center of pylon and the pin-clamp interface was equalized, being 70mm, in all the systems. Stiffness in axial compression, anteroposterior and lateral bending was measured. On axial compression and lateral bending tests, URHEF was stiffer than DynaExtor(R) and Ilizarov systems. On anteroposterior bending test, URHEF was less stiff than 90degrees-50degrees configuration of the Ilizarov system but stiffer than 45degrees-135degrees configuration. Considering the fact that instead of 90degrees-90degrees transfixing pin fixatin system, 45degrees-135degrees configuration system is generally used in clinical practice, URHEF appears to be significantly stiffer than unilateral(DynaExtor(R)) and circular (Ilizarov)fixation systems. This mechanical study implicates that URHEF can be beneficially applied in the clinical use with assurance of mechanical stability.
External Fixators ; Olea

A total of 16 metatarsal bones were treated for ten with brachymetatarsia using two different methods: single staged lengthening by bone graft(2 cases) and gradual distraction lengthening using unilateral external fixator(14 cases). Three cases of first metatasal bone and thirteen cases of fourth metatarsal bone were operated. All of the cases of the brachymetatarsia were congenital. The average amount of lengthening was 16.1 mm in gradual distraction lengthening while 10.5mm in single staged lengthening. Average percentile increase was 38.8% in gradual distraction lengthening and 23% in single staged lengthening. The average healing index of gradual distraction lengthening was 1.7(months/cm). Although single staged lengthening has advantage of cosmetics, gradual distraction lengthening using unilateral external fixator was thought to be effective functionally for metatarsal lengthening.
External Fixators ; Metatarsal Bones

The finite element method was utilized to find the rigidity of the device in changing the parameters, such as geometrical configuration, material property, and loading condition in an external fixation. In the experimental analysis, a universal testing machine(UTM) was used to evaluate the rigidity of EBI, Monofixator and Hoffmann under the different type of lodings, such as axial compression, bending and torsion in changing the parameters. The result was compared with those of the experimental work. The results were as follows: 1) In standard condition, the yielding loads in axial compression were 85Kg in the EBI, 55Kg in the Hoffmann, and 100Kg in the Monofixator, The rigidity figures were 2930N/cm in the EBI, 764N/cm in the Hoffmann, and 2391M/cm in the Monofixator. Z) The experimental method was adapted to figure out the effect of parametric change on the stiffness of 3 different external fixation apparatus(Monofixator,EBI, Hoffmann). A Monofixator with a parametric change of pin diameter from 6mm to 5mm indicated 40% reduction of stiffness in axial compression and 60% reduction of stiffness in torsion. Also, in the case of the change of pin group separation from 20cm to 15cm it showed 64% increase of stiffness in, AP bending. EBI with the increase of the distance between pin and aluminum bar to 8cm showed 32% decrement of stiffness in axial compression and 38% decrement of stiffness in AP bending. The stiffness of the Hoffmann device was remarkable according to the number of the pin used and the distance between the pin and the aluminum bar. 3) Concerning the difference between the experimental analysis and finite element method in a Monofixator, the results of the experimental analysis were 10% to 37% lower than those of the finite element method. The reason is thought to be caused by complete binding. The obtained data shed light on the future guide-lines and future alterations of the design factors in external fixation device. Approprate use of the obtained information is desirable for the optimal,treatment of the fractured long bone.
Aluminum ; External Fixators ; Methods

No abstract available.
Arthrodesis* ; External Fixators* ; Knee*

PURPOSE: To know biomechanical differences in methods of limb lengthening between using monolateral external fixator and using external fixator over an intramedullary nail. MATERIALS AND METHODS: In acryl rods, saw-bone, and cadeveric bone, we created two lengthening models of using monolateral external fixator and using external fixator over an intramedullary nail. The axial compression test was done on the site of osteotomy for lengthening. To fix the models, half pins of 5 mm in diameter and nails of 9 mm in diameter were used. Using MTS (Material Test System) machine, we evaluated the differences of axial stiffness according to the presence of an intramedullary nail or the numbers of half-pins which were fixed at each side of osteotomy. RESULTS: Lengthening over an intramedullary nail, comparing to monolateral external fixator only, increased the axial stiffness by 1.1~1.2 times in acryl rods, 1.2~1.6 times in saw bones, and 15.6~15.9 times in cadeveric bones when the same numbers of half-pins were used. In saw bone and cadaveric bone, the group of two half pins in lengthening over an intramedullary nail was stiffer than the group of three pins in lengthening with monolateral external fixator. CONCLUSION: In the distraction of the limb, the addition of an intramedullary nail may increase the axial stiffness of the frame of monolateral external fixator. In lengthening over an intramedullary nail, it is enough to distract the bone with fixing two half pins at each sides of osteotomy.
Cadaver ; External Fixators* ; Extremities ; Osteotomy

No abstract available.
External Fixators* ; Fractures, Open* ; Tibia*

No abstract available.
External Fixators* ; Foot Deformities* ; Foot*