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At least 55 records · Page 3Linked to original sources
PubMed2006

Evaluation of residual rotator cuff defects after in vivo single- versus double-row rotator cuff repairs.

PURPOSE: As arthroscopic rotator cuff surgery has advanced, new techniques have emerged to maximize the biomechanical strength of the repair construct. The double-row repair has been recommended as a means of increasing the contact area of the repaired rotator cuff to the native bone bed. This study attempts to sequentially examine and measure the rotator cuff footprint (in vivo) before cuff repair, after an initial lateral-row repair (before the medial-row sutures are tied), and finally, after the double-row repair. In this way, the rotator cuff footprint of single- and double-row repairs can be quantified and compared. METHODS: Between October 2004 and February 2005, 26 patients were enrolled in the study. These patients had rotator cuff tears that were amenable to double-row repair by means of performing the lateral-row repair before the medial-row repair. After preparation of the greater tuberosity footprint, the native footprint was measured in the medial-to-lateral direction. Next, the medial-row anchors and sutures were passed through the cuff (but not tied), and then the lateral row was secured via suture anchors and the arthroscope was reinserted into the intra-articular space. A depth gauge was introduced through the repaired cuff (lateral row only), and the residual bare footprint was measured. The medial row was then tied, and the cuff was again visualized from the intra-articular position to measure any remaining bare footprint. RESULTS: The mean footprint measured 17.0 +/- 1.9 mm from medial to lateral. After repair of the lateral row, the mean residual uncovered footprint measured 9.0 +/- 2.0 mm. This constituted a 52.7% +/- 9.2% uncovered area after a single lateral-row repair. After the medial row was secured, there were no remaining residual deficits of the cuff footprint. CONCLUSIONS: After an isolated lateral-row repair, 52.7% +/- 9.2% of the rotator cuff footprint remains uncovered. On average, the double-row repair offered over twice the footprint coverage yielded by a single-row repair. CLINICAL RELEVANCE: The arthroscopic shoulder surgeon should be aware of the enhanced footprint coverage offered by double-row rotator cuff fixation as opposed to single-row rotator cuff fixation.

Arthroscopy↗
PubMedDate not supplied

Mini-open rotator cuff repair using a two-row fixation technique: outcomes analysis in patients with small, moderate, and large rotator cuff tears.

Mini-open rotator cuff repair has been used successfully to treat small- and moderate-sized rotator cuff tears but not large tears (>3 cm and <5 cm). We use a 2-row fixation technique of repairing the torn cuff to the humerus. We sought to determine if this technique would produce successful results in patients with larger rotator cuff tears. The results of 75 consecutive patients who underwent arthroscopic subacromial decompression with acromioplasty and mini-open rotator cuff repair were evaluated. All patients were evaluated at a minimum 24 months postoperatively (mean, 27 months). All patients were treated with a mini-open rotator cuff repair using a 2-row fixation technique. Patients were evaluated at follow-up with a focused shoulder examination, Hospital for Special Surgery (HSS) Shoulder Questionnaire, and the University of California Los Angeles (UCLA) Shoulder Rating Scale. There were 49 male and 26 female patients, with a mean age of 54 years (range, 34-72 years). All patients failed a preoperative course of physical therapy and nonoperative management. Thirty patients were found to have a large rotator cuff tear (group I), 35 were found to have a moderate-sized tear (group II), and 10 patients had a small tear (group III) at the time of arthroscopy. There was no statistically significant difference in outcome between groups. The mean UCLA Shoulder Rating Scale for all groups was 33.6/35. Mean HSS Shoulder Questionnaire at follow-up was 91%. The mean time from surgery to full recovery was 7 months. Patient's subjective satisfaction based on their preinjury level of performance at most recent follow-up was 92.6%. Eighty-three percent (74/89) of patients returned to their preinjury activity; 93% of patients reported that they would undergo the procedure again. We believe that mini-open rotator cuff repair using a 2-row fixation technique can yield excellent results in patients with small, moderate, and large rotator cuff tears. There was no detectable difference in outcome between groups at 2-year follow-up on clinical evaluation.

