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At least 19 recordsLinked to original sources

PubMed1986

Rotation of dielectrics in a rotating electric high-frequency field. Model experiments and theoretical explanation of the rotation effect of living cells.

Model experiments are carried out to clarify the mechanism of rotation of living cells in a rotating electric field. According to classical investigations of the rotation of macroscopic bodies in external fields, the rotation of spherical glass vessels or metal cylinder filled with electrolyte solutions was investigated. The relation of the calculations of Lertes (1921a,b) to the recent paper of Arnold and Zimmerman (1982) and our new derivations lead to equations explaining the rotation of objects. The results are compared with measurements using mesophyll protoplasts and data from the literature.

Cell Movement↗

PubMed2005

Development of rotating liquid membrane disk electrode and rotating liquid membrane ring-liquid membrane disk electrode and evaluation of characteristics of ion transfer reactions at the rotating aqueous/organic solution interface.

A liquid membrane disk electrode, LMDE, and a liquid membrane ring-liquid membrane disk electrode, LMRE-LMDE, were developed by placing a gelled polyvinyl chloride thin membrane impregnated with 2-nitrophenyl octyl ether, NPOE-LM, on the surface of a glassy carbon, GC, disk or ring electrode. The voltammogram for the ion transfer at the interface between an aqueous solution, W, and NPOE-LM was recorded by setting the developed electrode in W and rotating at a rate, omega, between 0 and 4000 rpm. The sensitivity of the ion-transfer current at the WINPOE-LM interface, I, was enhanced to be more than 100 times better than that at the WINPOE (solution) interface when LMDE was rotated at omega higher than 200 rpm. The reversibility of the ion transfer reaction could be evaluated based on the dependence of I on omega of LMDE, and the reaction product at LMDE could be identified at LMRE when the rotating LMRE-LMDE system was adopted.

Journal Article↗

PubMedDate not supplied

A spherical rotation coordinate system for the description of three-dimensional joint rotations.

Three-dimensional joint rotations in human movement analysis have been mainly described by Euler/Cardan angles. Due to sequence dependence, each combination of three Euler/Cardan angles defines a single pattern of joint rotation. When the rotation pattern is unknown, it needs to be considered using a particular sequence of Euler/Cardan angles to represent joint rotations. In this paper a spherical rotation coordinate system is developed for describing three-dimensional joint rotations using a method of rotation involving two steps: a long axis rotation and a pure axial rotation. Two angles of the classical spherical coordinate system--longitude and latitude--are used to describe long axis rotations in this newly proposed coordinate system. The spherical rotation coordinate system uses a radial rotation angle to describe pure axial rotation of a limb segment whereas the classical spherical coordinate system uses a radial displacement to describe motion of a point. An application of the spherical rotation coordinate system is given to define three-dimensional rotations of the glenohumeral joint. A mathematical proof shows that the long axis rotation and axial rotation are sequence independent. Two numerical examples are investigated which demonstrate that the spherical rotation angles can be uniquely determined in both forward and inverse kinematics without considering sequences rotations.

Biomedical Engineering↗

PubMed2006

[Initial results of shoulder MRI in external rotation after primary shoulder dislocation and after immobilization in external rotation].

