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 973 records · Page 54Linked to original sources
PubMed2001

The effect of forearm rotation on laxity and stability of the elbow.

OBJECTIVE: The purpose of this study was to quantify the relationship between forearm rotation and valgus/varus laxity of the elbow joint over the range of elbow flexion. BACKGROUND: There is little known about the influence of forearm rotation on the laxity and stability of the elbow joint. The general opinion exists that forearm rotation does not significantly influence the laxity and stability of the elbow joint. METHODS: Nine fresh-frozen cadaver elbows were used. Passive elbow flexion with the forearm in neutral rotation and in 40 degrees and 80 degrees of pronation and supination was performed under valgus/varus loads: (1) in intact elbows; (2) after a lateral surgical approach (lateral epicondylar osteotomy of the distal humerus); (3) after release of the anterior bundle of the medial collateral ligament; and (4) after release of the anterior bundle of the medial collateral ligament plus radial head resection. Valgus/varus elbow laxity was quantified using an electromagnetic tracking device. RESULTS: There was a statistically significant effect (P < 0.05) of forearm rotation on valgus/varus laxity throughout the range of flexion. The laxity was always greater in pronation than in supination, regardless of the surgical approach or the integrity of the anterior bundle of the medial collateral ligament or radial head. CONCLUSIONS: Valgus/varus laxity of the elbow is forearm rotation-dependent. The potential role of this effect should be considered and controlled for in the design of studies examining laxity and stability of the elbow joint. RELEVANCE: The observation that forearm pronation increases valgus/varus laxity, particularly in medial collateral ligament deficient elbows, implies a possible additional factor in throwing kinematics that might put professional baseball pitchers at risk of medial collateral ligament injury due to chronic valgus overload. Our data indicate that forearm rotation should be considered during the clinical examination of elbow instability.

Aged↗
PubMed2002

Asymmetries in finger-tapping interference produced by mental versus manual rotation of Shepard and Metzler type objects.

Two experiments were conducted using dual-task finger-tapping procedures to examine cerebral hemisphere laterization for mental versus manual rotation. Actual three-dimensional block-designs based on Shepard and Metzler's (1971) abstract three-dimensional cubes were constructed. Forty-eight right-handed introductory psychology students participated in each study. The first experiment showed greater right-hand than left-hand interference for mental rotation implicating more left-hemisphere involvement. In contrast, more left-hand than right-hand finger-tapping disruption with manual rotation was observed suggesting more right-hemisphere involvement. A second experiment was conducted to determine if the right-hemisphere involvement found with manual rotation was due to the manual activity of handling and rotating the blocks. Results showed that dual-task interference produced by irrelevant manual rotation combined with mental rotation was not lateralized. Thus, the pattern of results indicate that the manipulospatial processing required in the first experiment was responsible for the asymmetry implicating right-hemisphere involvement.

Adult↗
PubMed2003

Dissociation between the mental rotation of visual images and motor images in unilateral brain-damaged patients.

Deficits in the mental rotation of body parts and of external objects can be doubly dissociated (Rumiati, Tomasino, Vorano, Umiltà, & De Luce, 2001; Sirigu & Duhamel, 2001; Tomasino, Rumiati, & Umità, in press). The aim of this study was to replicate this finding and to then investigate the relevance of the specific hemispheres in these deficits. Nine patients with unilateral lesions (five in the Left Hemisphere and four in the Right) and 20 control subjects, performed a single task requiring mental rotation of hands, and two tasks requiring mental rotation of external objects. RH patients were impaired in the rotation of external objects, but showed intact performance on the rotation of hands; the opposite pattern was found for LH patients. These results support the view that the LH contributes to the mental rotation of hands, recruiting processes specific to motor preparation, while the RH is specialized for mental rotation of external objects.

Adult↗
PubMed1997

Effect of morphine on rotational behavior of unilaterally brain-lesioned mice and rats: morphine withdrawal and development of tolerance.