Adult↗
PubMed2001

Sensorimotor adaptation to rotated visual input: different mechanisms for small versus large rotations.

The present study investigates if sensorimotor adaptation to large visual rotations is achieved by a continuous angular change of the internal representation of space. Human subjects performed manual tracking movements under rotated visual feedback in two sessions; the magnitude of rotation in the second session was 45 degrees larger or smaller than in the first. We found mostly a facilitatory effect of the first adaptation on the second, which supports the view that the internal representation can gradually shift from one angular transformation to another. However, no facilitation was found for visual rotations in the 80-120 degrees range, suggesting that the internal model changes gradually only up to a limiting angle. A subsidiary experiment, employing small stepwise changes of visual rotation throughout a testing session, confirmed this view and placed the limiting angle near 120 degrees for an increasing, and near 70 degrees for a decreasing visual rotation. We conclude that adaptation to large-magnitude rotations may be achieved in two stages: a polarity inversion of both axes (=180 degrees rotation), followed by a "backward" shift toward somewhat smaller angles.

Adaptation, Physiological↗
PubMed2006

The role of mental rotation and memory scanning on the performance of laparoscopic skills: a study on the effect of camera rotational angle.

OBJECTIVE: The rotational angle of the laparoscopic image relative to the true horizon has an unknown influence on performance in laparoscopic procedures. This study evaluates the effect of increasing rotational angle on surgical performance. METHODS: Surgical residents (group 1) (n = 6) and attending surgeons (group 2) (n = 4) were tested on two laparoscopic skills. The tasks consisted of passing a suture through an aperture, and laparoscopic knot tying. These tasks were assessed at 15 degrees intervals between 0 degrees and 90 degrees , on three consecutive repetitions. The participant's performance was evaluated based on the time required to complete the tasks and number of errors incurred. RESULTS: There was an increasing deterioration in suturing performance as the degree of image rotation was increased. Participants showed a statistically significant 20-120% progressive increase in time to completion of the tasks (p = 0.004), with error rates increasing from 10% to 30% (p = 0.04) as the angle increased from 0 degrees to 90 degrees. Knot-tying performance similarly showed a decrease in performance that was evident in the less experienced surgeons (p = 0.02) but with no obvious effect on the advanced laparoscopic surgeons. CONCLUSIONS: When evaluated independently and as a group, both novice and experienced laparoscopic surgeons showed significant prolongation to completion of suturing tasks with increased errors as the rotational angle increased. The knot-tying task shows that experienced surgeons may be able to overcome rotational effects to some extent. This is consistent with results from cognitive neuroscience research evaluating the processing of directional information in spatial motor tasks. It appears that these tasks utilize the time-consuming processes of mental rotation and memory scanning. Optimal performance during laparoscopic procedures requires that the rotation of the camera, and thus the image, be kept to a minimum to maintain a stable horizon. New technology that corrects the rotational angle may benefit the surgeon, decrease operating time, and help to prevent adverse outcomes.

Clinical Competence↗
PubMed2004

Joint rotation between two attitudes in the spherical rotation coordinate system.

Three-dimensional joint rotation between two attitudes rather than starting from neutral position is the most common pattern of human movement. This paper presents a method for determining the joint rotations starting from a non-neutral attitude in the spherical rotation coordinate system based on a two-step rotation method. The method uses three spherical rotation angles that are consistent with clinical description of joint rotations and are mathematically proved to be sequence independent. The method can be easily understood by clinicians and applied in clinical practice. Two numerical examples of humeral rotations are presented to demonstrate the effectiveness of the method in dealing with different patterns of three-dimensional joint rotations between two attitudes.

Biomechanical Phenomena↗
PubMed2003

The mid-point of passive hip rotation range is an indicator of hip rotation in gait in cerebral palsy.

This study investigated the strength of any linear relationship between femoral anteversion and passive hip rotations, with rotation of the limb during gait. The data of 29 subjects (38 legs) with cerebral palsy (CP) were reviewed. Passive examination data were correlated with hip rotations during the whole gait cycle, and in stance only. Hip rotation in gait correlated significantly with passive external rotation (r=0.51-0.54), femoral anteversion (r=0.43-0.47), and passive internal rotation (r=0.36-0.41). The mid-point of passive hip rotation range correlated best with hip rotation in the stance phase of gait (r=0.57-0.58).

