Rotation Of Segment Research Articles

Visual Cues Promote Head First Strategies During Walking Turns in Individuals With Parkinson's Disease.

Anticipatory eye movement promotes cranio-caudal sequencing during walking turns. Clinical groups, such as Parkinson's disease (PD), do not produce anticipatory eye movements, leading to increased risk of falls. Visual cues may promote anticipatory eye movement by guiding the eyes into the turn. This study examined if visual cues could train anticipatory eye movement. Ten neurotypical young adults and 6 adults with PD completed three blocks of walking trials. Trials were blocked by visual condition: non-cued baseline turns (5 trials), visually cued turns (10 trials), and non-cued post turns (5 trials). A Delsys Trigno (Delsys, Boston, MA) recorded horizontal saccades at 1024 Hz via electrooculography (EOG). Two Optotrak cameras (Northern Digital Inc., ON, Canada) captured body segment kinematics at 120 Hz. Initiation of segment rotation with respect to ipsilateral foot contact (IFC1) prior to the turn was calculated. Neurotypical young adults (NYA) produced typical cranio-caudal rotation sequences during walking turns. Eyes led (407 ms prior to IFC1), followed by the head (50 ms prior to IFC1), then trunk and pelvis. In contrast, PD produced no anticipatory eye or segment movement at baseline. During pre-trials the eyes moved 96 ms after IFC1 and segment movement was initiated by the pelvis followed by trunk and head segments. After visual cue training however, PD produced anticipatory eye movements 161 ms prior to IFC1, followed by the head 88 ms following IFC1 but ahead of trunk and pelvis onset. These results suggest visual cues assist in producing cranio-caudal control during walking turns in PD.

Contribution of the arm segment rotations towards the horizontal ball and racket head velocities during forehand long shot and drop shot services in table tennis

ABSTRACT Service is assumed important in table tennis because an effective service may allow the serving player to control over the game; hence, the aim of this study was to determine the contribution of arm segment rotations towards ball impact during forehand service. Sixteen shake-hand grip collegiate table tennis athletes had participated in the study. It was revealed that by increasing the radial deviation angular velocity will increase the ball and racket velocities during drop shot service. Furthermore, it was revealed that increasing the wrist palmar flexion and radial deviation will enhance the racket velocity at impact during long shot service. However, it was recommended to the players not to concern on racket speed and arm segment rotations during contact phase as it could not accelerate the ball at impact during long shot service. Although it was the same forehand service, different length of flight ball lead to different contributions of arm segment rotations towards ball impact. The present findings highlight several better postures to increase racket and ball speed at impact during forehand long shot and drop shot services among advanced and intermediate players. Other ranked players may find this study useful as a fundamental understanding on kinematics serving arm.

A new 3D analysis on displacement of proximal segment after bilateral sagittal split osteotomy for class III asymmetry.

We aimed to quantify the displacement of the proximal segment after bilateral sagittal split osteotomy in patients with class III asymmetry and evaluate if the displacement was related to the movement of the distal segment. Forty adults with class III asymmetry corrected by bimaxillary surgery were studied. Cone-beam computed tomography taken before and 1week after surgery was used to measure the displacement of proximal segments and movement of the distal segment in terms of translation and rotation. The relationship between the displacemnt of the proximal segment and the movement of the distal segment was evaluated. After surgery, the deviated proximal segment was displaced forward and to the deviated side, rotated downward, tilted, and turned to the opposite side. The opposite proximal segment was displaced forward and rotated downward. The roll rotation of the proximal segment was correlated with the left/right movement and roll rotation of the distal segment. Early after orthognathic correction for class III asymmetry, the deviated proximal segment was displaced in a direction favorable for correction of asymmetry. The roll rotation of the proximal segment was affected by the transverse movement and roll rotation of the distal segment. Knowledge of the ability and limitation of the proximal segment rotation improves the virtual simulation.

