True Torsion Research Articles

A Novel Fluoroscopic Method for Assessing Rotational Malalignment of the Tibia.

To evaluate the accuracy and reliability of a novel fluoroscopic technique for assessing tibial rotation and compare it with a previously described fluoroscopic method. A multiplanar circular ring external fixator was secured to the tibial diaphysis of 5 cadaveric lower extremity specimens. Using deformity correction software, the frame and tibia were programed to randomly rotate 5, 10, 15, 20, 25, and 30 degrees of internal and external rotation. After each rotation, 2 blinded, independent observers measured the degree of tibial rotation using 2 different fluoroscopic methods: the previously described "mortise" method and the novel "intermalleolar" method. A total of 65 measurements were made by each observer. Accuracy and interobserver reliability were calculated. Both intermalleolar and mortise methods had a mean absolute rotational difference from the true torsion of 3 degrees (standard error 1; range, 0-10 degrees intermalleolar vs. 0-18 degrees mortise). We found that 98.5% (128/130) of measurements using the intermalleolar method were less than 10 degrees from the true rotation compared with 93.8% (122/130) using the mortise method. Both the intermalleolar and the mortise methods had excellent interobserver reliability (intraclass correlation coefficient 0.99 and 0.96, respectively). Measuring tibial rotation fluoroscopically using the intermalleolar method is both accurate and reliable. Compared with the previously described mortise method, it has similar accuracy and provides a value that approximates the true tibial rotation. Also, it can be used reliably and effectively intraoperatively to identify tibial malrotation and assist in intraoperative rotational corrections.

Can Ultrasound Reduce the Rate of Negative Testicular Exploration in Suspicious Acute Scrotum; A 5-Year Experience in A District Hospital

Objective: To retrospectively outline findings of testicular exploration in patients with suspicious acute scrotum and to compare the outcomes between exploration with and without US as a preoperative diagnostic tool. Methods: A retrospective analysis of patients underwent scrotal exploration from Jan2014 till Dec 2018 in our hospital was conducted. The data were divided into exploration with preoperative ultrasound (US group) and exploration without preoperative US (non-US group). Results: 47 patients (mean age 14-years) were explored during the 5-year period. The most common finding was torsion Cyst of Morgagni (34%, 16/47). True torsion was found in 27.6% (13/47) with 3 unsalvageable testes. Torsion rates were higher in patients who underwent US (7/14, 50%) than exploration without US (6/33, 18.1%). Time delay between two groups showed no statistical difference (p-value >.05). Also, US showed 70% sensitivity and 100% Specificity regarding torsion testis. Conclusion: Based on our numbers, negative exploration can be reduced with the help of US as a diagnostic tool for torsion. However, until further studies with larger populations and definitive pathway regarding ultrasound are commenced, we recommend urgent exploration as the standard intervention in dealing with suspicious acute scrotum.

Prospective Evaluation of Predictors of Testis Atrophy After Surgery for Testis Torsion in Children

To prospectively correlate pain duration, red scrotal skin, ultrasound appearance of testis, and intraoperative testis color to future testis atrophy after acute testicular torsion. Patients 2 months-18 years old with unilateral acute scrotum were consecutively enrolled in a National Institutes of Health transcutaneous near-infrared spectroscopy study, with a subgroup analysis of the true torsion group. Presence or absence of red scrotal skin, pain duration, testicular heterogeneity on preoperative ultrasound, and intraoperative testis color based on a novel visual chart 5 minutes after detorsion were recorded. All testes underwent orchiopexy regardless of appearance. Percent volume difference between normal and torsed testicles on follow-up ultrasound was compared between patients with and without risk factors. Thirty of 56 patients who had surgical detorsion underwent scrotal ultrasound at a mean of 117 days after surgery. A color of black or hemorrhagic 5 minutes after detorsion, pain duration >12 hours, and heterogeneous parenchyma on preoperative ultrasound were associated with significant testis volume loss in follow-up compared with normal testis. All patients with a black or hemorrhagic testis had >80% volume loss. Erythematous scrotal skin was not significantly associated with smaller affected testis volume in follow-up. Based on the high atrophy rate, orchiectomy can be considered for testes that are black or hemorrhagic 5 minutes after detorsion. Pain duration >12 hours and parenchymal heterogeneity on preoperative ultrasound were also associated with testis atrophy. Red scrotal skin was not a reliable predictor of atrophy and should not delay exploration.

