Neutral Position (neutral + position)

Distribution by Scientific Domains

Selected Abstracts

Evaluation of decision criteria for detection of spinal cord compression based on cervical myelography in horses: 38 cases (1981,2001)

J. Van Biervliet
Summary Reasons for performing study: Different criteria have been described based on height reduction of the total myelographic contrast column and components of it as tests for compression of the spinal cord due to cervical stenotic myelopathy (CSM). Fifty percent height reduction of the dorsal myelographic column (DMC), <2 mm empiric height of the DMC and a 40% reduction of the ratio of stenosis calculated based on the height reduction of the entire dural diameter (DD) have been described as decision criteria for considering the test result positive. The reasons for selecting these decision criteria or their accuracies have rarely been reported. Objectives: To evaluate the accuracy of diagnostic criteria based on reduced height of the total myelographic column and components of it for diagnosing extradural spinal cord compression using different decision criteria, and make recommendations for consistent myelographic interpretation in horses suspected of having CSM. Methods: Four measurements were obtained by 2 readers in a retrospective sample population of 38 horses in which both cervical myelography and histopathological examination of the cervical spinal cord were performed. The prevalence of CSM in the sample was 50%. At intervertebral sites, the minimum heights of the DD and DMC were measured. At intravertebral sites, the maximum heights of the entire DD and DMC were obtained. Percent height reductions of the DMC and DD were determined as the ratio of minimum intervertebral height to maximum intravertebral height within the next cranial vertebra. Histological examination was used as the gold standard for determining the actual site of spinal cord compression. Sensitivity and specificity for the diagnostic criteria were estimated at each site in neutral and flexed neck positions using several different decision criteria. Conclusions: At C6-C7, in neutral or flexed neck position and using 20% reduction of DD, the test was highly sensitive and specific for CSM. At other sites, reduced height of the myelographic column generally was not accurate for diagnosing extradural spinal cord compression. Using 20% reduction of DD in neutral position at the mid-cervical sites, the test had only low sensitivity and high specificity. Flexion of the neck appeared to increase detection of spinal cord compression in the mid-cervical region, but also substantially increased the frequency of false-positive diagnoses. Potential relevance: By using the reported sensitivity and specificity estimates, readers may decide on a decision criterion for diagnosis of extradural spinal cord compression due to CSM. However, in planning a surgical correction, it is difficult to define a decision criterion that combines acceptable sensitivity and specificity, especially at the mid-cervical sites. [source]

Phototactic responses of larvae from the marine sponges Neopetrosia proxima and Xestospongia bocatorensis (Haplosclerida: Petrosiidae)

Rachel Collin
Abstract. Previous studies suggest that phototaxis in sponge larvae is generated by the bending of a tuft of long posterior cilia (LPC). The photoresponsiveness of these cilia is often assayed by examining their reaction to sudden changes in light intensity. Here, we document and describe the larvae of the tropical marine sponges Neopetrosia proxima and Xestospongia bocatorensis and examine the phototactic behavior of their larvae. Both species brood ovoid, tufted parenchymella larvae, clearly countering an earlier hypothesis that all petrosid sponges are oviparous. Larvae of N. proxima were positively phototactic and settled after 2 d, while larvae of X. bocatorensis were negatively phototactic and settled in as little as 4 h. In both species, LPC quickly responded to changes in the light intensity. When the light intensity is reduced, the larvae of N. proxima fold the cilia inwards immediately without beating, then flare them outwards, beating for a few seconds, and then gradually return to the neutral position while continuing to beat. In contrast, the larvae of X. bocatorensis flare the cilia outwards when the light intensity is reduced and fold them inwards when the light intensity is increased. Comparisons with reported ciliary responses to light for other species demonstrate that these responses do not show the hypothesized one-to-one correspondence with phototactic behaviors and are, therefore, of limited use in explaining the mechanisms that coordinate larval swimming. [source]