Two-dimensional speckle tracking echocardiography in goats: repeatability, variability, and validation of the technique using an exercise test and an experimentally induced acute ischemic cardiomyopathy

BackgroundTwo-dimensional speckle tracking (2DST) technique has been validated in numerous animal species, but neither studies of repeatability nor measurements after exercise or in animals with cardiac disease have been reported in goats. Goats are an attractive candidate for animal models in human cardiology because they are easy to handle and have a body and heart size comparable to that of humans. Therefore, the aim of this study was to validate this technique in goats for further clinical and experimental applications in this species.ResultsThis study was divided into several steps. First, a standardized echocardiographic protocol was performed and 5 cineloops of a right parasternal short-axis view at papillary muscles level were recorded three times at one-day intervals in ten healthy adult unsedated Saanen goats to test repeatability and variability of 2DST measurements. Then, the same measurements were performed immediately before and after a standardized exercise on treadmill in seven of the goats, and at 24 h after induction of an experimental ischemic cardiomyopathy in five of the goats, to test the reliability of the technique to assess physiological and pathological changes. Average and regional measurements of radial and circumferential strain and strain rate, radial displacement, rotation and rotation rate were obtained. Comparisons were performed using two-way ANOVA (p < 0.05). Caprine 2DST average measurements have demonstrated a good repeatability with a low to moderate variability for all measurements except for the diastolic peaks of the circumferential strain rate, radial strain rate and rotation rate. Segmental 2DST measurements were less repeatable than average measurements. Time effect of two-way ANOVA was significant for anteroseptal segment diastolic peaks measurements, rotation and rotation rate measurements. Overall variability of segmental measurements was moderate or high. Segmental and average peak values obtained after exercise and after myocardial ischemia were significantly different than curves obtained at baseline.ConclusionsThe results of this study are consistent with those previously described in other animal species and humans. 2DST echocardiography is a valid technique to evaluate physiological and pathological changes in myocardial function in goats, despite the technical limitations observed in this species.

Patient-specific implant modification for alloplastic bridging of mandibular segmental defects in head and neck surgery

Displacement of the remaining mandibular segments may occur after alloplastic bridging of mandibular segmental defects using patient-specific reconstruction plates. Consequently, additional surgical devices are required for correct plate positioning. Patient-specific reconstruction plates with a conventional one beam-like design (cPSRP) have been modified by adding two flanges and giving a Y-shape to the distal ascending implant part to allow for segment positioning without using additional devices. We aimed to evaluate reconstruction results after using these modified patient-specific reconstruction plates (mPSRP). We compared the reconstruction results for mPSRP and cPSRP and evaluated mandibular segment dislocations after reconstruction using digital image analysis of the pre- and postoperative radiological data sets. Analysis showed better reconstruction results with mPSRP than with cPSRP; mean dislocation values concerning shifts and rotations of mandibular segments were lower for mPSRP (x-axis: 2.9 mm vs 1.1 mm, 4.2° vs 3.6°; y-axis: 6.0 mm vs 2.0 mm, 3.5° vs 2.8°; z-axis: 3.9 mm vs 3.3 mm, 4.2° vs 1.2°). Significant differences were found for shifts along the y-axis (p = 0.039) and rotations around the z-axis (p = 0.041). Therefore, implant design modifications with additional positioning elements could help simplify surgical reconstruction procedures and improve reconstruction in head and neck surgery.

Lower Limb Kinematics Using Inertial Sensors during Locomotion: Accuracy and Reproducibility of Joint Angle Calculations with Different Sensor-to-Segment Calibrations.

Inertial measurement unit (IMU) records of human movement can be converted into joint angles using a sensor-to-segment calibration, also called functional calibration. This study aims to compare the accuracy and reproducibility of four functional calibration procedures for the 3D tracking of the lower limb joint angles of young healthy individuals in gait. Three methods based on segment rotations and one on segment accelerations were used to compare IMU records with an optical system for their accuracy and reproducibility. The squat functional calibration movement, offering a low range of motion of the shank, provided the least accurate measurements. A comparable accuracy was obtained in other methods with a root mean square error below 3.6° and an absolute difference in amplitude below 3.4°. The reproducibility was excellent in the sagittal plane (intra-class correlation coefficient (ICC) > 0.91, standard error of measurement (SEM) < 1.1°), good to excellent in the transverse plane (ICC > 0.87, SEM < 1.1°), and good in the frontal plane (ICC > 0.63, SEM < 1.2°). The better accuracy for proximal joints in calibration movements using segment rotations was traded to distal joints in calibration movements using segment accelerations. These results encourage further applications of IMU systems in unconstrained rehabilitative contexts.