1. The effect of acute morphine administration on the rotational behavior of unilaterally brain-lesioned mice and on the amphetamine-induced rotational behavior of unilaterally brain-lesioned rats was studied. 2. The effect of repeated morphine administration on the rotational behavior of mice and rats was also investigated. 3. Acute administration of 40 mg/kg of morphine induced strong ipsilateral rotation in unilaterally brain-lesioned mice. 4. One day after withdrawal, mice given morphine repeatedly for 5 days and treated acutely with 40 mg/kg of morphine rotated significantly less ipsilaterally than mice that had received the same dose of morphine for the first time. 5. Rats given 2 mg/kg of morphine 1 hr before administration of 5 mg/kg of amphetamine tended to rotate slightly more in the ipsilateral direction than the similarly lesioned control rats that received amphetamine alone. 6. After 1 day of withdrawal from 5 days of repeated morphine administration, rats given morphine before amphetamine tended to rotate less ipsilaterally than those given morphine before amphetamine for the first time. 7. Thus, repeated administration of morphine appears to induce tolerance to the effect of morphine on circling behavior in unilaterally brain-lesioned mice and rats.

Amphetamine↗
PubMed2002

The effect of rotator cuff tears on reaction forces at the glenohumeral joint.

The rotator cuff muscles maintain glenohumeral stability by compressing the humeral head into the glenoid. Disruption of the rotator cuff compromises concavity compression and can directly affect the loads on the glenohumeral joint. The purpose of this study was to quantify the effect of rotator cuff tears on the magnitude and direction of glenohumeral joint reaction forces during active shoulder abduction in the scapular plane using nine cadaveric upper extremities. Motion of the full upper extremity was simulated using a dynamic shoulder testing apparatus. Glenohumeral joint reaction forces were measured by a universal force-moment sensor. Five conditions of rotator cuff tears were tested: Intact, Incomplete Supraspinatus Tear, Complete Supraspinatus Tear, Supraspinatus/Infraspinatus Tear, and Global Tear. Reaction forces at the glenohumeral joint were found to steadily increase throughout abduction and peaked at maximum abduction for all conditions tested. There were no significant differences in reaction force magnitude for the intact condition (337 +/- 88 N) or those involving an isolated incomplete tear (296 +/- 83 N) or complete tear (300 +/- 85 N) of the supraspinatus tendon. Extension of tears beyond the supraspinatus tendon into the anterior and posterior aspect of the rotator cuff led to a significant decrease in the magnitude of joint reaction force (126 +/- 31 N). Similarly, such tears resulted in a significant change in the direction of the reaction force at the glenohumeral joint. These results suggest that joint reaction forces are significantly affected by the integrity of the rotator cuff, specifically, by the transverse force couple formed by the anterior and posterior aspects of the cuff. The quantitative data obtained in this study on the effect of rotator cuff tears on magnitude and direction of the reaction force at the glenohumeral joint helps clarify the relationship between joint motion, joint compression and stability.

Aged↗
PubMed1998

Prediction of mandibular growth rotation: assessment of the Skieller, Björk, and Linde-Hansen method.

The purpose of this investigation was to assess the method proposed by Skieller, Björk, and Linde-Hansen in 1984 to predict mandibular growth rotation. Our sample consisted of 40 randomly selected, untreated, adolescent subjects representative of the patient population generally encountered in orthodontic practice. The four independent variables identified in the Skieller study as having the highest predictive value (mandibular inclination, intermolar angle, shape of the lower border of the mandible, and inclination of the symphysis) were identified on initial lateral cephalograms. The proposed regression equations were applied and predicted mandibular rotations obtained. Final lateral cephalograms made 6 years after the initial profile radiographs were superimposed and actual mandibular rotation recorded. The observed and predicted rotations were compared and regression analyses performed to determine the amount of variability in observed values accounted for by the four variables individually and in combination. Only 5.6% of the variability in mandibular growth rotation could be accounted for using the four variables individually. Only 9% of the variability could be accounted for with a combination of the variables. In addition, we performed a Monte Carlo analysis, which mirrored the Skieller analysis but used random numbers instead of actual cephalometric data, to determine if the Skieller results may simply have capitalized on chance. Using the same forward stepwise selection procedure with a rejection level of P >.1, we found after 5000 simulations that a mean of 84% and a median of 94% of mandibular growth rotation variability could be accounted for using meaningless data in the Skieller analysis. This result was comparable to the Skieller value of 86%. In conclusion, information derived from pretreatment lateral cephalograms using the Skieller, Björk, and Linde-Hansen method does not permit clinically useful predictions to be made in a general population relative to the direction of future mandibular growth rotation.