PURPOSE: A change in the strategy for treating primary anterior traumatic dislocation of the shoulder has occurred. To date, brief fixation of internal rotation via a Gilchrist bandage has been used. Depending on the patient's age, a redislocation is seen in up to 90 % of cases. This is due to healing of the internally rotated labrum-ligament tear in an incorrect position. In the case of external rotation of the humerus, better repositioning of the labrum ligament complex is achieved. Using MRI of the shoulder in external rotation, the extent of the improved labrum-ligament adjustment can be documented, and the indication of immobilization of the shoulder in external rotation can be derived. The aim of this investigation is to describe the degree of position changing of the labrum-ligament tear in internal und external rotation. MATERIALS AND METHODS: 10 patients (9 male, 1 female, mean age 30.4 years, range 15 - 43 years) with a primary anterior dislocation of the shoulder without hyper laxity of the contra lateral side and labrum-ligament lesion substantiated by MRI were investigated using a standard shoulder MRI protocol (PD-TSE axial fs, PD-TSE coronar fs, T2-TSE sagittal, T1-TSE coronar) by an axial PD-TSE sequence in internal and external rotation. The dislocation and separation of the anterior labrum-ligament complex were measured. The shoulders were immobilized in 10 degrees external rotation for 3 weeks. After 6 weeks a shoulder MRI in internal rotation was performed. RESULTS: In all patients there was a significantly better position of the labrum-ligament complex of the inferior rim in external rotation, because of the tension of the ventral capsule and the subscapular muscle. In the initial investigation, the separation of the labrum-ligament complex in internal rotation was 0.44 +/- 0.27 mm and the dislocation was 0.45 +/- 0.33 mm. In external rotation the separation was 0.01 +/- 0.19 mm and the dislocation was - 0.08 +/- 0.28 mm. After 6 weeks of immobilization in 10 degrees external rotation, the separation of the labrum was - 0.10 +/- 0.14 mm and the dislocation was - 0.23 +/- 0.21 mm. CONCLUSION: In anterior labrum-ligament tears, the axial MRI of the shoulder in external rotation demonstrates a more physiologic position of the glenoid. This may indicate an immobilization of the shoulder in external rotation, which results in a more anatomical healing of the glenoidal tear. Thus, in the case of labrum-ligament tears, MRI in external rotation is becoming indispensable.

Adolescent↗

PubMed2006

Torque and EMG in rotation extension of the torso from pre-rotated and flexed postures.

BACKGROUND: Back injury is a common place in our society. Up to two-thirds of back injuries have been associated with trunk rotation. However, the torque production ability with a rotated spine and electromyographic activity of trunk muscles in such efforts is poorly understood. Therefore, the objectives of this study are to study torque production capacity of variously rotated and flexed trunk and to measure the EMG of selected trunk muscles in these activities. METHODS: Nineteen normal young subjects (7 males and 12 females) were recruited. Subjects were stabilized on a posture-stabilizing platform and were instructed to assume a flexed and right rotated posture (20 degrees , 40 degrees and 60 degrees of rotation and 20 degrees , 40 degrees and 60 degrees of flexion) in a random order. The subjects were asked to exert their maximal voluntary contraction in the asymmetric plane of rotation-extension for a period of 5s. The surface EMG of the external and internal obliques, rectus abdominis, latissimus dorsi, erector spinae at the 10th thoracic and 3rd lumbar vertebral levels was recorded bilaterally along with the torque generated. FINDINGS: Whereas the torque generated was significantly affected by both rotation and extension in both genders (P<0.001), the EMG was independent of rotation but affected by flexion in females only (P<0.01). The torques produced by both genders in each of the nine postures was significantly different from each other (P<0.001). The EMG demonstrated a trend of increase with increasing rotation and flexion. The response surfaces of normalized peak EMG of the right external oblique and internal oblique was somewhat similar, indicating a rotator torque and a stabilizing effect. The left latissimus dorsi and right external oblique provided the rotational torque and the right erector spinae provided the extensor effort. Since the rotation-extension was performed in the plane of asymmetry, the effort required the recruitment of muscles involved in left rotation, stability of rotated spine and an extensor effort. INTERPRETATION: The torque production capacity of the human trunk is posture dependent and declines with increasing rotation. However, with increasing rotation and flexion, the magnitude of EMG increases. This implies that with increasing asymmetry, it requires more muscle effort (thus tissue stress) to generate less torque. Increasing asymmetry tends to weaken the system and may enhance chances of injury.

Abdomen↗

PubMed1988

Body-rotation induced analgesia in male mice: effects of duration and type of rotation procedure.