Biomechanical evaluation of adjacent segment degeneration after one- or two-level anterior cervical discectomy and fusion versus cervical disc arthroplasty: A finite element analysis

Background and objectiveTo compare the biomechanical changes of adjacent segment degeneration (ASD) after one- or two-level anterior cervical discectomy and fusion (ACDF) versus cervical disc arthroplasty (CDA). MethodsA three-dimensional finite element (FE) model of intact C2-C7 segments was constructed and validated. In the one-level surgery model, the cage with plate implant or Prestige LP cervical disc prosthesis were integrated at C5-C6 segment into the FE model; while in the two-level surgery model, the prostheses were integrated at both C4-C5 and C5-C6 segments into the FE model. A pure moment of 1.0 Nm combined with a follower load of 73.6 N were imposed on C2 to investigate the flexion-extension, lateral bending, and axial rotation of different segments in the FE model. The segmental range of motion (ROM) and intradiscal pressure of the surgery models were investigated and compared with the intact model. ResultsIn the one-level model of ACDF, the ROM at C5-C6 was decreased, the ROM and intradiscal pressure at C4-C5 and C6-C7 segments were increased. In the two-level model of ACDF, the ROM at C4-C5 and C5-C6 were decreased, the ROM and intradiscal pressure at C3-C4 and C6-C7 were increased. However, in both one- and two-level models of CDA, the ROM of surgery segments were preserved, avoiding the increase of the ROM and intradiscal pressure at the adjacent segments. ConclusionsAbnormal ROM and intradiscal pressure at the adjacent segments may contribute to the higher risk of ASD after ACDF compared with CDA.

Patient-Specific Mandibular Reconstruction Plates Increase Accuracy and Long-Term Stability in Immediate Alloplastic Reconstruction of Segmental Mandibular Defects

ObjectivesThe aim of the current study was to evaluate potential differences in the accuracy of mandibular reconstruction and long-term stability, with respect to different reconstructive procedures.MethodsIn total, 42 patients who had undergone primary segmental mandibular resection with immediate alloplastic reconstruction, with either manually pre-bent or patient-specific mandibular reconstruction plates (PSMRP), were included in this study. Mandibular dimensions, in terms of six clinically relevant distances (capitulum [most lateral points], capitulum [most medial points], incisura [most caudal points], mandibular foramina, coronoid process [most cranial points], dorsal tip of the mandible closest to the gonion point) determined from tomographic images, were compared prior to, and after surgery.ResultsDimensional alterations were significantly more often found when conventionally bent titanium reconstruction plates were used. These occurred in the area of the coronoid process (p = 0.014). Plate fractures were significantly (p = 0.022) more often found within the manually pre-bent group than within the PSMRP group (17%/0%).ConclusionThe results suggest that the use of PSMRP may prevent rotation of the proximal mandibular segment, thus avoiding functional impairment. In addition, the use of PSMRP may potentially enhance the long-term stability of alloplastic reconstructions.

Monitoring System for Circular Deformation in Metro Shield Tunnels in Soft Soils

For in‐service metro shield tunnels in soft soils, large circular deformations are a major concern because they usually lead to various problems, such as water leakage, joint openings, and concrete cracks. However, the monitoring of circular deformation depends mainly on manual surveying, and the automatic monitoring methods developed in recent years generally have low economic applicability and are not widely implemented. In this study, an automatic and cost‐effective system was presented to monitor circular deformation in shield tunnels by using only inclinometers. Experiments were conducted to prove the assumption that each segment can be regarded as a rigid body and to investigate the position of the joint rotation center. Then, a method for monitoring circular deformation based on the rigid body and plane section assumptions was proposed. The joint opening angle, maximum joint opening width, horizontal diameter convergence, and bolt strain were calculated from rotation angles of segments which can be monitored directly by inclinometer. A case study was conducted for a section of a metro shield tunnel with an ongoing pit excavation nearby. The rotation of segments was measured using MEMS inclinometers, and the data were transmitted using ZigBee and general packet radio service (GPRS) wireless communication technology. Results show that the proposed system could be implemented to improve transportation safety in relevant situations and similar conditions.

Posterior techniques for correcting deformity in adolescent idiopathic scoliosis––How much correction is optimal?

