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At least 37 records · Page 2Linked to original sources
PubMed1994

Changes in the moment arms of the rotator cuff and deltoid muscles with abduction and rotation.

The behavior of the moment arms of the rotator cuff and deltoid muscles was studied during simple and combine movements of abduction and rotation about the glenohumeral joint. This was done by experimental measurement of excursions of the muscles in an in vitro cadaver model and by use of a multiple-regression analysis to delineate the changes in the moment arms as a function of abduction and rotation. The results demonstrated the potential of some rotator cuff muscles to contribute to both abduction and rotation, the sensitivity of the abductor moment-arm lengths to internal and external rotation and of the rotator moment-arm lengths to the degree of abduction, and the capacity of the abductor moment-arm lengths of the deltoid to increase with increasing abduction. Characterization of this behavior resulted in an increased understanding of the complex role of the rotator cuff and deltoid muscles about the gleno-humeral joint and provided quantitative descriptions of functional relationships. This study demonstrates the capacity of the infraspinatus and subscapularis muscles to contribute not only to external and internal rotation, respectively, but also to elevation of the arm in the plane of the scapula, a role for which these muscles have been given little or no consideration. Furthermore, it demonstrates that the contribution of the infraspinatus to abduction is enhanced with internal rotation while that of the subscapularis is enhanced with external rotation. Thus, dysfunction of the supraspinatus muscle need not preclude good elevation of the arm, and rehabilitation to reprogram and strengthen the remaining muscles becomes an important consideration.

Aged↗
PubMed2006

Descriptive report of shoulder range of motion and rotational strength 6 and 12 weeks following rotator cuff repair using a mini-open deltoid splitting technique.

STUDY DESIGN: Retrospective chart review. OBJECTIVES: To measure short-term postsurgery glenohumeral internal rotation and external rotation strength, shoulder range of motion (ROM), and subjective self-report ratings following mini-open rotator cuff repair of full-thickness rotator cuff tears. BACKGROUND: Physical therapists provide rehabilitation for patients following mini-open rotator cuff repair. Long-term outcome studies have reported a high percentage of good and excellent results following surgery; however, little has been published regarding the immediate short-term results of this procedure, during which the patient is under the direct care of the physical therapist. MATERIALS AND METHODS: Charts from 11 female and 26 male patients, with a mean +/- SD age of 57.3 +/- 9.9 years, were reviewed following rotator cuff repair, using an arthroscopically assisted mini-open deltoid-splitting approach. All patients underwent postsurgery rehabilitation by the same therapist using a standard protocol. Retrospective chart review was used to obtain descriptive profiles of shoulder joint ROM at 6 and 12 weeks postsurgery and isokinetically assessed shoulder strength at 12 weeks postsurgery. RESULTS: For the postsurgical shoulder, ROM deficits ranging between 5 degrees to 7 degrees were measured for shoulder abduction and external rotation and internal rotation at 90 degrees of abduction. The postsurgical extremity had greater flexion ROM (9 degrees ) compared to the contralateral side. Isokinetic external rotation strength deficits of 5% to 7% were present at 12 weeks postsurgery, with 2% to 11% greater internal rotation shoulder strength on the operative extremity, when compared to the other side. Patients completed the self-report section of the modified American Shoulder Elbow Surgeons (ASES) Rating Scale at 12 weeks postsurgery and scored a mean of 38.7/45.0 points. CONCLUSION: The application of early ROM and progressive strengthening following mini-open rotator cuff repair allows for the successful return of ROM and strength 12 weeks postsurgery. The results of this study provide objective data for both shoulder ROM and strength at time points during which patients are traditionally receiving physical therapy following surgery.

Aged↗
PubMed1992

Translational head movements of pigeons in response to a rotating pattern: characteristics and tool to analyse mechanisms underlying detection of rotational and translational optical flow.

