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PubMed2001

Optical coherence tomography of tractional macular elevations in eyes with proliferative diabetic retinopathy.

PURPOSE: To document the findings of optical coherence tomography in eyes with tractional macular elevation associated with proliferative diabetic retinopathy, paying special attention to differentiating between tractional retinal detachment and retinoschisis. DESIGN: Observational case series. METHODS: We retrospectively reviewed images of optical coherence tomography obtained from 17 consecutive eyes (17 patients) with proliferative diabetic retinopathy without vitreous opacity and showing tractional macular elevation with or without foveal involvement. RESULTS: Tractional retinal detachment and retinoschisis could be differentiated in the cross-sectional images of optical coherence tomography. Retinoschisis with or without associated retinal detachment was observed in 16 of 17 eyes (94%), whereas retinal detachment was observed in only six of 17 eyes (35%). Five eyes showed both findings of retinal detachment and retinoschisis. CONCLUSIONS: Optical coherence tomography is useful for distinguishing tractional retinoschisis from retinal detachment in eyes with proliferative diabetic retinopathy and macular elevation. Tractional retinoschisis with or without retinal detachment is the most frequent pattern of tractional macular elevation in eyes with proliferative diabetic retinopathy.

Adult↗
PubMed1992

Tractional elevations of the retina in patients with diabetes.

Tractional retinoschisis and tractional retinal detachment are both complications of proliferative diabetic retinopathy. The two conditions are frequently confused because they are similar in diagnostic features. We determined the respective incidence of tractional retinoschisis and tractional retinal detachment in 200 eyes with tractional elevations of the retina in patients with diabetes. In 39 eyes, the diagnosis was unequivocally tractional retinoschisis because the retinal elevation maintained its concave contour despite the development of retinal holes. In 65 eyes, tractional retinal detachment was diagnosed with equal certainty, either because pigment lines were present or because the elevation, after a retinal hole developed, rapidly became convex and extended to the ora serrata. The remaining 96 eyes, in which retinal holes or pigment lines were absent, were classified by other features that had been tested for significance in the already diagnosed eyes. On that basis, the diagnosis was retinoschisis in 46 eyes and retinal detachment in 50 eyes.

Diabetes Mellitus, Type 1↗
PubMed2002

[Diabetic tractional retinal detachment].

Diabetic tractional retinal detachment is a severe complication in diabetic retinopathy. The decision for a surgical intervention has to consider the spontaneous course of the disease, intraoperative and postoperative complications and the expected functional results. An extramacular tractional detachment can remain stable for a long time and can be observed as long as the centre of the macula is not threatened. Traction to the macula can cause oedema and reduced vision, even if the macula itself is not detached. In these cases vitreous surgery can improve vision. Retinal breaks due to tractional membranes can cause a traction-rhegmatogenous retinal detachment which is usually rapidly progressive and requires early surgery. For cases with tractional detachment of the macula there is no alternative to surgery. In cases with long-standing and complete tractional detachment with severe retinal ischaemia the functional prognosis even after anatomically successful surgery is poor and it may be better not to operate.

Diabetic Retinopathy↗
PubMed1997

Limited usefulness of traction-compression films in the radiographic diagnosis of lumbar spinal instability. Comparison with flexion-extension films.

STUDY DESIGN: A prospective, within-patient comparison of two methods for functional radiography of lumbar spine with consecutive patients. OBJECTIVE: To evaluate the usefulness of traction-compression radiography compared with conventional flexion-extension radiography in diagnosis of lumbar spinal instability. SUMMARY OF BACKGROUND DATA: Flexion-extension radiography generally is used and widely recognized as an effective method for diagnosis of segmental lumbar spinal instability, but the usefulness and findings of traction-compression films are less well known. METHODS: Flexion-extension and traction-compression radiography were performed on 306 consecutive patients (mean age, 43 years; range, 14-68 years) with clinically suspected lumbar spinal instability. Radiography was performed of each patient in an upright position. Axial traction was accomplished by letting the patient hang by his or her hands from a horizontal bar. Compression views were taken when the patient had sandbags of approximately 30% of the his or her weight on the shoulders. Main interest was translational forward and backward displacement of one vertebra on another. RESULTS: Signs of translational instability were present on the functional radiographs of 27% (84 of 306) of the patients. In diagnosis of instability, the overall agreement of flexion-extension and traction-compression films was only 0.786, and also statistic Kappa remained poor (0.05). Flexion-extension films more frequently revealed signs of instability than traction-compression films: 81 versus seven patients. CONCLUSIONS: Traction-compression films seem to be of questionable value in diagnosis of lumbar spinal instability.

