Mean Rotation Research Articles

Intra-individual variance of bilateral femoro-tibial leg rotation: a CT study of 105 healthy subjects

PurposeIn cases of suspected rotational deformity of the lower limb, in particular in post-traumatic malalignment following closed nailing, there is a lack of adequate reference values. Available publications on leg rotation have either small sample sizes or do not include bilateral or whole leg rotation of healthy legs. This study aimed to determine side-specific reference values of lower limb rotation in a large healthy sample. This may be helpful in acute clinical settings as well as for medical expert opinion.Methods226 consecutive bilateral lower limb computed tomography (CT) angiographies were screened. 105 patients (210 legs) were included (40 females, 65 males, mean age 67 ± 12 years). Bilateral axial femoral and tibial rotation alignment were independently measured and overall leg rotation was computed by two methods. Distributions, sex, and side differences were analyzed.ResultsTwo-sided paired t tests showed significant differences between right and left for all measurements. The left side showed a more pronounced mean anteversion in the femur of 2.2° (p = 0.002) and the right side higher mean external rotation in the tibia of 2.8° (p < 0.001). Overall leg rotation showed 5.1° more mean external rotation on the right side (p < 0.001) with both methods. Absolute side-to-side whole leg rotation difference was 9.5°. Absolute differences between both methods were 3.3°. The variance was high. 23 femora were retroverted, 1 tibia internally rotated, and 9 legs were overall internally rotated. No variables differed between female and male subjects except for femoral version (right p = 0.003 and left p = 0.002). Correlation coefficients were high (rho 0.550–0.934, all p < 0.001).ConclusionThere is a significant prevalence of side-to-side asymmetry in femoro-tibial torsion. Although side-to-side differences are not extraordinary, comparative axial femoro-tibial rotation alignment should always be interpreted with caution.Level of evidenceDiagnostic, retrospective cohort study, level III.

Pivotal Role of Cervical Rotation for Rehabilitation Outcomes in Patients with Subaxial Cervical Spinal Cord Injury

BackgroundLimitation of active cervical range of motion as a sequel of both spinal instrumentation and neurological injury may occur after Cervical Spinal Cord Injury (CSCI) surgery. The majority of tasks performed in daily life require a minimum of Active Cervical Range of Motion (ACROM). The aim of this study was to report ACROM in patients with subaxial CSCI, and in a control group with asymptomatic cervical spine. MethodsA cross-sectional study was performed in 46 cases of traumatic complete motor CSCI and 41 asymptomatic cases. Patients underwent quantitative measurement of ACROM on six movements, using an analogue inclinometer, and rehabilitation status assessment on the Spinal Cord Independence Measure (SCIM) III. ResultsForty-six CSCI cases and 41 asymptomatic controls were included. Mean flexion, extension, rotation, and lateral inclination were significantly lower in the CSCI group than in controls (P<0.0001). SCIMIII self-care subscores in the CSCI group showed significant correlation with mean cervical rotation (correlation coefficient, +0.508, P=0.0003). Regression analysis on mean ACROM in the CSCI group, yielded significant a negative correlation with age (P=0.037). ConclusionsCSCI significantly affected ACROM. Also, restriction of cervical rotation had significant negative correlation with SCIM-III self-care subscores.

Automatic Alignment of Cranial CT Examinations to the Anterior Commissure/Posterior Commissure (ACPC) Reference Plane forReliable Interpretation and Quality Assurance.