The effects of body-rotation in a horizontal plane on the nociceptive responses of male mice were examined. In the first experiment the mice were rotated (70 rpm, schedule of 15 sec on; 5 sec off) for 30 minutes or exposed to sham rotation. The animals were then placed on a warm surface (47.5 degrees C) and their latency to show a foot-licking response was measured. Immediately after the preceding rotation procedure a trend toward a significant increase in response latencies, indicative of analgesia, was observed (p = 0.057). However, if tested 30 minutes after the end of the rotation period, no analgesia could be demonstrated (p greater than 0.50). In Experiment 2 mice were rotated (15 sec on; 5 sec off) or sham rotated for durations of 60 or 90 minutes. Response latencies were significantly elevated (p less than 0.01) after both rotation durations, but not differentially so (p greater than 0.20). In the last experiment the effects of 60 minutes of the intermittent rotation procedure (15 sec on; 5 sec off) were compared to those of 60 minutes of continuous rotation. Both types of rotation resulted in the induction of analgesia and the intermittent procedure produced a significantly greater degree of analgesia than the continuous rotation (p less than 0.05). These experiments demonstrate that 60 to 90 minutes of body-rotation can produce a significant "stress-induced" analgesia in mice and that an intermittent schedule of rotation is more effective than a continuous rotation exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗

PubMed2004

Spinal shape changes resulting from scoliotic spine surgical instrumentation expressed as intervertebral rotations and centers of rotation.

This paper reports the changes in spinal shape resulting from scoliotic spine surgical instrumentation expressed as intervertebral rotations and centers of rotation. The objective is to test the hypothesis that the type of spinal instrumentation system (Cotrel-Dubousset versus Colorado) does not influence these motion parameters. Intervertebral rotations and centers of rotation of the scoliotic spines were computed from the pre- and post-operative radiographs of 82 patients undergoing spinal correction. The three-dimensional (3D) reconstruction of six anatomical landmarks was achieved for each of the thoracic and lumbar vertebrae. A least-squares approach based on singular value decomposition was used to calculate the rigid body transformation parameters. Average centers of rotation for all intervertebral levels are located in the neural canal at the mid-sagittal plane and approximately at the superior endplate level of the inferior vertebra. Intervertebral rotations have components in all planes: 6.7 degrees (frontal), 5.5 degrees (sagittal) and 4.5 degrees (transverse) RMS for all intervertebral levels. Nearly all intervertebral rotations and centers of rotation are not significantly different for the two instrumentation systems. Various intervertebral rotations and 3D reconstruction errors were simulated on a theoretical model of a lumbar functional unit to assess the proposed method. Intervertebral rotation errors were 1.7 degrees when simulating 3D errors of 3mm on the position of the landmarks. Maximum errors for the position of centers of rotation were below 1cm in the case of intervertebral rotations larger than 2.5 degrees (most cases), but were larger (38 mm) for small intervertebral rotations (<1 degrees ). The type of instrumentation system did not influence intervertebral rotations and centers of rotation. These results provide valuable data for the development and validation of simulation models for surgical instrumentation of idiopathic scoliosis.

Adult↗

PubMed1978

Nocturnal rotation in normal rats: correlation with amphetamine-induced rotation and effects of nigrostriatal lesions.

Normal unoperated rats were observed to rotate (turn in circles) at night. For most (91.7%) rats, the preferred direction of rotation was consistent across hours and days and was the same as the direction of rotation elicited by D-amphetamine (1.0 mg/kg) during the day. The magnitudes of nocturnal and D-amphetamine-induced rotation were also highly correlated. After rats showed stable diurnal patterns of rotation, unilateral lesions were made in either the substantia nigra, the nigrostriatal bundle or the caudate nucleus. All lesions produced transient contralateral rotation within the first 24-48 h after surgery. The time-course of this contralateral rotation was more prolonged after nigral lesions than after nigrostriatal bundle lesions and least after caudate lesions, suggesting that the duration of a degeneration release of dopamine is proportional to the length of the degenerating axon. Lesion size was correlated with the intensity of contralateral rotation but not with the time-course. At each rostralcaudal level, the magnitude of contralateral rotation was greater if the lesion was in the side of the brain opposite to the preoperative direction of rotation than if in the same side. By three days after surgery, all rats returned to a mostly normal diurnal cycle with the direction of rotation now being ipsilateral to the lesion. D-Amphetamine potentiated the ipsilateral rotation, though rats with lesions in the same side of the brain as the preoperative direction of rotation had larger drug responses than rats with similar lesions in the opposite side of the brain. By one month after surgery, the direction of spontaneous rotation of most rats had returned to the preoperative direction. As at all other times, the magnitude of rotation was, in part, dependent on the side of the lesion with respect to the preoperative bias. It is suggested that, following a unilateral lesion, compensatory processes occur to a greater extent if the lesion is in the normally more active side of the brain.