Adolescent↗
PubMed1995

Does catheter traction reduce post-transurethral resection of the prostate blood loss?

OBJECTIVE: To determine if traction on a catheter after transurethral resection of the prostate (TURP) reduces post-operative bleeding. PATIENTS AND METHODS: This prospective trial included 115 consecutive patients undergoing TURP. After resection patients were randomly selected to have either traction (57) or no traction (58) on the catheter for 30 min. Blood loss was measured during and for 2 h after the operation. A simple method for applying constant traction is described. RESULTS: Catheter traction reduced post-operative bleeding while applied, but had no further effect after the removal of traction. CONCLUSION: Catheter traction is a useful technique to aid the control of post-TURP bleeding.

Aged↗
PubMed2002

Spatial and temporal traction response in human airway smooth muscle cells.

Tractions that cells exert on their substrates are essential in cell spreading, migration, and contraction. These tractions can be determined by plating the cells on a flexible gel and measuring the deformation of the gel by using fluorescent beads embedded just below the surface of the gel. In this article we describe the image correlation method (ICM) optimized for determining the displacement field of the gel under a contracting cell. For the calculation of the traction field from the displacement field we use the recently developed method of Fourier transform traction cytometry (FTTC). The ICM and FTTC methods are applied to human airway smooth muscle cells during stimulation with the contractile agonist histamine or the relaxing agonist isoproterenol. The overall intensity of the cell contraction (the median traction magnitude, the energy transferred from the cell to the gel, and the net contractile moment) increased after activation with histamine, and decreased after treatment with isoproterenol. Cells exhibited regional differences in the time course of traction during the treatment. Both temporal evolution and magnitude of traction increase induced by histamine varied markedly among different cell protrusions, whereas the nuclear region showed the smallest response. These results suggest that intracellular mediators of cell adhesion and contraction respond to contractile stimuli with different rates and intensities in different regions of the cell.

Adrenergic beta-Agonists↗
PubMed2005

Cyclic changes in keratocyte speed and traction stress arise from Ca2+-dependent regulation of cell adhesiveness.

The activation of stretch-activated calcium channels (SACs) in keratocytes can induce spatially coordinated increases in traction stress that promote protrusion at the cell front, while simultaneously inducing retraction at the rear. To investigate how this occurs, we correlated calcium-induced changes in traction stress with alterations in cell speed and shape. Cyclic changes in these parameters were associated with each calcium transient. In addition, an inverse relationship was found between traction stress and cell speed, suggesting that alternating changes in adhesiveness were occurring at the rear. We investigated this further by inhibiting or inducing calcium transients and observing the effects on traction stress, cell speed and shape. Inhibition of calcium transients prevented retraction and led to a slow increase in traction stress. In addition, large aggregates of vinculin developed at the lateral rear edges of treated keratocytes, consistent with an increase in adhesiveness. Induction of a calcium transient resulted in a rapid retraction, involving both increased traction stress and adhesion disassembly at the rear. We also found that keratocytes exhibiting frequent transients generated larger traction stress and moved significantly faster than other cells. Together, these data suggest that calcium transients coordinate changes in adhesiveness with SAC-mediated cycles of mechano-chemical feedback.

Animals↗
PubMed1990

Mechanism of the natriuretic effect of unilateral carotid artery traction in the rat.