Alignment of cranial CT scans (cCTs) to a common reference plane simplifies anatomical-landmark-based orientation and eases follow-up assessment of intracranial findings. We developed and open sourced a fully automated system, which aligns cCTs to the Anterior Commissure/Posterior Commissure (ACPC) line and exports the results to the PACS. FMRIB's Linear Image Registration Tool (FLIRT) with an ACPC-aligned atlas is used in the alignment step. Five mm mean slabs are generated with the top non-air slice as the starting point. For evaluation, 301 trauma cCTs from the CQ500 dataset were processed. In visual comparison with the respective ACPC-aligned atlas, all were successfully aligned. Image quality (IQ) and ease of identification of the central sulcus (CS) were rated on a Likert scale (5 = excellent IQ/immediate CS identification). The median IQ was 4 (range: 2-4) in the original series and 5 (range: 4-5) in the ACPC-aligned series (p < 0.0001). The CS was more easily identified after fatbACPC (original scans: 4 (range: 2-5); ACPC-aligned: 5 (range: 4-5); p < 0.0001). The mean rotation to achieve alignment was|X| = 6.4 ± 5.2° ([-X,+X] = -26.8°-24.2°), |Y| = 2.1 ± 1.7°([-Y,+Y] = -8.7°-9.8°), and |Z| = 3.1 ± 2.4° ([-Z,+Z] = -14.3°-12.5°). The developed system can robustly and automatically align cCTs to the ACPC line. Degrees of deviation from the ideal alignment could be used for quality assurance. KEY POINTS:: · fatbACPC automatically aligns cranial CT scans to the Anterior Commissure/Posterior Commissure plane.. · ACPC-aligned images simplify anatomical-landmark-based orientation.. · fatbACPC does not impact image quality.. · fatbACPC is robust, fully PACS-integrated, and Open Source: https://github.com/BrainImAccs. CITATION FORMAT: · Rubbert C, Turowski B, Caspers J. Automatic Alignment ofCranial CT Examinations to the Anterior Commissure/Posterior Commissure (ACPC) Reference Plane for Reliable Interpretation and Quality Assurance. Fortschr Röntgenstr 2021; 193: 61 - 67.

Comparison of the rotational stability between plate-haptic toric and C-loop haptic toric IOLs in myopic eyes.

To compare the rotational stability of a plate-haptic toric intraocular lens (IOL) vs a C-loop haptic toric IOL in myopic cataract eyes. Eye and Ear, Nose, and Throat Hospital of Fudan University, China. Prospective, randomized, controlled study. Cataract eyes with axial length (AL) more than 24.5 mm were randomly assigned to receive implantation of a C-loop haptic toric IOL (AcrySof Toric IOL) (Group A) or a plate-haptic toric IOL (AT TORBI 709M IOL) (Group B). IOL rotation, residual astigmatism, visual acuity, and higher-order aberrations (HOAs) evaluated with OPD-Scan III aberrometer were compared at 3 months postoperatively. In total, 62 eyes of 62 patients were eligible for analysis: 31 in Group A and 31 in Group B. The mean rotation of toric IOLs was greater in Group A than that in Group B (8.00 ± 3.60 degrees vs 4.42 ± 3.24 degrees, respectively, P < .001), especially when IOLs were vertically placed. IOL rotation was positively correlated with AL in Group A, whereas no such correlations were found in Group B. Residual astigmatism in Group A was greater than that in Group B (-0.76 ± 0.30 diopter [D] vs -0.51 ± 0.29 D, respectively, P = .001). Fewer eyes achieved residual astigmatism of 0.50 D or less in Group A than in Group B (38.71% vs 64.52%). Group A had worse postoperative uncorrected visual acuity and higher total HOAs and coma for a 6.0 mm pupil than Group B, whereas postoperative corrected visual acuity was not different between the 2 groups. The plate-haptic toric IOL might be a better choice for myopic cataract eyes with corneal astigmatism because of reduced postoperative rotation.

Reflections and focusing of inertial waves in a librating cube with the rotation axis oblique to its faces

The response to librational forcing of a cube in rapid rotation about a diagonal axis is explored. In this orientation, the faces of the cube are all oblique to the rotation axis. The system supports inertial waves, which predominantly comprise beams emitted from the edges and vertices of the cube. Which ones emit and the resulting complicated pattern of three-dimensional reflections and subsequent focusing depend on the libration frequency. Direct numerical simulations of the Navier–Stokes flows with no-slip boundary conditions at low Ekman number ( $\text{E}=10^{-7}$ ) and small libration amplitude ( $\unicode[STIX]{x1D716}=10^{-7}$ ) exhibit complicated spatio-temporal structure that is remarkably well described by considerations of the inviscid reflections of wavebeams over the whole range of libration frequencies from zero to twice the mean rotation rate of the cube.

Birkhoff averages and rotational invariant circles for area-preserving maps

Rotational invariant circles of area-preserving maps are an important and well-studied example of KAM tori. John Greene conjectured that the locally most robust rotational circles have rotation numbers that are noble, i.e., have continued fractions with a tail of ones, and that, of these circles, the most robust has golden mean rotation number. The accurate numerical confirmation of these conjectures relies on the map having a time-reversal symmetry, and such high accuracy has not been obtained in more general maps. In this paper, we develop a method based on a weighted Birkhoff average for identifying chaotic orbits, island chains, and rotational invariant circles that does not rely on these symmetries. We use Chirikov’s standard map as our test case, and also demonstrate that our methods apply to three other, well-studied cases.