Animals↗

PubMed2004

Early and late clinical outcomes after rotational atherectomy with stenting versus rotational atherectomy with balloon angioplasty for complex coronary lesions.

Limited data are available on the effect of rotational atherectomy plus stenting versus rotational atherectomy plus balloon angioplasty for complex coronary lesions. We compared the early and late clinical outcomes between rotational atherectomy plus stenting (158 patients, 171 lesions) and rotational atherectomy plus balloon angioplasty (165 patients, 186 lesions) for complex lesions. Baseline characteristics were similar between the two groups. The procedural success rate was similar between the 2 groups (94% in rotational atherectomy plus stenting versus 96% in rotational atherectomy plus balloon angioplasty; p = 0.54). There were no significant differences in the in-hospital complications between the 2 groups. During mean follow-up of 40.4 +/- 20.2 months, fourteen patients died: 6 in rotational atherectomy plus stenting and 8 in rotational atherectomy plus balloon angioplasty. Target lesion revascularization was similar between the 2 groups (20% in rotational atherectomy plus stenting versus 24% in rotational atherectomy plus balloon angioplasty; p = 0.46). Three-year event (death, nonfatal myocardial infarction and target lesion revascularization)-free survival rate was 79 +/- 4% in the rotational atherectomy plus stenting group and 75 +/- 3% in the rotational atherectomy plus balloon angioplasty group (p = 0.44). In conclusion, rotational atherectomy followed by stenting or balloon angioplasty is associated with favorable long-term outcomes. Compared with rotational atherectomy plus balloon angioplasty, routine stenting after rotational atherectomy does not provide additional benefits in the clinical outcomes in complex coronary lesions.

Angioplasty, Balloon, Coronary↗

PubMed2005

Visual information processing in the lion-tailed macaque (Macaca silenus): mental rotation or rotational invariance?

Mental rotation is a widely accepted concept indicating an image-like mental representation of visual information and an analogue mode of information processing in certain visuospatial tasks. In the task of discriminating between image and mirror-image of rotated figures, human reaction times increase with the angular disparity between the figures. In animals, tests of this kind yield inconsistent results. Pigeons were found to use a time-independent rotational invariance, possibly indicating a non-analogue information processing system that evolved in response to the horizontal plane of reference birds perceive during flight. Despite similar ecological demands concerning the visual reference plane, a sea lion was found to use mental rotation in similar tasks, but its processing speed while rotating three-dimensional stimuli seemed to depend on the axis of rotation in a different way than found for humans in similar tasks. If ecological demands influence the way information processing systems evolve, hominids might have secondarily lost the ability of rotational invariance while retreating from arboreal living and evolving an upright gait in which the vertical reference plane is more important. We therefore conducted mental rotation experiments with an arboreal living primate species, the lion-tailed macaque. Performing a two-alternative matching-to-sample procedure, the animal had to decide between rotated figures representing image and mirror-image of a previously shown upright sample. Although non-rotated stimuli were recognized faster than rotated ones, the animal's mean reaction times did not clearly increase with the angle of rotation. These results are inconsistent with the mental rotation concept but also cannot be explained assuming a mere rotational invariance. Our study thus seems to support the idea of information processing systems evolving gradually in response to specific ecological demands.

Animals↗

PubMed2001

Torque and EMG in isometric graded flexion-rotation and extension-rotation.