Unilateral traction on a carotid artery is known to activate the carotid baroreceptor reflex. This maneuver increases sodium excretion in a manner not completely dependent on the renal nerves, suggesting that a humoral factor(s) could be involved. We measured sodium excretion before and after unilateral carotid artery traction or sham traction in anesthetized rats and related the results to the plasma concentration of immunoreactive (IR)-gamma-melanocyte stimulating hormone (gamma-MSH), a peptide known to be natriuretic in other circumstances. In 12 rats undergoing sham traction, sodium excretion did not change and plasma IR-gamma-MSH activity at the end of the experiment was 10.5 +/- 5.4 (SD) fmol/mL. Carotid artery fraction in 20 other rats caused a transient dip in mean arterial pressure of 20.1 +/- 13.2 mm Hg, and sodium excretion increased from 746 +/- 431 to 1,739 +/- 1,436 nEq/min (P less than 0.005). Plasma IR-gamma-MSH was increased to 21.1 +/- 7.1 fmol/mL (P less than 0.001 versus sham). Prior ipsilateral carotid sinus denervation markedly attenuated the carotid artery traction-related dip in blood pressure and prevented both the natriuresis and the increase in IR-gamma-MSH activity seen after this maneuver in intact rats. Pretreatment with anti-gamma-MSH antiserum also blocked the natriuretic response to carotid artery traction, despite a similar transient dip in blood pressure of 18.3 +/- 9.9 mm Hg. These observations suggest that activation of the carotid baroreceptor reflex by unilateral carotid artery traction causes natriuresis that is mediated largely by an increase in the plasma concentration of a peptide or peptides closely related to the gamma-MSH sequence.

Animals↗
PubMed1986

[Biomechanical studies of the role of the interfragmentary traction screw in plate osteosynthesis exemplified by a short oblique tibial shaft fracture].

In oblique fractures of the shaft of the tibia, plate osteosynthesis is combined with an interfragmentary traction screw to enhance the stability. Depending on the position of the fracture, the screw is introduced separately or via a plate hole near to the fracture. The maximum resistance to bending and the plastic deformation of plate osteosyntheses were studied in the tibiae of human corpses, with or without traction screw; in some cases, pure traction screw osteosyntheses were used in this study. It was found that the additional traction screw enhanced the stability by 52%, whereas plastic deformation was markedly reduced. Furthermore, the traction screw more than doubled the rigidity of the osteosynthesis, facilitating early healing of the fracture. Theoretical considerations show that a traction screw will greatly reduce the harmful shear stress of the fracture and increase interfragmentary compression, depending on the direction of the screw. If the screw is introduced, as recommended by Danis, in the bisector of the angle between the perpendicular on the fracture fissure and the perpendicular on the bone axis, one obtains high interfragmentar compression and reduction of shear stress by one-half. If the traction screw progresses perpendicularly to the bone axis, however, interfragmentary compression will be less, whereas the shear forces are fully compensated. Hence, the procedure according to Danis is meaningful in low-tension plate osteosyntheses (e.g. neutralisation plates), whereas transverse positioning of the screw appears to yield more favourable results in osteosyntheses applied under high tension.

Biomechanical Phenomena↗
PubMed1984

Home traction in the management of congenital dislocation of the hip.

A retrospective review of sixty children with seventy-eight congenitally dislocated hips who had pre-reduction traction at home was undertaken to assess the effectiveness of the traction and the incidence of severe complications, with specific reference to the incidence and severity of avascular necrosis. Thirty other children with forty-two congenitally dislocated hips who had pre-reduction traction while in the hospital were used as controls. Traction failed to radiologically improve the position of the head in relation to the acetabulum in two hips in each group. The incidence of avascular necrosis was 17.9 percent in hips treated at home and 23.8 percent in hips treated in the hospital. The hospital control group demonstrated higher incidences of the more severe types of necrosis. Traction at home was found to be an advantageous alternative to traction in the hospital, in that it is safe, effective, and less costly; however, it must be stressed that proper patient selection and careful monitoring of the program are required.

Adolescent↗
PubMed1994

Effects of axial traction stress on solute transport and proteoglycan synthesis in the porcine intervertebral disc in vitro.