The optimal surgical treatment of adolescent idiopathic scoliosis is heavily debated in the literature. This study aimed to review posterior surgical techniques in the treatment of adolescent idiopathic scoliosis. Literature review was performed. In treating adolescent idiopathic scoliosis with posterior spine fusion, there are many factors to consider when determining where to start and end the fusion construct: skeletal maturity, stress/bending radiographs, and assessment of vertebral rotation and translation. When considering selective thoracic fusion, the relative magnitudes of the main thoracic (MT) and thoracolumbar/lumbar (TL/L) curves and the overall sagittal profile of the thoracolumbar junction are assessed. Selective thoracic fusion can be appropriate if two of the three are found to be true: the MT-to-TL/L Cobb angle ratio is >1.2, the MT-to-TL/L apical vertebral translation (AVT) ratio is >1.2, and/or the MT-to-TL/L apical vertebral rotation (AVR) ratio is >1.2. Moreover, selective thoracic fusion can be an option in the presence of a nonstructural lumbar curve (bending Cobb angle <25°) with thoracolumbar (T10-L2) kyphosis <20°. When choosing the uppermost and lowest instrumented vertebra, one must consider standing coronal balance and regional kyphosis to lessen risk of postoperative complication. The uppermost instrumented vertebra should be a stable, neutral vertebra with <5° of junctional kyphosis; and the lowest instrument vertebra should be touched by the central sacral vertical line and within two vertebrae proximal to the neutral vertebra. To aid in correction, the addition of posterior surgical releases improves the mobility of spine, especially in more rigid curves, but may increase intraoperative blood loss and operative time. Rod derotation and vertebral translation appear to have similar results in correcting coronal and sagittal deformities. The addition of direct vertebral rotation and segmental rotation plays a role in surgical correction as well.

Reactive Postural Responses to Continuous Yaw Perturbations in Healthy Humans: The Effect of Aging.

Maintaining balance stability while turning in a quasi-static stance and/or in dynamic motion requires proper recovery mechanisms to manage sudden center-of-mass displacement. Furthermore, falls during turning are among the main concerns of community-dwelling elderly population. This study investigates the effect of aging on reactive postural responses to continuous yaw perturbations on a cohort of 10 young adults (mean age 28 ± 3 years old) and 10 older adults (mean age 61 ± 4 years old). Subjects underwent external continuous yaw perturbations provided by the RotoBit1D platform. Different conditions of visual feedback (eyes opened and eyes closed) and perturbation intensity, i.e., sinusoidal rotations on the horizontal plane at different frequencies (0.2 Hz and 0.3 Hz), were applied. Kinematics of axial body segments was gathered using three inertial measurement units. In order to measure reactive postural responses, we measured body-absolute and joint absolute rotations, center-of-mass displacement, body sway, and inter-joint coordination. Older adults showed significant reduction in horizontal rotations of body segments and joints, as well as in center-of-mass displacement. Furthermore, older adults manifested a greater variability in reactive postural responses than younger adults. The abnormal reactive postural responses observed in older adults might contribute to the well-known age-related difficulty in dealing with balance control during turning.

Early Progressive Maxillary Changes with Nasoalveolar Molding: Randomized Controlled Clinical Trial.

Quantitative assessment of 3-dimensional progressive changes of the maxillary geometry in unilateral cleft lip palate (UCLP) with and without nasoalveolar molding (NAM). The study was designed as a prospective 2-arm randomized controlled clinical trial conducted in parallel. Forty infants with nonsyndromic UCLP were randomly assigned into a NAM-treated group (n = 20) and non-NAM treated group (n = 20). A total of 120 laser-scanned maxillary casts were collected and blindly analyzed via a modified algorithm at T0 (initial visit; baseline), T1 (after 3 wk; first interval), and T2 (after 6 wk; second interval). The main outcome measures were the amount and rate of cleft gap changes, the midline position, and the transverse, sagittal, and vertical growth through intervals. More than 50% of the cleft gap (56.42%; P < 0.001) was reduced in the first 3 wk of alveolar molding (AM). The end point of the AM was obtained in 6 wk (86.25%; P < 0.001); then, the kinks of the greater segment were noticed. The AM effect decreased as far as posterior; the anterior arch width reduced slightly (1.23%; P < 0.001), while the middle and posterior arches increased slightly (P > 0.999 and P = 0.288, respectively). The posterior arch width was the least changing and was considered a baseline, while the anterior was the pivot of the segment rotation. Both groups showed different patterns of segment rotation and sagittal growth. The non-NAM treated group showed a slight increase in cleft gap length, arch width, and midline position. Based on this study, it was concluded that the NAM treatment is effective in minimizing cleft severity and realigning maxillary segments without the deterioration of the transverse and vertical arch growth. Near follow-up visits are recommended to monitor the rapid gap reduction within the first 3 wk. Further trials are recommended to compare the outcomes regarding the sagittal growth to reference values (ClinicalTrials.gov NCT03029195). The results of this study will help clinicians understand nasoalveolar molding biomechanics that may improve the treatment outcomes for patients with unilateral cleft lip and palate. The trial data can be a valuable guide to the qualitative and quantitative predictive virtual molding in computer aided design-simulated nasoalveolar molding therapy. The modified algorithm can be used by researchers to quantify the rate, the sequence, and the direction of the maxillary segments movement in unilateral cleft lip and palate.