The main objective of the study was to measure the magnitude and pattern of electromyographic (EMG) activity of the trunk muscles in combined motions of flexion-rotation and extension-rotation. Another objective of the study was to determine the torque-EMG Root Mean Square (RMS) relationship in these activities for predictive purposes. Nineteen normal young adult subjects who met the inclusion criteria were fitted with 12 pairs of surface electrodes on their external and internal oblique, rectus abdominis, latissimus dorsi, and erector spinae muscles at T10 and L3 levels bilaterally. Using a Posture Stabilizing Platform (PSP) they were fixed in 40 degrees flexed and 40 degrees right rotated trunk postures. From this posture subjects attempted an isometric extension-rotation and flexion-rotation in the plane defined by the asymmetrical postural axis in the plane of rotation of the assumed posture. Contractions of 25, 50 and 75% of the previously measured maximal voluntary contraction (MVC) were attempted using a Static Dynamic Strength Tester (SDST) and force monitor attached by a steel cable to a rigid thoracic harness worn by the subjects. The data were acquired at 1 kHz. Descriptive statistics were calculated and ANOVA, correlation and regression analyses were carried out. With linear increase in flexion-rotation and extension-rotation torque, the magnitude of total EMG output increased exponentially. In flexion-rotation the EMG magnitude of all muscles increased with increasing grades of contraction (% of MVC). However, in proportional terms, the magnitude of erector spinae EMG declined. In extension-rotation there was a reversal of roles between the ventral and dorsal muscles compared to the flexion-rotation. For the two genders, all muscles and grades of contractions were significantly different from each other (p<0.01). There was a significant but modest correlation between EMG and torque (r = 0.25 to 0.54; p<0.01). The regressions were significant (p<0.01) and explained up to 74% of the variance in torque. The flexion-rotation and extension-rotation torques can be predicted with only a moderate accuracy.

Abdominal Muscles↗

PubMed2002

Isometric axial rotation of the human trunk from pre-rotated postures.

The purpose of this investigation was to study the torque and electromyogram (EMG) in axial rotation from pre-rotated postures. A group of 50 young adults (27 men and 23 women) volunteered for the study. These prepared subjects carried out axial rotation with pre-rotated postures in the direction of pre-rotation and away from it. Torque and EMG were recorded bilaterally from latissimus dorsi, erector spinae at L(3) and T(10) levels, pectoralis, rectus abdominis, external and internal oblique. In 15 degrees pre-rotated posture the axial rotation in the direction of pre-rotation reduced the torque by between 11% and 17% and away from it increased the torque by 12% to 16%. In 30 degrees pre-rotated posture the decrement in torque in the direction of pre-rotation was 24%-33%, and in the opposite direction the gain was between 21% and 32%. Even with decreased torque with rotation in the pre-rotation direction the EMG increased up to 123%. The EMG magnitude and slopes of EMG in these activities demonstrated significant increases while in the opposite direction slight decreases were observed. The EMG of each muscle was significantly different from all other muscles ( P<0.001). A significant ( P<0.01) but low correlation between EMG and torque was obtained. Significant linear regressions between torque and EMG of different muscles were obtained ( P<0.01; r=up to 0.70).

Adolescent↗

PubMed2001

Rotational moment arms of the medial hamstrings and adductors vary with femoral geometry and limb position: implications for the treatment of internally rotated gait.

Persons with cerebral palsy frequently walk with a crouched, internally rotated gait. Spastic medial hamstrings or adductors are presumed to contribute to excessive hip internal rotation in some patients; however, the capacity of these muscles to produce internal rotation has not been adequately investigated. The purpose of this study was to determine the hip rotation moment arms of the medial hamstrings and adductors in persons with femoral anteversion deformities who walk with a crouched, internally rotated gait. A musculoskeletal model with a "deformable" femur was developed. This model was used, in conjunction with kinematic data obtained from gait analysis, to calculate the muscle moment arms for combinations of joint angles and anteversion deformities exhibited by 21 subjects with cerebral palsy and excessive hip internal rotation. We found that the semimembranosus, semitendinosus, and gracilis muscles in our model had negligible or external rotation moment arms when the hip was internally rotated or the knee was flexed -- the body positions assumed by the subjects during walking. When the femur was excessively anteverted, the rotational moment arms of the adductor brevis, adductor longus, pectineus, and proximal compartments of the adductor magnus in our model shifted toward external rotation. These results suggest that neither the medial hamstrings nor the adductors are likely to contribute substantially to excessive internal rotation of the hip and that other causes of internal rotation should be considered when planning treatments for these patients.

Adolescent↗

PubMed2003

The dynamic behavior of bacterial macrofibers growing with one end prevented from rotating: variation in shaft rotation along the fiber's length, and supercoil movement on a solid surface toward the constrained end.