Pigeons freely standing in the centre of a two-dimensionally textured cylinder not only rotate but also laterally translate their head in response to the pattern sinusoidally oscillating or unidirectionally rotating around their vertical axis. The translational head movement dominates the response at high oscillation frequencies, whereas in a unidirectionally rotating drum head translation declines at about the same rate as the rotational response increases. It is suggested that this is a consequence of charging the 'velocity storage' in the vestibulo-ocular system. Similar to the rotational head movement (opto-collic reflex), the translational head movement is elicited via a wide-field motion sensitive system. The underlying mechanism can be described as vector integration of movement vectors tangential to the pattern rotation. Stimulation of the frontal visual field elicits largest translational responses while rotational responses can be elicited equally well from any azimuthal position of a moving pattern. Experiments where most of the pattern is occluded by a screen and the pigeon is allowed to view the stimulus through one or two windows demonstrate a short-range inhibition and long-range excitation between movement detectors that feed into the rotational system. Furthermore, the results obtained from such types of experiments suggest that the rotational system inhibits the translational system. These mechanisms may help the pigeon to decompose image flow into its translational and rotational components. Because of their translational response to a rotational stimulus, it is concluded, however, that pigeons either generally cannot perfectly perform the task or they need further visual information, like differential image motion, that was not available to them in the paradigms.

Animals↗
PubMed2003

Distributing vertical forces between the digits during gripping and lifting: the effects of rotating the hand versus rotating the object.

During pinch grip we partition the vertical tangential forces at the digits according to the friction at the grip surfaces, and the mass distribution of the object. However, we cannot predictively partition the vertical forces to adjust to new frictional conditions after viewing a 180-deg rotation of an object with different textures at each grip surface. Hence, the processes that lead to predictive force partitioning may not access object representations, thereby suggesting that these processes are digit-specific. If this is true, then we should fail to predictively partition our fingertip forces when we rotate our hand. We tested this prediction by comparing the effects of object rotation with hand rotation for repeated lifts of an object that had one slippery grip surface and one rough grip surface. Subjects did not predictively redistribute the vertical tangential forces upon grasping the rotated object. Following object rotation, the vertical tangential force trajectories during the first 100 ms after contact indicated that 12/15 subjects failed to anticipate the reversed digit-friction relationships. All subjects appropriately partitioned the vertical tangential forces between the digits by the second lift after object rotation, confirming previous reports that sensory signals update the memory associated with lifting the object. In contrast, after hand rotation, 13/15 subjects anticipated the new digit-friction relationships and upon grasping the object immediately generated a steep rise in the vertical force trajectory at the rough surface. They also delayed the initial rise in vertical tangential force at the digit encountering the low-friction surface by approximately 65 ms. Thus, anticipatory partitioning of vertical fingertip forces is not strictly digit-specific. Internally driven motor plans can access the relevant memories or internal models for predictively partitioning the vertical tangential forces. It is not clear if this process involves rotating internal representations of fingertip force directly, or if the forces are derived after internally rotating a representation of the object. In contrast to the robust effects of vision on reach kinematics, or on wrist and finger configuration, visual signals about object rotation and orientation apparently do not influence vertical tangential fingertip forces.

Adult↗
PubMedDate not supplied

Anterior cruciate ligament graft rotation. Reproduction of normal graft rotation.

The purpose of this study was to determine normal rotation of the anterior cruciate ligament and to provide a technique for reproduction of this rotation. Ten fresh-frozen knees were dissected of all soft tissue except for the anterior cruciate ligament. Specimens were secured in a vise in 60 degrees of flexion. Each tibia was allowed to spin freely on the femur, and rotation was recorded. Anterior cruciate ligament reconstructions, using bone-patellar tendon-bone grafts, were then performed on all specimens using four graft rotations. Each specimen was then tested to assess how the graft twist affected tibial rotation. The average tibial rotation of the normal anterior cruciate ligaments was 55 degrees internally. Previous descriptions of anterior cruciate ligament reconstructions have advocated medial or internal rotation of the graft to reproduce normal anatomic rotation of the anterior cruciate ligament. Our cadaveric dissections have demonstrated that the anterior cruciate ligament normally produces internal rotation of the tibia in relation to the femur. Reproduction of this anatomic rotation is accomplished with 90 degrees of lateral rotation of the tibial plug toward the fibula.