Fast registration of forest terrestrial laser scans using key points detected from crowns and stems

ABSTRACT Registration of TLS data is an important prerequisite to overcome the limitations of occlusion. Most existing registration methods rely on stems to determine the transformation parameters. However, the complexity of the registration problem increases dramatically as the number of stems grows. It is tricky to reduce the stems and determine the valid ones that can provide reliable registration transformation without a knowledge of the two scans. This paper presents an automatic and fast registration of TLS point clouds in forest areas. It reduces stems by selecting from the overlap areas, which are recovered from the mode-based key points that are detected from crowns. The proposed method was tested in a managed forest in Finland, and was compared with the stem-based registration method without reducing stems. The experiments demonstrated that the mean rotation error was 2.09′, and the mean errors in horizontal and vertical translation were 1.13 and 7.21 cm, respectively. Compared with the stem-based method, the proposed method improves the registration efficiency significantly (818 s vs 96 s) and achieves similar results in terms of the mean registration errors (1.94′ for rotation error, 0.83 and 7.38 cm for horizontal and vertical translation error, respectively).

Effectiveness of Mckenzie Traction and Exercises on Neck Pain Secondary to Upper Crossed Syndrome.

OBJECTIVES : To examine the effects of McKenzie traction and exercises on neck pain, cervical ranges, functional activities and posture secondary to upper crossed syndrome. METHODS: Randomized control trial was conducted on patient of neck pain secondary to upper crossed syndrome from physical therapy setups of Lahore and Sargodha in total six months. 120 patients of 20-60 years’ age group were allocated in two groups (experimental and control), both contained 60 respondents, both groups received neck pain exercises with TENS for eight weeks, weekly three times and McKenzie traction and exercises were additionally received by experimental group. Partakers were assessed after eight weeks of treatment. Oswestry questionnaire was used for assessment, reed co scale and goniometer parameters, was used. RESULTS: Collected data was analyzed in SPSS 20. Independent sample t-test was applied to compare mean of quantitative data at the end of treatment in both groups. Mean pre-treatment Oswestry disability score in general exercise group and McKenzie group was 60.37 and 56.82 respectively (with p-value > .05). Mean post treatment Oswestry disability score in general exercise group was 30.63 and in McKenzie group was 26.70 (with p-value.02). Mean pre-treatment flexion, extension, side flexion and rotation means in general group were 36.38, 47.10, 36.32, and 66.37 respectively whereas in McKenzie these values were 38.30, 45.47, 37.47 and 67.38 respectively (with p-value > .05). CONCLUSION: Both general exercises and McKenzie treatment improved neck pain secondary to upper crossed syndrome, however the McKenzie treatment stood significantly better than general exercise. Keywords: Mckenzie Traction, Exercise, Neck Pain, Mckenzie Treatment, Syndrome DOI: 10.7176/JHMN/74-07 Publication date: May 31 st 2020

Cyclic variations in the main components of the solar large-scale magnetic field

ABSTRACT We consider variations of the dipole and quadrupole components of the solar large-scale magnetic field. Both axial and equatorial dipoles exhibit a systematic decrease during the past four cycles, in accordance with the general decrease of solar activity. The transition of the pole of a dipole from the polar region to the midlatitudes occurs rather quickly, so that the longitude of the pole changes little. With time, however, this inclined dipole region shifts to larger longitudes, which suggests an acceleration of dipole rotation. The mean rotation rate exceeds the Carrington velocity by 0.6 per cent. The behaviour of a quadrupole differs dramatically. Its decrease over the last four cycles was much smaller than that of the dipole moment. The ratio of the quadrupole and dipole moments has increased for four cycles more than twice, in contrast to sunspot numbers, which displayed a twofold decrease for the same time interval. Regarding quadrupole rotation, the mean longitude of the poles of one sign decreased by 600° over four cycles, which suggests that the mean rotation rate was lower than the Carrington velocity by 0.28 per cent. We do not, however, see any conclusive evidence that, in the period under discussion, a mode of quadrupole symmetry was excited in the Sun along with the dipole mode.