BACKGROUND: Bacterial macrofibers twist as they grow, writhe, supercoil and wind up into plectonemic structures (helical forms the individual filaments of which cannot be taken apart without unwinding) that eventually carry loops at both of their ends. Terminal loops rotate about the axis of a fiber's shaft in contrary directions at increasing rate as the shaft elongates. Theory suggests that rotation rates should vary linearly along the length of a fiber ranging from maxima at the loop ends to zero at an intermediate point. Blocking rotation at one end of a fiber should lead to a single gradient: zero at the blocked end to maximum at the free end. We tested this conclusion by measuring directly the rotation at various distances along fiber length from the blocked end. The movement of supercoils over a solid surface was also measured in tethered macrofibers. RESULTS: Macrofibers that hung down from a floating wire inserted through a terminal loop grew vertically and produced small plectonemic structures by supercoiling along their length. Using these as markers for shaft rotation we observed a uniform gradient of initial rotation rates with slopes of 25.6 degrees /min. mm. and 36.2 degrees /min. mm. in two different fibers. Measurements of the distal tip rotation in a third fiber as a function of length showed increases proportional to increases in length with constant of proportionality 79.2 rad/mm. Another fiber tethered to the floor grew horizontally with a length-doubling time of 74 min, made contact periodically with the floor and supercoiled repeatedly. The supercoils moved over the floor toward the tether at approximately 0.06 mm/min, 4 times faster than the fiber growth rate. Over a period of 800 minutes the fiber grew to 23 mm in length and was entirely retracted back to the tether by a process involving 29 supercoils. CONCLUSIONS: The rate at which growing bacterial macrofibers rotated about the axis of the fiber shaft measured at various locations along fibers in structures prevented from rotating at one end reveal that the rate varied linearly from zero at the blocked end to maximum at the distal end. The increasing number of twisting cells in growing fibers caused the distal end to continuously rotate faster. When the free end was intermittently prevented from rotating a torque developed which was relieved by supercoiling. On a solid surface the supercoils moved toward the end permanently blocked from rotating as a result of supercoil rolling over the surface and the formation of new supercoils that reduced fiber length between the initial supercoil and the wire tether. All of the motions are ramifications of cell growth with twist and the highly ordered multicellular state of macrofibers.

Bacillus subtilis↗

PubMed2001

Influence of rotational inertia on turning performance of theropod dinosaurs: clues from humans with increased rotational inertia.

The turning agility of theropod dinosaurs may have been severely limited by the large rotational inertia of their horizontal trunks and tails. Bodies with mass distributed far from the axis of rotation have much greater rotational inertia than bodies with the same mass distributed close to the axis of rotation. In this study, we increased the rotational inertia about the vertical axis of human subjects 9.2-fold, to match our estimate for theropods the size of humans, and measured the ability of the subjects to turn. To determine the effect of the increased rotational inertia on maximum turning capability, five subjects jumped vertically while attempting to rotate as far as possible about their vertical axis. This test resulted in a decrease in the average angle turned to 20 % of the control value. We also tested the ability of nine subjects to run as rapidly as possible through a tight slalom course of six 90 degrees turns. When the subjects ran with the 9.2-fold greater rotational inertia, the average velocity through the course decreased to 77% of the control velocity. When the subjects ran the same course but were constrained as to where they placed their feet, the average velocity through the course decreased to 65 % of the control velocity. These results are consistent with the hypothesis that rotational inertia may have limited the turning performance of theropods. They also indicate that the effect of rotational inertia on turning performance is dependent on the type of turning behavior. Characters such as retroverted pubes, reduced tail length, decreased body size, pneumatic vertebrae and the absence of teeth reduced rotational inertia in derived theropods and probably, therefore, improved their turning agility. To reduce rotational inertia, theropods may have run with an arched back and tail, an S-curved neck and forelimbs held backwards against the body.