Aged↗
PubMed2001

Susceptibility to motion sickness induced by optokinetic rotation and self-rotation by walking around a vertical pole.

31 subjects viewed an optokinetic rotating drum for 12 min. in one session and self-rotated by walking quickly around a vertical pole with eyes closed while alternately flexing and extending the neck in another session. The self-rotation session contained 6 trials (3 clockwise and 3 counterclockwise rotations). Each trial contained 20 cycles of self-rotations. Self-reported ratings of nausea and symptoms of motion sickness were obtained for each session. The subjects developed symptoms of nausea, sweating, dizziness, headache, drowsiness, and changes in salivation in both drum rotation and self-rotation sessions. However, the subjects reported higher ratings of nausea in the session of optokinetic rotation than in the session of self-rotation around a vertical pole. These results indicated that both optokinetic rotation and self-rotation with eyes closed while alternately flexing and extending the neck are effective means of inducing nausea and motion sickness.

Adolescent↗
PubMed1991

Axes of eye rotation and Listing's law during rotations of the head.

1. The vestibuloocular reflex (VOR) was examined in four alert monkeys during rotations of the head about torsional, vertical, horizontal, and intermediate axes. Eye positions and axes were recorded in three dimensions (3-D). Visual targets were used to optimize gaze stabilization. 2. Axes of eye rotation during slow phases showed small but systematic deviations from collinearity with the axes of head rotation. These noncollinearities apparently resulted from vector summation of torsional, vertical, and horizontal VOR components with different gains. 3. VOR gain was lowest about a head-fixed torsional axis that was correlated with the primary gaze direction, as determined by Listing's law for saccades. As a result, rotation of the head about a partially torsional axis produced noncollinear slow phases, with axes that tilted toward Listing's plane. 4. During slow phases, eye position changed not only in the direction of rotation, but also systematically in other directions. Even axes of eye rotation within Listing's plane caused eye position to move out of the plane to a torsional position that was then held. Thus Listing's law for saccades cannot be a product of plant mechanics. 5. VOR slow phases were simulated with the use of a model that incorporated 3-D rotational kinematics into the indirect path and the oculomotor plant. This demonstrated that the observed pattern of position changes is the expected consequence of rotating the eye about a fixed axis and that to hold these positions the indirect path must employ a 3-D velocity-to-position transformation. 6. Quick phases not only corrected the violations of Listing's law produced by slow phases but anticipated them by directing the eye toward a plane rotated in the direction of head rotation. This was modeled by inputting the vestibular signal to a Listing's law operator that is shared by the quick phase and saccadic systems.

Animals↗
PubMed2001

Reliability of lateral bending and axial rotation with validity of a new method to determine axial rotation on anteroposterior cervical radiographs.

OBJECTIVE: To investigate the reliability of a new radiographic measurement of axial rotation and lateral bending on anterior-posterior cervical views by using a computer and sonic digitizer. DESIGN: A blind, repeated-measure design was used. Anteroposterior cervicothoracic radiographs were presented to each of 3 examiners in random order. Each film was digitized, and 1 week later the films were randomized for a second run. SETTING: Private, primary-care chiropractic clinic. MAIN OUTCOME MEASURES: The interclass and intraclass correlation coefficients (ICC) for intraexaminer and interexaminer reliability were calculated from measurements on radiographs for determining axial rotations (Ry) and lateral bending (Rz) of C3 to T3. RESULTS: When the new axial rotation method was applied to small rotations of a C3 plastic model, the average error was less than 1 degrees. For the calculations of axial rotation (Ry), the ICC values were in the good to excellent range. For axial rotation, the intraclass correlation coefficients were ICCs > or =0.78, and the interclass correlation coefficients were ICCs > or =0.67. For lateral flexions (Rz) of C3 to T3, all intraclass and interclass correlation coefficients were in the excellent range (ICCs > 0.87). CONCLUSIONS: Methods of calculating axial rotations in the spine have been reported for large angles (5 degrees to 30 degrees ) but not for smaller angles. A new method for determining axial rotations of the cervical segments on AP views, based on the chord across the arc displaced by the spinous-lamina junction, had reliability (ICC values) in the good to excellent range. Compared with measured rotations of a C3 model (-5 degrees to +5 degrees ), the new method had an average error of less than 1 degrees and approximately 11.5%. The reliability for the axial rotation measurements was in the good to excellent range, and the lateral bending measurements were all in the excellent range.

