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At least 235 records · Page 13Linked to original sources
PubMed1986

Dynamic axial fixation. A rational alternative for the external fixation of fractures.

Conventional external fixation systems neither inhibit motion at the fracture site sufficiently to permit primary bone healing, nor do they allow sufficient motion to encourage adequate external callus formation. Healing with such systems is therefore prolonged. These methods are usually reserved for the most severe fractures when internal fixation may be contraindicated. A unilateral, dynamic axial fixation system (Orthofix - registered trademark) is described which allows for simple conversion from a rigid to a dynamic mode, and so can be readily adapted to the changing physiological patterns of fracture repair. In 288 fresh fractures a success rate of 94% was achieved, with an average time to healing of 4.4 months. The incidence of pin-track infection was only 0.6%. The contribution which the mechanical and design features of the apparatus make to the results obtained is discussed. It is suggested that the system is capable of extending the range of indications for an externally mounted system to include many cases which would formerly have been treated by internal fixation, plaster cast or traction.

Adult↗
PubMed1984

[Functionally stable fixation in severe midface fractures using an external cranial fixator].

With the external Cranial-fixator we can achieve a stable fixation of the severe maxillofacial injuries. In a period of 10 years (1973-1982) 61 patients were treated with a external cranial fixation, which is tolerated very well by the patients. The intermaxillary fixation is not necessary, the application is easy, the morbidity rate is low and the results are good (table 3 und 4).

Adolescent↗
PubMed1979

Fixation of mammalian tissues in different fixatives and its influence on the staining with methyl green-pyronin.

This investigation is a study on the role of fixation of different mammalian tissues in different fixatives as well as in 10% neutral formalin containing different metal cations and its effect on the staining with the dye-mixture, methyl green-pyronin. The results indicate variation in the colour of the nuclei in tissues fixed in the different fixatives. The possible role of the fixatives on nuclear colouration has been discussed.

Animals↗
PubMedDate not supplied

The influence of mode of fixation on morphometrical data derived from terminal villi in the human placenta at term: a comparison of immersion and perfusion fixation.

The placenta is a highly vascular organ which is subjected to a variable degree of compression during delivery. Partial collapse of the fetal capillary network inevitably results, and this has significant effect upon the maternofetal diffusion distance. Fixation via a dual perfusion system operating at physiological pressures can redistend the vascular tree to its antenatal state. Morphometrical analysis provides a volume fraction for the fetal capillaries within the terminal villi of 38.4 per cent, a figure which approximates closely to values obtained from in situ biopsy of the placenta. The harmonic mean diffusion distance was found to be 3.6 micron. Perfusion fixation resulted in a lower coefficient of variation for many parameters compared with traditional immersion fixation. By negating the unpredictable influence of the placental transfusion, it is considered that perfusion fixation will make true interplacental variations easier to detect.

Female↗
PubMed2005

Cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up.

PURPOSE: To determine if there is a different clinical outcome after cross-pin versus interference screw fixation in anterior cruciate ligament (ACL) reconstruction with hamstring tendons. TYPE OF STUDY: Prospective randomized clinical follow-up study. METHODS: Sixty-two patients were randomized into either TransFix cross-pin (Arthrex, Naples, FL) (TransFix group, n = 31) or metal interference screw femoral fixation (screw group, n = 31) in ACL reconstruction with hamstring tendons. The distal fixations were an AO screw with spiked washer post and metal interference screw. The evaluation methods were clinical examination, CA 4000 laxity (OSI, Hayward, CA), and Lido isokinetic muscle torque measurements (Lido MultiJoint II; Loredon, West Sacramento, CA) as well as International Knee Documentation Committee (IKDC), Tegner activity level, Lysholm knee, and Kujala patellofemoral scores. RESULTS: There were no differences between the study groups preoperatively. For the 2-year follow-up, 26 patients of the TransFix group and 30 patients of the screw group were available (90%). The evaluation methods disclosed no statistical differences between the groups at the 1- or 2-year follow-up examinations. At the 2-year follow-up, 22 (85%) of the TransFix and 22 (73%) of the screw group patients were in the IKDC A or B categories. There were significantly more additional procedures postoperatively in the TransFix group owing to the removal of the tibial fixation post hardware in 15 (48%) cases. CONCLUSIONS: There were no statistically or clinically relevant differences in the results 1 or 2 years postoperatively and both techniques seemed to improve patients' performance. LEVEL OF EVIDENCE: Level I.