The effects of axial traction stress on intradiscal hydration, solute transport and proteoglycan synthesis were examined in 658 porcine coccygeal intervertebral discs in vitro. Measurements were performed in three tissue fractions: nucleus pulposus, inner and outer annulus fibrosus. At 0.80 MPa traction stress, the equilibrium hydration did not change in the nucleus pulposus. However, in the inner and outer annulus, the equilibrium hydration was reduced, and the change led to an increase of the effective fixed charge density. Diffusion of solute to the nucleus pulposus was significantly suppressed at 0.80 MPa traction stress. The fluid flow of the intervertebral disc tended to be suppressed during the creep recovery process after compression. The proteoglycan synthesis rate in the outer annulus was markedly suppressed by traction stress of 0.80 MPa for 4 h, but not that in the nucleus pulposus. These results suggest that a prolonged excessive axial traction stress induces a decrease in tissue hydration in the annulus fibrosus, and this may lead to an increase in the fractional volume of solid in the matrix and tissue osmotic pressure, resulting in diffusion inhibition of solute and suppression of proteoglycan synthesis. Thus, prolonged and excessive spinal traction may accelerate disc degeneration.

Animals↗
PubMed1996

Acetabular labral tears: contrast-enhanced MR imaging under continuous leg traction.

OBJECTIVE: The objective of this study was to evaluate the effects of continuous leg traction on contrast-enhanced MR imaging of the hip joint and to determine whether MR imaging under these conditions is useful for demonstrating acetabular labral tears. DESIGN AND PATIENTS: Nineteen hips underwent MR imaging with a T1-weighted spin-echo sequence, followed by MR imaging under continuous leg traction after intravenous injection of gadolinium-DTPA. Joint fluid enhancement and labral contour detection were evaluated. Eleven hips had labral tears shown by conventional arthrography, arthroscopy and macroscopic surgical findings. Assessment of labral tears by MR imaging was correlated with the diagnosis based on these standard techniques. RESULTS AND CONCLUSIONS: Joint fluid enhancement was obtained in all hips at 30 min after injection. Superior and inferior labral surfaces were completely delineated in 1 hip on the unenhanced MR images, and in 7 and 13 hips, respectively, on the enhanced images under traction. The enhanced images under traction depicted 9 of the 11 labral tears. Comparison between the unenhanced image and the enhanced image under traction avoided mistaking undercutting of the labrum for a tear in 4 hips. Contrast-enhanced MR imaging under traction was valuable for detecting labral tears non-invasively and without radiation. Follow-up examinations using this method in patients with acetabular dysplasia can help to clarify the natural course of labral disorders and enable better treatment planning.

Acetabulum↗
PubMed2005

The effect of traction on compartment pressures during intramedullary nailing of tibial-shaft fractures. A prospective randomised trial.

Our aim was to study the effect of traction on the compartment pressures during intramedullary nailing of closed tibial-shaft fractures. Thirty consecutive patients with Tscherne C1 fractures were randomised into two groups. Sixteen patients underwent intramedullary nailing of the tibia with traction and 14 patients without traction. Compartment pressures were measured before the application of traction or commencement of the procedure and at the end of the procedure. The data collected was analysed using Student's t test. There was no statistically significant difference (p>0.05) in the pre-operative mean compartment pressures for both groups. The mean post-operative measurements were higher in all four compartments in the traction group (p<0.05). None of the pressures reached the critical level. These results show that traction as an aid unnecessarily increases compartment pressures.

Adult↗
PubMed2006

The effect of traction on esophageal structure in children with long-gap esophageal atresia.

We examined the esophageal structure in children who underwent traction to achieve primary repair of long-gap esophageal atresia. High-resolution ultrasound was used to compare thickness of the proximal and distal esophagus in children who had traction to achieve primary repair (n=15) to cases of esophageal atresia with shorter gaps that did not require traction (n=8). The muscularis propria of the upper esophagus was thicker in the traction compared to the non-traction group, though not statistically significant (respectively, 0.79 (0.18) mm vs. 0.71 (0.16) mm; p=0.29), measurements were similar for the lower esophagus (respectively, 0.79 (0.21) mm vs. 0.75 (0.13) mm; p=0.64). Combined mucosa and submucosa was very similar in both groups for the upper (respectively, 1.03 (0.15) mm vs. 1.04 (0.16) mm; p=0.95) and lower esophagus (respectively, 1.09 (0.23) mm vs. 1.01 (0.13) mm; p=0.37). The thickness of individual mural layers is maintained after increasing esophageal length with traction.

