Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Rotation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82Linked to original sources
PubMed1999

Contribution of ankle, knee, and hip joints to the perception threshold for support surface rotation.

The purpose of the present experiment was to investigate the extent to which subjects can perceive, at very slow velocities, an angular rotation of the support surface about the medio-lateral axis of the ankle, knee, hip, or neck joint when visual cues are not available. Subjects were passively displaced on a slowly rotating platform at .01, .03, and .05 deg/sec. The subjects' task was to detect movements of the platform in four different postural conditions allowing body oscillations about the ankle, knee, hip, or neck joint. In Experiment 1, subjects had to detect backward and forward rotation (pitching). In Experiment 2, they had to detect left and right rotations of the platform (rolling). In Experiment 3, subjects had to detect both backward/forward and left/right rotations of the platform, with the body fixed and the head either fixed or free to move. Overall, when the body was free to oscillate about the ankle, knee, or hip joints, a similar threshold for movement perception was observed. This threshold was lower for rolling than for pitching. Interestingly, in these postural conditions, an unconscious compensation in the direction opposite to the platform rotation was observed on most trials. The threshold for movement perception was much higher when the head was the only segment free to oscillate about the neck joint. These results suggest that, in static conditions, the otoliths are poor detectors of the direction of gravity forces. They also suggest that accurate perception of body orientation is improved when proprioceptive information can be dynamically integrated.

Adult↗
PubMed1994

Perceived motion in structure from motion: pointing responses to the axis of rotation.

We investigated the ability to match finger orientation to the direction of the axis of rotation in structure-from-motion displays. Preliminary experiments verified that subjects could accurately use the index finger to report direction. The remainder of the experiments studied the perception of the axis of rotation from full rotations of a group of discrete points, the profiles of a rotating ellipsoid, and two views of a group of discrete points. Subjects' responses were analyzed by decomposing the pointing responses into their slant and tilt components. Overall, the results indicated that subjects were sensitive to both slant and tilt. However, when the axis of rotation was near the viewing direction, subjects had difficulty reporting tilt with profiles and two views and showed a large bias in their slant judgments with two views and full rotations. These results are not entirely consistent with theoretical predictions. The results, particularly for two views, suggest that additional constraints are used by humans in the recovery of structure from motion.

Attention↗
PubMed1993

Arthroscopic management of rotator cuff disease.

The etiology of rotator cuff disease is controversial, but is not always secondary to cuff impingement between the humeral head and the coracoacromial arch. Rotator cuff disease, and not impingement syndrome, more accurately describes this process. The spectrum of rotator cuff disease begins with rotator cuff inflammation (Stage I) and progresses to tendinitis (Stage II) and partial or full thickness tears (Stage III). Refractory Stage II and III disease without rotator cuff tears undergoes subacromial bursectomy and acromioplasty. Partial thickness tears are debrided with an acromioplasty, bursectomy, and removal of inferior clavicular osteophytes. Full thickness tears are treated arthroscopically or open, depending on the tear size and the patient expectations. In general, tears from 0 to 5 cm in active patients undergo subacromial decompression and a mini-open repair. Low demand patients with 0 to 5 cm tears or tears greater than 5 cm are treated with subacromial decompression and rotator cuff debridement.

Acromion↗
PubMed2004

[Influence of rotation speed of X-ray computed tomography on image quality].

The rotation speed of X-ray CT is known to influence the quality of images. We examined changes in imaging characteristics according to various physical characteristics. The physical characteristic of rotation speed (1.0, 0.8, 0.7, 0.6, 0.5 sec/rot) was evaluated at the FOV center (isocenter) and 90 mm outside the center (off-center). The items of evaluation included low contrast resolution, high contrast resolution, noise, definition, and artifacts. High contrast resolution and definition declined at a rotation speed of 0.6 sec/rot or less at off-center. An increase in shower artifact and change in the shape of the wire section were found at a rotation speed of 0.6 sec/rot or less at off-center. It was determined that image quality was especially influenced in terms of definition characteristics when the speed of rotation was high. A decrease in the number of views can be considered the main cause; that is, the use of high-speed rotation degrades image quality. Therefore, it is important to consider proper usage as it corresponds with purpose.