Surface and mantle records reveal an ancient slab tear beneath Gondwana

Vertical slab-tearing has been widely reported in modern convergent settings profoundly influencing subduction and mantle dynamics. However, evaluating a similar impact in ancient convergent settings, where oceanic plates have been subducted and the geological record is limited, remains challenging. In this study, we correlate the lower mantle structure, which retained the past subduction configuration, with the upper-plate geological record to show a deep slab rupture interpreted as a large-scale tearing event in the early Mesozoic beneath southwestern Gondwana. For this purpose, we integrated geochronological and geological datasets with P-wave global seismic tomography and plate-kinematic reconstructions. The development of a Late Triassic-Early Jurassic slab-tearing episode supports (i) a slab gap at lower mantle depths, (ii) a contrasting spatiotemporal magmatic evolution, (iii) a lull in arc activity, and (iv) intraplate extension and magmatism in the Neuquén and Colorado basins. This finding not only has implications for identifying past examples of a fundamental process that shapes subduction zones, but also illustrates an additional mechanism to trigger slab-tearing in which plate rupture is caused by opposite rotation of slab segments.

Contribution of lower body segment rotations in various height soccer volley kicking

ABSTRACT We aimed to quantify the contribution of lower body segment rotations in producing foot velocity during the soccer volley kick. Fifteen male experienced university players kicked a soccer ball placed at four height conditions (0, 25, 50 and 75 cm). Their kicking motion was captured at 500 Hz. The effectiveness of lower body segment rotations in producing forward (Ffv) and upward (Fuv) foot velocity were computed and time integrated. Major contributors for Ffv were a) left hip linear velocity, b) knee extension and c) pelvis retroflexion (the pitch rotation). The contribution of a) become smaller as the ball height increased while those of b) and c) did not change significantly. Moreover, the pelvis clockwise rotation (the yaw rotation) showed apparent contribution only for volley kicking (except 0 cm height). Major contributors for Fuv were 1) knee flexion, 2) hip internal rotation, 3) pelvis clockwise rotation (the roll rotation) and 4) hip flexion. The contributions of 1) and 4) become consistently smaller as the ball height increased, while those of 2) and 3) become larger systematically. Soccer volley kicking was found to have unique adaptations of segmental contributions to achieve higher foot position while maintain foot forward velocity.

Paleomagnetism of the Carboniferous Gresford Block, Tamworth Belt, southern New England Orogen: minor counter-clockwise rotation of a primary arc segment

Four oroclinal structures have been identified from structural, magnetic and gravity trends across a Carboniferous continental arc, forearc basin [Tamworth Belt (TB)] and conjugate accretionary complex in the southern New England Orogen (SNEO) of eastern Australia. None of the structures has yet been confirmed conclusively by paleomagnetism as oroclinal. Ignimbrites are common within the forearc basin and have been demonstrated to retain primary magnetisations despite prevalent overprinting. They are well exposed across six major tectono-stratigraphic blocks with partly interlinked stratigraphies, making the forearc basin highly prospective to oroclinal testing by comparing pole path segments for individual blocks across curved structures. Paleomagnetic studies have shown no noticeable rotation across the western/southwestern TB (Rocky Creek, Werrie and Rouchel blocks), but documented herein is a minor counter-clockwise rotation of the Gresford Block of the southern TB. This study details paleomagnetic, rock magnetic and magnetic fabric results for 87 sites (969 samples) across the southern Gresford Block. Predominantly thermal, also alternating field and liquid nitrogen, demagnetisations show a widely present low-temperature overprint, attributed to regional late Oligocene weathering, and high-temperature primary and overprint components residing in both mainly magnetite and mainly hematite carriers. Subtle, but systematic, directional differences between magnetite and hematite subcomponents show the latter as the better cleaned, better-defined, preferred results, detailing nine primary poles of middle and late Carboniferous ages and Permian and Permo-Triassic overprints as observed elsewhere in the western/southwestern TB. The primary poles update a poorly defined mid-Carboniferous section of the SNEO pole path and demonstrate counter-clockwise rotation, quantified at about 15° ± 13° from comparison of mid-Carboniferous Martins Creek Ignimbrite Member poles for the Rouchel and Gresford blocks, that may not necessarily have been completed prior to the Hunter–Bowen phase of the Gondwanide Orogeny. This minor counter-clockwise rotation of the Gresford Block accentuates a primary curvature of the southwestern/southern TB and heralds further, more complex, rotations of the Myall Block of the southeastern TB.

