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 1,279 records · Page 71Linked to original sources
PubMed2002

[Usefulness of ultrasonography in the diagnosis of rotator cuff tears].

UNLABELLED: The purpose of this study was to determine the diagnostic performance of high-resolution ultrasonography compared with arthroscopy examination for the detection and characterization of rotator cuff tears. 31 patients with shoulder pain who had undergone preoperative ultrasonography and subsequent arthroscopy were identified. RESULTS: Ultrasonography for full-thickness rotator cuff tears has sensitivity of 80%, specificity of 100%, PPV of 100%, NPV of 82%. Ultrasonography for partial-thickness rotator cuff tears has sensitivity of 78.5%, specificity of 82%, PPV of 85%, NPV of 75%. CONCLUSION: Ultrasonography was highly accurate for detecting full-thickness rotator cuff tears; it was less sensitive and specific for detecting partial-thickness rotator cuff tears. Because of its low cost ultrasonography could be the first diagnostic tool for the rotator cuff tears.

Arthroscopy↗
PubMed2003

[All arthroscopic treatment of rotator cuff tears].

Although shoulder arthroscopy was initially performed solely for subacromial decompression, at present it is widely used for rotator cuff repairs and reconstruction. All arthroscopic rotator cuff repairs have been performed increasingly over the past decade and favorable long-term results have been reported in the literature. All arthroscopic rotator cuff repair has advantages over mini-open, or open rotator cuff repair, because it is associated with less postoperative pain and morbidity, and a more rapid improvement in shoulder motion. However, complete arthroscopic rotator cuff repair is a technically difficult procedure, with some limitations including relative weakness of tendon sutures and the need for more experience. It is essential that the merits and demerits associated with this technique should be balanced depending on the individual condition of the patient and the degree of experience gained. This article revisits all arthroscopic rotator cuff repair with regard to advantages and disadvantages, surgical techniques, indications, postoperative rehabilitation, and the results both in the light of the literature and our experience.

Arthroscopy↗
PubMed1992

Ultrasonography of rotator cuff tears.

This is a prospective study of ultrasonography of the rotator cuff mechanism as an alternative to arthrography for screening rotator cuff tears. Seventy-two patients (40 men and 32 women) with possible rotator cuff tears were referred for shoulder arthrography. Before arthrography, bilateral shoulder sonography was performed by a technician under the direction of a radiologist. Arthrograms and sonograms were read separately, and a decision as to the absence or presence of a rotator cuff tear was made without knowledge of the results of the other examination. The results showed 90% sensitivity and 91% specificity, with a positive accuracy of 87%, and a negative accuracy of 93%. Ultrasonography of the rotator cuff is a noninvasive, painless, and cost-effective screening method for patients with a suspected rotator cuff tear.

Adolescent↗
PubMedDate not supplied

Sonographically detected subacromial/subdeltoid bursal effusion and biceps tendon sheath fluid: reliable signs of rotator cuff tear?

PURPOSE: Our purpose was to determine the association between sonographically detected subacromial/subdeltoid (SA/SD) bursal and biceps tendon sheath effusions and arthrographically proven rotator cuff tears. METHODS: Shoulder sonography reports and sonograms of 105 shoulders in 102 patients who also underwent arthrography were retrospectively reviewed for the presence of fluid within the biceps tendon sheath and SA/SD bursa. Reports and sonograms for 151 asymptomatic shoulders were also reviewed. RESULTS: Biceps tendon sheath effusion and/or bursal fluid were detected in 50 (48%) of 105 shoulders. Fifty-one patients had rotator cuff tears; 28 of them had effusions at 1 or both sites. The sensitivity, specificity, and positive predictive value (PPV) of biceps tendon sheath effusions for diagnosing rotator cuff tear were 35%, 74%, and 56%, respectively. For SA/SD bursal effusions, the sensitivity, specificity, and PPV were 8%, 94%, and 57%, respectively. For combined biceps tendon sheath and bursal effusions, the sensitivity, specificity, and PPV were 12%, 91%, and 54%, respectively. There was no statistically significant association between rotator cuff tears and effusions in the biceps tendon sheath, SA/SD bursa, or both. Among the 151 asymptomatic shoulders, 12 (7.9%) had biceps tendon sheath fluid, 5 (3.3%) had SA/SD bursal effusion, and 2 (1.3%) had both biceps tendon sheath and bursal effusions. CONCLUSIONS: The sonographic detection of intraarticular fluid, SA/SD bursal fluid, or both has a low sensitivity and PPV in the diagnosis of rotator cuff tears. Isolated intra-articular and/or SA/SD bursal effusions are not reliable signs of rotator cuff tear.