Reliability and validity of the Japanese version of the INSPIRE measure of staff support for personal recovery in community mental health service users in Japan

BackgroundSupporting personal recovery in people with mental health difficulties is central to mental health services. This study aimed to develop the Japanese version of INSPIRE and Brief INSPIRE measure of staff support for personal recovery and to evaluate its reliability and validity.MethodsA questionnaire survey was conducted from October to December 2015. The authors asked users to participate in the survey of 14 community mental health services in the Kanto region of Japan. The service users completed self-administered questionnaires that include the Japanese version of INSPIRE, the Recovery Assessment Scale, the Client Satisfaction Questionnaire, the patient version of the Scale to Assess Therapeutic Relationship in Community Mental Health care and the Short Form Health Survey. Internal consistency was assessed using Cronbach’s alpha coefficient, and test-retest reliability was assessed using the intraclass correlation coefficient (ICC) and weighted kappa. Convergent validity was examined by assessing correlation with other scales. Factor validity was evaluated by exploratory factor analysis (EFA) with generalized least-squares mean and oblimin rotation. In addition, confirmatory factor analysis was used to check the fitness of the factor structure models derived from the EFA.ResultsA total of 195 out of 212 users gave written informed consent and participated in the study. Data from 190 respondents were analyzed (response rate 89.6%). INSPIRE, Brief INSPIRE, and the subscales all showed Cronbach’s alpha coefficient over 0.78. ICC and weighted kappa derived more than 0.92 for subscales and Brief INSPIRE. These numerical values indicated good reliability. The convergent validity of Brief INSPIRE and the subscales was significantly positively correlated with the other scales. Different from the previous study, the factor structure was extracted using EFA. Both factor structures were checked by CFA, but the degree of fitness index was not good in either. Therefore, the factor analysis did not show goodness of fit.ConclusionsThis study found the Japanese version of INSPIRE and Brief INSPIRE to be reliable and valid for use among community mental health service users in Japan.

Prevalence of Rotational Malalignment After Intramedullary Nailing of Tibial Shaft Fractures: Can We Reliably Use the Contralateral Uninjured Side as the Reference Standard?

Intramedullary (IM) nailing is the treatment of choice for most tibial shaft fractures. However, an iatrogenic pitfall may be rotational malalignment. The aims of this retrospective analysis were to determine (1) the prevalence of rotational malalignment using postoperative computed tomography (CT) as the reference standard; (2) the average baseline tibial torsion of uninjured limbs; and (3) based on that normal torsion, whether the contralateral, uninjured limb can be reliably used as the reference standard. The study included 154 patients (71% male and 29% female) with a median age of 37 years. All patients were treated for a unilateral tibial shaft fracture with an IM nail and underwent low-dose bilateral postoperative CT to assess rotational malalignment. More than one-third of the patients (n = 55; 36%) had postoperative rotational malalignment of ≥10°. Right-sided tibial shaft fractures were significantly more likely to display external rotational malalignment whereas left-sided fractures were predisposed to internal rotational malalignment. The uninjured right tibiae were an average of 4° more externally rotated than the left (mean rotation and standard deviation, 41.1° ± 8.0° [right] versus 37.0° ± 8.2° [left]; p < 0.01). Applying this 4° correction to our cohort not only reduced the prevalence of rotational malalignment (n = 45; 29%), it also equalized the distribution of internal and external rotational malalignment between the left and right tibiae. This study confirms a high prevalence of rotational malalignment following IM nailing of tibial shaft fractures (36%). There was a preexisting 4° left-right difference in tibial torsion, which sheds a different light on previous studies and current clinical practice and could have important implications for the diagnosis and management of tibial rotational malalignment. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Grand Minima in a spherical non-kinematicα2Ω mean-field dynamo model

We present a non-kinematic axisymetricα2Ω mean-field dynamo model in which the completeα-tensor and mean differential rotation profile are both extracted from a global magnetohydrodynamical simulation of solar convection producing cycling large-scale magnetic fields. The nonlinear backreaction of the Lorentz force on differential rotation is the only amplitude-limiting mechanism introduced in the mean-field model. We compare and contrast the amplitude modulation patterns characterizing this mean-field dynamo, to those already well-studied in the context of non-kinematicαΩ models using a scalarα-effect. As in the latter, we find that large quasi-periodic modulation of the primary cycle are produced at low magnetic Prandtl number (Pm), with the ratio of modulation period to the primary cycle period scaling inversely with Pm. The variations of differential rotation remain well within the bounds set by observed solar torsional oscillations. In this low-Pm regime, moderately supercritical solutions can also exhibit aperiodic Maunder Minimum-like periods of strongly reduced cycle amplitude. The inter-event waiting time distribution is approximately exponential, in agreement with solar activity reconstructions based on cosmogenic radioisotopes. Secular variations in low-latitude surface differential rotation during Grand Minima, as compared to epochs of normal cyclic behavior, are commensurate in amplitude with historical inferences based on sunspot drawings. Our modeling results suggest that the low levels of observed variations in the solar differential rotation in the course of the activity cycle may nonetheless contribute to, or perhaps even dominate, the regulation of the magnetic cycle amplitude.