Sonography of the normal scapholunate ligament and scapholunate joint space

James Francis Griffith FRCR
Abstract Purpose The aims of this study were to assess the visibility of the normal scapholunate ligament on sonography and to establish the normal scapholunate joint space width in the neutral position and radial and ulnar deviation. Methods Two hundred normal wrists in 100 subjects (55 men and 45 women; mean age, 40 years; range, 19,83 years) were examined with high-resolution sonography (5,12-MHz linear-array transducer). The visibility and thickness of the scapholunate ligament were recorded. The width of the scapholunate joint space, or interval, was measured in the neutral position and radial and ulnar deviation. The width of the distal radius was recorded as a comparative standard for the patients' body habitus. Results The dorsal scapholunate ligament was completely (100%) visible in 95 wrists (48%), partially (, 50%) visible in 60 (30%), barely (< 50%) visible in 15 (8%), and not visible in 30 (15%). The volar scapholunate ligament was completely visible in 13 wrists (7%), partially visible in 17 (9%), barely visible in 15 (8%), and not visible in 151 (76%). The proximal component of the ligament was not visible in any subject. Measurement of the scapholunate interval was limited by the lack of identifiable anatomic marks for reference. The mean width of the dorsal scapholunate interval was 4.2 mm (range, 2.3,6.3 mm) in the neutral position. The interval did not differ more than 2.5 mm between the left and right wrists. No predictable change in width on ulnar or radial deviation was evident. The mean scapholunate intervals and mean distal radial width were significantly wider in men than in women and on the right side than on the left side. Conclusions The dorsal scapholunate ligament is completely or partially visible in 78% of normal wrists. Its detection following injury may help to exclude the possibility of scapholunate dissociation. There is a quite wide variation in scapholunate interval widths on sonography and an unpredictable response with stress testing. The absence of a visible scapholunate ligament on sonography does not indicate injury. © 2001 John Wiley & Sons, Inc. J Clin Ultrasound 29:223,229, 2001. [source]

The proximal hip joint capsule and the zona orbicularis contribute to hip joint stability in distraction

Hiroshi Ito
Abstract The structure and function of the proximal hip joint capsule and the zona orbicularis are poorly understood. We hypothesized that the zona orbicularis is an important contributor to hip stability in distraction. In seven cadaveric hip specimens from seven male donors we distracted the femur from the acetabulum in a direction parallel to the femoral shaft with the hip in the neutral position. Eight sequential conditions were assessed: (1) intact specimen (muscle and skin removed), (2) capsule vented, (3) incised iliofemoral ligament, (4) circumferentially incised capsule, (5) partially resected capsule (distal to the zona orbicularis), (6) completely resected capsule, (7) radially incised labrum, and (8) completely resected labrum. The reduction of the distraction load was greatest between the partially resected capsule phase and completely resected capsule phase at 1, 3, and 5 mm joint distraction (p,=,0.018). The proximal to middle part of the capsule, which includes the zona orbicularis, appears grossly and biomechanically to act as a locking ring wrapping around the neck of the femur and is a key structure for hip stability in distraction. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 989,995, 2009 [source]

Stress analysis of the anterior tibial post in posterior stabilized knee prostheses

Chang-Hung Huang
Abstract Recent retrieval studies have indicated a high incidence of polyethylene wear on the anterior tibial post caused by impingement. This study investigated the influences of post-cam design features and component alignment on the stress distribution in the anterior tibial post when subjected to the impingement loading. Two three-dimensional finite element models of posterior stabilized knee prostheses were constructed, one with flat on flat (FF) and another with curve on curve (CC) contact surfaces between anterior tibial post and femoral cam. The polyethylene insert was modeled with elastoplastic properties. Nine cases, three hyperextension angles (0°, 5°, and 10°) combined with three axial tibial rotations (0°, 2.5°, and 5°) simulating different component alignments were analyzed. A vertical compressive load of 2,000 N and an extension moment of 45 Nm were applied simultaneously. The FF model had larger stress increases than the CC model in both hyperextension and tibial rotation compared with the neutral position. The maximum increase for the FF model was 68% in peak contact stress, 125% in von Mises stress, and 58% in tensile stress in the extreme case of 10° of hyperextension combined with 5° of axial rotation. Stress concentration was found at the anterior corner of the post in the FF model; this was not found in the CC model. The curve on curve design can reduce edge loading on the tibial post, especially during axial tibiofemoral rotation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:442,449, 2007 [source]

