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At least 307 records · Page 17Linked to original sources
PubMed1974

A study of foot-and-mouth disease virus strains by complement fixation. I. A model for the fixation of complement by antigen-antibody mixtures.

An examination was made of the relations between antigen, antibody and fixation of complement with foot-and-mouth disease virus (FMDV). It was found that complement fixation in this system follows the same principles as models developed in other antigen/antibody systems. The assumption that there is a relation of direct proportionality between the amount of complement fixed and the amount of antiserum reacting with constant antigen was found to be incorrect. An alternative method was proposed for the quantitative differentiation of FMDV strains by comparing the titres of an antiserum when reacting with optimum amounts of homologous or heterologous antigens.

Animals↗
PubMedDate not supplied

Distal tibiofibular syndesmosis fixation: a cadaveric, simulated fracture stabilization study comparing bioabsorbable and metallic single screw fixation.

Metal screws that are used for ruptured tibiofibular syndesmosis repair are often removed within 3 months of placement, suggesting the utility of bioabsorbable screws. A biomechanical study was performed to compare fixation of a simulated syndesmosis separation with a 5-mm oriented copolymer bioabsorbable (82:18 poly-L-lactic acid/poly-glycolic acid) versus a stainless steel screw. Eight pairs of cadaveric lower-leg specimens were cleaned and a pronation external rotation-type injury was created in each. The syndesmosis was fixed with a single, tricortical bioabsorbable screw in 1 ankle and a metal screw in the contralateral ankle (matched pairs). Sequential testing of the specimens showed that torsional stiffness of the fixed, relative to intact, specimens was nearly equivalent (0.730 +/- 0.260 for copolymer, 0.770 +/- 0.300 for stainless steel; P = .401). Application of 1000 cycles of axial load (90 to 900 N) resulted in a significant decrease ( P < .0001) in axial stiffness for each fixation method, but the relative decrease was equivalent for both ( P = .211). Failure torque (17.8 +/- 8.3 N.m copolymer, 21.0 +/- 11.5 N.m stainless steel; P = .238) and angle of rotation at failure (47.9 +/- 13.6 degrees copolymer, 42.0 +/- 11.5 degrees stainless steel; P = .199) were also nearly equivalent. It appears that the 5.0-mm diameter copolymer screw is biomechanically equivalent to the 5.0-mm diameter stainless steel screw for repair of syndesmosis disruption.

Absorbable Implants↗
PubMed2003

A prospective randomized controlled study of fixation of long oblique and spiral shaft fractures of the proximal phalanx: closed reduction and percutaneous Kirschner wiring versus open reduction and lag screw fixation.

Patients with an isolated spiral or long oblique fracture of the proximal phalanx were randomized into two groups. One was treated by closed reduction and Kirschner wire fixation and the second treated by open reduction and lag screw fixation. An independent observer assessed function, pain, movement, grip strength and intrinsic muscle function. X-rays were assessed for malunion. Thirty-two patients were entered the study and 15 in the Kirschner wire and 13 in the lag screw group were reviewed at a mean follow-up of 40 months. There was no significant difference in the functional recovery rates or in the pain scores for the two groups. X-rays showed similar rates of malunion and there were no statistically significant differences in range of movement or grip strength.

Adolescent↗
PubMedDate not supplied

Fixation of fractures of the proximal humerus with the PlantTan Humerus Fixator Plate: early experience with a new implant.

The majority of fractures of the proximal humerus can be managed nonoperatively. However, displaced fractures generally require operative repair, and in the young patient with good bone quality, the results are usually satisfactory. In contrast, the osteoporosis found in the elderly patient makes internal fixation problematic and frequently contributes to failure of fixation and poor results. We report our early experience with a new plate that locks two humeral head cancellous screws to the plate. In 3 of 7 patients, all under 65 years of age, the results were good. However, in the remaining 4 patients, all over the age of 75 years, there was a 100% failure rate, with screw penetration of the head in 3 patients and secondary displacement of the fracture at 7 days postoperatively in another. We conclude that this implant is unsatisfactory for patients with osteopenic bone in the humeral head.

Adult↗
PubMed1992

Survivorship analysis of pedicular fixation systems in the treatment of degenerative disorders of the lumbar spine: a comparison of Cotrel-Dubousset instrumentation and the AO internal fixator.