Adult↗
PubMed1999

Psoas major and its controversial rotational action.

The action of psoas major muscle as a primary flexor of the hip joint is undisputed. However it is also variably reported as being a medial and a lateral rotator of the femur at the hip joint. The psoas and iliacus muscles, along with their common insertion, were isolated by dissection in six adult cadaveric specimens. The action of psoas muscle was assessed by pulling the muscle along its long axis and then observing the effects on rotation of the femur, with a visual estimation of the rotation in degrees. The experiment was repeated with the hip joint capsule removed. In the anatomical position, applied traction along the long axis of the muscle produced hip flexion with no rotational component. With the hip in the abducted position, traction produced flexion, adduction, and lateral rotation of the femur at the hip joint. In adduction of the hip, traction on psoas produced only flexion at the hip joint, with no rotation. In maximal flexion, traction also produced adduction. The results were unaffected by the removal of the joint capsule.

Aged↗
PubMed1983

Rotational dynamics of spin-labelled muscle proteins.

Electron paramagnetic resonance (EPR) spectroscopy on spin-labelled proteins was used to investigate the role of rotational motions in the two key ATPase systems of muscle: (a) the force-generating interaction of myosin and actin and (b) the calcium pump of sarcoplasmic reticulum (SR). The spin labels in these studies were rigidly fixed to the protein framework, so there were none of the nanosecond motions detectable by conventional EPR techniques. Thus conventional EPR was useful only in the study of static orientation in oriented systems (parallel muscle fibres or membrane bilayers), while saturation transfer EPR was required to detect protein motions in the microsecond range. Spin labels attached to myosin 'heads' were used to test the proposal that these heads form force-generating cross-bridges to actin that rotate when driven by the ATPase cycle. These probes are highly oriented and strongly immobilized when heads are bound to actin, but undergo microsecond rotations when the heads are detached from actin. During contraction, the majority of heads are mobile and disoriented, indicating detachment, while the remainder appear to be attached with the same orientation as in the absence of ATP. Thus the probed part of the myosin head does not appear to rotate during force generation. Saturation transfer EPR was used to monitor the microsecond rotational motions of the Ca2+-ATPase in SR membranes, while conventional EPR was used to monitor lipid hydrocarbon rotations in the microsecond time range. Changes in lipid fluidity and protein mobility, induced by changes in lipid/protein ratio, lipid composition, [Ca2+] and protein cross-linking, correlate well with changes in enzymic activity, suggesting the importance of molecular motions for Ca2+ transport.

Actins↗
PubMed2004

On rotation, torsion, lateralization, and handedness of the embryonic heart loop: new insights from a simulation model for the heart loop of chick embryos.

The internal organs of vertebrates show specific anatomical left-right asymmetries. The embryonic heart is the first organ to develop such asymmetries during a process called dextro-looping. Thereby the initially straight heart tube curves toward its original ventral side and the resulting bend becomes displaced toward the right side of the embryo. Abnormal displacement of the heart loop toward the left is rare and is called levo-looping. Descriptive studies have shown that the lateralization of the heart loop is driven by rotation around its dorsal mesocardium. However, nothing was known on the modes of this process. To gain insight into this subject, different modes of rotation were tested in a simulation model for the looping chick embryo heart. The morphological phenotypes obtained in this model were compared with normal and mirror-imaged embryonic hearts. The following observations were made. One, rotation of the heart loop around its dorsal mesocardium has two consequences: first, lateral displacement of its bending portion either toward the right (D-loop) or left (L-loop) side of the embryo, and second, torsion of the cardiac bend into a helical structure that is wound either clockwise (right-handed helix) or counterclockwise (left-handed helix). The normal loop presents as a D-loop with left-handed helical winding and its mirror image presents as an L-loop with right-handed helical winding. This conflicts with the use to define D-loops as right- and L-loops as left-handed structures. Two, dextro-looping might be driven almost exclusively by rightward rotation of the arterial pole of the loop. It becomes complemented by leftward rotation of the venous pole during the subsequent phase of looping. An inverse mode of rotation might drive levo-looping. Three, the two different helical configurations of heart loops both can occur as right-sided, median, or left-sided positional variants. When viewed from the front, all right-sided variants appear as D-loops and all left-sided variants appear as L-loops at the end of dextro- or levo-looping. Their true asymmetric phenotypes become fully apparent only after simulation of the subsequent phase of looping. The terms D- and L-loop obviously do not fully define the chirality of heart loops. The chirality of their helical configuration should be defined, too. The implications of these data with respect to molecular and experimental data are discussed.