Artifacts↗
PubMed2006

"Uncoverage" of the humeral head by the anterolateral acromion and its relationship to full-thickness rotator cuff tears.

The relationship between the humeral head and the anterolateral acromion was compared for subjects with and without full-thickness rotator cuff tears, as indicated by magnetic resonance imaging, using a case-control design. "Uncoverage" of the humeral head by the anterolateral acromion was defined as the percentage of the humeral head width not covered superiorly by the anterolateral acromion, as measured digitally on magnetic resonance imaging scans of the shoulder in the oblique coronal plane. The uncoverage of the humeral head by the anterolateral acromion was 32.0% for men > or = 40 years of age with normal rotator cuffs (n = 39) and 38.2% for men > or = 40 years of age with full-thickness rotator cuff tears (n = 43). The difference in uncoverage of 6.2% was statistically significant (p < 0.001). The uncoverage of the humeral head by the anterolateral acromion was 36.1% for women > or = 40 years of age with normal rotator cuffs (n = 10) and 41.8% for women > or = 40 years of age with full-thickness rotator cuff tears (n = 17). The difference in uncoverage of 5.72% was not statistically significant with the number of subjects available (p = 0.108). We concluded that increased uncoverage of the humeral head by the anterolateral acromion may be a factor in the pathogenesis of full-thickness rotator cuff tears.

Acromion↗
PubMed2004

Geometry corrections in a rotating 3-dimensional sonographic system.

OBJECTIVE: To devise a system for geometry corrections in a rotating 3-dimensional sonographic system. METHODS: A 3-dimensional sonographic imaging system based on a standard sonography machine was developed. The transducer mounted in a specially designed holder was rotated about its axis to acquire the spatial information. The most important postulate in rotating 3-dimensional systems is the assumption of parallelity between the rotation axis and the transducer axis. It allows the use of simple geometric relationships between 2-dimensional slices in a 3-dimensional reconstruction. The errors appearing in the 3-dimensional reconstruction when the axes are not parallel were investigated. RESULTS: A simple correction method based on phantom measurements is proposed. The phantom contains a plane, which is inclined to the rotation axis. The analysis of 2-dimensional plane images allows the geometric corrections. The construction of the phantom is described, and the formulas used in the calculations are presented. The method was tested in computer simulations and in patient investigations. CONCLUSIONS: A complete method of the geometric investigations and corrections useful in 3-dimensional sonographic systems based on rotational geometry is proposed. Both the computer simulations and the phantom measurements confirmed the usefulness, precision, and simplicity of the proposed method.

Algorithms↗
PubMed1976

Roentgenographic evaluation of vertebral rotation.

To examine the accuracy of vertebral rotation determinations made from roentgenographic pedicle-shadow offset measurements, roentgenograms were made of fifteen cadaver vertebrae with different sagittal and frontal inclinations and longitudinal axis rotations ranging from 15 degrees left to 45 degrees right. It was found that significant uncertainties arise when vertebral rotation is evaluated from measurements of pedicle-shadow offset: true and apparent offsets in a single vertebra differ markedly; vertebrae from different spines have different offsets for the same degree of rotation and the same inclinations; and changes in the sagittal and frontal inclinations of a single vertebra alter its offset in the same manner as changes in rotation. From these results, it seems unlikely that precise measurements of rotation changes in spines with mild or moderate scolioses, for example, can be made from anteroposterior roentgenograms.

Biomechanical Phenomena↗
PubMed1999

Chronic unilateral loss of otolith function revealed by the subjective visual vertical during off center yaw rotation.