We retrospectively analyzed the frequency and clinical consequences of pedicular fixation system failure in 50 patients who underwent Cotrel-Dubousset transpedicular instrumentation (CDI), and 46 patients who underwent AO internal fixator (IF) instrumentation for similar indications. After 2 years, 14 implants in the CDI group and 13 in the IF group had failed. The overall probability of implant survival was similar in both groups (CDI, 71.9% versus IF, 71.7%). However, more implant failures were associated with nonunion, loss of reduction, and nerve-root compromise in the IF group (four versus none) than in the CDI group. Implant failure usually occurred after solid fusion, and did not significantly affect the short-term clinical results. Therefore, implant failure does not a priori indicate failure of the operation.

Adolescent↗
PubMed1994

Biomechanical effects of internal fixation of the distal tibiofibular syndesmotic joint: comparison of two fixation techniques.

This biomechanical study compares two methods of internal fixation of the tibiofibular syndesmosis used in Weber type C malleolar fractures of the ankle. The transverse syndesmotic 3.5-mm screw was compared with two 1.5-mm Kirschner wires introduced obliquely across the distal tibiofibular syndesmosis. The influence of implants on distal tibiofibular joint motion and contact characteristics of the intact ankle joint were determined. Up to 1.25 mm of lateral displacement and 2 degrees of external rotation of the lateral malleolus during uninjured ankle dorsiflexion was recorded. Both techniques stabilized the injured syndesmotic joint and limited its normal motion during flexion and extension of the ankle. Pressure distribution displaced laterally in internally stabilized ankles compared with intact specimens, regardless of the type of fixation used. Therefore, both techniques alter joint biomechanics equivalently compared with the intact ankle.

Ankle Injuries↗
PubMedDate not supplied

Influence of the design for fixation implants on local infection: experimental study of dynamic compression plates versus point contact fixators in rabbits.

OBJECTIVES: Comparison of infection resistance after local bacterial challenge associated with two different designs for fixation implants: the conventional dynamic compression plate (DCP) and the point contact fixator (PC-Fix). DESIGN: Randomized, prospective study in experimental animals. Grouped sequential experimental procedure. Observation time was twenty-eight days, with twenty animals per group. SETTING: Following surgery, animals were kept without restrictions in individual hutches. ANIMALS: Forty White New Zealand rabbits. Thirty-eight animals, nineteen per group, were included in the final evaluation. INTERVENTION: Under sterile conditions, specially manufactured titanium DCP or PC-Fix of identical dimensions were fixed to rabbit tibiae. After wound closure, different concentrations of Staphylococcus aureus, between 2 x 10(4) and 2 x 10(8) colony-forming units (CFU), were inoculated percutaneously at the implant site. MAIN OUTCOME MEASUREMENTS: Implants, underlying bone, and surrounding soft tissues were removed under sterile conditions and quantitatively evaluated for bacterial growth. Infection was defined as positive bacterial growth at the bone-implant interface. RESULTS: The overall infection rate was 45 percent. The infection dose of 50 percent (ID50) was 7.08 x 10(5) CFU for the DCP group and 8.51 x 10(6) CFU for the PC-Fix group. The infection rate was 63 percent (twelve of nineteen animals) for the DCP group and 26 percent (five of nineteen animals) for the PC-Fix group. This difference was statistically significant (p = 0.022). CONCLUSIONS: After local bacterial challenge, we found a statistically significant difference in the infection rates depending on the implant design. The higher infection resistance associated with the PC-Fix design seems to be related to the reduced contact area at the bone-implant interface.

Animals↗
PubMed1988

Biomechanical evaluation of spinal fixation devices: II. Stability provided by eight internal fixation devices.

The three-dimensional stability provided by eight spinal fixation devices has been studied in an in vitro biomechanical model using seven-vertebrae (T9-L3) fresh cadaveric thoracolumbar specimens. An injury was created at T12-L1 by complete transection of the posterior elements and posterior half of the intervertebral disc, leaving the anterior half of the intervertebral disc and anterior longitudinal ligament intact. The three-dimensional rotational and translational motions, measures of biomechanical instabilities, were determined under physiologic loads for the intact specimen after injury and instrumentation with each of the eight fixation devices. The tested devices were: Dunn's anterior device (DD); Harrington distraction (HD); Harrington compression (HC); Harrington distraction-compression combination (HDC); Harrington distraction with sleeves (HDS); Luque rods (LQ); Luque rectangle (LR); and Luque short rectangle (LSR). The following devices were stable under the four loads: Flexion: HC, HD, HDC, HDS, LQ, and LR; Extension: HD, HDC, HDS, LQ, and LR; Lateral Bending: LQ and LR; and Axial Rotation: none.