Cervical Vertebrae↗
PubMed1993

AF64A lesions of mouse striatum result in ipsilateral rotations to D2 dopamine agonists but contralateral rotations to muscarinic cholinergic agonists.

Behavioral and anatomical evidence supports an interaction between the dopaminergic and cholinergic systems in regulating certain behavioral conditions and motor functions. In this study, we utilized the cholinotoxin, acetylethylcholine mustard aziridinium ion (AF64A), to lesion the mouse corpus striatum in order to examine the role of cholinergic interneurons in striatum on cholinergic- and dopaminergic-mediated rotational behavior. Mice were unilaterally lesioned with AF64A and then challenged with a variety of dopaminergic and cholinergic agonists and antagonists. The results show that mice with AF64A-induced lesions rotate ipsilaterally to challenge doses of the dopamine agonists, apomorphine and pergolide, but rotate contralaterally to challenge injections of the cholinergic agonist, oxotremorine. The gamma aminobutyric acid (GABA) agonist, muscimol, and the M1 agonist, (4-hydroxy-2-butynyl)-1-trimethylammonium m-chlorocarbanilate chloride failed to elicit rotational behavior. The D1 dopamine receptor antagonist, R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl- 2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride, inhibited rotations induced by apomorphine at concentrations 10-fold lower than those needed to block the effects of pergolide. However, the D2 dopamine receptor antagonist, sulpiride, blocked pergolide-induced rotations at concentrations about 4-fold lower than those needed to inhibit apomorphine-induced rotational behavior. Atropine blocked oxotremorine-induced contralateral rotations but enhanced apomorphine- and pergolide-induced ipsilateral rotations induced in AF64A-lesioned mice. Atropine was 10 times more effective in blocking oxotremorine-induced rotations than was the M3 antagonist, 4-diphenylacetoxy-N-methyl piperidine methiodide, and was 100 times more potent than the M2 and M1 antagonist, N,N'-bis[6-[[(2- methoxyphenyl)methyl]amino]hexyl]-1,8-octanediamine tetrahydrochloride, or the M1 antagonist, pirenzepine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

EMG power spectra of trunk muscles during graded maximal voluntary isometric contraction in flexion-rotation and extension-rotation.

The purpose of this study was to determine the electromyographic (EMG) power spectral characteristics of seven trunk muscles bilaterally during two complex isometric activities extension-rotation and flexion-rotation, in both genders to describe the frequency-domain parameters. Eighteen normal young subjects volunteered for the study. The subjects performed steadily increasing isometric extension-rotation and flexion-rotation contractions in a standard trunk posture (40 degrees flexed and 40 degrees rotated to the right). A surface EMG was recorded from the external and internal oblique, rectus abdominis, pectoralis, latissimus dorsi, and erector spinae muscles at the 10th thoracic and the 3rd lumbar vertebral levels, at 1 kHz and 25%, 50%, 75% and 100% of maximal voluntary contraction (MVC). The median frequency (MF), mean power frequency (MPF), frequency spread and peak power were obtained from fast Fourier transform analysis. The MF and MPF for both extension-rotation and flexion-rotation increased with the grade of contraction for both males and females. The EMG spectra in flexion-rotation were different from those of extension-rotation (P < 0.001). The left external and right internal oblique muscles played the role of antagonists in trunk extension-rotation. There was an increase in the MF of the trunk muscles with increasing magnitude of contraction. Frequency-domain parameters for both the male and female subjects were significantly different (P < 0.001).