Assessing the subjective visual vertical, SVV, in a static upright position is an easy clinical test in which a deviation of some 10 degrees from true vertical indicates an acute loss of unilateral (otolithic) vestibular function on the side to which the SVV is tilted. Because this deviation of the SVV is compensated during the following months, patients with chronic unilateral vestibular loss do no longer differ from normal subjects. This study presents an experimental set-up that allows for clear detection of compensated chronic loss of unilateral otolithic function by testing the SVV. 21 normals and 17 unilaterally vestibular deafferentiated (UVD) patients (vestibular neurectomies) were first rotated on a human centrifuge about an earth vertical yaw axis through the midsagittal plane of the head (240 degrees/s). This induced tilts of the gravito-inertial force (GIF) vectors, which differed at the two inner ears by 8 degrees. During constant velocity rotation, the subjects were moved in pseudo-randomized steps laterally up to 16 cm apart from the rotation axis, inducing roll tilts of the GIF vectors up to 16 degrees. Normal subjects set their SVV to pre-centrifugation values at positions with the midsagittal plane of their head close to the rotation axis, while chronic UVD patients indicated pre-centrifugation values during positions with the rotation axis 5.9 +/- 2.5 cm paramedian on the side of the intact ear. Tilts of the GIF vectors shifted the SVV with a gain of 0.70 in normals and only 0.32 in UVD patients. Roll gains for laterally directed GIF vectors relative to the intact inner ear did not differ from medially directed roll gains in the UVD patients. The roll gains observed in this experimental set-up were lower than those observed with static body tilts or during eccentric rotation with a larger radius, which might be at least partially due to conflicting stimulation between otolithic and extra-vestibular cues.

Adult↗
PubMed2000

The effect of habituation and plane of rotation on vestibular perceptual responses.

A technique was applied to assess vestibular sensation without reference to external spatial, position cues. The stimuli were stopping responses to velocity-steps of 90 deg/s in the dark. Subjects indicated their perceived angular velocity by turning a flywheel connected to a tachogenerator. Two separate experiments were conducted. In one, subjects were rotated in yaw about an earth-vertical axis before and after prolonged rotational or visual (optokinetic) stimuli. In the second experiment, subjects were rotated in roll supine, with either the head ('roll centred') or the feet ('roll eccentric') on the axis of rotation. The two aims of the paper were to (i) examine the effect of repetitive vestibular and optokinetic stimulation on the time constant of decay of vestibular sensation in yaw; (ii) to compare vestibular sensation responses to rotation in roll both with and without the addition of a Z-axis centrifugal force. The pre-habituation sensation response in yaw decayed exponentially with a median time constant of 12.8 s. The duration of the sensation responses were significantly reduced following both prolonged vestibular and optokinetic stimulation. The reduction in vestibular responses following prolonged visual and vestibular stimuli, 1) is likely to occur in velocity storage mechanisms mediating ocular and perceptual responses, 2) may represent a mechanism for reducing the disorientating consequences of visual-vestibular conflict and 3) supports the use of optokinetic stimuli as a treatment for vestibular patients. The time constant of the sensation responses in roll was shorter and not significantly influenced by head position: 5.7 s in the head-centred position compared to 4.7 s in the eccentric head position. Therefore, perceptual as well as ocular responses to rotation in roll are determined primarily by cupula dynamics and not influenced by velocity storage.

Adult↗
PubMed2001

Manual and virtual rotation of a three-dimensional object.

An orientation-matching task, based on a mental rotation paradigm, was used to investigate how participants manually rotated a Shepard-Metzler object in the real world and in an immersive virtual environment (VE). Participants performed manual rotation more quickly and efficiently than virtual rotation, but the general pattern of results was similar for both. The rate of rotation increased with the starting angle between the stimuli meaning that, in common with many motor tasks, an amplitude-based relationship such as P. M. Fitts' (1954) law is applicable. When rotation was inefficient (i.e., not by the shortest path), it was often because participants incorrectly perceived the orientation of one of the objects, and this happened more in the VE than in the real world. Thus, VEs allow objects to be manipulated naturally to a limited extent, indicating the need for timing-scale factors to be used for applications such as method-time-motion studies of manufacturing operations.

Adult↗
PubMed2002

Eccentric rotational acetabular osteotomy for acetabular dysplasia: follow-up of one hundred and thirty-two hips for five to ten years.

