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RoFo : Fortschritte Auf Dem Gebiete Der... May 2009
Topics: Adult; Diagnosis, Differential; Follow-Up Studies; Humans; Joint Dislocations; Magnetic Resonance Imaging; Male; Tendon Injuries; Tomography, X-Ray Computed; Trapezoid Bone; Wrist Injuries
PubMed: 19391069
DOI: 10.1055/s-0028-1109161 -
Injury Nov 2017To compare the finite element models of two different composite radius fracture patterns, reduced and stabilised with four different fixed-angle dorsal plates during... (Comparative Study)
Comparative Study
PURPOSE
To compare the finite element models of two different composite radius fracture patterns, reduced and stabilised with four different fixed-angle dorsal plates during axial, dorsal and volar loading conditions.
METHODS
Eight different plastic models representing four AO/ASIF type 23-A3 distal radius fractures and four AO/ASIF 23-C2 distal radius fractures were obtained and fixed each with 1 of 4 methods: a standard dorsal non-anatomical fixed angle T-plate (3.5mm Dorsal T-plate, Synthes), anatomical fixed-angle double plates (2.4mm LCP Dorsal Distal Radius, Synthes), anatomical fixed angle T-plate (2.4mm Acu-Loc Dorsal Plate, Acumed) or anatomical variable-angle dorsal T-plate (3.5mm, Dorsal Plate, Zrinski). Composite radius with plate and screws were scanned with a 3D optical scanner and later processed in Abaqus Software to generate the finite element model. All models were axially loaded at 3 points (centrally, volarly and dorsally) with 50 N forces to avoid the appearance of plastic deformations of the models. Total displacements at the end of the bone and the stresses in the bones and plates were determined and compared.
RESULTS
Maximal von Mises stress in bone for 3-part fracture models was very similar to that in 2-part fracture models. The biggest difference between models and the largest displacements were seen during volar loading. The stresses in all models were the highest above the fracture gap. The best performance in all parameters tested was with the Zrinski plate and the most modest results were with the Synthes T-plate.
CONCLUSION
There was no significant difference between 2-part (AO/ASIF type 23-A3) and 3-part (AO/ASIF 23-C2) fracture models. Maximal stresses in the plates appeared above the fracture gap; therefore, it is worth considering the development of plates without screw holes above the gap.
Topics: Biomechanical Phenomena; Bone Plates; Bone Screws; Finite Element Analysis; Fracture Fixation, Internal; Fractures, Comminuted; Humans; Models, Anatomic; Radius; Radius Fractures
PubMed: 29122121
DOI: 10.1016/S0020-1383(17)30738-6 -
Cahiers D'anesthesiologie 1994
Topics: Analgesics, Opioid; Humans; Neurons, Afferent; Pain; Receptors, Opioid; Spinal Cord
PubMed: 7767714
DOI: No ID Found -
The Journal of Cell Biology Jan 2011During Drosophila melanogaster dorsal closure, lateral sheets of embryonic epidermis assemble an actomyosin cable at their leading edge and migrate dorsally over the...
During Drosophila melanogaster dorsal closure, lateral sheets of embryonic epidermis assemble an actomyosin cable at their leading edge and migrate dorsally over the amnioserosa, converging at the dorsal midline. We show that disappearance of the homophilic cell adhesion molecule Echinoid (Ed) from the amnioserosa just before dorsal closure eliminates homophilic interactions with the adjacent dorsal-most epidermal (DME) cells, which comprise the leading edge. The resulting planar polarized distribution of Ed in the DME cells is essential for the localized accumulation of actin regulators and for actomyosin cable formation at the leading edge and for the polarized localization of the scaffolding protein Bazooka/PAR-3. DME cells with uniform Ed fail to assemble a cable and protrude dorsally, suggesting that the cable restricts dorsal migration. The planar polarized distribution of Ed in the DME cells thus provides a spatial cue that polarizes the DME cell actin cytoskeleton, defining the epidermal leading edge and establishing its contractile properties.