Adolescent↗
PubMed1987

Perfusion-fixation of the human brain for immunohistochemistry: comparison with immersion-fixation.

A method of perfusion-fixation of the human brain is described and compared with immersion-fixation by immunoperoxidase staining for several substances (tyrosine hydroxylase, substance P, choline acetyltransferase, glutamate decarboxylase, Met-enkephalin, and neuron-specific enolase) in human striatum. Results from 1-cm slices fixed by immersion for 1, 2, 4 and 8 days were compared with results from slices of perfused brain postfixed for the same time periods. The fixative used in all steps was 4% paraformaldehyde at 4 degrees C. In the immersion-fixed brains, optimal immunoreaction for tyrosine hydroxylase and glutamate decarboxylase was limited to a depth of 1-2 mm from the surface of the brain slice. In contrast, staining density in perfusion-fixed brains was relatively homogeneous and of high quality. The other antigens studied displayed more uniform staining throughout the section with both perfused and immersed brains. Investigators intending to study human brain immunohistochemistry using immersion-fixation should be aware of the possibility of depth-related variations in staining intensity and would be wise to determine whether this effect is significant for the antigens they choose to study.

Aged↗
PubMed1960

Electron microscopy of retinal photoreceptors. The use of chromation following formaldehyde fixation as a complementary technique to osmium tetroxide fixation.

The fine structure of the cone and rod outer segments of the toad was studied under the electron microscope after fixation in osmium tetroxide and fixation in formaldehyde followed by chromation. In the OsO(4)-fixed specimens, the rod outer segment appears to be built of a stack of lobulated flattened sacs, each of which is made of two membranes of about 40 A separated by an innerspace of about 30 A. The distance between the rod sacs is about 50 A. The sacs in the cone outer segment are originated by the folding of a continuous membrane. The thickness of the membranes and width of the spaces between the cone sacs is the same as in rod, but the sac innerspace is slightly narrower in the cone ( approximately 20 A). After fixation in formaldehyde and chromation, two different dense lines (l(1) and l(2)) separated by spaces of less density appear. One of the lines, l(1), has a thickness of 70 A and is less dense than the other, l(2), which is 30 A thick. The correlation of the patterns obtained with both fixatives is considered and two possible interpretations are given. The possibility that l(2) is related to a soluble phospholipid component is discussed. It is suggested that the outer segments have a paracrystallin organization similar to that found in myelin.

Animals↗
PubMed2002

Advantage of pedicle screw fixation directed into the apex of the sacral promontory over bicortical fixation: a biomechanical analysis.

STUDY DESIGN: A biomechanical study of human cadaveric sacra using insertional torque and bone mineral density was conducted to determine the optimal sagittal trajectory of S1 pedicle screws. OBJECTIVE: To measure the maximal insertional torque of sacral promontory versus bicortical pedicle screw fixation. SUMMARY OF BACKGROUND DATA: Fixation of instrumentation to the sacrum is commonly accomplished using S1 pedicle screws, with previous studies reporting biomechanical advantages of bicortical over unicortical S1 screws. The biomechanical effect of bicortical screws (paralleling the endplate) versus screws directed into the apex of the sacral promontory is unknown. METHODS: For this study, 10 fresh frozen cadaver sacra were harvested and evaluated with dual-energy radiograph absorptiometry to assess bone mineral density. Matched 7.5-mm monoaxial stainless steel pedicle screws then were randomly assigned by side (left versus right) and placed bicortically or into the apex of the sacral promontory under direct visualization. Maximum insertional torque was recorded for each screw revolution with a digital torque wrench (TQJE1500, Snap-On Tools, Kenosha, WI). RESULTS: Maximum bicortical S1 screw insertional torque averaged 5.22 +/- 0.83 inch-pounds, as compared with the maximum sacral promontory S1 screw insertional torque of 10.34 +/- 1.94 inch-pounds. This resulted in a 99% increase in maximum insertional torque (P = 0.005) using the "tricortical" technique, with the screw directed into the sacral promontory. Mean bone mineral density was 940 +/- 0.25 mg/cm2 (range, 507-1428 mg/cm2). The bone mineral density correlated with maximal insertional torque for the sacral promontory technique (r = 0.806; P = 0.005), but not for the bicortical technique (r = 0.48; P = 0.16). CONCLUSIONS: The screws directed into the apex of the sacral promontory of the S1 pedicle resulted in an average 99% increase in peak insertional torque (P = 0.005), as compared with bicortical S1 pedicle screw fixation. Tricortical pedicle screw fixation correlates directly with bone mineral density.