Cephalometry↗
PubMedDate not supplied

Mandibular autorotation in orthognathic surgery: a new method of locating the centre of mandibular rotation and determining its consequence in orthognathic surgery.

Rotation of the mandible is simulated through the centre of the condyle in planning orthognathic surgery. Previous studies have suggested that the initial mandibular movement is better characterized as multiple parts of the segments of a circle with the average centre located below and behind the centre of the condyle. This paper describes a method of locating the centre of mandibular rotation by computer-analysis of two lateral cephalograms with different degrees of opening. The method was used on 10 normal individuals showing an average centre of mandibular rotation 14.9 mm below and 5.0 mm behind the superior midsurface of the condyle for movements from occlusion to an opening of 10 mm. The implications of the located centre of rotation on orthognathic surgery was determined by simulating a closure of a 9.5 mm open bite. An error of up to 9.3 mm in the horizontal position of the maxilla would occur if the centre of the condyle was used. A retrospective study on 10 patients with increased anterior facial height was undertaken and a mean centre of rotation 8.4 mm behind and 25.1 mm below the centre of the condyle was found. Simulating the rotation of the mandible through the centre of the condyle would have resulted in a difference between the predicted and actual horizontal position of the maxilla ranging from 0.4-10.4 mm. It was concluded that using the centre of the condyle as the centre of mandibular rotation in the planning of superior maxillary movement with a Le Fort I osteotomy may cause considerable error in the horizontal position of the maxilla in most cases.

Cephalometry↗
PubMedDate not supplied

Electromyographic analysis of internal rotational motion of the shoulder in various arm positions.

The electromyographic activity of 9 muscles of the rotator cuff and shoulder girdle was measured in 8 volunteers during active motion and isometric contraction during internal rotation of the shoulder in four positions as follows: neutral rotation with the arm at the side, neutral rotation at 90 degrees abduction in the frontal plane, the zero-position as described by Saha, and the position of the liftoff test from the midlumbar spine as described by Gerber and Krushell. The subscapularis was active at levels of about 44% maximal manual muscle test (MMT) during active internal rotation in the liftoff test position, whereas the activity of the subscapularis decreased remarkably to about 2% to 12% MMT in the other positions. The subscapular is exceptionally important as an internal rotator in the liftoff test position. During resistive motion at the zero-position, the activity level of the subscapularis (81.7%) was higher than that of other muscles. These results indicate that internal rotation at the zero-position may selectively exercise the subscapularis muscle.

Adult↗
PubMed1998

Microsecond rotational dynamics of spin-labeled myosin regulatory light chain induced by relaxation and contraction of scallop muscle.

