Mean Inclination Research Articles

Inclination shallowing in Eocene Linzizong sedimentary rocks from Southern Tibet: correction, possible causes and implications for reconstructing the India–Asia collision

A systematic bias towards low palaeomagnetic inclination recorded in clastic sediments, that is, inclination shallowing, has been recognized and studied for decades. Identification, understanding and correction of this inclination shallowing are critical for palaeogeographic reconstructions, particularly those used in climatemodels and to date collisional events in convergent orogenic systems, such as those surrounding the Neotethys. Here we report palaeomagnetic inclinations from the sedimentary Eocene upper Linzizong Group of Southern Tibet that are ∼20◦ lower than conformable underlying volcanic units. At face value, the palaeomagnetic results from these sedimentary rocks suggest the southern margin of Asia was located ∼10◦N, which is inconsistent with recent reviews of the palaeolatitude of Southern Tibet. We apply two different correction methods to estimate the magnitude of inclination shallowing independently from the volcanics. The mean inclination is corrected from 20.5◦ to 40.0◦ within 95 per cent confidence limits between 33.1◦ and 49.5◦ by the elongation/inclination (E/I) correction method; an anisotropy-based inclination correction method steepens the mean inclination to 41.3 ± 3.3◦ after a curve fitting- determined particle anisotropy of 1.39 is applied. These corrected inclinations are statistically indistinguishable from the well-determined 40.3 ± 4.5o mean inclination of the underlying volcanic rocks that provides an independent check on the validity of these correction methods. Our results show that inclination shallowing in sedimentary rocks can be corrected. Careful inspection of stratigraphic variations of rock magnetic properties and remanence anisotropy suggests shallowing was caused mainly by a combination of syn- and post-depositional processes such as particle imbrication and sedimentary compaction that vary in importance throughout the section. Palaeolatitudes calculated from palaeomagnetic directions from Eocene sedimentary rocks of the upper Linzizong Group that have corrected for inclination shallowing are consistent with palaeolatitude history of the Lhasa terrane, and suggest that the India-Asia collision began at ∼20◦N by 45-55 Ma

Acetabular Component Positioning in Total Hip Arthroplasty With and Without a Computer-Assisted System: A Prospective, Randomized and Controlled Study

In a study of the acetabular component in total hip arthroplasty, 20 hips were operated on using imageless navigation and 20 hips were operated on using the conventional method. The correct position of the acetabular component was evaluated with computed tomography, measuring the operative anteversion and the operative inclination and determining the cases inside Lewinnek's safe zone. The results were similar in all the analyses: a mean anteversion of 17.4° in the navigated group and 14.5° in the control group (P=.215); a mean inclination of 41.7° and 42.2° (P=.633); a mean deviation from the desired anteversion (15°) of 5.5° and 6.6° (P=.429); a mean deviation from the desired inclination of 3° and 3.2° (P=.783); and location inside the safe zone of 90% and 80% (P=.661). The acetabular component position's tomography analyses were similar whether using the imageless navigation or performing it conventionally.

Measurements of the atmospheric turbulence in the coastal zone of the sea during weak wind from a mountainous coast

Results of measurements of the atmospheric turbulence in the layer between 1.5 and 21 m above sea level and the drag coefficient of the sea surface as the wind blows from a 4-km-long mountainous slope with a mean inclination of 11° are presented. The measurements of wind-speed profiles and its fluctuations at several levels, waves, and the main meteorological parameters were carried out in autumn 2005 and 2008 from a stationary platform located in the Black Sea at a distance of approximately 1 km from the southern coast of Crimea. It is shown that during weak synoptic wind a low-level wind jet develops at night over the sea with a maximum velocity up to 5–6 m/s at a level of approximately 6 m over the sea induced by the katabatic wind over the coastal slope. According to the approximate estimates, the horizontal scale of the low-level jet can reach a few tens of kilometers. This flow is characterized by the dissipation rate of the turbulence energy independent of height and low-frequency velocity fluctuations related to the gravity waves and advection of turbulence from the coast. It is shown that the lower part of the boundary layer (up to a height of 3 m) is adjusted to the sea-surface roughness. The dependencies of the drag coefficient on the wind speed or wave age are steadier than in the data for the open sea. However, the age of the waves is not a universal parameter at long and short fetches.