Animals↗
PubMed1992

Dynamic response of the occipito-atlanto-axial (C0-C1-C2) complex in right axial rotation.

The torque-angular deformation in right axial rotation until failure of the ligamentous occipito-atlanto-axial complex subjected to variable loading rate (dynamic) axial torque was characterized using a biaxial MTS system. A special fixture and gear box that permitted right axial rotation of the specimen until failure without imposing any additional constraints were used to obtain the data. The specimens were divided into three groups and tested until failure at three different dynamic loading rates: 50, 100, and 400 degrees/s. A previous study by the authors provided data for quasi-static (4 degrees/s) loading conditions. The torque versus rotation curves can be divided into two straight regions and two transition zones. The plots clearly indicated that at loading rates higher than 4 degrees/s, the specimens became stiffer in the region of steadily increasing resistance prior to failure. The increase in stiffness was maximum at 100 degrees/s. The stiffness decreased somewhat at 400 degrees/s in comparison with 100 degrees/s, but this decrease was not significant. The resulting torque-right axial rotation curves were also examined to estimate the magnitude of maximum resistance (torque) and the corresponding angular rotation value. The average maximum resistance torque increased from 13.6 Nm at 4 degrees/s to 27.8 Nm at 100 degrees/s. The corresponding right angular rotation data (65-78 degrees), however, did not show any significant variation with loading rate. Posttest dissection of the specimens indicated that the type of injury observed was related to the rate of axial loading imposed on a specimen during testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

The entire rotator cuff contributes to elevation of the arm.

The function of the infraspinatus, teres minor, and subscapularis during elevation of the arm remains poorly defined. These muscles may generate moments that contribute to abduction of the arm, although they frequently are classified as humeral depressors. The purposes of this study were to measure the contributions to abduction made by the more inferiorly positioned rotator cuff muscles relative to the contributions of the supraspinatus and to determine the range of motion at which the muscles are most effective. Five fresh cadaveric shoulder girdles were mounted in an apparatus designed to simulate contraction of the deltoid and rotator cuff while maintaining the normal relationship between glenohumeral and scapulothoracic motions. The deltoid force required for elevation was measured without simulated contraction of the rotator cuff and with simulated contraction of the entire rotator cuff, of the supraspinatus only, and of the infraspinatus-teres minor and subscapularis only. A significant reduction in deltoid force when other muscle activity was added indicated that the additions contributed significantly to abduction. The deltoid force required with concurrent contraction of the entire rotator cuff averaged 41% less than with the deltoid alone but was not significantly different than with the deltoid and supraspinatus or with the deltoid, infraspinatus-teres minor, and subscapularis. Concurrent application of forces to the supraspinatus or the infraspinatus-teres minor and subscapularis significantly reduced the required deltoid force over the range of motion studied by an average of 28 and 36%, respectively. The contributions of the rotator cuff muscles to abduction of the arm were greatest at low abduction angles (30 and 60 degrees) and were insignificant by 120 degrees. The infraspinatus-teres minor and subscapularis contribute significantly to abduction: their contribution was equal to that of the supraspinatus and, like the supraspinatus, they are most effective during the first 90 degrees of abduction.

Aged↗
PubMed1996

A mechanism for rotation restraints in the knee joint.