Prediction of the aerodynamic sound generated due to flow over a cylinder performing combined steady rotation and rotary oscillations.

Analysis of sound generated due to a laminar flow past a circular cylinder subjected to the mean rotation along with the rotary oscillating motion has been performed for the Reynolds number Re = 150 and the Mach number M = 0.2. The direct numerical simulation approach has been used to study modifications in the generated sound field over a range of forcing parameters using disturbance pressure field information. Flow and sound fields are accurately resolved over a nondimensional radial distance r≤100 from the center of the cylinder. Frequencies, as well as wavelengths of generated sound waves, have been effectively altered by varying the forcing frequency-ratio, whereas the directivity nature of the radiated sound field has been modified by varying the forcing amplitude-ratio. Doak's decomposition technique has been used to understand the reasons behind changes in the radiated sound fields as the forcing parameters are varied.

Use of propeller flaps for reconstruction of extensor side elbow defects

Introduction: Extensor side elbow defects are difficult to repair among upper extremity injuries. The bulk of surrounding soft tissue is limited and often affected by the trauma, although seems to be ideal, propeller flaps are not being widely adopted for upper extremity soft-tissue reconstructions. In the present study, we set out to share the results of the perforator propeller flaps that are based on either the arm or the forearm, which we thought the perforator vessel anatomy is relatively constant. Patients and Methods: All patients who underwent elbow defect repair between June 2016 and June 2018 were evaluated retrospectively. Patients were evaluated in terms of the etiology and demographic parameters. Flaps were assessed by the artery system, on which they were based on the dimensions of skin island, the rotation angle of the skin paddle, and closure method of the donor site. Outcomes were noted during bimonthly follow-up visits. Results: In 11 patients, the dominant etiology was chronic bursitis. The mean flap skin paddle size was 48.8 ± 16.9 cm2. For defect repair, radial collateral artery (RCA) perforator flaps were used in six patients. Posterior interosseous artery (PIA) perforator flaps were used in remaining five patients. All the flaps were based on a single perforator artery. The mean rotation degree was measured as 165° ±11.6°. In nine cases, the flap donor site was closed primarily, whereas split-thickness skin grafts were used in two cases. The average follow-up period was 13 ± 5 months. No limitation in the range of motion of the elbow joint was noted. Distal marginal necrosis was observed in two flaps. Conclusion: We advocate that both PIA and RCA perforator flaps are very useful options for soft-tissue reconstruction of extensor side elbow defects.

Soft-tissue prostate intrafraction motion tracking in 3D cine-MR for MR-guided radiotherapy

To develop a method to automatically determine intrafraction motion of the prostate based on soft tissue contrast on 3D cine-magnetic resonance (MR) images with high spatial and temporal resolution. Twenty-nine patients who underwent prostate stereotactic body radiotherapy (SBRT), with four implanted cylindrical gold fiducial markers (FMs), had cine-MR imaging sessions after each of five weekly fractions. Each cine-MR session consisted of 55 sequentially obtained 3D data sets (‘dynamics’) and was acquired over an 11 s period, covering a total of 10 min. The prostate was delineated on the first dynamic of every dataset and this delineation was used as the starting position for the soft tissue tracking (SST). Each subsequent dynamic was rigidly aligned to the first dynamic, based on the contrast of the prostate. The obtained translation and rotation describes the intrafraction motion of the prostate. The algorithm was applied to 6270 dynamics over 114 scans of 29 patients and the results were validated by comparing to previously obtained fiducial marker tracking data of the same dataset. Our proposed tracking method was also retro-perspectively applied to cine-MR images acquired during MR-guided radiotherapy of our first prostate patient treated on the MR-Linac. The difference in the 3D translation results between the soft tissue and marker tracking was below 1 mm for 98.2% of the time. The mean translation at 10 min were X: 0.0 0.8 mm, Y: 1.0 1.8 mm and Z: mm. The mean rotation results at 10 min were X: , Y: 0.1 0.6° and Z: 0.0 0.7°. A fast, robust and accurate SST algorithm was developed which obviates the need for FMs during MR-guided prostate radiotherapy. To our knowledge, this is the first data using full 3D cine-MR images for real-time soft tissue prostate tracking, which is validated against previously obtained marker tracking data.