The use of a dual-mobility concept in total hip arthroplasty patients with spastic disorders

Total hip arthroplasty (THA) is one of the treatment options in patients with cerebral palsy (CP) with painful osteoarthritis of the hip. However, the risk of dislocation of the prosthesis is higher in patients with CP when compared with physically normal patients. In this retrospective study of ten consecutive cases, we hypothesized that the use of a dual-mobility cup could reduce this risk of dislocation combined with good functional results. From January 2008 until October 2010, eight patients (ten hips) with CP who consecutively received a THA using a dual-mobility cup were identified. At the time of surgery, the average age of the patient group was 54 years (range 43-61). Latest follow-up took place after on average 39 months (range 22-56 months). All patients or their caregivers were interviewed by telephone. They were asked if dislocation of the prosthesis had occurred. To evaluate quality of life and health in general, patients completed the SF-36 questionnaire. None of the prostheses had dislocated at the latest follow-up. Reoperation was needed in one patient after a periprosthetic fracture. Radiologic evaluation showed a mean cup inclination of 46 (range 27-58). On average, the quality of life of patients in this study was found to be limited in particular on the domains of physical health and functioning, while a fair to good score was measured at the six other different domains. The use of a dual-mobility cup in THA in patients with CP can lead to favourable results with respect to dislocation and clinical outcome.

Paleomagnetism of Bhander Sediments from Bhopal Inlier, Vindhyan Supergroup

Abstract: Paleomagnetic investigations have been carried out on poorly determined radiometric age controls of Bhander sandstones within the vicinity of Bhopal Inlier of the Upper Vindhyan Supergroup. Available ages assigned to the Upper Vindhyan sequence range from Cambrian to the Mesoproterozoic and are derived from a variety of sources and methods. Paleomagnetic data generated from the Bhander Group of Bhopal Inlier yielded a mean declination of 357° and mean inclination of 58° (k=17.69, α95 = 16.38) with a Virtual Geomagnetic Pole (VGP) at 74° N, 69.0° E. This pole position is falling close to the Malani Igneous Suite (MIS) mean palaeomagnetic pole of 67.8° N and 72.5° E (A95=8.8°) by Gregory et al. (2009). The results obtained from this study and previous work on the 1073 Ma Majhgawan kimberlite, as well as detrital zircon geochronology of the Upper Bhander sandstone suggest that the Upper Vindhyan sequence may be older than is commonly thought earlier.

Paleomagnetism of ca. 2.3 Ga mafic dyke swarms in the northeastern Southern Granulite Terrain, India: Constraints on the position and extent of Dharwar craton in the Paleoproterozoic

The pole positions reported for the mafic dykes occurring in the northeastern Southern Granulite Terrain and easterly trending dykes of Dharwar craton are alike while their ages differ by ca. 700Ma confounding tectonic reconstruction. To resolve the discordance and to constrain the position of the Indian continent in the Proterozoic, paleomagnetic and geochronological studies have been carried out on the mafic dyke swam in the northeastern Southern Granulite Terrain. Two distinct pole positions are obtained, one from the group of Tiruvannamalai dykes as 27.7°S, 231.5°E (dp, dm=12°, 14°) with corresponding mean declination (Dm) and inclination (Im) as 125° and −73.8° (κ, α95=22, 7.6°) respectively, and second from the East Coast Dykes as 2.32°S, 188.2°E (dp, dm=5°, 8°) with corresponding mean Dm and Im as 88.9° and −33.8° (κ, α95=48, 7.1°) respectively. The Remanent Efficiency of Magnetization values between 0.01 and 0.08 suggest that the dykes have been cooled through Curie temperature of magnetite which is the carrier of magnetization. The baked contact test confirms that the Characteristic Remanent Magnetization is the primary magnetization. The Sm–Nd mineral-whole-rock isochron, from one of the Tiruvannamalai dykes, yielded an age of 2318±60Ma (MSWD=1.9). This age is the time of intrusion of the Tiruvannamalai dykes and is similar, within errors, to the age of dykes in the Dharwar craton. Thus, the contiguity of Dharwar craton with the Northern Block of Southern Granulite Terrain, as early as 2.3Ga ago, is established. The pole position thus obtained corresponds to a high-latitudinal position of Dharwar craton during early Paleoproterozoic.