Ligament function in restraining axial rotation of the tibia relative to the femur cannot be revealed by analysis of ligament forces alone. The action of the articular surfaces should be taken into account as well. In this study, three-dimensional mathematical models of four human knee joints were used to determine the limits of axial rotation between 0 and 90 degrees of flexion, whereby the forces in the ligaments and articular contact were calculated, together with their contribution to the restraint moment that was required to counterbalance the applied axial moment of 3 Nm. In external rotation, the direct axial restraint was provided by the collateral ligaments. In internal rotation, when the cruciate ligaments and medial collateral ligament were predominantly loaded, the direct restraint moment resulting from the ligament forces was not sufficient to counterbalance the applied moment. The articular contact forces, which resulted from balancing the axial components of the ligament forces, contributed considerably to the restraint of internal rotation. Depending on the flexion angle, the contact forces provided approximately 50-85% of the internal restraint, whereas 95-100% of the external rotation restraint was accounted for by the ligament forces.

Humans↗
PubMed1993

A comparison of solid intraventricular and dissociated intraparenchymal fetal substantia nigra grafts in a rat model of Parkinson's disease: impaired graft survival is associated with high baseline rotational behavior.

It has been established that substantia nigra (SN) grafts can produce a behavioral effect in animal models of Parkinson's disease when transplanted either into the lateral ventricles as solid tissue fragments or directly into the striatum as dissociated cells. These two transplantation methods (solid-intraventricular and dissociated-intraparenchymal) were directly compared in the present study. Adult male rats received unilateral SN lesions by stereotaxic injection of 6-hydroxydopamine. Fetal ventral mesencephalon, containing the SN, was harvested from 15-day gestational rat fetuses. Equal weights of tissue were transplanted, either as solid-intraventricular or dissociated-intraparenchymal grafts. In the animals with surviving grafts, similar decreases in apomorphine-induced rotational behavior were seen in both dissociated (40.2% at 6 weeks, 29.6% at 12 weeks, N = 12) and solid (31.8% at 6 weeks, 51.0% at 12 weeks, N = 11) graft groups. Control animals receiving tectal grafts showed smaller decreases (dissociated: 12.6% at 6 weeks, 18.8% at 12 weeks, N = 20; solid: 4.1% at 6 weeks, 8.0% at 12 weeks, N = 20). There were no significant overall differences between the effects of the solid and dissociated grafts; however, in the subgroup of animals with high baseline levels of rotational behavior, the solid-intraventricular grafts produced a significantly larger effect then did the dissociated-intraparenchymal SN grafts. There was also a tendency for the effect of the solid-intraventricular grafts to increase gradually over the 12-week testing period, whereas the effects of the dissociated-intraparenchymal grafts were maximal by 6 weeks after transplantation. For both SN graft groups, there were significant correlations between decreases in rotation and numbers of surviving tyrosine hydroxylase-immunoreactive neurons in the grafts. It was also found that animals with no surviving transplanted tyrosine hydroxylase-positive neurons had higher baseline levels of rotational behavior. Therefore, in the present model, solid-intraventricular and dissociated-intraparenchymal SN grafts have similar effects on apomorphine-induced rotational behavior, except that the solid-intraventricular grafts tended to produce a larger effect in animals with high baseline levels of rotational behavior.

Animals↗
PubMed2000

Light-induced rotation of a transmembrane alpha-helix in bacteriorhodopsin.

Spin labeling EPR spectroscopy has been used to characterize light-induced conformational changes of bacteriorhodopsin (bR). Pairs of nitroxide spin labels were attached to engineered cysteine residues at strategic positions near the cytoplasmic ends of transmembrane alpha-helices B, F, and G in order to monitor distance changes upon light activation. The EPR analysis of six doubly labeled bR mutants indicates that the cytoplasmic end of helix F not only tilts outwards, but also rotates counter-clockwise during the photocycle. The direction of the rotation of helix F is the opposite of the clockwise rotation previously reported for bovine rhodopsin. The opposite chirality of the F helix rotation in the two systems is perhaps related to the differences in the cis-trans photoisomerization of the retinal in the two proteins. Using time-resolved EPR, we monitored the rotation of helix F also in real time, and found that the signal from the rotation arises concurrently with the reprotonation of the retinal Schiff base.

Animals↗
PubMed1992

Detection of rotating gravity signals.