Does the amount of mandibular setback during bimaxillary surgery correlate with the degree of surgical relapse?

The aim of this study was to investigate postoperative horizontal relapse of the mandible in terms of the effects of the magnitude of mandibular setback movement and ramus inclination after LeFort I osteotomy and sagittal split ramus osteotomy. A retrospective study of patients who underwent orthognathic surgery for mandibular prognathism was performed. Postoperative relapse at point B was analyzed with regard to the magnitude of mandibular setback and the ramus inclination. Serial cephalograms were used to measure surgical changes and evaluate postoperative relapse. Nineteen men and 31 women (mean age 23.1 years) were retrospectively enrolled. Mean surgical backward movement of the mandible at point B was 8.2 mm, mean ramus inclination was 3.56 degrees, and mean relapse 1 year postoperatively was 0.95 mm (11.6%). Horizontal relapse of the mandible was significantly correlated with the magnitude of mandibular setback (r=-0.52; P=.007) and ramus inclination (r=0.48; P=.014). Increased horizontal mandibular relapse after bimaxillary surgery was associated with greater mandibular setback movement and increased proximal segment clockwise rotation. Mandibular relapse after bimaxillary surgery may be minimized via adequate control of intraoperative clockwise rotation of the proximal segment.

Comparison of Postoperative Stability Between BSSRO and Le Fort 1 Osteotomy with BSSRO in Skeletal Class III Malocclusion with Severe Open Bite.

We aimed to investigate postoperative stability after orthognathic surgery in patients with skeletal class III malocclusion with severe open bite by comparison between bilateral sagittal splitting osteotomy (BSSRO) and BSSRO with Le Fort 1 osteotomy. Seventeen patients with skeletal class III malocclusion with severe open bite who were needed more than 6 degree counterclockwise rotation of distal segment by only BSSRO in preoperative cephalometric prediction. The subjects were divided into group A, where 9 patients were treated by BSSRO, and group B, where 8 patients were treated by BSSRO with Le Fort 1 osteotomy. Patient's characteristics of age, gender, preoperative over jet (OJ) and over bite (OB) were not found to be significantly different between the two groups. Counterclockwise rotation of distal segment in preoperative cephalometric prediction by only BSSRO was not found to be significantly different between group A of 7.6 (6-10.6) degree and group B of 9 (6-13) degree. The amount of rotation was reduced to 5.4 (3-10) degree by bimaxillary surgery using BSSRO and Le Fort 1 osteotomy in group B. OJ and OB were measured as occlusal stability factor. Distance between ANS-to-PNS plane and the edge of upper incisor (NF-U1Ed), and distance between Menton and edge of lower incisor (Me-L1Ed) were measured as skeletal stability factor using cephalometric analysis. These lengths were measured at pre-surgery (T0), 2weeks after surgery (T1) and 1year after surgery (T2), and these differences between the two groups were statistically analyzed. OJ and OB kept a good relation at any experimental periods. The change of Me-L1Ed was significantly larger in group A (1.21mm at T0-T1, 1.02mm at T0-T2) than in group B (0.14mm at T0-T1, 0.16mm at T0-T2). The change of NF-U1Ed was not significantly different between group A (1.07mm at T0-T1, 0.57mm at T0-T2) and group B (0.51mm at T0-T1, - 0.05mm at T0-T2). In case with more than 6 degree counterclockwise rotation of distal segment, skeletal stability was better after bimaxillary surgery than only BSSRO; however, OJ and OB kept a good relation.