Combined archaeomagnetic and thermoluminescence study of a brick kiln excavated at Fontanetto Po (Vercelli, Northern Italy)

A combined archaeomagnetic and thermoluminescence study was carried out as part of a rescue archaeological excavation on a kiln discovered during the installation of methane gas pipelines beneath a rice field, along the southern border of Fontanetto Po village (Vercelli province, Italy). A total of 23 independent brick samples have been collected, oriented in situ with an inclinometer; the use of magnetic and sun compass was not possible due to the existence of metallic tubes beneath the kiln and a plastic cover above it. Standard archaeomagnetic procedures have been used for the determination of the archaeomagnetic inclination and absolute geomagnetic intensity. Stepwise thermal demagnetization shows a very stable characteristic remanent magnetization and the calculated mean inclination of the 23 samples is I = 65.3° with α95 = 2.4° and k = 156. Archaeointensity experiments have been performed using the classical Thellier method as modified by Coe, with regular partial thermoremanent magnetization (pTRM) checks. The cooling rate and remanence anisotropy effects upon thermoremanent magnetization (TRM) have been investigated in all the specimens. A total of 19 archaeointensity determinations (at specimen level) that correspond to linear NRM–TRM plots were used for the calculation of the site mean archaeointensity that is 46.4 ± 2.9 μT. Archaeomagnetic dating results show two possible dating intervals for the last 1000 years, calculated at 95% confidence interval: a first one from 1511 to 1614 AD, and a second one from 1768 to 1872 AD. Thermoluminescence (TL) study has been also performed on two brick samples from the kiln's internal wall, using conventional laboratory procedures. According to the thermoluminescence results the kiln's last usage lies between 1796 and 1914 AD. This age is in good agreement with the second dating interval obtained by the archaeomagnetic analysis. The combined archaeomagnetic and thermoluminescence results suggest that the last firing of the kiln could have occurred between the end of the 18th century and the beginning of 20th century.

New palaeomagnetic and rock magnetic results on Mesoproterozoic kimberlites from the Eastern Dharwar craton, southern India: Towards constraining India's position in Rodinia

New palaeomagnetic and rock magnetic results are reported for 1.1Ga Mesoproterozoic kimberlites from the distinct fields of Wajrakarur (WKF), Narayanpet (NKF) and Raichur (RKF) occurring within the Eastern Dharwar craton, southern India. In all, 35 oriented block samples were collected from ten kimberlite pipes and our results constitute first of their kind for the kimberlites from NKF and RKF. Palaeomagnetic data reveal that characteristic remanent magnetization (ChRM) directions of the studied kimberlites show a mean declination of 39 and mean inclination of −16 (N=4, k=37.6 and α95=15.2) and yield a virtual geomagnetic pole at 44.5°N, 195.4°E (dp=8.0, dm=15.6). This new pole position is identical to the earlier reported palaeomagnetic pole that lies at 36.8°N, 212.5°E for some Wajrakarur kimberlites and other such global results at 1100Ma from Umkondo dolerites, Kalahari craton, southern Africa. The newly obtained palaeomagnetic pole also correlates well with the virtual geomagnetic pole (VGP) generated from the 1.1Ga Majhgawan kimberlite, Mahoba dyke and the Bhander–Rewa sedimentary Group in the Upper Vindhyan sequence within the Bundelkhand craton of Northern India. Our results support a Mesoproterozoic closure age of the upper sedimentary horizons for the ‘Purana’ sedimentary basins and provide evidence for accretion of the northern and southern Indian cratonic blocks prior to 1.1Ga. Our study also demonstrates that in ∼1.1Ga palaeomagnetically based Rodinia reconstructions, India occupies a lower palaeolatitudinal position, was much separated from Australia and that East Gondwana very likely did not form an assembly until the terminal Neoproterozoic.