Absorptiometry, Photon↗
PubMed2000

Low chronic pacing thresholds of steroid-eluting active-fixation ventricular pacemaker leads: a useful alternative to passive-fixation leads.

Active-fixation pacemaker leads enable pacing at various sites, have a low dislodgment rate, and are easier to extract than passive-fixation leads, though are usually not routinely implanted in the ventricle because of their higher pacing threshold. The long-term pacing threshold associated with an active-fixation steroid-eluting lead was prospectively measured in 18 women and 20 men. At a mean follow-up of 14 months (range 3-25 months), pacing threshold increased from 0.71 +/- 0.29 V to 0.96 +/- 0.28 V (P = 0.01) between implant and the first month of follow-up, then remained stable over time, consistently allowing the long-term programming of the ventricular output at 2.5 V, while lead impedance remained stable (from 647 +/- 161 omega at implant to 666 +/- 122 omega at last follow-up). If the long-term performance of this type of lead is confirmed, the routine implantation of ventricular steroid-eluting active-fixation leads should be considered since lead extraction has become a major concern.

Adult↗
PubMed1998

Mechanical comparison of biplanar proximal closing wedge osteotomy with plantar plate fixation versus crescentic osteotomy with screw fixation for the correction of metatarsus primus varus.

Proximal crescentic metatarsal osteotomy is a clinically successful technique for correcting metatarsus primus varus in hallux valgus surgery. However, there have been instances of dorsal elevation of the metatarsal head with this technique. Mechanical testing on 10 matched pairs of cadaver feet was performed to evaluate a new technique combining a biplanar closing wedge osteotomy and plantar plate fixation versus crescentic metatarsal osteotomy. The specimens were tested in cantilever-bending mode on an MTS Mini Bionix test frame. The mean load-to-failure values were 127.2 +/- 81.9 N (SD) for biplanar osteotomy with plate fixation and 44.9 +/- 43.3 N for crescentic osteotomy (P = 0.019); the mean stiffness values at the initial portion of the load-deflection curve were 83.11 +/- 73.76 N/mm and 31.95 +/- 43.00 N/mm, respectively (P = 0.012). The biplanar wedge osteotomy with plantar plate fixation demonstrated significantly stronger fixation than the crescentic osteotomy, with higher mean load-to-failure and stiffness values. This newly described technique may provide an acceptable alternative for patients at risk for dorsal elevation of the metatarsal, particularly those who are noncompliant or have osteopenia. Clinical study will determine whether this new technique offers satisfactory long-term results.

Biomechanical Phenomena↗
PubMed2003

Luxated intraocular lens fixation using anterior chamber slipknot of the haptic to the sclera: a simple procedure to fixate intraocular lens to the sclera.

PURPOSE: To describe a technique for suturing a luxated intraocular lens (IOL) in the vitreous cavity directly to the ciliary sulcus using intraocular slipknot without IOL extraction. DESIGN: Noncomparative interventional case series. MATERIALS AND METHODS: A three-port vitrectomy was performed in all cases. According to the Lewis procedure, two scleral flaps and relative sclerectomies were performed at 3 and 9 o'clock position. IOL was rescued from vitreous cavity by means of perfluorocarbon and stabilized in anterior chamber by intravitreal forceps. Corneal endothelium was preserved by a dispersive ophthalmic viscosurgical device coating. Double armed 10-0 polypropylene was introduced into the vitreous cavity through the 9 o'clock sclerotomy incision and both the needles were passed out of the eye by the 3-o'clock position sclerotomy, guided by a bent 27-gauge needle 1.5 mm from the limbus. Hooking the slipknot around the haptics of the IOL in the anterior chamber by means of vitreous forceps, the 10-0 polypropylene was pulled so that the IOL haptic was fixated onto the sulcus. The same procedure was used to fixate the opposite haptic to the ciliary sulcus at the opposite position. RESULTS: In all four cases, the IOL fixated stably and remained well positioned. No significant intraoperative or postoperative complications occurred. CONCLUSIONS: This technique enables secure fixation of the luxated IOL in the vitreous without extracting it.