Adolescent↗
PubMed1991

Rotating the plane of imposed vibration can rotate the plane of flagellar beating in sea-urchin sperm without twisting the axoneme.

When the head of a sea-urchin sperm is held in the tip of a micropipette and vibrated laterally, the flagellum beats in phase with the imposed vibration. Rotation of the plane of pipette vibration around the head axis induces a corresponding rotation of the plane of beating, in both live and reactivated sperm. Detailed analysis of the waveforms occurring at different stages of this rotation shows that the characteristic asymmetry of the flagellar bending waves rotates along with the plane of beat. The positions of small polystyrene beads attached as markers on the axonemes of demembranated sperm flagella appear unaffected by the rotation of the beat plane and asymmetry. The imposed rotation of the waveform is thus the result of a rotation of the coordinated pattern of sliding among the doublet tubules of the axoneme, and is not accompanied by a twisting of the whole axonemal structure. These data indicate that neither the plane of flagellar beat nor the direction of beat asymmetry is tightly dependent upon a structural or chemical specialization of particular members of the nine outer doublet microtubules, but that both are the result of some regulatory structure that can be forced to rotate relative to the outer structure of the axoneme.

Animals↗
PubMed2006

Van der waals interactions and decrease of the rotational barrier of methyl-sized rotators: a theoretical study.

Rotational barriers of methyl-sized molecular rotators are investigated theoretically using ab initio and empirical force field calculations in molecular models simulating various environmental conditions experienced by the molecular rotors. Calculations on neopentane surrounded by methyl groups suggest that the neopentane's methyl rotational potential energy barrier can be reduced by up to an order of magnitude by locating satellite functional groups around the rotator at a geometry that destabilizes the staggered conformation of the rotator through van der Waals repulsive interactions and reduces the staggered/eclipsed relative energy difference. Molecular mechanics and molecular dynamics calculations indicate that this barrier-reducing geometry can also be found in molecular rotators surface mounted on graphite surfaces or carbon nanotube models. In these models, molecular dynamics simulations show that the rotation of methyl-sized functional groups can be catalyzed by van der Waals interactions, thus making very rigid rotators become thermally activated at room temperature. These results are discussed in the context of design of nanostructures and use of methyl groups as markers for microenvironmental conditions.

Journal Article↗
PubMed1992

Mental rotation, physical rotation, and surface media.

Subjects made mirror-normal discriminations on alphanumeric characters shown in different orientations in the picture plane. Either the characters or the background rotated during stimulus presentation in Experiments 1-3. Character rotation in the direction of mental rotation facilitated mental rotation, whereas rotation in the opposite direction inhibited it. In Experiment 4, characters were presented in different surface media so as to stimulate only one representation at a time. Mental rotation performance was similar whether the stimuli were defined by luminance, color, texture, relative motion, or binocular disparity, suggesting that mental rotation occurs at a level beyond that of the independent analyses of these different media. These results support those of Experiments 1-3 in excluding the participation of low-level motion analysis centers in the mental rotation processes.

Adult↗
PubMedDate not supplied

Correlation and quantification of relative 2-dimensional projected vertebral endplate z-axis rotations with 3-dimensional y-axis vertebral rotations and focal spot elevations.