Biomechanical Phenomena↗
PubMed1992

The coccidioidal complement fixation and immunodiffusion-complement fixation antigen is a chitinase.

Culture filtrates and autolysates of Coccidioides immitis have provided suitable crude antigens for the serodiagnosis and prognosis of coccidioidomycosis. One of these, a heat-labile antigen which participates in the immunodiffusion reaction corresponding to the complement fixation reaction (IDCF), has been characterized as a 110-kDa native protein that, when subjected to reducing conditions and heat, yields a 48-kDa component. The present report provides serologic and biochemical evidence that this antigen is a chitinase. This chitinase, isolated from 48-h culture filtrate of the spherule-endospore-phase C. immitis by affinity adsorption to chitin, formed a line of identity with the IDCF reference antigen and participated in the complement fixation reaction with human serum. It lost its enzymatic as well as antigenic activity when heated, but when not heated it retained its enzymatic activity even when precipitated with coccidiodal antibody present in human serum. This chitinase represents a significant serodiagnostic substance and may be important in the morphogenesis of C. immitis.

Antigens, Fungal↗
PubMed1993

Spinal fixation. Part 2. Fixation techniques and hardware for the thoracic and lumbosacral spine.

Spinal fixation devices are used in the thoracic and lumbosacral spine to stabilize the spine, reduce deformities and fractures, and replace abnormal vertebrae. A bone fusion is usually attempted along with placement of the instrumentation because in most cases the hardware would eventually fail if it were used alone. The thoracolumbar spine is inherently unstable, and early operative intervention improves mobilization and rehabilitation. In some cases of lumbar spinal pain, surgical intervention is necessary for the treatment of conditions such as herniated disks, spondylolysis with spondylolisthesis, and degenerative disease with scoliosis. Surgical procedures consist of posterior (posterior elements) and anterior (vertebral body) fixation. Radiologists face continual changes in both surgical technique and instrumentation and should be knowledgeable about the devices available and the biomechanical principles that direct their use. They need to work with their surgical colleagues to become familiar with the techniques used at their institutions.

Humans↗
PubMed1990

Immunoelectron microscopy of tissues processed by rapid freezing and freeze-substitution fixation without chemical fixatives: application to catalase in rat liver hepatocytes.

We report on the immunohistochemical demonstration of an enzyme at the electron microscopic level using specimens processed by rapid freezing and the freeze-substitution technique without the use of any chemical fixatives. Fresh rat liver tissue blocks were rapidly frozen by the metal contact method using liquid nitrogen, and were freeze-substituted with acetone without any chemical fixatives at -80 degrees C. Some of the freeze-substituted tissues were embedded in Lowicryl K4M at -20 degrees C; the others were returned to room temperature and embedded in Epok 812 at 60 degrees C. Ultra-thin sections were stained using anti-peroxisomal catalase antibody by the protein A-gold technique. The ultrastructure of the hepatocytes was very well preserved compared with that of conventionally processed tissues. The labeling for catalase was confined to peroxisomes. When the labeling density was compared among freeze-substituted tissues and conventionally processed tissues, that of freeze-substituted and Lowicryl K4M-embedded tissues was the most intense. These results show the usefulness of freeze-substituted tissues for immunohistochemical analysis of cell organelles.

Animals↗
PubMed1978

Fixatives and methods of fixation in selected tissues of the laboratory rat.

The histologic appearances of tissues fixed by immersion and perfusion were compared, as well as the effects of these different fixatives: 10% neutral buffered formalin, Carnoy's fluid, and Bouin's fluid. Intravascular perfusion provided better tissue preservation than fixation by immersion. The quality of preservation by neutral buffered formalin was equal to that of Carnoy's fluid and Bouin's fluid, but the overall staining quality of the latter two was judged to be superior.

Animals↗
PubMed1984

Internal fixation of femoral neck fractures. Compression screw compared with nail plate fixation.