The effect of measurement protocol on active cervical motion in healthy subjects

Professor Zeevi Dvir
Abstract Background and Purpose Although the assessment of cervical motion is routinely performed in clinical practice, no standard protocol for this procedure has ever been established formally. The specific aim of the present study was to select from four different measurement protocols the one which was most stable in terms of reproducibility and was appropriate for clinical and/or medicolegal applications. Method A repeated measurement, test,retest of cervical motion study design using an ultrasound-based system for three-dimensional (3D) motion analysis; cervical range of motion was measured along the six primary directions: flexion; extension; right and left rotation; and right and left lateral flexion, in 20 healthy subjects who were tested twice over a period of lasting from one to four weeks. ,Protocol A' (reciprocal,intermittent testing) consisted of moving the head along a given primary direction, return to the neutral position, a pause and then motion to the opposite primary direction and return to neutral position. These movements were repeated three times. ,Protocol B' (reciprocal,continuous testing) was identical to Protocol A, but without the pause between the primary directions. ,Protocol C' consisted of three repetitions of the same primary direction with a break between two consecutive primary directions. Three sets of six randomly ordered primary directions constituted ,Protocol D'. Results Protocol D was associated with a significantly smaller range of motion and with the least intra-test reproducibility, as indicated by the coefficient of variation. The differences between the other protocols were largely negligible. Conclusion In routine clinical practice, either of protocols A, B or C may be applied. Copyright © 2002 Whurr Publishers Ltd. [source]

Cervicocephalic kinaesthesia: reliability of a new test approach

Eythor Kristjansson Faculty of Medicine
Abstract Background and Purpose Relocating either the natural head posture (NHP) or predetermined points in range are clinical tests of impaired neck proprioception but memory might influence these tests. Three new tests, reasoned to be more challenging for the proprioceptive system, were developed. The objectives were to assess the reliability of all tests and whether the three new tests were more challenging for the proprioceptive system. Method A test,retest design was used to assess the reproducibility and errors of all five tests. Twenty asymptomatic volunteers were assessed a week apart, using an electromagnetic movement sensor system, the 3-Space Fastrak. A measure of error magnitude was used to detect kinaesthetic sensibility. Comparison of the means and their corresponding dispersion were analysed descriptively. The between-day intraclass correlation coefficients (ICCs) were calculated and plots of mean differences between days 1 and 2 were conducted to estimate test reliability. Multivariate analysis of variance (MANOVA) and least significant difference (LSD) pairwise comparisons were performed to compare the test accuracy between different target positions. Results ICCs were between 0.35 and 0.9, but plotting the data modified the interpretation in some tests. Relocating a NHP was easier when the trunk was in a neutral position than when pre-rotated (error 2.46° (±0.2°) versus 5.95° (±0.7°). Relocating a 30° rotation position (error 5.8° (±0.6°) and repeatedly moving through a target (error 4.82° (±0.7°) was also difficult. Conclusions The new tests were more challenging than relocating the NHP but the reliability of tests relocating uncommon positions was questionable. Copyright © 2001 Whurr Publishers Ltd. [source]

Effects of head rotation on the right internal jugular vein in infants and young children

ANAESTHESIA, Issue 3 2010
M. J. Gwak
Summary We investigated the effects of head rotation on the cross-sectional area of the right internal jugular vein and its relative position to the carotid artery. Eighty-eight subjects were divided into infants and children groups. The cross-sectional area of the right internal jugular vein and the degree of the carotid artery overlap were measured at 0° (neutral), 40° and 80° of head rotation. The cross-sectional area of the right internal jugular vein was significantly larger at 40° and 80° head rotation compared with the neutral position in both infants and children (p < 0.001). As the head was rotated, the percentage overlap of the carotid artery increased significantly (p < 0.001). We suggest that 40° head rotation appears to be optimal for right internal jugular vein cannulation in paediatric patients. [source]


