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PubMed2004

Structural and antigenic preservation of plant samples by microwave-enhanced fixation, using dedicated hardware, minimizing heat-related effects.

We explored the use of microwave technology in fixation with the objective of achieving quicker fixation regimes, lower concentrations of toxic and volatile reagents, and enhanced antigen detection. We used a modified domestic microwave oven (900 W) and a low-power (5 W) microwave bench. The work was done on plant materials. The oven was supplemented with a cooling device, a stirring system, and a record of the sample temperature and the time of effective irradiation. The sample, immersed in a fixative solution of 1% paraformaldehyde (PFA) in PBS, was irradiated for only 10 minutes. The sample temperature did not exceed 37 degrees C. In these mild conditions, the quality of the (ultra)structural preservation of the samples, morphometrically assessed, was at the same level as obtained with the same fixative, using conventional methods. On the contrary, samples fixed in the same conditions without irradiation showed a poor structural preservation. The antigenic preservation of the irradiated samples was excellent, since the labeling levels of two nucleolar proteins, detected by immunogold, were three times higher than in conventionally fixed samples. In the so-called microwave bench, the pathway of microwaves is guided, so that low-power microwaves directly hit the sample and there is no dispersion of energy. Temperature of fixative did not increase after microwave irradiation. Fixation in the bench with either 4% PFA, or 1% PFA, for 20 minutes resulted in structural preservation of samples similar in quality as obtained with conventional fixation and in a similar or better level of antigen preservation. Therefore, controlling temperature and effective irradiation is crucial in order to obtain optimal structural and antigen preservation with microwave-enhanced fixation. The dramatic differences observed between microwave-irradiated samples and samples fixed in the same conditions without irradiation, strongly support the existence of specific effects of microwaves on fixation, independent from the mere heating of the samples.

Allium↗
PubMedDate not supplied

Cytochrome oxidase activity and confocal laser scanning microscopic analysis of the hamster submandibular gland using microwave irradiated fixation.

Submandibular glands of the hamster were irradiated in 2% paraformaldehyde (pFA)-0.5% pure glutaraldehyde (PGA) with a microwave (MW) processor at temperatures of 10 degrees and 37 degrees C. Electron microscopy showed that cytochrome oxidase activity was taking place in the mitochondrial intermembrane-intracristal space of the granular duct cell when the temperature of the MW-irradiated fixatives was at 10 degrees C. However, a decrease of this activity was observed when we took care to keep the temperature of the MW-irradiated fixatives at 37 degrees C. The distinct reduction of cytochrome oxidase activity allowed by MW irradiation seems to be due the thermal affects of fixatives. Of course, the possibility cannot be excluded that MW irradiation caused other undetectable membrane damage. Then, we used confocal laser scanning microscopy for the preservation check of the mitochondrial membrane for cytochemistry with MW-irradiated fixation. The fluorescence of rhodamine 123 was observed in the inner spaces of the mitochondria at temperatures of 10 degrees and 37 degrees C. When the same tissues were fixed with 2% pFA using an MW processor as the sole fixative at 10 degrees C, no mitochondrial fluorescence was observed. Cytochrome oxidase activity, by contrast, could be seen in the mitochondrial intermembrane-intracristal spaces in the same condition. Formaldehyde is not the best aldehyde for the purpose of ultrastructural preservation. On the other hand, light and electron microscopy showed that the endogenous peroxidase activity was localized in the nuclear envelope, endoplasmic reticulum, secretory granules, and Golgi apparatus of the hamster submandibular gland using 2% pFA-0.5% PGA fixative with and without MW irradiations at temperatures of 10 degrees and 37 degrees C. Some of the same cells were fixed with only 2% pFA under MW irradiation at 10 degrees C; however, marked diffuseness of the peroxidase activity was observed. Therefore, these results indicated that cytochrome oxidase activity was sensitive to heat with MW-irradiated fixation. Peroxidase activity was very resistant to heat with MW-irradiated fixation but not with pFA solo fixation, therefore, PGA had to be used.

Animals↗
PubMed2005

Outcome after surgery of distal radius fractures: no differences between external fixation and ORIF.