Vascular plant species richness along environmental gradients in a cool temperate to sub-alpine mountainous zone in central Japan

In order to clarify how vegetation types change along the environmental gradients in a cool temperate to sub-alpine mountainous zone and the determinant factors that define plant species richness, we established 360 plots (each 4 × 10 m) within which the vegetation type, species richness, elevation, topographic position index (TPI), slope inclination, and ground light index (GLI) of the natural vegetation were surveyed. Mean elevation, TPI, slope inclination, and GLI differed across vegetation types. Tree species richness was negatively correlated with elevation, whereas fern and herb species richness were positively correlated. Tree species richness was greater in the upper slope area than the lower slope area, whereas fern and herb species richness were greater in the lower slope area. Ferns and trees species richness were smaller in the open canopy, whereas herb species richness was greater in the open canopy. Vegetation types were determined firstly by elevation and secondary by topographic configurations, such as topographic position, and slope inclination. Elevation and topography were the most important factors affecting plant richness, but the most influential variables differed among plant life-form groups. Moreover, the species richness responses to these environmental gradients greatly differed among ferns, herbs, and trees.

Arthroscopic bone block augmentation of the anterior glenoid through the rotator interval: a cadaveric feasibility study

Arthroscopic augmentation of the anterior glenoid using a free bone graft through the rotator interval is possible without compromising the fixation and position of the graft In 7 cadavers arthroscopic augmentation of the anterior glenoid was performed. A preshaped, free graft was introduced and fixated with 1 central screw without desinsertion or split of the subscapularis tendon. Postoperatively, the orientation and position of the screw and position of the graft in the vertical and horizontal plane were analyzed on computer tomography (CT) scan. Macroscopic dissection was performed to assess damage to the conjoined and subscapularis tendon and surrounding neurovascular structures and to verify the position of the graft. Postoperative CT scans showed no intra-articular perforation of the screw. The mean inclination angle in the axial plane was 21,2° (range, 9-48°). Postoperative dissection showed no damage to surrounding neurovascular structures. Fraying occurred at the lateral border of the conjoined tendon in 3 specimens, at the upper border of the subscapularis in 5 cases, but no tears were noted. In the vertical plane, the augmentation block was correctly (subequatorial) positioned in 5 cases; 2 blocks were at the level of the equator. In the horizontal plane, the augmentation block was flush with the articular surface in 5 cases and too medial in 2 cases (<5 mm). This study showed that it is technically possible to perform a bone block procedure arthroscopically through the rotator interval without compromising the position and fixation of the graft and fixation screw.

Interacting planetary nebulae

We discuss the classification and orientation of planetary nebulae that interact with the interstellar medium throughout the Milky Way. A sample of 117 confirmed interacting planetary nebulae is used for this purpose. Our results indicate that the majority of interacting objects are located close to the Galactic plane, and ∼77% of them are located inside the Galactic thin disk. One third of the sample is less than 100 parsec from the Galactic plane and thus may interact with molecular and cold neutral clouds. There is a tendency for the planetary nebula interaction region to be parallel to the Galactic plane. We found that ∼73% of interacting planetary nebulae have inclination angles (defined as the angles that join the planetary nebula centroid and the interaction area or bow shock with the Galactic plane) larger than 45 ◦ and ∼38% larger than 70 ◦ , which highlights the possible effect of interstellar magnetic fields. While it is sometime believed that the interaction preferentially occurs in old planetary nebulae, our analysis indicates that the majority of observed planetary nebulae are in the mid stage of their evolution. The mean inclination angle, Galactic height, linear size, and dynamical age are estimated for each stage of interaction. The results indicate strong correlations between the mean inclination angle and the above parameters.