Abdominal Muscles↗
PubMed1984

What is rotated in mental rotation?

Two hypotheses regarding mental rotation were contrasted. If subjects rotate each stimulus image to the upright (the image rotation hypothesis), then response time should depend solely on the extent of angular deviation from the upright. But if subjects rotate their frame of reference to match that of the disoriented stimulus (the frame rotation hypothesis), then response time should vary with the angular deviation between the current stimulus and the preceding stimulus. In four experiments, one involving normal and reflected letters (Experiment 1) and the other three involving lexical decisions on Hebrew letter strings (Experiments 2, 3A, and 3B), much stronger evidence for the image rotation hypothesis was found, though weak but systematic effects of frame rotation were also obtained. Increased likelihood that the same orientation would be repeated (Experiment 4) did not yield any stronger frame rotation effects. Also there was no indication of consistent individual differences in the preference for the frame rotation strategy (Experiment 3B). Additional findings pertinent to the application of the mental rotation paradigm to word recognition were discussed.

Female↗
PubMed2005

Mental rotation and rotational invariance in the Rhesus monkey (Macaca mulatta).

The mode of visual information processing during visuospatial tasks differs across species and is supposed to depend on evolutionary and ecological factors. Humans show reaction times that increase with angular disparity when tested in mental rotation tasks. Pigeons show a time-independent rotational invariance that possibly evolved in response to the horizontal reference plane birds perceive while flying. As it was suggested that hominids may have secondarily lost the ability of rotational invariance while retreating from arboreal living and evolving upright gait where the vertical reference plane is more important, mental rotation tests with various recent primate species promise to model the evolution of the respective modes of information processing. The results of recent corresponding experiments with a mainly arboreal living primate species could not be explained by either mode, thus supporting the idea of information processing systems having gradually evolved. Here, we conducted mental rotation experiments with three Rhesus monkeys, a more terrestrial living primate species. In a two-alternative matching-to-sample procedure, we measured the monkeys' reaction times for decisions between rotated figures representing image and mirror-image of a previously shown upright sample. The results of our three monkeys were inconsistent. Linear regression analyses showed for one test animal significant correlation coefficients for mean reaction times depending on angular disparity and thus clearly indicated mental rotation. The other two test animals showed reaction times not consistent with mental rotation, whereas rotational invariance might explain the responses to the smaller angles of rotation. Our results suggest that two separately evolved information processing systems may be coexisting to a certain extent in species with correspondingly overlapping ecological demands.

Adaptation, Psychological↗
PubMed1993

The rotator crescent and rotator cable: an anatomic description of the shoulder's "suspension bridge".

Twenty fresh frozen cadaver shoulders were dissected in order to study the rotator cable-crescent complex. The rotator crescent is a term that we have used to describe the thin, crescent-shaped sheet of rotator cuff comprising the distal portions of the supraspinatus and infraspinatus insertions. The crescent was found to be bounded on its proximal margin by a thick bundle of fibers that we have called the rotator cable. This cable-crescent configuration was found to consistently span the insertions of supraspinatus and infraspinatus tendons. The dimensions of the rotator cable and crescent were measured by a digital micrometer. The rotator cable was found to be a very substantial structure, averaging 2.59 times the thickness of the rotator crescent that it surrounded. This anatomic study supports the concepts of stress-shielding of the rotator crescent by the stout rotator cable and stress transfer by this loaded cable system.

Aged↗
PubMed2005

Determination of neutral tibial rotational alignment in rotating platform TKA.