Field-in-field breast planning for a jawless, double-stack MLC LINAC using flattening-filter-free beams.

BackgroundThis study intends to develop an efficient field‐in‐field (FiF) planning technique with the Eclipse treatment planning system (TPS) to determine the feasibility of using the Halcyon treatment delivery system for 3D treatment of breast cancer.MethodsTen treatment plans were prepared on the Halcyon treatment planning system and compared to the same patients’ clinically delivered TrueBeam plans which used flattened 6 MV and 10 MV beams. Patients selected for this study were treated via simple, tangential breast irradiation and did not receive radiotherapy of the supraclavicular or internal mammary lymph nodes. Planning target volumes (PTV) volumes ranged from 519 cc to 1211 cc with a mean target volume of 877 cc. Several planning techniques involving collimator, gantry rotation, and number of FiF segments were investigated as well as the use of the dynamically flattened beam (DFB) — a predefined MLC pattern that is designed to provide a flattened beam profile at 10 cm depth on a standard water phantom. For comparison, the clinically delivered TrueBeam plans remained unaltered except for normalization of the target coverage to more readily compare the two treatment delivery techniques.ResultsUsing the physician defined PTV, normalized such that 98% of the volume was covered by 95% of the prescribed dose, the Halcyon plans were deemed clinically acceptable and comparable to the TrueBeam plans by the radiation oncologist. Resulting average global maximum doses in the test patients were identical between the TrueBeam and Halcyon plans (108% of Rx) and a mean PTV dose of 102.5% vs 101.6%, respectively.ConclusionsFrom this study a practical and efficient planning method for delivering 3D conformal breast radiotherapy using the Halcyon linear accelerator has been developed. When normalized to the clinically desired coverage, hot spots were maintained to acceptable levels and overall plan quality was comparable to plans delivered on conventional C‐arm LINACs.

The outcome of skeletofacial reconstruction with mandibular rotation for management of asymmetric skeletal class III deformity: A three-dimensional computer-assisted investigation

The mandibular proximal ramus segments should be moved and rotated during orthognathic surgery-based skeletofacial reconstruction for the correction of challenging patients with facial asymmetry and malocclusion, but quantitative data regarding this rotation were not sufficient to date. This 3D computer-assisted study measured the proximal ramus segment rotation after 3D simulation-guided two-jaw surgery in patients with facial asymmetric deformity and class III malocclusion (n = 31). Using 3D mandible models and a reliable proximal ramus segment-related plane, angular changes in pitch, roll and yaw directions were measured before and one month after surgery. Significant rotational changes (p < 0.01) were observed in the left and right sides and overall proximal ramus segments after surgery, with absolute differences of 4.1 ± 3.0 (range −7.8 to 6.9), 2.8 ± 2.3 (−8.8 to 5.0), and 2.7 ± 2.4 (−6.6 to 9.9) degrees in pitch, roll, and yaw rotations, respectively. Numbness and mouth opening limiting occurred within the first 6 months after surgery but the patients had an unremarkable long-term postoperative course, with no revisionary surgery required. This study contributes to the multidisciplinary-related literature by revealing that proximal ramus segment rotation and rigid fixation with no postoperative intermaxillary immobilization was practicable in skeletofacial surgery for the successful treatment of asymmetric deformity and class III malocclusion.

Effects of the changes in the condylar long axis angle and condylar position on temporomandibular symptoms after intraoral vertical ramus osteotomy: a preliminary study

This study was conducted to characterize the effects of the changes in the condylar long axis and position on temporomandibular symptoms with respect proximal segment position after intraoral vertical ramus osteotomy (IVRO). Twenty Japanese patients with diagnosed jaw deformity underwent IVRO without internal fixation. Long-term changes in condylar long axis and position were assessed during postoperative follow-up examinations by using computed tomography, and t tests were performed for comparison. In addition, changes in temporomandibular symptoms were examined. The degree of axial rotation of the proximal segment changed significantly when the proximal segment was located laterally. Downward changes in condylar position significantly differed when the proximal segment was located posterolaterally. Forward changes in condylar position significantly differed when the proximal segment was located laterally; moreover, when the proximal segment was located laterally, temporomandibular symptoms disappeared. Lateral location of the proximal segment may be an important factor in the positive effects of IVRO, with respect to temporomandibular symptoms.