Palaeomagnetic results from the Chiapanecan Volcanic Arc, Chiapas, Southern Mexico: geomagnetic and geodynamic significance

This article presents the first palaeomagnetic results from 13 independent cooling units in the Chiapanecan Volcanic Arc (ChVA). Six sites were directly dated by Ar–Ar or K–Ar methods: their dates range from 2.14 to 0.23 Ma. We isolated the characteristic palaeodirections for all 13 lavas. Eleven non-transitional directions yield a mean direction with inclination, I = 30.7°, declination, D = 4.1°, and precision parameters k = 63 and α95 = 5.8°. The corresponding mean palaeopole position is Plat = 83.3°, Plong = 203.8°, K = 227, A 95 = 5.1°. The mean inclination is in good agreement with the expected value for the last 5 million years, as derived from the synthetic North American polar wander path [Besse and Courtillot 2002, Apparent and true polar wander and the geometry of the magnetic field in the last 200 million years: Journal of Geophysical Research, v. 107, no. B11, p. 2300], but a measured rotation of the palaeodeclination of about 8° with respect to the expected direction suggests the possibility of a clockwise rotation of the studied ChVA units. We have estimated the characteristics of palaeosecular variation through study of the scatter of virtual geomagnetic poles, obtaining a palaeosecular variation parameter S b = 14.5° with upper limit S U = 19.6° and lower limit S L = 11.7°, in reasonable agreement with the fit of model G [McFadden et al., 1988, Dipole/quadrupole family modeling of paleosecular variation: Journal of Geophysical Research, v. 93, no. B10, p. 11583–11588; 1991, Reversals of the Earth's magnetic field and temporal variations of the dynamo families: Journal of Geophysical Research, v. 96, no. B3, p. 3923–3933] to the Johnson et al. [2008, Recent investigations of the 0–5 Ma geomagnetic field recorded by lava flows: Geochemistry, Geophysics, Geosystems, v. 9, no. 4, ID Q04032, doi:10.1029/2007GC001696] databases for the last 5 million years. In those cases in which age determinations are available, the polarity obtained for the studied flows is consistent with their stratigraphic positions, except for the Huitepec site, which probably reflects the transitional geomagnetic regime prior to the Matuyama–Brunhes geomagnetic reversal.

Evaluation of a visual feedback system in gait retraining: A pilot study

Abnormal gait pattern of the frontal plane (i.e. Duchenne gait and Trendelenburg gait) may be caused by a variety of diseases. The aim of this pilot study was to evaluate the instantaneous effect of a visual feedback system on frontal plane pelvis and trunk movements in order to use it in patients with THR in subsequent studies. A total of 24 women (45–65 years) were included in the study. According to acute functional impairments the subjects were assigned to the control group (CG, no gait disorders, n=15, age=59±11 years, BMI=27±4) or to the intervention group (IG, n=9, age=61±4, BMI=29±5), respectively. First, in Measurement 1 (M1) kinematic reference values were captured in a standardized clinical gait analysis (MVN, XSens). Afterwards, the influence of a visual real-time feedback on gait pattern was examined while using the feedback system (M2). While there was a significant difference of IG vs. CG in M1 in the mean inclination regarding pelvis and trunk movements, this was not detected in M2. Therefore it is concluded, especially in subjects with abnormal gait pattern, that the visualization leads to an improvement of the movement pattern of pelvis and trunk in the frontal plane while using the device.