The purpose of this study was to determine the most appropriate surgical treatment from three procedures used for fractures of the distal radius. In a retrospective comparative study, 166 out of 237 patients who underwent surgery for AO/ASIF A3 or C2 distal radius fractures were evaluated. Surgical procedures were external fixation or open reduction and internal fixation with either palmar or dorsal plates. Radiological outcomes were palmar tilt, radial angle, radial length and ulnar variance. Functional outcomes were range of motion and grip strength. In addition, outcomes according to Gartland and Werley and the Disabilities of the Arm, Shoulder and Hand questionnaire were compared. Further outcome criteria were the treatment time and the number of complications. Data were analysed using an analysis of variance statistical procedure respective of the chi2-test. Open reduction and internal fixation, in particular palmar plate fixation, demonstrated the best radiological and functional results. Subjective assessment of ORIF proved better than that of external fixation as treatment time was shorter and complications were more rarely seen. However, most of the differences between groups were not significant. Although there were no significant differences between groups, our data indicates that most dorsally displaced distal radius fractures can be treated successfully by open reduction and internal fixation. Palmar plate fixation seems to have slight advantages compared to both the external fixation and dorsal plate fixation surgical procedure.

Adult↗
PubMed1995

Fracture line stability as a function of the internal fixation system: an in vitro comparison using a mandibular angle fracture model.

PURPOSE: This study was conducted to determine and compare the initial mechanical stability and functional capability of six contemporary internal fixation systems used to fix mandibular angle fractures. MATERIALS AND METHODS: An iterative analog of a mandibular angle fracture was developed to ensure replicability of material properties and fracture configuration across the test constructs. Each of six sets of mandible analog (1 set = 3 mandibles) was reduced according to prescribed technique by a variety of compressive and adaptive fixation systems. The compressive systems included the 1) eccentric dynamic compression plate, 2) Würzburg plate, 3) Luhr plate, and 4) solitary lag screw technique. The Champy miniplate and the Mennen clamp plate represented the adaptive fixation systems. The reduced analogs were placed in a straining frame, and simulated masticatory loads were applied to predetermined occlusal sites. Fracture line displacements were acquired and registered by displacement transducers attached to a computer-based data acquisition program. A coordinate transformation procedure was used to convert the generalized displacements at the fracture line into the individual rotations of the segments. An "instability factor" computed from the force-displacement data recorded at various loading conditions for each test construct was used to characterize a particular system's ability to restrain relative motion at the fracture surfaces. RESULTS: There were minimal variations in the stability profiles of the individual compressive fixation systems. However, the fixation stability provided by the compressive and adaptive systems differed significantly (P < or = .0001). A large initial setting and a susceptibility to variations in loading patterns characterized the functional stability provided by the adaptive systems. Even at low masticatory loads (2 DaN), the adaptive systems had an instability that was two to three times as much as that of the compressive systems. Post-hoc comparisons between pairs of devices showed that angle fractures fixed by compressive systems provided significantly greater stability (P < or = .05) than those fixed by the Champy and Mennen systems. Between the adaptive systems tested, fracture fixation with Mennen plates was more stable than reduction by Champy miniplates (P < or = .05) when averaged over loads. CONCLUSIONS: Compressive fixation systems are biomechanically superior to adaptive systems and provide good immediate functional stability to reduced mandibular angle fractures. The Champy and Mennen systems permit significantly higher motion at the fracture site, even at the attenuated masticatory forces encountered in the early postoperative period. Because the functional stability afforded by these adaptive systems is influenced by variations in the biting patterns, the risk of infection and complicated healing is correspondingly increased. Also, the low displacement resistance of the adaptive systems may not protect the alignment of the mandibular segments through the healing period and may manifest as occlusal discrepancies in the dentate patient. The biomechanical test system developed for this study allows an equitable comparison of fixation stability and appears to be a promising tool for investigating a variety of fixation systems and optimizing device design on a rational basis.

Analysis of Variance↗
PubMed2004

Influence of initial fixation protocol on the appearance of primary cilia on the rabbit corneal endothelial cell apical surface as assessed by scanning electron microscopy.