UNLABELLED: Use of a fixed anatomic landmark to set rotation of the tibial component may lead to rotational malalignment. Post wear in stabilized components, backside wear in any conforming modular system, and patellar maltracking may result from tibiofemoral rotational incongruence. We aimed to quantify tibial rotational alignment in 109 primary rotating platform TKAs. After trial components were inserted with the knee properly balanced, we recorded the neutral point of the rotating tibial insert, in extension, relative to the most medial aspect of the tibial tubercle. We hypothesized that all neutral points would lie within 10 degrees of the mean. Divergence of the neutral point was recorded as being internal or external to the medial border of the tibial tubercle to the nearest 5 degrees increment. Our results showed a mean divergence of 5 degrees +/- 5 degrees external to the medial border of the tubercle. Five percent of knees, however, had neutral points > or = 10 degrees from the mean. Surgeons who use fixed-bearing modular components with any rotational constraint must be cautious in choosing a fixed anatomic tibial landmark to determine the rotational alignment of the tibial component. Doing so may create tibiofemoral rotational malalignment in full extension that may lead to suboptimal outcomes. LEVEL OF EVIDENCE: Diagnostic study, Level II-3. See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2001

Dynamic measurement of axial vertebral rotation and rotational flexibility in scoliosis by flouroscopic method.

The Pedriolle torsion meter is an established method of vertebral rotation assessment in scoliosis. However, the assessment of scoliosis by this method is static and indirect. The objective of this study is to compare the accuracy of a direct method of assessing scoliosis rotation by fluoroscopy compared to the Pedriolle torsion meter. Secondly, to determine that vertebral body rotation changes with supine posture compared to erect position. Eight volunteers with idiopathic scoliosis were assessed for the apical vertebral rotation with this method and the Pedriolle torsion meter. These patients were also assessed in the supine and erect position with the fluoroscopic method to determine if the apical vertebral rotation would change with posture. The mean Cobb angle of the curves was 62.8 degrees (range 45 degrees to 86 degrees). The mean apical vertebral rotation in a standing position was assessed to be 21.5 degrees by Pedriolle torsion meter and 29 degrees by the fluoroscopic method. This difference was not statistically significant by the student t-test. In most patient, the rotation of vertebrae improved by a varying degree ranging from none to 24 degrees in the supine position. In conclusion, the fluoroscopic method is an alternate mean of measuring vertebrae rotation in idiopathic scoliosis, with comparable accuracy to the Pedriolle torsion meter method. The amount of vertebral rotation changes with posture of the patient.

Adolescent↗
PubMedDate not supplied

Effect of arm elevation and rotation on the strain in the repaired rotator cuff tendon. A cadaveric study.

In 14 cadaveric shoulders, a rotator cuff tear (2 cm wide and 1.5 cm long) was created and repaired under a 3-kg tensile force with the arm in adduction. Strain on the repaired tendon was measured at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of elevation in the sagittal, scapular, and coronal planes and from 60 degrees of internal rotation to 60 degrees of external rotation. The strain in all of the planes decreased significantly with the arm elevated more than 30 degrees. With 30 degrees of elevation in the scapular and coronal planes, the strain increased in internal rotation and decreased in external rotation. In all of the positions measured, the strain in the sagittal plane was significantly greater than in the other planes. We concluded that more than 30 degrees of elevation in the coronal or scapular plane and rotation ranging from 0 degrees to 60 degrees of external rotation compose the safe range of motion after repair of the rotator cuff.

Aged↗
PubMed1992

[The temporal course of nystagmus reactions after rotational stimulation (modified Veits long rotational method). Part II. Recommendations for the simplification of nystagmus evaluation in the rotational test].

In this study, on the basis of the graphics showing the time course of the nystagmus reactions following rotatory stimuli (Part I), some practical proposals are made on how the nystagmus responses following the rotatory test can be routinely analysed more quickly. The recommendations are oriented to the requirement that the selection of defined 30-second-intervals during the per- and postrotatory phase for the nystagmus analysis should reflect the total reaction in healthy subjects as well as in patients with acute vestibular lesions in a representative manner. It is also shown that reducing the analysis intervals to only 15 seconds or selecting unfavourable segments, can lead to an unacceptable falsification of the results.

Electronystagmography↗