We have used saturation transfer electron paramagnetic resonance (ST-EPR) to study the rotational dynamics of spin-labeled regulatory light chain (RLC) in scallop (Placopecten magellanicus) muscle fibers. The single cysteine (Cys 51) in isolated clam (Mercenaria) RLC was labeled with an indanedione spin label (InVSL). RLC was completely and specifically extracted from scallop striated muscle fibers, eliminating the Ca sensitivity of ATPase activity and isometric force, which were both completely restored by stoichiometric incorporation of labeled RLC. The EPR spectrum of the isolated RLC revealed nanosecond rotational motions within the RLC, which were completely eliminated when the labeled RLC was bound to myosin heads in myofibrils or fibers in rigor. This is the most strongly immobilized RLC-bound probe reported to date and thus offers the most reliable detection of the overall rotational motion of the LC domain. Conventional EPR spectra of oriented fibers indicated essentially complete probe disorder, independent of ATP and Ca, eliminating orientational dependence and thus making this probe ideal for unambiguous measurement of microsecond rotational motions of the LC domain by ST-EPR. ST-EPR spectra of fibers in rigor indicated an effective rotational correlation time (taureff) of 140 +/- 5 microseconds, similar to that observed for the same spin label bound to the catalytic domain. Relaxation by ATP induced microsecond rotational motion (taureff = 70 +/- 4 microseconds), and this motion was slightly slower upon Ca activation of isometric contraction (taureff = 100 +/- 5 microseconds). These motions in relaxation and contraction are similar to, but slower than, the motions previously reported for the same spin label bound to the catalytic domain. These results support a model for force generation involving rotational motion of the LC domain relative to the catalytic domain and dynamic disorder-to-order transitions in both domains.

Animals↗
PubMed1997

Mental rotation interferes with response preparation.

Reaction times (RTs) and lateralized readiness potentials (LRPs) were studied to find out whether response preparation begins after mental rotation finishes, as assumed by discrete-stage models. Stimuli were disoriented normal or mirror-image characters, with character name determining which hand would respond. In Experiment 1, the normal/mirror-image information determined whether the response was to be executed (go) or withheld (no-go), and LRPs indicated that responses were weakly prepared before the end of mental rotation. Mental rotation was not required in Experiment 2, and significantly more response preparation was observed. In Experiment 3, probe RT trials embedded in the mental rotation task indicated that hand information is available to the response preparation process during rotation. Apparently, some response preparation occurs before mental rotation finishes, but rotation interferes with response preparation.

Adolescent↗
PubMed1981

Shape, orientation, and apparent rotational motion.

Apparent rotational motion was investigated in polygonal shapes ranging in rotational symmetry from random to self-identical under 180 degrees rotation. Observers adjusted the rate of alternation between two computer-displayed orientations of any given polygon to determine the point of breakdown of perceived rigid rotation between those two orientations. For asymmetric polygons, the minimum stimulus-onset asynchrony yielding apparent rigid rotation increased approximately linearly with orientational disparity, as anticipated on the basis of the extension of Korte's third law to rotational motion by Shepard and Judd. For nearly symmetric polygons, however, the critical time increased markedly as the disparities approached 180 degrees, owing to the availability of a shorter, nonrigid rotation in the opposite direction. The results demonstrate the existence of competing mental tendencies to preserve the rigid structure of an object and to traverse a minimum transformational path.

Discrimination, Psychological↗
PubMed2001

Direct observation of DNA rotation during transcription by Escherichia coli RNA polymerase.

Helical filaments driven by linear molecular motors are anticipated to rotate around their axis, but rotation consistent with the helical pitch has not been observed. 14S dynein and non-claret disjunctional protein (ncd) rotated a microtubule more efficiently than expected for its helical pitch, and myosin rotated an actin filament only poorly. For DNA-based motors such as RNA polymerase, transcription-induced supercoiling of DNA supports the general picture of tracking along the DNA helix. Here we report direct and real-time optical microscopy measurements of rotation rate that are consistent with high-fidelity tracking. Single RNA polymerase molecules attached to a glass surface rotated DNA for >100 revolutions around the right-handed screw axis of the double helix with a rotary torque of >5 pN nm. This real-time observation of rotation opens the possibility of resolving individual transcription steps.

DNA↗
PubMed1999

Factors involved in the 'rotation' of the human embryonic stomach around its longitudinal axis: computer-assisted morphometric analysis.