The objective was to examine primary cilia at the apical surface of corneal endothelial cells after using different fixatives. Female albino rabbits (2 kg) were euthanised at 15:00 h and the corneas fixed immediately (usually with an isotonic 2% glutaraldehyde-cacodylate fixative) either after dissection, by application fixative at 4 degrees C, by immersion of the eyeball in fixative at room temperature (RT), or by application of an isotonic or a hypertonic (Karnovsky-type) fixative at RT. Images at 2000x were taken from the central corneal region, and number and length of primary cilia assessed. The length was the same regardless of method (overall average of 1.67+/-0.70 microm), but the incidence of primary cilia was hypertonic fixative (87% of cells) >cold drop fixation (71%), >whole globe immersion (68%) >dissect then fix methods (67%) >RT drop fixation (34%). The first four methods however yielded cells with unacceptable artefacts (especially distortion). More details should be provided of the primary fixation method used.

Animals↗
PubMed2004

Atomic force microscopy of BHK-21 cells: an investigation of cell fixation techniques.

The atomic force microscope (AFM) has been used to image a wide variety of biological samples, including cultured cells, in air. Whilst cultured cells have been prepared for AFM analysis using a variety of matrices and fixatives, a definitive study of sample preparation and its effects on cell morphology has not, as far as the authors are aware, previously been reported. Although a considerable number of cell fixatives exist, no single fixative is ideal for all investigations. Prior to the performance of specialised techniques, such as atomic force microscopy of cultured cells in air, the cell fixation method must be investigated and optimised. The fixative abilities of 2% paraformaldehyde-lysine-periodate, 0.25% glutaraldehyde, paraformaldehyde-glutaraldehyde, 4% phosphate-buffered formal saline, 1% formaldehyde, methanol:acetone, formal saline, 4% paraformaldehyde and ethanol:acetic acid were assessed in this study. A qualitative assessment system was used to evaluate the efficacy of the above fixatives using conventional fixation criteria (i.e. the presence of fibroblastic morphology consistent with optical microscopy and the absence of fixation artifacts). The optimal fixative was identified as 4% paraformaldehyde, which was capable of providing optically consistent images of BHK-21 (fibroblastic) cells, whose heights remained within the measurement capability of the AFM instrument used in this study.

Animals↗
PubMed2001

Treatment of diaphyseal fractures of the forearm using the Point Contact Fixator (PC-Fix): results of 387 fractures of a prospective multicentric study (PC-Fix II).

Fractures of the forearm are considered to be a very good indication for plating. Conventional plating is still technically demanding. Extensive animal studies show that there is potential for improvement. The method consists of using an internal fixator that minimizes implant contact to the bone to reduce biological damage. Furthermore, foregoing the need for precise reduction and interfragmental compression makes it easier to use and, therefore, it should be safer. The goal of the study was to observe handling qualities, healing, and complications. For this purpose the study was designed to yield a very high follow-up in clinics with adequate experience and with a number of different surgeons performing the internal fixation. The study was designed as a prospective multicentre investigation in 16 trauma centres worldwide. To test the new approach to internal fixation, diaphyseal fractures of the forearm were stabilized surgically with the PC-Fix (Point-Contact Fixator) system, namely, 387 fractured bones involving 277 forearms in 272 patients. Internal fixation was performed using 387 PC-Fixators. 21% of the fractures were open and 25% occurred in polytraumatized patients. The rate of follow-up was 97%. 355 fractured bones healed uneventfully within four months. Overall, there were 32 complications before bone union occurred; 27 of these bones required re-operation (27 of 387, 7%). All of them subsequently healed without further complications. There were 15 delayed or non-unions and seven implant loosenings, two of which were associated with infection. Two superficial (0.6%) and two deep infections (0.6%) occurred in 306 closed fractures. Deep infection developed in one of 81 osteosyntheses of open fractures (1.2%). Other complications included one synostosis, fractures with the implant in situ with adequate trauma involving three bones, and two secondary correction procedures for postoperative malalignment. There were seven refractures occurring at a mean of three weeks after the removal of 150 PC-Fixators (4.7%). This study demonstrated that the technique of using an internal fixator is a simple one for the fixation of forearm fractures, resulting in shorter duration of surgery with a low rate of complications compared with the data reported in the literature on conventional techniques for forearm fracture stabilization.