Jonathan W. Serpell
Background: Patients undergoing thyroidectomy are positioned with the neck extended to facilitate exposure of the neck. Computed tomography (CT) scanning of the thyroid, without i.v. contrast, is often used preoperatively to investigate the extent of large goitres. Currently, patients are scanned in the neutral position rather than the surgical position of neck extension. The aim of the present study was to determine the degree, if any, of movement of the thyroid, as measured by CT, achieved by neck extension. Methods: A trial was designed using CT scanning of the neck. Fourteen patients were studied. Patients attended for the usual CT thyroid. In addition, they were then rescanned with their neck extended. The position of the inferior aspect of the gland in relation to the sternal notch was measured in both positions. The degree of neck extension was measured and correlated with the extent of thyroid gland movement. The data were analysed with the Wilcoxon signed rank test and Spearman correlation coefficients. Results: Results showed a median difference between the two positions of 5 mm (P = 0.0002). Conclusion: The minimal cephalad movement of the thyroid achieved by neck extension, although statistically significant, is of doubtful clinical use, and overextension of the neck should be avoided because of its associated risks of pain, vomiting and spinal damage. [source]

1344: The author, the reviewer and the associate editor: a literary drama triangle

Purpose To provide an insight into interactions between authors, reviewers and editors. Methods Personal experience of the author as a writer, reviewer and associate editor is used to discuss the scholarly interaction involved in having a manuscript reviewed and eventually published. Results The drama triangle is a psychological model of human interaction first described by Karpman. It proposes three ancestral psychological roles which people often take in a social situation: 1. The person who is treated as, or accepts the role of, a victim, 2. the person who pressures or persecutes the victim, and 3. the rescuer, who intervenes to help the situation or the underdog; this role often is one of a mixed or covert motive. The scenario of most novels, plays and movies is based on the drama triangle. Moreover, most of us are neurologically programmed to play any of the three roles. Depending on the context, we will thus - consciously or unconsciously - choose one of them. The roles can consequently also insinuate into the manuscript review process: the author is liable to become the victim and the reviewer the villain; the editorial staff member may then assume the role of the rescuer. Be as it may, the editors should try to identify reviewers whose comments are - often unconsciously - hostile from those whose advice is constructively critical, and then filter these in their targeted advice, keeping a neutral position. Sometimes he may need to guide an author who declares himself a victim or a reviewer who plays rescuer. Conclusion The best way to avoid being trapped in a drama triangle is by being watchful not take one of the three roles. Ideally, all three players work in unison toward a paper which makes best use of the data and of the talent of the authors and reviewers. [source]

The oblique cord of the forearm in man

R. Shane Tubbs
Abstract There is minimal and often conflicting data in the literature regarding the oblique cord of the forearm. The current study seeks to elucidate further the anatomy of this structure of the upper extremity. In adult cadavers, the oblique cord was observed for and, when found, measurements were made of it. Ranges of motion were carried out while observation of the oblique cord was made. An oblique cord was found on 52.6% of sides. Gantzer's muscle was found on 55% of sides and, when present, had attachment into the oblique cord on five sides. The oblique cord was present on 13 sides with a Gantzer's muscle. Of the 20 sides with an oblique cord, no Gantzer's muscle was found on 10. The mean length of the oblique cord was 3.4 cm. In the majority of specimens, this cord tapered from proximal to distal. The proximal, middle, and distal widths of this structure had means 9, 7, and 4 mm, respectively. The oblique cord was found to travel ,45 degrees from a line drawn through the ulna and more or less traveled perpendicular to the insertion site of the bicipital tendon. This ligament was lax in the neutral position and with pronation became lax in all specimens. The oblique cord progressively became taut with increased supination from the neutral position and was maximally taut with the forearm fully supinated. Tautness of this cord was also found with distal distraction of the radius. Following the transection of the oblique cord, no discernable difference was observed in regard to maximal supination of the forearm or distal distraction of the radius. No obvious instability of the proximal forearm was found following transection of the oblique cord. Functionally, although the oblique cord may resist supination, it is unlikely that this structure affords significant stability to the proximal forearm, as it was often absent, of a very small caliber, and based on our observations, following its transection, the amount of supination of the forearm did not increase. Moreover, one would expect that this structure would never resist supination alone, as the larger overlying muscles would become taut prior to calling upon the action of this cord. Based on our findings, the function of the oblique cord appears insignificant in providing significant stability to the proximal forearm; however, further investigative studies are now necessary to confirm these data. Clin. Anat. 20:411,415, 2007. © 2006 Wiley-Liss, Inc. [source]