The evolution of magnetic field and spin‐down of young pulsars

AbstractHere, we summarize our recent work on the evolution of magnetic field and spin‐down of young pulsars including high‐B pulsars and magnetars. Our work includes the following three parts: (a) Based on the estimated ages of their potentially associated supernova remnants (SNRs), we estimate the values of the mean braking indices of eight magnetars with SNRs and find that five magnetars have smaller mean braking indices of 1 &lt; n &lt; 3, and we interpret them within a combination of magnetodipole radiation and wind‐aided braking. (b) The low braking index of n = 0.9(2) for PSR J1734‐3333 could undergo a supercritical accretion soon after its formation in a supernova explosion. The buried multipole magnetic fields will merge into a dipole magnetic field. Retaining the current field growth index ϵ = 1.34, this pulsar will become a magnetar with dBp∼6.2(2) × 1014 G and dBp∼1.06(4) × 1015 G after 50 kyrs and 100 kys, respectively. (c) By introducing a mean rotation energy conversion coefficient and combining the pulsar's high‐energy and timing observations with a reliable nuclear equation of state, we estimate the initial spin period, initial dipole magnetic field, and true age of PSR J1640‐4631. For this source, its measured high braking index n = 3.15(3) is attributed to a long‐term dipole magnetic field decay, and its soft X‐ray emission is attributed to anisotropic heating.

Anatomical deformation due to horizontal rotation: towards gantry-free radiation therapy

Gantry-free radiation therapy systems may be simpler and more cost effective, particularly for MRI-guided photon or hadron therapy. This study aims to understand and quantify anatomical deformations caused by horizontal rotation with scan sequences sufficiently short to facilitate integration into an MRI-guided workflow.Rigid and non-rigid pelvic deformations due to horizontal rotation were quantified for a cohort of 8 healthy volunteers using a bespoke patient rotation system and a clinical MRI scanner. For each volunteer a reference scan was acquired at 0° followed by sequential faster scans in 45° increments through to 360°. All fast scans were registered to the 0° image via a three-step process: first, images were aligned using MR visible couch markers. Second, the scans were pre-processed then rigidly registered to the 0° image. Third, the rigidly registered scans were non-rigidly registered to the 0° image to assess soft tissue deformation. The residual differences after rigid and non-rigid registration were determined from the transformation matrix and the deformation vector field, respectively.The rigid registration yielded mean rotations of ⩽2.5° in all cases. The average 3D translational magnitudes range was 5.8 ± 2.9 mm–30.0 ± 11.0 mm. Translations were most significant in the left–right (LR) direction. Smaller translations were observed in the anterior–posterior (AP) and superior–inferior (SI) directions. The maximum deformation magnitudes range was: 10.0 ± 0.9 mm–28.0 ± 2.8 mm and average deformation magnitudes range: 2.3 ± 0.6 mm–7.5 ± 1.0 mm. Average non-rigid deformation magnitude was correlated with BMI (correlation coefficient 0.84, p = 0.01).Rigid pelvic deformations were most significant in the LR direction but could be accounted for with on-line adjustments. Non-rigid deformations can be significant and will need to be accounted for in order to facilitate the delivery of gantry-free therapy with an automated patient rotation system.