Adolescent↗
PubMed1998

"Biological" internal fixation of long bone fractures: a biomechanical study of a "noncontact" plate system.

Based on existing knowledge of noncontact plates, an experimental prototype of a nonperiosteal contact internal fixation implant ("noncontact internal fixator") has been designed. The construct rigidity of osteotomised synthetic composite femora, fixed with the noncontact fixator and a reamed, statically-locked intramedullary nail were compared in axial compression, two plane bending and torsion in four types of diaphyseal fractures. With the exception of axial loading in the presence of extensive comminution, the fixation stability provided by the noncontact fixator is significantly higher than that of the tested intramedullary nail. Any degree of cortical contact between the two main fragments is important for the stability of this nonperiosteal contact fixation system under axial load. Appropriately-designed "internal fixators" could provide not only a number of biological and technical advantages, but also fixation stability comparable and in certain aspects superior to that of other fixation methods.

Biomechanical Phenomena↗
PubMed2003

A natural compound (reuterin) produced by Lactobacillus reuteri for biological-tissue fixation.

The study was undertaken to examine the degree of tissue fixation by reuterin, a natural compound produced by Lactobacillus reuteri, at distinct fixation conditions (pH, temperature, and fixative concentration). Additionally, the rate of tissue fixation by reuterin was investigated using glutaraldehyde as a control. It was found by the Fourier transformed infrared spectroscopy and nuclear magnetic resonance spectroscopy that both mono- and di-aldehyde reuterin oligomers may be present in the acidic and basic aqueous reuterin solutions. Therefore, reuterin may crosslink biological tissues as glutaraldehyde (a di-aldehyde agent). The degree of tissue fixation by reuterin is significantly affected by its fixation conditions. Generally, with increasing the pH, temperature, or fixative concentration, the reduction in free-amino-group content, denaturation temperature, tensile strength, and resistance against enzymatic degradation of the reuterin-fixed tissue increased significantly. Also, the rate of tissue fixation by reuterin is significantly slower than that by glutaraldehyde. However, after fixation, it was noted that the reuterin-fixed tissue has comparable free-amino-group content, denaturation temperature, tensile strength, and resistance against enzymatic degradation as the glutaraldehyde-fixed tissue.

Aldehydes↗
PubMed2002

Effects of one-plane and two-plane external fixation on sheep osteotomy healing and complications.

OBJECTIVES: Comparison of one-plane and two-plane external fixation in terms of successful healing, incidence of complications, and biomechanical stability in a sheep model. BACKGROUND: Rigid fixation is preferred in open and comminuted fractures with a reduced blood supply, preventing infection and healing delay, but more often a flexible device is recommended even in unfavourable healing conditions. METHODS: The left tibiae of fifteen sheep were osteotomized and laterally fixed with a four-screw unilateral fixator frame (axial stiffness 183 N/mm) to a 3 mm gap size. In 9 of 15 sheep, an additional four-screw unilateral external fixator was anterolaterally attached (total axial stiffness of both frames 388 N/mm). After sacrificing, quality of osteotomy healing was assessed by mechanical and radiological evaluations. Osteogenesis was measured using fluorescence microscopy. RESULTS: Two distal fractures through the pin-tracks, three non-unions and four deep infections occurred after two-plane fixation. These failures excluded, osteotomy healing showed inferior results after two-plane fixation with reduced callus formation, bone mineral content, and bending stiffness amounts, respectively. Osteogenesis was halved following two-plane fixation in the remaining sheep. CONCLUSIONS: Two-plane fixation was not sufficient to reach successful osteotomy healing in our study. While higher rigidity was expected to prevent complications, healing in this group might have been disturbed by a reduced blood supply. The optimal stabilisation for a given fracture depends on many factors, including the biomechanical and biological environment. RELEVANCE: Considering our results and the literature discussed in this manuscript, good bone healing with minor risks of infections can be achieved using an unilateral one-plane fixator with only four screws, and its application on a muscle free position like the medial and anterior site of the sheep tibia.