BACKGROUND: Eccentric rotational acetabular osteotomy for the operative treatment of acetabular dysplasia consists of a spherical but eccentric osteotomy and rotation of the acetabulum that moves the center of rotation of the head of the femur medially and distally. No bone graft is needed. The reorientation of the acetabular fragment not only improves acetabular coverage but also restores the center of rotation of the subluxated hip. The purpose of this paper was to describe eccentric rotational acetabular osteotomy for the treatment of acetabular dysplasia and to evaluate its clinical and radiographic outcomes. METHODS: We performed this procedure consecutively in 132 hips in 126 patients with dysplasia of the hip. Eighteen hips had no osteoarthritis, fifty-three had early osteoarthritis, and sixty-one had advanced osteoarthritis. Seven patients were male, and 119 were female. The average age was 36.5 years at the time of the index operation, and the average duration of follow-up was 7.5 years. Twenty-three hips in twenty-two patients were also treated with intertrochanteric valgus osteotomy to further improve joint congruency at the time of the acetabular osteotomy. RESULTS: The average preoperative Harris hip score of 71 points improved to an average score of 89 points at the time of the latest follow-up. The average center-edge angle improved from 0 to 36 . An apparent change in the stage of the arthritis was observed in seven hips (5%), one of which had had early-stage disease and six of which had had advanced disease preoperatively. CONCLUSIONS: Eccentric rotational acetabular osteotomy appears to be a good treatment option for young patients with either early or advanced hip osteoarthritis secondary to dysplasia.

Acetabulum↗
PubMed1975

[The vertical and rotatory components of ocular nystagmus induced by rotation in a horizontal plane].

During rotation of the rabbit around a vertical axis, movements of the eye were recorded on film. The rotation test involved positive angular accelaration (10 grade. sec(-2)), two-minute rotation with constant angular speed (166 grade. sec(-1)), and negative angular acceleration (10 grade. sec(-2)). Two variants of rotation were used: in one of them the rotation axis passed between labyrinths, in another - an excentricitet providing centrifugal force of 0.5 g was present. The successive processing of the film revealed simultaneous movements of the eye in three planes: horizontal, frontal, and sagittal. The movements in all the planes consisted of rhythmic (hystagmal proper) and tonic components. The movements in sagittal and frontal planes were comparable with those in horizontal planes. A tonic otolith reflex occurred additionally at the excentric rotation. The complex form of the nystagmus is regarded as a result of hydromechanical interaction between semicircular canals.

Animals↗
PubMed2003

The effects of various therapeutic measures on shoulder range of motion and cross-sectional areas of rotator cuff muscles after baseball pitching.

AIM: The purpose of this study was to investigate the effects of various therapeutic measures on the shoulder range of motion (ROM) and muscle cross-sectional area (mCSA) of rotator cuff muscles after baseball pitching. METHODS EXPERIMENTAL DESIGN: a mode of therapeutic measures was classified in 4 groups; the control (CON), ice treatment (IT), light shoulder exercise (LSE) and ice treatment with LSE (ILSE) groups. Each therapeutic measure was performed after pitching. PARTICIPANTS: 7 healthy, skilled baseball pitchers. MEASURES: ROM and mCSA were measured before pitching, immediately after pitching, at the time of the therapeutic measure, and 24 hours after pitching. Shoulder ROM at 90 inverted exclamation mark of abduction included internal rotation (IROM), maximum internal rotation (IMROM), external rotation (EROM) and maximum external rotation (EMROM). RESULTS: In all groups, both IROM and IMROM were significantly decreased after pitching compared with the pre-exercise values and conversely both EROM and EMROM were significantly increased. The mCSA of all rotator cuff muscles were increased significantly after pitching. For IMROM, ILSE showed a significant recovery at the post-therapeutic measure compared with the others and at 24 hours after pitching compared with IT, respectively. For IROM, both LSE and ILSE showed significant recovery compared with CON at the post-therapeutic measure. For the mCSA of external muscles, ILSE showed a greater decrease at the post-therapeutic measure than the others, and at 24 hours after pitching than CON. CONCLUSION: This study suggested the possibility that ILSE was more effective to recover ROM and decrease mCSA than the other methods.