The majority of studies as to whether gastric and nongastric factors are involved in the 'rotation' of the human embryonic stomach around its longitudinal axis have been morphological. The aim of this study was to analyse, with morphometric support, the influence on the angular modifications during gastric rotation of the simultaneous changes of the gastric walls and mesenteric growth, and the volumes of organs adjacent to the stomach (right, left and posterior groups). Computer imaging techniques were applied on cross sections of a graded series of 10 human embryos (from Carnegie stage (CS) 11) and 2 fetuses. A clockwise gastric rotation occurred during the embryonic period. The most rapid angular modifications took place from CS 11 to 16, after the rotation became oscillatory with angular changes in clockwise and anticlockwise directions, reaching the highest value at CS 18 (at the supraomental part of the stomach: 54.37 degrees; at the omental part: 68.03 degrees); after this period the angular values tended to stabilise. The predominant growth of the left gastric wall over the right and the changes in the width of the gastric mesentery were the most persistent factors involved in the modifications of the transverse gastric angle during the embryonic period although without relationship to their direction. During the increasing angular phases, clockwise rotation was promoted by the decrease of the volume of any group of organs adjacent to the stomach. When the volume of the left and posterior groups increased simultaneously, clockwise or anticlockwise angular directional change was related to the respective decrease or increase adjacent organ volume to the right. We conclude that the stomach of the human embryo undergoes heterogeneous and multifactorial rotation as a consequence of the overall increase in gastric wall growth to the left and the increase of gastric mobility produced by the previous mesenteric enlargement, and that the rotational direction results from the forces exerted on the stomach and the gastric mesenteries by the adjacent organs.

Embryonic and Fetal Development↗
PubMed2002

Dynamic splinting of forearm rotational contracture after distal radius fracture.

The results of dynamic forearm rotational splinting for the treatment of forearm rotational contractures in patients with acceptably aligned, healed distal radius fractures are documented. Fifteen patients with distal radius fractures that healed with < or =+5 mm ulnar variance and < or =20 degrees dorsal tilt had dynamic forearm rotational splinting for contractures that had failed conventional hand therapy. Average pronosupination arc before splinting was 83 degrees. Dynamic forearm rotational splinting increased forearm rotation by 52% to an average of 126 degrees. Only one patient with development of ectopic bone in the interosseous space during splinting failed to obtain at least 30 degrees pronation and supination after splinting. Dynamic forearm rotational splinting effectively treats rotational contractures in patients who have healed distal radius fractures that are in acceptable alignment.

Adult↗
PubMed1998

Opening rotations of the mandible during and after treatment.

In this retrospective cephalometric study of mandibular rotational change, we studied 60 cases. All patients were treated with full fixed appliances and exhibited an opening rotation of at least 1.5 degrees during treatment, as measured on the basis of the angle of the Y-axis to the sella-nasion line (SN). Our objective was to determine whether this opening rotation was sustained during retention. Paired t tests were used to test the hypothesis that the treatment change or opening rotation was stable and that these patients did not return to their original mandible-to-cranium relationship in the posttreatment period. Stepwise regression analysis was used to determine which (if any) changes in the independent variables during treatment could predict the subsequent behavior of the angle of the mandibular plane to the SN and the angle of the Y-axis to the SN during retention. During treatment, the mean increase in the angle of the Y-axis to the SN was 2.43 degrees. After an average posttreatment period of 54 months, this angle was reduced on average by only 0.73 degrees. Stepwise linear-regression analysis indicated that none of the treatment changes seen in the independent variables strongly predicted the ensuing closing rotation seen during retention. The correlation coefficient between the Y-axis angle and the mandibular-plane angle during treatment was 0.67. Mandibular opening rotations as a consequence of orthodontic treatment do not invariably return to the pretreatment value, and their negative effects--although sometimes small--cannot be discounted. Because the preponderant evidence of a closing rotation occurs in the terminal pubertal growth stages, the net effect may be even more significant.