In a prospective, randomized study of femoral neck fracture operations, a newly developed compression-screw device was compared with the McLaughlin nail-plate. One hundred and twenty-eight fractures were treated with the compression screw and 127 with a nail plate. The patients were followed up for 3 years. All undisplaced fractures healed in both groups. Eleven per cent of displaced Garden 3 and 4 fractures did not heal in the compression-screw group compared to 25 per cent in the nail-plate group. Late segmental collapse occurred in 15 per cent of the healed displaced fractures in the compression-screw group, compared to 21 per cent in the nail-plate group. Fixation of femoral neck fractures using the new compression-screw device gave fewer failures without concomitant disadvantages compared to nail plate fixation.

Aged↗
PubMed1984

Plate fixation of tibial fractures in the rabbit. Correlation of bone strength with duration of fixation.

Bone healing after metal plate fixation of rabbit tibial osteotomies was studied in order to gain information as to the optimum time for plate removal. The fracture had regained almost normal biomechanical properties after 6 weeks. Significantly greater strength and stiffness of the healing tibiae were obtained at 12 weeks when the plate was removed after 4, 6 or 9 weeks and no further fixation was subsequently applied, compared to those plated for 12 weeks. The results indicate that a metal plate should be removed as soon as the fracture has regained normal biomechanical properties; i.e. before the stress-protecting effect has secondarily weakened the bone. The findings suggest that metal plates should be removed at an earlier stage of the healing period than is usual in clinical practice.

Animals↗
PubMed1986

Effects of fixation stiffness on fracture healing. External fixation of tibial osteotomy in the rabbit.

In rabbit tibial osteotomies, the effects on bone healing of three different degrees of stiffness of external fixation were investigated. Redislocation occurred in one third of the osteotomies with the least rigid fixation, and the amount of external callus was greater in this group. At 6 weeks there were no significant differences between the groups regarding bending strength and stiffness of the bones.

Animals↗
PubMed1987

Stability of fixation in femoral neck fractures. Comparison of four fixation devices in vivo and in cadavers.

On human cadaveric femora, internal fixation of cervical osteotomies was performed with four different devices. With the use of a lever, a static force was applied through the acetabulum to the osteotomy site. Motion at the osteotomy site was measured by two strain gauges. The compression force necessary to inhibit motion at the osteotomy site during the fixation procedure was measured. This force was lower with a hook pin than with the other devices. During surgery in 12 patients with displaced femoral neck fractures, the forces holding the fracture surfaces together were measured with a dynamometer. The force at which widening of the fracture gap was observed by fluoroscopy was recorded. In seven fractures, the mean compression force was 110 (60-170) N. The remaining five fractures did not open up when pressures of up to 200 N were applied. These forces were always greater than the hook pin forces measured in the cadaver experiments, but often less than the forces obtained with the other devices.

Aged↗
PubMed1992

[Universal hip fixator "Zespol". Construction of the fixator, principles of function, instrumentation, surgical technique, indications and results of treatment].

The construction and principles of function of hip fixator based on Zespol method, with compression of the fragments provided by elastic deformation of a plate is presented. Original instrumentation, operative technique and indications for this type of osteosynthesis is described. Results analysis revealed that out of 64 patients 10 died within 6 month from surgery, all of them older than 80 years of age. In 46 from remaining 56 patients a union of fractured bone was found. There were 82.2% of good results in patients with femoral neck fracture and 87.5% in the group with trochanteric fractures. Few complications produces hope for Zespol hip fixator to become valuable device for treatment both trochanteric and femoral neck fractures.

Adult↗
PubMed1992

[Treatment of calcaneus and mid-foot fractures using closed reposition and fixation with the Ilisarov fixator].

Sixteen fractures of the calcaneus involving the subtalar joint were treated by closed reduction and external fixation using the Ilisarov apparatus. Except for four cases in which temporary arthrodesis of the subtalar or ankle joint was used, fixation was usually only used for the calcaneus. The operative technique is described precisely. Initial follow-up examinations (on average after 1 year) show advantages over conservative treatment, e.g. better anatomical reduction. In addition, early mobilization of the joint and early weight-bearing result in less pain from disuse osteoporosis. Furthermore, several case reports demonstrate the efficiency of this method in tarsal and metatarsal fracture-dislocations.

Adult↗