THE STATISTICS OF MULTI-PLANET SYSTEMS

We describe statistical methods for measuring the exoplanet multiplicity function - the fraction of host stars containing a given number of planets - from transit and radial-velocity surveys. The analysis is based on the approximation of separability - that the distribution of planetary parameters in an n-planet system is the product of identical 1-planet distributions. We review the evidence that separability is a valid approximation for exoplanets. We show how to relate the observable multiplicity function in surveys with similar host-star populations but different sensitivities. We also show how to correct for geometrical selection effects to derive the multiplicity function from transit surveys if the distribution of relative inclinations is known. Applying these tools to the Kepler transit survey and radial-velocity surveys, we find that (i) the Kepler data alone do not constrain the mean inclination of multi-planet systems; even spherical distributions are allowed by the data but only if a small fraction of host stars contain large planet populations (> 30); (ii) comparing the Kepler and radial-velocity surveys shows that the mean inclination of multi-planet systems lies in the range 0-5 degrees; (iii) the multiplicity function of the Kepler planets is not well-determined by the present data.

PLANETESIMAL AND PROTOPLANET DYNAMICS IN A TURBULENT PROTOPLANETARY DISK: IDEAL STRATIFIED DISKS

Due to the gravitational influence of density fluctuations driven by magneto-rotational instability in the gas disk, planetesimals and protoplanets undergo diffusive radial migration as well as changes in other orbital properties. The magnitude of the effect on particle orbits can have important consequences for planet formation scenarios. We use the local-shearing-box approximation to simulate an ideal, isothermal, magnetized gas disk with vertical density stratification and simultaneously evolve numerous massless particles moving under the gravitational field of the gas and the host star. We measure the evolution of the particle orbital properties, including mean radius, eccentricity, inclination, and velocity dispersion, and its dependence on the disk properties and the particle initial conditions. Although the results converge with resolution for fixed box dimensions, we find the response of the particles to the gravity of the turbulent gas correlates with the horizontal box size, up to 16 disk scale heights. This correlation indicates that caution should be exercised when interpreting local-shearing-box models involving gravitational physics of magneto-rotational turbulence. Based on heuristic arguments, nevertheless, the criterion L_h / R ~ O(1), where L_h is the horizontal box size and R is the distance to the host star, is proposed to possibly circumvent this conundrum. If this criterion holds, we can still conclude that magneto-rotational turbulence seems likely to be ineffective at driving either diffusive migration or collisional erosion under most circumstances.

Insertion of Buccally Tilted and Placed Implants in Edentulous Atrophic Posterior Mandibular Sites

ABSTRACTThis paper presents our new methodology and evaluates the feasibility of buccally tilted and placed implant combined with standard abutment placement in patients with insufficient bone height through implant software programme. Forty patients with 62 mandibular sites were measured in computed tomography (CT) imaging. The Buccally tilted and placed implants combined with standard abutment simulation were administered in implant software programme. The different parameters were measured in CT. The localization of inferior alveolar nerve and implant, inclination degree of implant, transversal and vertical thickness of local distances etc. were evaluated in order to eliminate the nerve injury with providing interocclusal relationship. The buccal distance at the mandibular canal level was higher than the lingual distance in posterior mandible at lower first molar region. The mean inclination degree of the implant fixtures were 17.85 ± 8.01. The mean measurement of the acquired length of implant during implant placement simulation was 11.06 ± 1.73. The mean distance of the vertical gain was 3.81 ± 1.84. The hypothesis of buccally positioned and tilted implant placement instead of advanced surgical procedures would be preferable in atrophic posterior mandibula.

The effect of component position on clinical outcomes in resurfacing hip arthroplasty