BACKGROUND: The use of lines erected on the vertebral endplates of the anterior-to-posterior radiograph to assess z-axis vertebral rotation is a common clinical practice. OBJECTIVE: To quantify the projection/distortion error of lateral flexion (z-axis rotation) measurement, which results from actual axial (y-axis) rotation and changes in focal spot elevation, on AP radiographs. STUDY DESIGN: A 3-dimensional model of a 4th and 5th lumbar vertebrae was constructed with a computer. The angle between the projected inferior vertebral endplate of the 4th lumbar vertebra, and the projected superior vertebral endplate of the 5th lumbar vertebra was measured. This was done for combinations of 0, 7, 14, and 21 degrees of axial (-y-axis) rotation with 0, 15, and 30 cm of elevation of a modeled focal spot. RESULTS: An angle was produced between the projected inferior 4th lumbar vertebral endplate and the projected superior 5th lumbar vertebral endplate as a result of y-axis rotation of the 3-dimensional model. Increasing magnitudes of y-axis rotation and increasing focal spot elevation produced a lack of confidence in this measurement. CONCLUSION: In a clinical setting, limited ranges of y-axis rotation have little significant effect on the accuracy of this measurement. Increases in y-axis rotation and focal spot elevation can affect measurement accuracy.

Computer-Aided Design↗
PubMed1993

Limits on the comprehension of rotational motion: mental imagery of rotations with oblique components.

Mental imagery of rotational motion across variation in the orientation of a square to an axis of rotation, the orientation of the axis to the environment/viewer, and the starting orientation of the rotation were investigated in three experiments. The experimental method included specifying the particular rotations that subjects should consider and obtaining exact predictions of the outcomes of the rotations. When the square was normal to the axis and the axis was normal to the environment/viewer, performance was excellent. When either of these relationships was oblique, performance was quite good. When both of these relationships were oblique, nearly every subject made large errors on every problem. The difficulty of the double-oblique rotations was reduced when the initial orientation of the square was not canonical. Current views of the comprehension of rotational motion are discussed. It appears that the comprehension of rotational motion can be understood as an organizaiton of the symmetric space traced out by the motion. People succeed in organizing this space when it is aligned with a principal spatial reference system.

Adult↗
PubMed2004

Job rotation in nursing: a study of job rotation among nursing personnel from the literature and via a questionnaire.

AIMS: To obtain information on job rotation among nursing personnel from the literature and via a questionnaire. BACKGROUND: A nursing career no longer means a series of steps leading up a hierarchy. It has become more like a process of individual growth, involving improvement of employee expertise and skills. Job rotation in connection with career development in a Finnish hospital is considered essential, and participating in job rotation is one requirement for newly vacant nursing posts. METHODS: Describing job rotation by means of reference to literature, and studying a survey on attitudes of ophthalmic nurses (n = 84) to job rotation. RESULTS: There has been little theoretical or empirical research on job rotation. In this study, one in three had participated in job rotation that was most often considered a positive experience. Self-development was rated substantially useful, but fewer were interested in participating in various kinds of developmental activities. CONCLUSION: Employee's motivation is the foundation of successful development activity, e.g. job rotation.

Adult↗
PubMed2001

Cognitive subprocesses of mental rotation: why is a good rotator better than a poor one?

The Vanderberg-Kuse Mental Rotation Test is a standard test of mental rotation ability. Recent experiments have demonstrated that mental rotation is a complex cognitive process wherein different subprocesses (focused attention, visual scanning, perceptual decision, visual memory) play important roles in performance. We classified the population as good and poor rotators by performance of mental rotation (ns = 47: 22 men and 25 women, respectively; mean age: 20.7 yr.). To examine differences cognitive subprocesses of mental rotation of these two groups were compared. There were significant differences between poor and good rotators in performance on Raven's test and the Pieron Focused Attention test scores. The good rotators scored better because their perceptual decision-analytical intelligence (Raven) and focused attention scores were higher.

Adult↗
PubMed1983

[Evaluation of the rotational deformity in scoliosis. II. Application of laser torsography to the follow-up of the clinical course of rotation deformity during treatment].