Animals↗
PubMedDate not supplied

External fixation of the lumbar spine in a canine model.

OBJECTIVE: To compare the mechanical properties of two types of external skeletal fixation of the lumbar spine with polymethylmethacrylate (PMMA)/Steinmann pin fixation in a canine unstable spine model. STUDY DESIGN: Cadaver study. SAMPLE POPULATION: Lumbar spines of 17 mature large-breed dogs. METHODS: Spine stiffness (N-m/deg) in flexion, extension, and rotation under physiological loading conditions and spine strength (N-m) in flexion were determined. Spines were destabilized at L3-L4, instrumented and retested. Fixation techniques included four-pin PMMA (PMMA4), eight-pin PMMA (PMMA8), eight-pin biplanar type I external skeletal fixator (ESF) (SK), and eight-pin spinal arch ESF (ARCHES). RESULTS: All fixation groups were as stiff as intact spines in extension and rotation and were significantly stiffer in flexion. In flexion, both PMMA8 and ARCHES were significantly stiffer than SK, and PMMA8 was significantly stiffer than PMMA4. In rotation, PMMA8 and ARCHES were significantly stiffer than SK, and in flexion to failure, PMMA8 and ARCHES were significantly stiffer than PMMA4. CONCLUSIONS: External skeletal spinal fixation (ESSF) has mechanical properties comparable to more commonly used PMMA/pin internal fixation techniques. CLINICAL RELEVANCE: External fixation of the canine spine has several potential advantages over internal fixation including minimal dissection for pin placement, the ability to span affected vertebrae with placement of implants distant from the site of injury, postoperative adjustability, and complete removal of implants after healing. This study supports the biomechanical stability ESSF of the canine lumbar spine. Further studies are indicated to evaluate zones of consistently safe and secure placement of pins and clinical efficacy.

Animals↗
PubMed1996

External fixation in war traumatology: report from the Rwandese war (October 1, 1990 to August 1, 1993)

Modern missiles cause important damage in the tissues. In case of bone injury, apart from the presence of foreign bodies and soil dirt in the foyer, the lesion is characterized by a certain instability caused by the smashing and resulting in the comminutive fractures, as well as severe lesions of the soft tissues. If primary treatment includes the necessity of a large wound excision, of which the modalities have been described for centuries, it also includes a rigorous immobilization of the foyer as precaution against shock and infection. All techniques proposed during former conflicts proved that they are little adapted to the final goal. Their inadequacy may lead to amputation, at any rate to severe sequelae. In war traumatology, opposed to the shortcomings of nonoperative methods and opposed to the prohibitions of intrafocal synthesis, external fixation is considered to be the best among compromises: it stabilizes fractures efficiently without risk, retains the distance between bone fragments, and prevents contracture of the muscles. External fixators promote debridement of the wounds, permit vascular repairs and control of the wounds, allow mobilization of the limbs, improve the injured's comfort, and facilitate evacuation . All types of external fixators can be used, but a number of military imperatives must be taken into account. Fixing of the device must be easy to every user, even with little training. A minimal number of parts must allow a maximal number of assemblies. Easy use implies simplicity, but the assembled set must be stable. It must reduce the reprise of reductions, its compression, and its distraction to a minimal number of acts. Moreover, it must be relatively cheap. In theory, all open war fractures should be treated by means of an external fixator. The problem, however of mass surgery under uncertain circumstances, the limited equipment, and a precarious supplying must be considered. Rwanda was involved in a war from October 1, 1990 to August 1, 1993 (Arusha's agreement). A Belgian medical team from the Military Cooperation had to cope with 4,646 different casualties. We treated 1,129 fractures, and among them 115 fractures of the arm, 122 fractures of the forearm, 80 fractures of the femur (including the neck and the condylae), and 148 fractures of the leg. We had to cope with 315 fractures of the hand, of which 220 fractures were of the metacarpal bone. "Strangely," there were always more lesions of the left hand (9.5%) than the right hand (5.8%), sometimes up to five times (the only exception was met in August 1993). We placed 209 external fixators (of which 20 bridging the joint in case of important impairment), including those used for an arthrodesis. In the majority fo the cases (93.3%), we used the French device Fixateur Externe du Service de Sante des Armees (FESSA). Until March 1993, we had no "orthopedic table." Since March 1988, we had an Image Intensifier, but not very appropriate to an operating room (no mobile C-arm). A more accurate one was lent by the Belgian Medical Service and set up in September 1992. The average time to place an external fixator was about 30 minutes. General practitioners were also trained to handle external fixators. According to the importance of mass casualties, an external fixator was used immediately upon arrival of the wounded or at revision day (5th day after debridement). The only exception were femoral fractures that were at first time-treated by traction for 10 days. Sometimes we had precarious supplying because the supplies had to be ordered in Europe. Sometimes one patient had to wait until material became available from another patient. External fixation was also used for reconstructive surgery, mainly for ankle arthrodesis. In conclusion, it was possible for a very small surgical team, on its own for 18 months, to cope with a lot of difficulties caused by lack of readiness of the Rwandan Armed Forces, lack of organization, and lack of discipline of the R