Animals↗

PubMed2006

Scapular angular positioning at end range internal rotation in cases of glenohumeral internal rotation deficit.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: Investigate the relationship between glenohumeral internal rotation range-of-motion deficit and 3-dimensional scapular angular positioning during active arm movements in participants with recent participation in overhead sports activity. BACKGROUND: Subacromial impingement is one of the most common shoulder pathologies and is multifactorial in etiology. Posterior glenohumeral joint capsule tightness has been theorized to contribute to one potential causal factor: abnormal scapular positioning. METHODS AND MEASURES: Twenty-three subjects, who had participated in competitive sports involving overhead activity within the last 5 years, were categorized into 2 groups based on the degree of glenohumeral internal rotation deficit (20% deficit threshold). Scapular angular positioning of subjects performing shoulder internal rotation from 90 degrees flexion and abduction shoulder positions was evaluated using 3-dimensional electromagnetic surface tracking. Additional sensors monitored trunk and humeral motion. Scapular position data at end range glenohumeral internal rotation, along with glenohumeral internal rotation range of motion measurements, were used to analyze the relationship between glenohumeral internal rotation deficit and scapular position using 2-way ANOVA and regression analyses. RESULTS: The internal rotation deficit group had significantly greater scapular anterior tilt (9.2 degrees difference, P = .04) across positions, as compared to the control group. Regression analysis demonstrated a significant association between glenohumeral internal rotation deficit and scapular position (tilting) during flexed internal rotation (r(2) = 0.37, P = .03) and for scapular position (anterior tilting and upward rotation) during abducted internal rotation (r = 0.35, P = .036). CONCLUSIONS: These findings demonstrate a significant relationship between glenohumeral internal rotation deficit and abnormal scapular positioning, particularly increased anterior tilt. This relationship identifies a possible mechanism for development of excessive scapular anterior tilt.

Adult↗

PubMed2005

Matrix molecule mRNA levels in the bursa and rotator cuff of patients with full-thickness rotator cuff tears.

PURPOSE: The purpose of this study was to evaluate at the mRNA level a subset of extracellular matrix molecules relevant during healing and remodeling of rotator cuff tears. TYPE OF STUDY: Controlled laboratory study. METHODS: Bursal and rotator cuff tissue from the margin of the rotator cuff tear were harvested from 10 patients (mean age, 57.5 +/- 7.3 years) undergoing surgical repair of full-thickness rotator cuff tears. There were six male and four female patients with a mean duration of symptoms of 14.6 months (range, 2 to 60 months). The mean tear size was 4.4 cm. In addition, tissue was obtained from 6 cadaveric specimens with no gross evidence of rotator cuff tearing. Reverse transcription polymerase chain reaction (RT-PCR) was performed for type I, II, and III collagen, biglycan, decorin, and aggrecan, and normalized to the housekeeping gene GAPDH. RESULTS: RT-PCR showed that both the bursa and rotator cuff margin had increased mRNA levels for type I and type III collagen in patients with full-thickness rotator cuff tears when compared with normal cadaveric controls. In addition, there was a significant decrease in decorin mRNA levels and an increase in aggrecan mRNA levels in the rotator cuff margin of torn rotator cuff tendons when compared with normal cadaveric controls. CONCLUSIONS: These results suggest that both the bursa and rotator cuff margin of patients with rotator cuff tears are actively remodeling after injury and that both tissues may potentially contribute to the healing process following repair. CLINICAL RELEVANCE: These findings may help clinicians determine what aspects of the repair process can be manipulated to affect optimal ruptured tendon repair.

Bursa, Synovial↗

PubMedDate not supplied

Activation of the rotator cuff in generating isometric shoulder rotation torque.

This study compared and quantified electromyographic muscle activation of the rotator cuff with the isometric torque generated by performing shoulder rotation in various positions. Twenty healthy volunteers were tested in 29 shoulder positions. Using a Cybex II dynamometer synchronously with electromyography, surface electrodes were placed over the pectoralis major muscle and three parts of the deltoid muscle. Intramuscular wire electrodes were inserted into the four rotator cuff muscles. We found that the greatest external rotation isometric force is generated in the frontal and scapular planes in the neutral or full internal rotation positions. The sagittal, dependent, and the scapular plane with 45 degrees of elevation in rotational positions of either full or half external rotation generated the greatest torques for internal rotation isometric force. The rotator cuff muscles generated greatest electromyographic activity in neutral to midrotational positions. The scapular plane with 90 degrees of shoulder elevation in neutral rotation best isolated the subscapularis muscle. The infraspinatus-teres minor muscles were isolated in the sagittal plane with 90 degrees of shoulder elevation in a half externally rotated position. We were unable to isolate the supraspinatus muscle in any of these tested positions. These positions are recommended for manual muscle testing and for strengthening these muscles.

Adult↗