Accuracy and Reliability of Computed Tomography and Magnetic Resonance Imaging Compared With True Anatomic Femoral Version.

Abnormal torsion of the femur is correlated to lower extremity pathologies. Although computed tomography (CT) scan is the gold standard torsional measurement, magnetic resonance imaging (MRI) is proposed as a viable alternative. Our aim was to determine the accuracy and consistency of MRI and CT femur rotational studies based on 4 described protocols. Twelve cadaveric femora were stripped of soft tissue before imaging and physical assessment of torsion. Four advanced imaging series were obtained for each specimen: CT with axial cuts of the femoral neck (CT-axial); CT with oblique cuts of the femoral neck (CT-oblique); MRI with axial cuts of the femoral neck (MR-axial); MRI with oblique cuts of the femoral neck (MR-oblique). Anatomic specimens were placed with the posterior femoral condyles flat on a dissection table for assessment of true torsion with digital images. Three independent reviewers performed all measurements, including true torsion, using imaging software. Bland-Altman analysis was repeated with the data from each reviewer. Interobserver repeatability for all groups was high at 0.95, 0.87, 0.90, 0.97, and 0.92 for CT-axial, CT-oblique, MR-axial, MR-oblique, and true torsion, respectively. CT-axial had the lowest mean difference from clinical imaging for all three observers (all <1 degree) and held the tightest 95% limits of agreement for 2/3 observers. As torsion increases from neutral, MR-oblique linearly overestimates the rotation compared with true torsion. CT-oblique and MR-axial showed slightly greater differences from true torsion compared with CT-axial, but did not reach clinical significance. CT-axial was both most accurate and reproducible when compared with true torsion of the femur and should be the gold standard imaging modality; however, both MR-axial and CT-oblique were accurate to a level that is likely less than clinical significance. MR-axial images should be used in clinical situations where radiation exposure needs to be limited. MR-oblique images can overestimate true antetorsion and should not be used. CT-axial followed by MRI-axial is the most accurate and consistent in measuring true torsion of the femur.

Evaluation of left ventricular torsion using cardiac MRI. Validation of feature tracking

LV torsion Left ventricular torsion may be more sensitive in detecting pathology before changes in more traditional functional parameters, and the onset of symptoms. The current gold standard for evaluating torsion is CMR, but a wide variety of techniques exist and as yet the advantages and disadvantages remain to be determined. The use of feature tracking software offers a method using standard untagged SSFP images with a potential benefit of shorter scan time. Torsional shear angle is probably the best current measure of true torsion, but requires several parameters to be defined and no commercially available software exists to calculate this. The purpose of the study was to validate the CMR derived torsion,using an in-house developed software program using data from featuretracking. Methods 15 healthy volunteers underwent a low-dose dobutamine stress CMR (baseline, 7.5mcg/kg/min, 15mcg/kg/min). In-house developed software CMRTorsion is an Excelbased macro programme using Visual Basic that facilitates the calculation and graphical representation of principal strains, twist, torsion and circumferential longitudinal shear from processed bSSFP cine images obtained by a Siemens 1.5T Avanto CMR scanner. This was further refined to allow data derived from feature tracking software to be processed.

Validity and reliability of existing and modified clinical methods of measuring femoral and tibiofibular torsion in healthy subjects: Use of different reference axes may improve reliability

Previous studies have evaluated reliability and validity of clinical measurements of femoral and tibiofibular torsion, however, the results are conflicting, warranting an alternative method. The authors developed modified methods of measuring femoral and tibiofibular torsion using different reference axes, and validity and reliability of the modified and existing methods were examined in healthy subjects. Reference values were established using magnetic resonance imaging (MRI) for the validity study. There were significant differences between all clinical methods and corresponding MRI outcomes (P <0.05), whereas Pearson's correlation coefficients between the clinical methods and MRI ranged from 0.67-0.92. For modified methods, intraclass correlation coefficients were 0.89-0.97, whereas those of existing methods were 0.75-0.81. Modified methods were more precise, with standard error of measurements (SEM) of 1.5-2.9 degrees , compared to existing methods (SEM=4.0-5.1 degrees). These results indicate that clinical methods available currently do not accurately measure true torsion of the femur and tibia. Nevertheless, the clinical methods may be useful for screening and descriptive purposes as indices of true torsion, and use of different reference axes could improve their reliability.