Topics: Actins; Actomyosin; Amino Acid Motifs; Animals; Cell Adhesion; Cell Adhesion Molecules; Cell Movement; Cell Polarity; Drosophila Proteins; Drosophila melanogaster; Epidermal Cells; Epidermis; Intracellular Signaling Peptides and Proteins; Protein Structure, Tertiary; Repressor Proteins
PubMed: 21263031
DOI: 10.1083/jcb.201009022 -
Beitrage Zur Orthopadie Und... 1970
Topics: Brain Concussion; Humans; Joint Dislocations; Male; Middle Aged; Radiography; Radius Fractures; Wrist Injuries
PubMed: 5510558
DOI: No ID Found -
Pediatrie 1992
Topics: Child, Preschool; Female; Humans; Meningomyelocele; Syringomyelia
PubMed: 1319033
DOI: No ID Found -
Spine Nov 2007A biomechanical in vitro study on porcine and human spinal segments. (Comparative Study)
Comparative Study
STUDY DESIGN
A biomechanical in vitro study on porcine and human spinal segments.
OBJECTIVE
To investigate axial rotational stability of the thoracic spine under dorsal and ventral shear loads.
SUMMARY OF BACKGROUND DATA
Idiopathic scoliosis is a condition restricted exclusively to humans. An important difference between humans and other vertebrates is the fact that humans ambulate in a fully erect position. It has been demonstrated that certain parts of the human spine, more specifically the dorsally inclined lower thoracic and high lumbar parts, are subject to dorsally directed shear loads. It has been hypothesized that these dorsal shear loads reduce the rotational stability of the spine, thereby increasing the risk to initiate idiopathic scoliosis.
METHODS
Fourteen porcine and 14 human thoracic functional spinal units (FSUs) with intact costotransverse and costovertebral articulations were used for biomechanical testing. In both dorsal and ventral directions, shear loads were applied to the upper vertebra of the FSU in the midsagittal plane (centrally), and at 1 cm to the right and to the left (eccentrically), resulting in a rotary moment. Vertebral rotation was measured at 3 incremental loads by an automated optoelectronic 3-dimensional (3D) movement registration system.
RESULTS
The results of this study showed that eccentrically applied shear loads induce vertebral rotation in human as well as in porcine spinal segments. At the mid-thoracic and lower thoracic levels, significantly more vertebral rotation occurred under dorsal shear loads than under ventral shear loads.
CONCLUSION
These data show that, in humans and in quadrupeds, the thoracic spine is less rotationally stable under dorsal shear loads than under ventral shear loads.
Topics: Aged; Aged, 80 and over; Animals; Biomechanical Phenomena; Cadaver; Female; Humans; Male; Middle Aged; Rotation; Shear Strength; Species Specificity; Sus scrofa; Thoracic Vertebrae; Torque; Walking; Weight-Bearing
PubMed: 17978652
DOI: 10.1097/BRS.0b013e318158cd86 -
Injury Feb 2012The purpose of this study was to determine whether a displaced dorsal rim fracture has an adverse effect on wrist function after volar plate fixation of a dorsally...
INTRODUCTION
The purpose of this study was to determine whether a displaced dorsal rim fracture has an adverse effect on wrist function after volar plate fixation of a dorsally displaced distal radius fracture (DRF).
MATERIALS AND METHODS
Two matched cohorts of 23 matched patients, one with a displaced dorsal rim fracture >2mm (group 1), and the other without a dorsal rim fracture (group 2) were analysed in this study of volar locking plate fixation for dorsally unstable DRFs. The two cohorts were analysed for differences in wrist function and wrist pain, radiographic parameters and arthritic grades of radiocarpal joints. Displacement of dorsal rim fragments and diameters of the retained articular portions of dorsal rims in group 1 were measured.
RESULTS
No significant difference was found between the two groups in overall wrist function or wrist pain. Mean displacement of dorsal rims in group 1 was 3.0mm and the mean diameter of the retained articular portion of dorsal articular wall was 2.0mm. No significant difference was found between the two groups in terms of any radiographic parameters or the arthritic grading of radiocarpal joints.
CONCLUSION
A displaced dorsal rim fracture does not appear to affect outcomes adversely after volar locking plate fixation of dorsally displaced DRFs.