Adult↗
PubMedDate not supplied

Rigid internal fixation of the Austin/Chevron osteotomy with Herbert screw fixation: a retrospective study.

One of the adaptations of the Herbert bone screw (Zimmer Corp., Warsaw, Indiana) in podiatric surgery has been in the fixation of the Austin type osteotomy of the first metatarsal, to obtain rigid internal fixation. Technical difficulties in performing the procedure and complications have resulted in the development of several modifications of the original technique to better facilitate application of the Herbert screw. A brief review of the literature including history of distal metaphyseal osteotomies, and the uses of the Herbert screw is included. The purpose of this manuscript is to present utilization of the Herbert bone screw and modified jig in a modified Austin osteotomy, and to produce rigid internal fixation without the disadvantages of other internal fixation techniques.

Bone Screws↗
PubMed1990

Comparison of relapse in bilateral sagittal split osteotomies for mandibular advancement: rigid internal fixation (screws) versus inferior border wiring with anterior skeletal fixation.

A retrospective study of 28 patients treated by bilateral sagittal split ramus osteotomies for mandibular advancement and stabilized by two different methods of fixation was performed. Fourteen patients received rigid fixation, and 14 patients had inferior border wiring with anterior skeletal fixation. The postoperative and long-term cephalograms (greater than 6 months) were analyzed in a horizontal and vertical direction for relapse. In the horizontal direction, the rigid group experienced a 1.5% relapse in point B and a 3.2% relapse in pogonion. In the vertical direction, the rigid group experienced a 4% relapse in point B and a 9% relapse in pogonion, while the wire osteosynthesis group had a 13% relapse in point B and a 6% relapse in pogonion. These results support the belief that rigid fixation is more stable than is wire osteosynthesis and that it helps prevent relapse in the long-term results.

Bone Screws↗
PubMed1988

A comparative biomechanical study of spinal fixation using the combination spinal rod-plate and transpedicular screw fixation system.

A biomechanical study was performed comparing the stiffness and stability of the three-level combination spinal rod-plate and transpedicular screw (CSRP-TPS) fixation system with those of three anterior stabilization constructs that spanned three vertebral levels: iliac strut grafting, polymethylmethacrylate and anterior Harrington rod instrumentation (technique of Siegal et al.), and the Kaneda anterior device. The CSRP-TPS fixation system was also compared with five posterior instrumentation systems that spanned five vertebral levels: Harrington distraction rod instrumentation, segmentally wired Luque rectangular instrumentation, Cotrel-Dubousset transpedicular instrumentation. Steffee transpedicular screws and plates, and R. Roy-Camille plates under conditions of single-level instability. The relative stability of each instrumentation system was compared by mounting the fixation systems on calf spine segments containing five motion segments destabilized by complete L3 anterior corpectomies and L2-L3 and L3-L4 anterior diskectomies to simulate the two-column instability found clinically in spine fractures. Mechanical nondestructive cyclical testing in rotation, axial compression, and flexion was performed on 12 spines. All biomechanical tests were performed on a biaxial servo-controlled MTS 858 Bionix hydraulic materials testing device with a biaxial load cell. Intervertebral displacements between L2 and L4 were continuously recorded utilizing an extensometer with the knife edges placed directly adjacent to the L3 corpectomy defect during testing. This biomechanical study showed that CSRP-TPS instrumentation spanning three vertebral levels could restore the torsional, compressive, and flexural rigidity of the destabilized calf spines to that of the intact calf spines and provided more in vitro stability than either the traditional five-level Harrington distraction rod or the segmentally wired Luque rectangular instrumentation. The greatest torsional rigidity occurred with the five-level Cotrel-Dubousset instrumentation, the five-level Steffee plate and screw system, and the three-level Kaneda anterior device. In axial compression and flexural testing, the three-level CSRP-TPS system provided fixation comparable with the five-level Cotrel-Dubousset instrumentation, the five-level Steffee transpedicular screw and plate system, the five-level R. Roy-Camille plate and screw system, and the three-level Kaneda anterior device. Satisfactory levels of rigidity can be restored by three-level CSRP-TPS instrumentation under conditions of single-level instability in unstable thoracolumbar and lumbar spine fractures.