Adult↗
PubMed2003

Adaptation to rotating artificial gravity environments.

A series of pioneering experiments on adaptation to rotating artificial gravity environments was conducted in the 1960s. The results of these experiments led to the general belief that humans with normal vestibular function would not be able to adapt to rotating environments with angular velocities above 3 or 4 rpm. By contrast, our recent work has shown that sensory-motor adaptation to 10 rpm can be achieved relatively easily and quickly if subjects make the same movement repeatedly. This repetition allows the nervous system to gauge how the Coriolis forces generated by movements in a rotating reference frame are deflecting movement paths and endpoints and to institute corrective adaptations. Independent mechanisms appear to underlie restoration of straight movement paths and of accurate movement endpoints. Control of head movements involves adaptation of vestibulo-collic and vestibulo-spinal mechanisms as well as adaptation to motor control of the head as an inertial mass. The vestibular adaptation has a long time constant and the motor adaptation a short one. Surprisingly, Coriolis forces generated by natural turning and reaching movements in our normal environment are typically larger than those elicited in rotating artificial gravity environments. They are not recognized as such because self-generated Coriolis forces during voluntary trunk rotation are perceptually transparent. After adaptation to a rotating environment is complete, the Coriolis forces generated by movements within it also become transparent and are not felt although they are still present.

Adaptation, Physiological↗
PubMed2004

[Reconstruction of shoulder abduction and external rotation in obstetric brachial plexus palsy].

OBJECTIVES: We evaluated the results of the subscapularis and pectoralis major muscle releases and the transfer of the latissimus dorsi/teres major muscles to the rotator cuff in patients with internal rotation contractures due to obstetric brachial plexus palsy. METHODS: Seventy patients (44 boys, 26 girls; mean age 7.6 years; range 2 to 16 years) underwent transfer of the latissimus dorsi/teres major muscles to the rotator cuff. Spinal root involvement was at C5-C6 in 19 patients, at C5-C7 in 16 patients, and at C5-T1 in 35 patients. In 46 patients, the subscapularis muscle was released from the anterior surface of the scapula, and in 55 patients, the pectoralis major muscle was released by fractional tenotomy. The glenohumeral joint was evaluated by anteroposterior direct graphies and axial magnetic resonance scans. According to the Waters-Peljovich grading system, all the patients had type I or type II deformities. Pre- and postoperative range of motion values and Mallet scores were compared. The mean follow-up period was 37.9 months (range 24 to 64 months). RESULTS: The mean shoulder abduction increased to 132.6 degrees (range 90 degrees to 170 degrees; mean gain 60.3 degrees) and external rotation increased to 81.1 degrees (range 30 degrees to 100 degrees; mean gain 58.7 degrees). The mean postoperative Mallet scores for global abduction and external rotation were 3.9; hand-to-head, to-mouth, and to-back scores were 3.7, 3.4, and 2.5, respectively. No serious complications were seen during the follow-up period. CONCLUSION: The results of reconstruction techniques employed in our study show satisfactory increases in shoulder abduction and external rotation in patients with a minimal glenohumeral deformity.

Adolescent↗
PubMed2002

Transverse plane pelvic rotation measurement.

AIM: To determine how pelvic rotation in the transverse plane relates to coronal plane anatomical landmark location. The problem this addresses is the observation that iliac crest medial lateral width as seen in the coronal plane Cobb is often asymmetrical in patients with idiopathic scoliosis before treatment, and sometimes after treatment. MATERIALS AND METHODS: A pelvis was marked with radiographically opaque markers at symmetrical sites in the ilium, sacrum and acetabulum; mounted in a jig; and radiographed at varying degrees of transverse and sagittal plane angulation. The medial lateral distance from two similar landmarks on opposite sides of the pelvis was then determined and a left/right ratio correlated with the degrees of transverse plane angulation. In addition, a theoretically derived equation was developed to describe the effect of pelvic shape on the degree of transverse plane rotation. RESULTS: The left/right ratio for the distance from the sacro iliac joint to the anterior superior iliac spine proved to be the most reliable for determining the degree of pelvic rotation in the transverse plane. The relationship is nearly linear up to 25 rotation and is little influenced by the degree of sagittal plane angulation. Based on theoretical considerations, the importance of the anterior to posterior angular relationship of the two coronal plane landmarks measured influences the degree of rotation but not the linear relationship. CONCLUSION: Within limits the transverse plane rotation of the pelvis can be determined by a left/right ratio of the distances between two similar landmarks on each side of the pelvis.