It is shown in the preceding paper that neurons with two-dimensional spatio-temporal properties to linear acceleration behave like one-dimensional rate sensors: they encode the component of angular velocity (associated with a rotating linear acceleration vector) that is normal to their response plane. During off-vertical axis rotation (OVAR) otolith-sensitive neurons are activated by the gravity vector as it rotates relative to the head. Unlike "one-dimensional" linear accelerometer neurons which exhibit equal response magnitudes for both directions of rotation, "two-dimensional" neurons can be shown to respond with unequal magnitudes to clockwise and counterclockwise off-vertical axis rotations. The magnitudes of the sinusoidal responses of these neurons is not only directionally selective but also proportional to rotational velocity. Thus, responses from such "two-dimensional" neurons may represent the first step in the computations necessary to generate the steady-state eye velocity during OVAR. An additional step involving a nonlinear operation is necessary to transform the sinusoidally modulated output of these neurons into a signal proportional to sustained eye velocity. Similarly to models of motion detection in the visual system, this transformation is proposed to be achieved through neuronal operations involving mathematical multiplication followed by a leaky integration by the velocity storage mechanism. The proposed model for the generation of maintained eye velocity during OVAR is based on anatomical and physiological properties of vestibular nuclei neurons and capable of predicting the experimentally observed steady-state characteristics of the eye velocity.

Acceleration↗
PubMed1994

Ibotenic acid lesions of the striatum reduce drug-induced rotation in the 6-hydroxydopamine-lesioned rat.

Lesions of the dopaminergic nigrostriatal tract produce a range of motor and sensorimotor deficits. One of the simplest and most reliable is the rotational response of the animal following activation with drugs that stimulate the dopaminergic network, most notably amphetamine and apomorphine. Consequently, the rotation test has been extensively used in assessing the success of treatments designed to restore dopaminergic function, including neural transplants. The present study investigates whether rotation induced by 6-hydroxydopamine lesions of the nigrostriatal bundle in rats is modified by additional lesions in the neostriatum. It was found that apomorphine-induced rotation can be reduced by ibotenic acid lesions of the dopamine-deafferented striatum, and that the extent of the reduction was proportional to the size of the lesions. In contrast, such lesions produced a non-significant reduction in amphetamine-induced rotation, although the correlation between the extent of the reduction and the size of the lesion was again apparent. Since the pattern of change was similar in direction, albeit smaller in magnitude, than the previously reported effects of intrastriatal transplantation in rats with similar nigrostriatal lesions, rotation tests alone do not provide an unequivocal test of graft survival and function.

Amphetamine↗
PubMed1995

Modeling the vestibulo-ocular reflex of the squirrel monkey during eccentric rotation and roll tilt.

Model simulations of the squirrel monkey vestibulo-ocular reflex (VOR) are presented for two motion paradigms: constant velocity eccentric rotation and roll tilt about a naso-occipital axis. The model represents the implementation of three hypotheses: the "internal model" hypothesis, the "gravito-inertial force (GIF) resolution" hypothesis, and the "compensatory VOR" hypothesis. The internal model hypothesis is based on the idea that the nervous system knows the dynamics of the sensory systems and implements this knowledge as an internal dynamic model. The GIF resolution hypothesis is based on the idea that the nervous system knows that gravity minus linear acceleration equals GIF and implements this knowledge by resolving the otolith measurement of GIF into central estimates of gravity and linear acceleration, such that the central estimate of gravity minus the central estimate of acceleration equals the otolith measurement of GIF. The compensatory VOR hypothesis is based on the idea that the VOR compensates for the central estimates of angular velocity and linear velocity, which sum in a near-linear manner. During constant velocity eccentric rotation, the model correctly predicts that: (1) the peak horizontal response is greater while "facing-motion" than with "back-to-motion"; (2) the axis of eye rotation shifts toward alignment with GIF; and (3) a continuous vertical response, slow phase downward, exists prior to deceleration. The model also correctly predicts that a torsional response during the roll rotation is the only velocity response observed during roll rotations about a naso-occipital axis. The success of this model in predicting the observed experimental responses suggests that the model captures the essence of the complex sensory interactions engendered by eccentric rotation and roll tilt.

Acceleration↗
PubMed1995

Vertebral rotation and pedicle length asymmetry in the normal adult spine.