External Fixators↗
PubMed1997

Evolving fixation methods in endoscopically assisted forehead rejuvenation: controversies and rationale.

The goals of surgical rejuvenation of the forehead include component brow manipulation, attenuation of transverse forehead rhytids, and reduction of glabellar frown lines. The endoscopic approach has proved successful in achieving these goals in selective patients while minimizing incisions and improving scalp sensation. Efficacy of endoscopic brow manipulation is dependent on (1) complete release of the brow at the supraorbital rim, (2) brow depressor muscle resection/release, and (3) tension-free fixation of the brow position until wound healing has occurred. Fixation of the brow using an endoscopic technique, unlike the open technique, is dependent on skin retraction and tension-free scalp fixation during the process of wound healing to maintain the desired brow position. Techniques for endoscopic fixation are arbitrarily divided into endogenous and exogenous. Endogenous methods include extensive galea-frontalis-occipitalis release, lateral spanning suspension sutures, external bolster fixation, anterior port skin excision, galea-frontalis advancement, cortical tunnels, and tissue adhesives. Exogenous techniques include internal screw or plate fixation, Mitek anchor fixation, external screw fixation, and absorbable K-wires. This article provides a goal-oriented review of these evolving techniques and a rationale for the use of fixation methods in endoscopically assisted forehead rejuvenation.

Bone Plates↗
PubMed1999

Internal spinal fixator stiffness has only a minor influence on stresses in the adjacent discs.

STUDY DESIGN: Stresses in vertebral endplates and discs were calculated using the three-dimensional nonlinear finite-element model of a lumbar spine with an internal spinal fixation device. OBJECTIVE: To determine the influence of fixator stiffness on stresses in the adjacent discs. SUMMARY OF BACKGROUND DATA: There are few computer models of the lumbar spine with a fixator. Most of these models neglect the muscle forces. Fixator stiffness is assumed to influence greatly the stresses in the adjacent discs. METHODS: Two three-dimensional nonlinear finite-element models were used to determine stresses in the lumbar spine for standing and 60 degrees flexion of the upper body. One model had an internal spinal fixator, the other did not. In a parameter study, the diameters of the longitudinal rod of the fixator were assumed to be 3, 5, 7, and 10 mm. In the computer model, the forces of the trunk muscles were simulated. RESULTS: The diameter of the longitudinal rod strongly affected the fixator loads but hardly influenced the stresses in the vertebral endplates. The stresses in the bridged discs were strongly reduced. However, the internal fixator had only a minor influence on the stresses in the anulus fibrosus and the pressure in the nucleus pulposus of the adjacent discs. CONCLUSIONS: The stiffness of an internal spinal fixation device has only a minor influence on stresses in the adjacent discs.

Elasticity↗
PubMed2003

Role of soft tissues in metacarpal fracture fixation.