Analysis of Variance↗
PubMed1986

Segmental spine plates with pedicle screw fixation. A new internal fixation device for disorders of the lumbar and thoracolumbar spine.

A new segmental spine plate fixation system, utilizing a posterior approach and screw fixation, has been developed for disorders of the lower thoracic or lumbar spine. The indications are significant instability and severe pain relieved by immobilization. This new system uses multiple segmental fixation points through the pedicle "force nucleus" of the vertebral body. The spine plates can be contoured for anatomic positioning, reduction, and rigid stabilization to enhance graft consolidation and fusion. The surgical fixation technique is demonstrated in five case presentations illustrating the application and versatility of the method.

Adult↗
PubMed1998

An aiming device for pin fixation at the iliac crest for external fixation in unstable pelvic fracture.

To improve the accuracy of pinning at the iliac crest during external fixation of the pelvic fracture, an aiming device has been designed. The device consists of 3 parts: a sleeve which accommodates a 5.0 Shanz pin, a handle and guide points. The guide points were designed to grasp the iliac crest to allow proper pin fixation. The device has undergone trials to fix Shanz pins on the iliac crests of 10 cadavers by 10 recently graduated doctors. All pins were fixed in proper position and passed into the bone between the two tables of the iliac crest without penetrating the tables. The device has so far been used in 50 patients who had unstable pelvic fractures. All pins were in the proper positions and there had been no loosening at the time the pins were removed. The use of this aiming device for pinning the iliac crest for external fixation of pelvic fracture has given encouraging results.

Adult↗
PubMed2002

[Role of external fixators for treatment of humeral fractures: report of 23 cases using Orthofix fixators].

From 1991 to 1998, 23 humeral fractures has been treated using the Orthofix external fixator. Average age of the patient was 42 y and average follow-up 55.5 m. Initial trauma was: 13 traffic accidents, four falls at home, two devastating farming accidents, two sports accidents, one aggression and one gun accident. AO classification was used and location of the fracture was classified using Hackethal classification modified by de la Caffinière. Majority of fractures were located at the one-third distal humerus and the majority was also comminuted. At follow-up, elbow range of motion was 130 degrees, shoulder range of motion 161 degrees, external rotation 69.5 degrees and internal rotation 92.5 degrees. Using the classification of Stewart and Hundley, eight excellent, seven good, three fair and two bad results were obtained. There were no postoperative radial nerve palsy. Two external fixators had to be removed because of pin mobility. Failures were: non union and pin mobility in one patient which has to be reoperated on; two non unions have been grafted on and plated. There were no malunion in the postoperative X-rays. This device is our favourite for this type of injury because of its rigidity and the possibility of secondary dynamization. The external fixator was removed after union: this explains the long delay of union in our series.

Accidents↗
PubMed1964

SPECIFIC FRACTIONATION OF HUMAN ANTIDEXTRAN ANTIBODIES. II. ASSAY OF HUMAN ANTIDEXTRAN SERA AND SPECIFICALLY FRACTIONATED PURIFIED ANTIBODIES BY MICROCOMPLEMENT FIXATION AND COMPLEMENT FIXATION INHIBITION TECHNIQUES.

Human antidextran of one individual, absorbed specifically on sephadex, was fractionated into two populations of antibody molecules by successive elution with oligosaccharides of the isomaltose series of increasing size. The purified antibody fractions and some whole antidextran sera were found to fix complement with dextrans of molecular weight of 195,000 and above. It could be demonstrated by quantitative microcomplement fixation inhibition assays that the antibody eluted with isomaltotriose had a higher affinity for smaller oligosaccharides relative to isomaltohexaose, indicating a high content of antibody molecules with smaller combining sites, while with the second fraction, eluted with isomaltohexaose, the small haptens were very poor inhibitors and the larger oligosaccharides inhibited readily, presumably due to a higher proportion of molecules with larger combining site size. Assays of similarly prepared fractions, obtained from earlier bleedings of the same individual (1), with inhibition of complement fixation were in good agreement with those obtained by inhibition of precipitation. The two purified antidextran fractions were shown to differ with respect to their complement-fixing capacity. The fraction with molecules with smaller size-combining sites fixed only about half as much complement per unit antibody N as did the fraction containing largely molecules with larger combining sites suggesting that the strength of complement fixation is affected by the strength of the antigen-antibody interaction.

Antibodies↗