Measurement accuracy of proximal femoral geometry using biplanar radiography.

Experimental testing indicates that the neck-shaft angle of the proximal femur can be reliably measured from biplanar radiographs, but torsion cannot. Calculated torsion varies significantly from true torsion as a function of the error created by femoral rotation, while the calculated neck-shaft angle is invariant with respect to rotation even though the calculated neck-shaft angle is mathematically dependent on calculated torsion. Theoretical considerations support this finding and demonstrate for the first time why it is true. This study demonstrates that clinical measurements of frontal plane hip deformities using existing biplanar radiography are quite accurate, but clinical measurements of torsional abnormalities are unreliable. These errors can be minimized if investigators specify the angle of the lateral X-ray beam on the anteroposterior film using methods described in this paper and if patient position is radiographically verified. The magnitude and types of errors inherent in biplanar radiography should be considered in planning preoperative strategies and in postoperative assessments of hip geometry.

TWIST GEOMETRY AND TWIST LIMITS IN YARNS AND CORDS

In the first part of this paper, the geometry of twisted yarns is analysed and, by the introduction of the term “basic” twist (defined as twist per unit of untwisted length), some interesting and apparently new relations are obtained which show why there is a limit to twist and why snarling is inevitable above this limit, even when the yarn is held taut. This theoretical onset of snarling may have useful applications in the analysis of the twisted zone in false-twist bulking processes, where the highest twist is used and temporary snarling is intentionally induced. In the second part, the geometry of primary cording, i.e., the twisting together of two or more twisted yarns, is investigated with the approximation of neglecting their curvature whilst taking proper account of their true length and true torsion. This approximation allows the results of the first part of the paper to be applied and leads to a fairly simple solution without need to consider the path of individual filaments. The resultant equations show that there is a cord twist at which the “de-twist” (more accurately, reduction of torsion) of the plies is a maximum: further increase of cord twist beyond this level increases ply torsion towards the pre-twisted level. This explains the minimum found experimentally when outside filament-angle relative to the ply axis is plotted against cord twist. In the third part, the existence of a limit to cord twist is demonstrated, above which snarling must occur. This is when the plies in the cord are corded as close together as possible, very similar to a close-coiled spring, and though it seems likely that the existence of this limit must be known, at least experimentally to some, yet there appears to be no mention of it in the literature.

TORSION OF THE EYE ON OBLIQUE GAZE

WHETHER or not torsion of the eye occurs on oblique gaze has been a subject of controversy for some time. Some have held for instance, that, on upward and outward gaze the eye intorts1; some, that it extorts,2and some, that it does neither.3The group who have claimed that torsion occurs are divided into those who speak of true torsion and those who say that only apparent (false) torsion exists. The methods used for determining the amount of torsion have been based on the study of after-images and models, mathematical analysis and speculation. It seems that the question is subject to direct experimental approach. It is difficult to estimate torsional movements unless one observes in the vertical plane containing the visual axis of the eye under investigation (fig. 1). PRESENT INVESTIGATION Method. —After instillation anesthesia, and while the subject gazes ahead, ink marks are made at

Torsion of the eye on oblique gaze.

WHETHER or not torsion of the eye occurs on oblique gaze has been a subject of controversy for some time. Some have held for instance, that, on upward and outward gaze the eye intorts1; some, that it extorts,2and some, that it does neither.3The group who have claimed that torsion occurs are divided into those who speak of true torsion and those who say that only apparent (false) torsion exists. The methods used for determining the amount of torsion have been based on the study of after-images and models, mathematical analysis and speculation. It seems that the question is subject to direct experimental approach. It is difficult to estimate torsional movements unless one observes in the vertical plane containing the visual axis of the eye under investigation (fig. 1). PRESENT INVESTIGATION Method. —After instillation anesthesia, and while the subject gazes ahead, ink marks are made at