Topics: Adult; Aged; Aged, 80 and over; Analysis of Variance; Bone Plates; Case-Control Studies; Cohort Studies; Female; Fracture Fixation, Internal; Humans; Male; Middle Aged; Palmar Plate; Radiography; Radius Fractures; Range of Motion, Articular; Treatment Outcome; Young Adult
PubMed: 21514587
DOI: 10.1016/j.injury.2011.03.049 -
The Journal of Hand Surgery Jul 2005To see if locking volar plates approach the strength of dorsal plates on a dorsally comminuted distal radius fracture model. Volar plates have been associated with fewer...
PURPOSE
To see if locking volar plates approach the strength of dorsal plates on a dorsally comminuted distal radius fracture model. Volar plates have been associated with fewer tendon complications than dorsal plates but are thought to have mechanical disadvantages in dorsally comminuted distal radius fractures. Locking plates may increase construct strength and stiffness. This study compares dorsal and volar locking and nonlocking plates in a dorsally comminuted distal radius fracture model.
METHODS
Axial loading was used to test 14 pairs of embalmed radii after an osteotomy simulating dorsal comminution and plating in 1 of 4 configurations: a standard nonlocking 3.5-mm compression T-plate or a 3.5-mm locking compression T-plate applied either dorsally or volarly. Failure was defined as the point of initial load reduction caused by bone breakage or substantial plate bending.
RESULTS
No significant differences in stiffness or failure strength were found between volar locked and nonlocked constructs. Although not significant, the stiffness of dorsal locked constructs was 51% greater than that of the nonlocked constructs. Locked or nonlocked dorsal constructs were more than 2 times stiffer than volar constructs. The failure strength of dorsal constructs was 53% higher than that of volar constructs. Failure for both volar locked and nonlocked constructs occurred by plate bending through the unfilled hole at the osteotomy site. Failure for both dorsal locked and nonlocked constructs occurred by bone breakage.
CONCLUSIONS
Locking plates failed to increase the stiffness or strength of dorsally comminuted distal radius fractures compared with nonlocking plates. Failure strength and stiffness are greater for locked or nonlocked dorsal constructs than for either locked or nonlocked volar constructs. Whether the lower stiffness and failure strength are of clinical significance is unknown. The unfilled hole at the site of comminution or osteotomy is potentially a site of weakness in both volar locked and nonlocked plates.
Topics: Biomechanical Phenomena; Bone Plates; Cadaver; Equipment Design; Fracture Fixation, Internal; Fractures, Comminuted; Humans; Radius Fractures; Random Allocation; Treatment Outcome
PubMed: 16039369
DOI: 10.1016/j.jhsa.2005.04.017 -
The Journal of Urology Aug 2005We created an experimental model of urethral defect and then repaired it using a tunica vaginalis graft applied on the dorsal surface of the urethra. We studied the...
PURPOSE
We created an experimental model of urethral defect and then repaired it using a tunica vaginalis graft applied on the dorsal surface of the urethra. We studied the histological and radiological characteristics of free tunica vaginalis graft urethroplasty.
MATERIALS AND METHODS
In 20 New Zealand rabbits a dorsal urethral defect was created by excising a portion of the dorsal urethral surface. The tunica vaginalis graft was placed dorsally over the corpora cavernosa and tied with 4 interrupted sutures. The mucosal margin of the urethral defect was sutured to the graft using 6-zero polydioxanone sutures in continuous fashion. The animals were divided into 4 equal groups and were sacrificed 14 days, and 4, 8 and 12 weeks after surgery, respectively. A retrograde urethrogram was done at autopsy. The penis was sent for histological analysis and an experienced pathologist evaluated the severity of acute and chronic inflammation, foreign body reaction and scar formation.
RESULTS
There were no deaths related to the procedure and no intraoperative complications. All rabbits voided spontaneously after surgery. Retrograde urethrograms showed no fistula or stricture. As time after surgery increased, the signs of inflammation response disappeared, and the orientation of collagen fibrils and smooth muscle fascicles resembled that of a normal urethra. The mesothelial lining of the tunica vaginalis gradually became replaced by a more stratified epithelial lining, similar to the urothelial lining of the native urethra.
CONCLUSIONS
In the current study we noted that a tunica vaginalis graft placed dorsally can be a successful urethral substitute in the animal model.
Topics: Animals; Inflammation; Male; Penis; Rabbits; Radiography; Serous Membrane; Testis; Urethra
PubMed: 16006973
DOI: 10.1097/01.ju.0000164725.53219.be