Adolescent↗
PubMed2002

Three-dimensional facial morphology, following primary cleft lip repair using the triangular flap with or without rotation advancement.

INTRODUCTION: There are numerous methods of repairing a cleft lip. In our institution, two methods have been used for primary lip repair, the triangular flap method, and the rotation-advancement plus small triangular flap method. The purpose of this study was to compare postsurgical anthropometric results following these two surgical methods. PATIENTS: Twenty children with a unilateral complete cleft lip, alveolus and palate (UCLAP) were selected for this study. Ten underwent primary lip repair by the triangular flap method (Triangular Group), and the other 10 underwent repair by the rotation-advancement plus small triangular flap method (Rotation Group). METHOD: They were documented with a three-dimensional optical scanner, and analysed with computer-aided anthropometric method reported previously (Comput. Methods Programs 58: 159-173, 1999a; J. Cranio-Maxillofac Surg 27: 345-353, 1999b). RESULTS: The shapes of the nose and nostril were a little better in the Rotation Group. However, in the Rotation Group, differences between good and poor cases were more extreme than in the Triangular Group. The shape of Cupid's bow was good shortly after surgery in the Triangular Group. A good shape of Cupid's bow was also obtained in the Rotation Group, but the improvement was more delayed. On the non-cleft side, the length of Cupid's bow was more extended in the Triangular Group. Certain deformities were common to both groups, such as deviation of the columella and a flattened ala on the cleft side. CONCLUSION: Rotation-advancement plus the small triangular flap method was thought to produce somewhat better results, however, further improvements in the technique are needed.

Alveolar Process↗
PubMedDate not supplied

[Histomorphology versus three-dimensional ultrasound morphology of the rotator cuff].

AIM: Sonographic evaluation is a reliable method for the detection of rotator cuff tears. However, the diagnostic value of the different echogenic patterns of the rotator cuff, especially in elderly patients, has led to a controversial discussion. The present study elucidates whether three-dimensional ultrasound can increase the diagnostic significance of different sonographic echogenicity patterns of tendons compared to histopathological tissue degeneration. METHOD: To evaluate the sonographic appearance of tendons in elderly patients, the sonographic echogenicity of 33 rotator cuff specimens with macroscopic absence of rotator cuff lesions was classified in three groups and compared with the histopathological morphology. RESULTS: The sonographic appearance of the degenerated rotator cuff in elder patients correlates with a reduced sonographic echogenicity. The two-dimensional ultrasound evaluation of the rotator cuff led to a sensitivity of 84.0%, a specificity of 42.9%, a positive predictive value of 63.6%, a negative predictive value of 69.2%, and an accuracy of 65.2%. The three-dimensional ultrasound evaluation of the rotator cuff led to a sensitivity of 91.6%, a specificity of 50.0%, a positive predictive value of 66.6%, a negative predictive value of 84.6% and an accuracy of 71.%, respectively. CONCLUSION: As a high incidence of false positive results has to be taken into consideration, neither the two-dimensional, nor the three-dimensional ultrasound evaluation seems to lead to a reliable correlation.

Aged↗
PubMedDate not supplied

Anatomy and functional aspects of the rotator interval.

The anatomy of the region between the supraspinatus and subscapularis tendons, called the rotator interval, was studied in 22 shoulders of 12 cadavers. Its function was then examined by sequential cutting of tendon or rotator interval structures. The rotator interval was found to be composed of parts of the supraspinatus, subscapularis, coracohumeral ligament, superior glenohumeral ligament, and glenohumeral joint capsule. A medial part composed of 2 layers was defined and distinguished from a more lateral part composed of 4 layers. The most superior 3 layers of the lateral part formed a fibrous plate. The medial part was found to primarily limit inferior translation and, to a lesser extent, external rotation. The fibrous plate of the lateral part of the rotator interval mainly limited external rotation of the adducted arm. The coracohumeral ligament played a key role in external rotation as well as in inferior translation.

Adolescent↗