Rotation in the horizontal plane of vertebra T8, T9 or T10 was determined on CT scans of 25 male and 25 female patients with normal spines. The pedicle length was measured using a new method, and the right/left pedicle length index was calculated. In 38 (76%) of the patients there was vertebral rotation to the right with a mean Cobb angle of 3.0 degrees, and in 4 (8%) rotation to the left, mean Cobb angle 2.2 degrees (P < 0.01). In 8 (16%) there was no measurable rotation. The pedicle length index was greater than 1.05 in 9 subjects, between 0.95 and 1.05 in 16 and less than 0.95 in 25, indicating a predominance of longer pedicles on the left side. In 21 out of the 38 patients with vertebral rotation to the right, the left pedicle was longer than the right one (P < 0.01). The results indicate that the normal spine is afflicted with a vertebral rotation to the right in association with a longer pedicle on the left. The significance of these observations for the pathogenesis of idiopathic scoliosis remain uncertain.

Adolescent↗
PubMed1988

Nystagmus induced by off-vertical rotation axis in the cat.

1) In the alert cat, nystagmus induced by off-vertical axis rotation (OVAR) was recorded following steps in head velocity or ramps of velocity at constant acceleration below canal threshold. Dependence of nystagmus characteristics on tilt angle of rotation axis and head velocity was studied. Similar results were obtained with both types of stimulation. 2) Mean and modulation amplitude of horizontal eye velocity increased with tilt angle in the range 0-30 degrees. 3) Both variables increased also with head velocity, but with different trends, probably because they are set by different mechanisms. When head rotational velocity was increased above 80 degrees/s, mean eye velocity progressively decreased to zero. 4) In spite of variations from one animal to another, some regularity was observed in the phase of eye velocity modulation. In several cases, a reduction in phase lead of eye velocity with respect to conventional origin of phases (nose-down position) was observed when head velocity increased. 5) Time constant of post-OVAR nystagmus decreased with the tilt angle of the rotation axis from gravity, but not with the orientation of the head with respect to rotation axis. 6) The results could be accounted for by a general equation describing the vestibulo-ocular reflex, provided that estimates of kinematic variables of head movement (head rotational and translational velocities), and visual target distance could be computed by the Central Nervous System.

Animals↗
PubMed1988

Eye movements induced by off-vertical axis rotation (OVAR) at small angles of tilt.

Off-vertical rotation (OVAR) in darkness induced continuous horizontal nystagmus in humans at small tilts of the rotation axis (5 to 30 degrees). The horizontal slow eye velocity had two components: a mean velocity in the direction opposite to head rotation and a sinusoidal modulation around the mean. Mean velocity generally did not exceed 10 deg/s, and was less than or equal to the maximum velocity of optokinetic after-nystagmus (OKAN). Both the mean and modulation components of horizontal nystagmus increased with tilt angle and rotational velocity. Vertical slow eye velocity was also modulated sinusoidally, generally around zero. The amplitude of the vertical modulation increased with tilt angle, but not with rotational velocity. In addition to modulations in eye velocity, there were also modulations in horizontal and vertical eye positions. These would partially compensate for head position changes in the yaw and pitch planes during each cycle of OVAR. Modulations in vertical eye position were regular, increased with increases in tilt angle and were separated from eye velocity by 90 deg. These results are compatible with the interpretation that, during OVAR, mean slow velocity of horizontal nystagmus is produced by the velocity storage mechanism in the vestibular system. In addition, they indicate that the otolith organs induce compensatory eye position changes with regard to gravity for tilts in the pitch, yaw and probably also the roll planes. Such compensatory changes could be utilized to study the function of the otolith organs. A functional interpretation of these results is that nystagmus attempts to stabilize the image on the retina of one point of the surrounding world. Mean horizontal velocity would then be opposite to the estimate of head rotational velocity provided by the output of the velocity storage mechanism, as charged by an otolithic input during OVAR. In spite of the lack of actual translation, an estimate of head translational velocity could, in this condition, be constructed from the otolithic signal. The modulation in horizontal eye position would then be compensatory for the perceived head translation. Modulation of vertical eye velocity would compensate for actual changes in head orientation with respect to gravity.

Adult↗