Child, Preschool↗
PubMed1992

Preoperative traction in patients with hip fractures.

A series of 80 patients with cervical, trochanteric or subtrochanteric hip fractures were randomized to either treatment without traction, skin traction, or skeletal traction during the 1883 h between admission and operation. The institution of skin or skeletal traction was not particularly painful for the patient, but we found no indication that either was of discernible benefit. The number of analgesic medications needed was no higher in patients without traction. We conclude that traction should not be administered routinely to patients awaiting operation for hip fracture.

Aged↗
PubMed1997

Modelling biological gel contraction by cells: mechanocellular formulation and cell traction force quantification.

Traction forces developed by most cell types play a significant role in the spatial organisation of biological tissues. However, due to the complexity of cell-extracellular matrix interactions, these forces are quantitatively difficult to estimate without explicitly considering cell properties and extracellular mechanical matrix responses. Recent experimental devices elaborated for measuring cell traction on extracellular matrix use cell deposits on a piece of gel placed between one fixed and one moving holder. We formulate here a mathematical model describing the dynamic behaviour of the cell-gel medium in such devices. This model is based on a mechanical force balance quantification of the gel visco-elastic response to the traction forces exerted by the diffusing cells. Thus, we theoretically analyzed and simulated the displacement of the free moving boundary of the system under various conditions for cells and gel concentrations. This model is then used as the theoretical basis of an experimental device where endothelial cells are seeded on a rectangular biogel of fibrin cast between two floating holders, one fixed and the other linked to a force sensor. From a comparison of displacement of the gel moving boundary simulated by the model and the experimental data recorded from the moving holder displacement, the magnitude of the traction forces exerted by the endothelial cell on the fibrin gel was estimated for different experimental situations. Different analytical expressions for the cell traction term are proposed and the corresponding force quantifications are compared to the traction force measurements reported for various kind of cells with the use of similar or different experimental devices.

Animals↗
PubMed2006

Increases in COX II mRNA in the rat spinal cord induced by cauda equina traction.

This article investigated the time response of COX II induction by traction of the cauda equina assessed by a quantified RT-PCR method. Under deep GOI anesthesia, male Wistar rats were fixed in the prone position and a laminectomy of the dorsal part of the first and second sacral vertebrae was performed. Following, COX II-mRNA levels in the cervical, thoracic, lumbar, sacral, and caudal segments were measured at 2, 4, 6, and 24 h after traction by a quantified RT-PCR method. After cauda equina traction, significant levels of COX II mRNA were detected in all segments of the spinal cord examined. Maximum levels in each segment were determined 4 h after traction of the cauda equina. Particularly in the sacrocaudal segments significantly higher levels of COX II mRNA were measured 24 h after traction. These results indicate that significant induction of spinal COX II mRNA was caused by cauda equina traction and that such induction plays a regulatory role in the nociceptive pain pathway.

Animals↗
PubMed1985

Effect of intermittent, supine cervical traction on the myoelectric activity of the upper trapezius muscle in subjects with neck pain.

This study was undertaken to compare the myoelectric activity of the upper trapezius muscle before, during, and after intermittent, supine cervical traction. Twelve people with diagnosed disease or injury of the cervical spine served as subjects. Electromyographic recordings were taken from the upper trapezius muscle with bipolar surface electrodes. The subjects were treated with 20 minutes of intermittent, cervical traction at a force of 8% of their body weight. Recordings were taken with the subjects in the supine position before the traction, during one pull and release phase of the 10th and 20th minutes of traction, and after completion of the traction treatment. An analysis of variance with repeated measures showed no significant differences in the myoelectrical activity during the six time periods measured. The results of this study do not support the clinical use of intermittent, supine traction to produce cervical muscle relaxation.

Adolescent↗