The contribution of soft tissues in stabilizing fracture fixation in metacarpals is appreciated clinically, but no quantitative biomechanical study of their role has been done. All previous studies of fracture fixation in vitro have been done on metacarpals denuded of soft tissues. To quantify the role of soft tissues in metacarpal fracture fixation, the biomechanical effectiveness of four fixation devices was examined in human cadaver metacarpals with and without soft tissues. Values were compared for three nonrigid methods (expandable intramedullary fixation devices, crossed Kirschner wires, and single half-pin frames) and one rigid method (dorsal plates) in 45 disarticulated metacarpals stripped of soft tissues (denuded) and in 46 metacarpals in whole hands with all soft tissues remaining (intact). Mechanical testing to complete failure in three-point apex dorsal bending was done in all specimens. Ultimate moment (strength) of each of the four fixation methods was significantly greater in intact specimens than in denuded specimens. Crossed Kirschner wires were most stable in intact specimens, and dorsal plates were more stable in denuded specimens. The results show that soft tissues contribute to the strength of fracture fixation. Clinically, surgeons may be able to use a less invasive fixation method than plating without compromising the strength of metacarpal fixation in patients whose soft tissues are not severely disrupted and the fracture configuration allows. Plating may offer optimum stability in patients whose soft tissues are damaged severely and provide less strengthening of the fracture construct.

Biomechanical Phenomena↗
PubMed2003

A comparison of monolateral and circular external fixation of unstable diaphyseal tibial fractures in children.

Forty-six tibial fractures in 44 children, which were treated by external fixation at our institution between 1 January 1991 and 31 December 1999, were retrospectively identified. Twenty-nine fractures were treated with monolateral fixation and 16 were treated with circular fixation. The average age of the patients was 11 years 8 months (range 3 years 11 months-17 years 7 months). External fixators were left in place for a mean of 13.7 weeks (range 9-33 weeks). Eleven significant complications occurred. Loss of reduction necessitating return to the operating room occurred in four patients (13%) and malunion occurred in an additional patient with monolateral fixators. Four of these patients had comminuted fracture patterns. All of the patients with loss of reduction were 12 years of age or older. No patient with a circular fixator developed mal-alignment. Final alignment in 45 of the 46 fractures was acceptable. External fixation is a safe and effective method of treating unstable diaphyseal tibia fractures in children. Patients over the age of 12 years, particularly with comminuted fracture patterns may be more effectively treated with circular external fixation or, if treated with monolateral fixation, require close observation.

Adolescent↗
PubMed1997

Modified formalin and methanol fixation methods for molecular biological and morphological analyses.

Several simplified fixation methods were examined to determine their suitability for both molecular biological analyses and morphological study. Fixation with 10% v/v formalin alone at 4 degrees C and containing 5 mmol/L ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA) at room temperature preserved significantly more high-molecular-weight DNA than 10% v/v formalin fixation at room temperature. The morphological differences between tissues fixed using these modified formalin fixation methods and conventional 10% v/v formalin fixation were negligible. Of the dehydration fixatives tested, 100% methanol did not cause regional differences due to artificial tissue shrinkage and the morphology of sections prepared by methanol fixation was preserved consistently better than that of acetone- or ethanol-fixed sections. All three dehydration fixatives preserved relatively higher-molecular-weight DNA and RNA, compared with formalin. Cold formalin, formalin containing EDTA at room temperature and 100% methanol are recommended as standard and additional fixatives routine clinicopathological laboratory use.

Breast↗
PubMedDate not supplied

Mechanical evaluation of half-pin (type 1) external skeletal fixation in combination with a single intramedullary pin.

Half-pin (type 1) external skeletal fixators with four, three, and two fixation pins and an intramedullary pin, and four-pin external skeletal fixators without an intramedullary pin were applied to prepared canine femurs. Load to failure, load to yield, safe load, and stiffness under compressive and torsional loads were calculated. When tested in compression, all measurements for the four-pin fixators with an intramedullary pin were significantly higher than for the two-pin fixators with an intramedullary pin. The values for all parameters except load to yield were significantly higher for the four-pin fixators with an intramedullary pin than for the four-pin fixators without an intramedullary pin. When tested in torsion, all measurements for the four-pin fixators with an intramedullary pin were significantly higher than for the two or three-pin fixators with an intramedullary pin.

Animals↗