Acetabulum↗
PubMed1992

(-)-stepholidine: a dopamine receptor antagonist shows agonistic effect on rotational behavior in 6-hydroxydopamine-lesioned rats.

(-)-Stepholidine ((-)-SPD), a well demonstrated dopamine (DA) receptor antagonist in normal rats, could markedly induce contralateral rotational behavior in 6-hydroxydopamine (6-OHDA)-lesioned rats. This peculiar behavioral action of (-)-SPD, proposed to be an agonistic action on DA receptors, was further studied in this paper. The rotational behavior challenged by (-)-SPD (4 mg.kg-1, ip) or SKF-38393 (selective D1 agonist) had a gradually progressive process with a long latent period and a plateau response after 56-67 postlesion days. On the contrary, the action of apomorphine (APO) or D2 selective agonist N-0347, had a short latent period and a plateau response after d 21 of postlesion. In the latent period of rotation, (-)-SPD (4 mg.kg-1) was primed by pretreatment of APO (0.2 mg.kg-1, ip). In the period of steady contralateral rotation, a dose-dependent action of (-)-SPD was found in a range of 0.5-8 mg.kg-1 and a linear correlation (r = 0.77, P less than 0.01) between the rotation induced by (-)-SPD (4 mg.kg-1) and by APO (0.2 mg.kg-1) was also shown. These results suggest that the agonistic effect of (-)-SPD on rotation behavior in 6-OHDA-lesioned rats resembles that of D1 agonist SKF-38393. Taken together, the dual actions of (-)-SPD, antagonistic on normosensitive DA receptors and agonistic on supersensitive DA receptors, were proposed.

Animals↗
PubMed2006

Rotation velocity change and motion sickness in an optokinetic drum.

BACKGROUND: Stationary subjects who view the interior of an optokinetic drum often experience motion sickness (MS) symptoms, perhaps because visual and vestibular sensory inputs are in conflict. It was predicted that intermittently changing drum rotation velocity would cause an increase in sensory conflict, and subsequently lead to more MS. Visual input indicating frequent changes in self-motion would not be consistent with vestibular input indicating no self-motion. When drum rotation is steady, visual and vestibular inputs are more likely to agree given that the vestibular organs only respond to change. METHODS: There were 12 individuals who participated in the experiment (7 men, 5 women, mean age = 24.0 yr). In two conditions subjects viewed the interior of an optokinetic drum that steadily rotated at either 5 RPM or 10 RPM. In a third condition drum velocity alternated every 30 s between 5 RPM and 10 RPM (5/10 RPM condition). In all conditions the subject's head was immobilized in the center of the drum that rotated on an Earth-vertical axis. Subjects completed the Simulator Sickness Questionnaire (SSQ) designed by Kennedy and colleagues both before a trial and after 4 min of drum viewing. A total SSQ score and three SSQ sub-scores (nausea, oculomotor, and disorientation) were obtained. RESULTS: Mean post-treatment total SSQ scores (mean = 41) were significantly the highest in the 5/10 RPM condition followed by the conditions of steady rotation velocity at 10 RPM (mean = 36) and 5 RPM (mean = 24). Likewise, mean nausea sub-scores were also the highest (mean = 24) in the 5/10 RPM condition followed by the 10 RPM condition (mean = 19) and the 5 RPM condition (mean = 11). CONCLUSIONS: These results support the hypothesis that a conflict between sensed and expected effects of self-motion alone can lead to MS. Changing rotation velocity increases sensory conflict that in turn leads to more MS.

Adult↗