Impact of Insertion Technique and Iliac Artery Anatomy on Fenestrated Endovascular Aneurysm Repair

Purpose: To develop a mechanically realistic aortoiliac model to evaluate anatomic variables associated with stent-graft rotation and to assess common deployment techniques that may contribute to rotation. Materials and Methods: Idealized aortoiliac geometries were constructed either through direct 3-dimensional (3D) printing (rigid) or through casting with polyvinyl alcohol using 3D-printed molds (flexible). Flexible model bending rigidity was controlled by altering wall thickness. Three flexible patient-specific models were also created based on the preoperative computed tomography angiograms. Zenith infrarenal and fenestrated devices were used in this study. The models were pressurized to 100 mm Hg with normal saline. Deployments were performed under fluoroscopy at 37°C. Rotation was calculated by tracking the change in position of gold markers affixed to the devices. Results: In the rigid idealized models, stent-graft rotation increased with increasing torsion; torsion levels of 1.6, 2.6, and 3.6 mm−1 had mean rotations of 5.2°±0.03°, 11.2°±4.8°, and 27.6°±13.0°, respectively (p<0.001). In the flexible models, the highest rotation (58°±3.0°) was observed in models with high torsion and high rigidity (7.5 mm−1 net torsion and 254 N·m2 flexural rigidity). No rotation was observed in the absence of torsion. Applying torque to the device during insertion significantly increased stent-graft rotation by an average of 28° across all levels of torsion (p<0.01). Multiple device insertions prior to deployment did not change the observed device rotation. The patient-specific models accurately predicted the degree of rotation seen intraoperatively to within 5°. Conclusion: Insertion technique plays an important role in the degree of stent-graft rotation during deployment. Our model suggests that in vivo correction of device orientation can increase the observed rotation and supports the concept of fully removing the device, adjusting the orientation, and subsequently reinserting. Additionally, increasing iliac artery torsion in the presence of increased vessel rigidity results in stent-graft rotation.

Co-localized augmented human and X-ray observers in collaborative surgical ecosystem.

Image-guided percutaneous interventions are safer alternatives to conventional orthopedic and trauma surgeries. To advance surgical tools in complex bony structures during these procedures with confidence, a large number of images is acquired. While image-guidance is the de facto standard to guarantee acceptable outcome, when these images are presented on monitors far from the surgical site the information content cannot be associated easily with the 3D patient anatomy. In this article, we propose a collaborative augmented reality (AR) surgical ecosystem to jointly co-localize the C-arm X-ray and surgeon viewer. The technical contributions of this work include (1) joint calibration of a visual tracker on a C-arm scanner and its X-ray source via a hand-eye calibration strategy, and (2) inside-out co-localization of human and X-ray observers in shared tracking and augmentation environments using vision-based simultaneous localization and mapping. We present a thorough evaluation of the hand-eye calibration procedure. Results suggest convergence when using 50 pose pairs or more. The mean translation and rotation errors at convergence are 5.7mm and [Formula: see text], respectively. Further, user-in-the-loop studies were conducted to estimate the end-to-end target augmentation error. The mean distance between landmarks in real and virtual environment was 10.8mm. The proposed AR solution provides a shared augmented experience between the human and X-ray viewer. The collaborative surgical AR system has the potential to simplify hand-eye coordination for surgeons or intuitively inform C-arm technologists for prospective X-ray view-point planning.

Posterior C1-2 Temporary Fixation without Fusion for Recent Odontoid Fractures

ABSTRACT BACKGROUND: Posterior C1-2 fusion techniques are the commonly used treatment for odontoid fracture. But this is usually associated with limitation in the cervical spine range of motion especially the rotational motion. Posterior C1-2 temporary-fixation technique can spare the range of motion (ROM) of the atlantoaxial joint after odontoid fracture healing. OBJECTIVE: To assess the clinical and radiological outcome of the posterior C1-2 temporary fixation technique in the treatment of a new odontoid fracture. STUDY DESIGN: It is a retrospective study with clinical and radiological evaluation before and after instrumentation removal. PATIENTS AND METHODS: 12 consecutive patients, suffering from Type II odontoid fracture. The age ranged between 15-43 years old with a mean age was 24±11.6 years old, eight were male and four females. All cases were post traumatic. Eight patients were dislocated and four cases were in place. Only two patients were suffering from partial neurologic deficit pre-operative. The second surgery was done after a mean 15.5 weeks from the first surgery. RESULTS: The radiological outcome showed partial restoration of the rotation after removal of instrumentations with a mean total rotation restoration of 30±8°, using multi slice thin cuts CT scan. Significantly better functional outcomes were observed after the temporary-fixation removal using visual analog scale score (VAS) for neck pain (P=0.0033), neck stiffness and the patient satisfaction. CONCLUSION: Posterior atlanto-axial temporary fixation is a good salvage approach in dealing with odontoid fracture, especially when anterior odontoid screw is contraindicated. By regaining partial ROM, the functional outcome of the patients improved.