In the previous paper (part I), a new approach which makes it possible to evaluate the rotational deformity of scoliosis both qualitatively and quantitatively was proposed and named Laser Torsography. In the present paper this new method is applied to observation of clinical courses of scoliotic patients in order to demonstrate changeability of the rotational deformity during treatment. Thirty-five idiopathic scoliotic patients were treated conservatively (5 cases: observation only, 30 cases: brace treatment) and effects of the treatment were evaluated by means of roentgenographic examination (Cobb method) and Laser Torsography at average intervals of 15 months and the attitude of the rotation deformity was compared with that of the lateral flexion deformity. The results show that in more than half of the cases the prognosis of the rotation deformity differed from the lateral flexion deformity. Consequently the importance of measuring the rotation deformity separately should be emphasized. Seventeen scoliotic patients were treated surgically and correctability of the rotation deformity was assessed by comparing preoperative and postoperative Laser Torsography. Out of them there are 10 cases on which Harrington instrumentation with DTT were performed. The effects of this procedure on rotation were as follows: little improvement or adverse effect in 6 cases, moderate improvement in 3 cases and remarkable improvement in one case. It is expected from this investigation that Laser Torsography will play an important role in the therapeutic occasion of scoliosis as an indispensable diagnostic tool for the estimation of the rotational deformity.

Adolescent↗
PubMed2000

Association of intramuscular cysts of the rotator cuff with tears of the rotator cuff: magnetic resonance imaging findings and clinical significance.

Cystic lesions that arise adjacent to the shoulder have been reported in association with labral tears or as an unusual manifestation of massive rotator cuff tears. The purpose of this study was to define the relationship between intramuscular cysts of the rotator cuff and tears of the rotator cuff. Thirteen cases of intramuscular cysts of the rotator cuff were identified on magnetic resonance imaging of the shoulder and analyzed retrospectively along with the clinical data. Surgical findings were retrospectively reviewed in 5 patients who underwent follow-up arthroscopy. This series shows that intramuscular cysts of the rotator cuff are associated with small, full-thickness tears or partial undersurface tears of the rotator cuff. These cysts are easily identified on T2-weighted sequences and, when present, should always prompt a thorough search for associated rotator cuff pathology.

Aged↗
PubMed2002

Effect of rotator cuff exercise on humeral rotation torque in healthy individuals.

Conservative management of rotator cuff pathology often involves certain therapeutic exercises. Although a major goal of these exercises is to increase strength of the rotator cuff, little empirical evidence supports this assertion. In this study, 34 nonpathologic young adults were pretested using a LIDO Multijoint II isokinetic device for average and peak torque generated during internal and external rotation. Subjects were arbitrarily assigned to a right-arm- or left-arm-trained group, exercised for 4 weeks, and then posttested for changes in humeral rotation torque. Moderate but significant increases in torque (8-10%) as well as in total work done were observed in both groups, only in the trained arm. Subjects who trained the nondominant (left) arm experienced gains similar to those who trained the right arm. Gains were significant in the case of both internal and external rotation (also average as well as peak torque), with men and women experiencing the same relative increases. These data, in addition to supporting the use of selected exercises to increase humeral rotation torque in a healthy population, offer a potential model for the rehabilitation of patients with rotator cuff injury.

Adult↗
PubMed1983

Compensatory eye movement and gaze fixation upon passive head- and body rotation and active head rotation.

To detect differences in compensatory eye movement and gaze fixation, normal subjects and patients with bilateral loss of labyrinthine functions were subjected to passive head-and-body rotation and performed active head rotation. In normal subjects, there was no difference between passive and active rotation with respect to compensatory eye movement in the dark and spatial gaze fixation; on the other hand, the ability to gaze fixedly on a head-fixed target was better during passive than active rotation. In our patients, the findings obtained upon passive rotation resembled those already reported for active rotation, indicating that observing compensatory eye movements and gaze fixation during passive rotation is useful in the detection of disorders of the vestibulo-ocular reflex.

Adult↗
PubMed1987

Varus-valgus and rotational stability in rotationally unconstrained total knee arthroplasty.

This study was designed to test the ability of the ligaments to restore rotational stability to the knee after rotationally unconstrained anterior cruciate-sacrificing total knee arthroplasty (TKA). Rotational and varus-valgus stability both were returned to near-normal values, and the normal screw home pattern of coupled external rotation with extension was restored when the ligaments were correctly tensioned. When the ligaments were tensioned so that the knee was either too loose or too tight, both varus-valgus and rotational laxity were affected equally. Rotational constraint is not necessary in a TKA system to achieve normal rotational stability of the knee, as long as normal varus-valgus stability is restored.

Humans↗