The aim of this study was to evaluate the relationship between component position and clinical results in resurfacing hip arthroplasty. Resurfacing hip arthroplasty was performed on 41 hips of 38 patients (22 male, 16 female; mean age: 53.7 years; mean follow-up time: 20.1 ± 5.8 months). The femoral and acetabular component orientation angles in the coronal plane were evaluated on anteroposterior radiographs. Harris and Oxford hip scores were used in the clinical evaluation. The mean angle between the collum and diaphysis was 139.5 ± 8.8 degrees. In 22 hips, the femoral component angle between collum and diaphysis was less than 5 degrees valgus position when compared with the same anatomical femur angle. In the other 19 hips, the femoral component angle was greater than 5 degrees valgus position. The mean inclination angle of the acetabular component was 46.1 ± 7 degrees. In 22 hips, the mean inclination angle of the acetabular components was 45 degrees or less. There was no significant difference in the clinical outcomes between patients with femoral component angles of greater than 5 degrees valgus position and those with angles of less than 5 degrees valgus position (p>0.05). There was also no significant difference between the clinical results of patients with an acetabular inclination of 45 degrees or less and those with an acetabular inclination exceeding 45 degrees (p>0.05). The orientation of femoral and acetabular components in the coronal plane does not appear to have an effect on clinical outcomes in resurfacing hip arthroplasty.

A comparison of a less invasive piriformis-sparing approach versus the standard posterior approach to the hip

We undertook a randomised controlled trial to compare the piriformis-sparing approach with the standard posterior approach used for total hip replacement (THR). We recruited 100patients awaiting THR and randomly allocated them to either the piriformis-sparing approach or the standard posterior approach. Pre- and post-operative care programmes and rehabilitation regimes were identical for both groups. Observers were blinded to the allocation throughout; patients were blinded until the two-week assessment. Follow-up was at six weeks, three months, one year and two years. In all 11 patients died or were lost to follow-up. There was no significant difference between groups for any of the functional outcomes. However, for patients in the piriformis-sparing group there was a trend towards a better six-minute walk test at two weeks and greater patient satisfaction at six weeks. The acetabular components were less anteverted (p = 0.005) and had a lower mean inclination angle (p=0.02) in the piriformis-sparing group. However, in both groups the mean component positions were within Lewinnek's safe zone. Surgeons perceived the piriformis-sparing approach to be significantly more difficult than the standard approach (p = 0.03), particularly in obese patients. In conclusion, performing THR through a shorter incision involving sparing piriformis is more difficult and only provides short-term benefits compared with the standard posterior approach.

Preoperative incisor inclination in patients with Class III dentofacial deformities treated with orthognathic surgery

Our aim was to evaluate cephalometrically the preoperative inclination of the incisors in a group of 50 patients with Class III dentofacial deformities whose immediate preoperative lateral cephalometric radiographs were analysed after they had been treated by maxillary advancement. The radiographs were hand-traced by the same operator who made the cephalometric analysis. Mean values for each measurement were compared with the normal values using Student's t-test (p<0.05). Results showed significantly increased inclination of the upper incisors, with a mean U1-NA angle of 27.58° and a mean U1-PP angle of 116°. The lower incisors were also inclined lingually, with a mean L1-NB angle of 22.53° and a mean IMPA of 83.13°. Thirty-five of the patients had labial inclination of the upper, and 28 lingual inclination of the lower, incisors. Mean inclinations of upper and lower incisors differed from the normal values, and the inclination of the lower incisors was more likely to be decompensated than that of the upper incisors.

Effect of Pelvic Obliquity on the Orientation of the Acetabular Component in Total Hip Arthroplasty

In infrapelvic obliquity, coronal pelvic malrotation entails a change in the spatial location of the bony acetabulum. In the present study, 77 patients presented with infrapelvic obliquity with types 1 and 2 hip pathologies in which the pelvis is lower and higher, respectively, on the short-leg side. The 2 types were classified into 3 subtypes (A, B, and C) according to the severity of the pelvic obliquity (0°-3°, 3°-6°, and >6°). Angles of inclination of pelvic obliquity postoperatively, anteversions, and inclinations (abduction angle) for acetabular components were measured after total hip arthroplasty. Increased inclination (mean, 8.79°) was observed in type 1C, where the angle of inclination to pelvic obliquity postoperatively was minimally corrected. This increase may lead to cup instability. Rebalancing the pelvis in these cases with preoperative skeletal traction and/or sufficient release of hip contractures may be necessary. A correction of the mean inclination of the cup by 8.79° is required.