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PubMed2002

Spine-rib rotation differences at the apex in preoperative patients with adolescent idiopathic scoliosis: evaluation of a three-level ultrasound method.

This paper evaluates a new real-time ultrasound method to assess the difference between axial spinal (laminal) rotation and rib rotation at the apex of the scoliosis curve. An Aloka SSD 500 portable ultrasound machine with a veterinary long (172mm) 3.5 MHz linear array transducer was used to assess the reproducibility of the method in 13 preoperative patients with AIS. With the subject in a prone position and her head supported, readings of laminal and rib rotation were made directly on the back at 18 and 12 levels respectively The subject was repositioned after walking around the room and a second set of spinal and rib rotations obtained (repeats). All the readings were made by one observer (ASK). After plotting on graphs three levels of maximal difference between spine rotation and rib rotation about the apex were chosen visually by one observer (RGB) for which the mean apical spine-minus-rib rotation difference (SRRD) was calculated for each repeat. Findings for apical SRRDs. The mean apical SRRDs for the two repeats are 7.1 degrees and 6.9 degrees (range 2-18 degrees) with coefficients of variation of 49% and 62% respectively. Reproducibility. Graphic representation of spinal and rib rotation by 12 levels shows a fairly good agreement between repeats for most subjects. Spinal rotation is always greater than rib rotation. A paired t-test for the mean apical SRRD of the repeats shows no significant difference. Linear regression analysis of the mean apical SRRD repeats correlate significantly (r=0.70, P=0.008) with a residual mean square of 6.9 degrees (rms = 2.6 degrees). The technical error of the measurement (TEM) is 2.3 degrees and coefficient of reliability (R) 0.66. Conclusions. Real-time ultrasound can assess the difference between spinal and rib rotation about the apex of the scoliosis curve without the altered position detectably affecting the findings. The error (2-3 degrees) is high relative the mean apical SRRD (6-7 degrees). The apical SRRD findings have relevance to the pathogenesis of AIS.

Adolescent↗
PubMed2005

MRI of rotator cuff muscle atrophy in relation to glenohumeral joint incongruence in brachial plexus birth injury.

PURPOSE: To evaluate rotator cuff muscles and the glenohumeral (GH) joint in brachial plexus birth injury (BPBI) using MRI and to determine whether any correlation exists between muscular abnormality and the development of glenoid dysplasia and GH joint incongruity. MATERIALS AND METHODS: Thirty-nine consecutive BPBI patients with internal rotation contracture or absent active external rotation of the shoulder joint were examined clinically and imaged with MRI. In the physical examination, passive external rotation was measured to evaluate internal rotation contracture. Both shoulders were imaged and the glenoscapular angle, percentage of humeral head anterior to the middle of the glenoid fossa (PHHA) and the greatest thickness of the subscapular, infraspinous and supraspinous muscles were measured. The muscle ratio between the affected side and the normal side was calculated to exclude age variation in the assessment of muscle atrophy. RESULTS: All muscles of the rotator cuff were atrophic, with the subscapular and infraspinous muscles being most severely affected. A correlation was found between the percentage of humeral head anterior to the middle of the glenoid fossa (PHHA) and the extent of subscapular muscle atrophy (r(s)=0.45, P=0.01), as well as between its ratio (r(s)=0.5, P P=0.01). Severity of rotator cuff muscle atrophy correlated with increased glenoid retroversion and the degree of internal rotation contracture. CONCLUSIONS: Glenoid retroversion and subluxation of the humeral head are common in patients with BPBI. All rotator cuff muscles are atrophic, especially the subscapular muscle. Muscle atrophy due to neurogenic damage apparently results in an imbalance of the shoulder muscles and progressive retroversion and subluxation of the GH joint, which in turn lead to internal rotation contracture and deformation of the joint.

Adolescent↗
PubMed2000

EMG and strength correlates of selected shoulder muscles during rotations of the glenohumeral joint.

OBJECTIVE: To identify activation patterns of several muscles acting on the shoulder joint during isokinetic internal and external rotation. DESIGN: Combined EMG and isokinetic strength analysis in healthy subjects. BACKGROUND: EMG studies of the shoulder region revealed intricate muscular activation patterns during elevation of the arm but no parallel studies regarding pure rotations of the joint could be located. METHODS: Fifteen (n=30 shoulders) young, asymptomatic male subjects participated in the study. Strength production during isokinetic concentric and eccentric internal and external rotations at 60 and 180 degrees /s was correlated with the EMG activity of the rotator cuff, biceps, deltoid and pectoralis major. Analysis of the smoothed EMG related to the timing of onset of the signal and to the normalized activity at the angle of the peak moment. Determination of the association between the EMG and the moment was based on strength ratios. RESULTS: Findings indicated that for both types of rotations, the rotator cuff and biceps were active 0.092+/-0.038-0.215+/-0.045 s prior to the initiation of the actual movement and 0.112-0.034 s prior to onset of deltoid and pectoralis major activity. These differences were significant in all of the eight conditions (P<0.05). In terms of the strength ratios, strong association was found between electrical activity and moment production in the subscapularis and infraspinatus (r(2)=0.95 and 0. 72, respectively) at the low and high angular velocities. CONCLUSIONS: Prior to actual rotation of the shoulder joint, normal recruitment of the rotator cuff and biceps is characterized by a non-specific presetting phase which is mainly directed at enhancing the joint 'stiffness' and hence its stability. Once movement is in progress, the EMG patterns of these muscles become movement specific and are correlated with the resultant moment. RELEVANCE: Muscular dysfunction relating to delayed onset activity or altered activation patterns, due to pain, perturbed mechanics or disturbed neural activation have been implicated as concomitant factors in other joint associated pathologies. Through highlighting the role of the rotator cuff in shoulder joint rotations, this study lends further support to the argument that a parallel situation may prevail with respect to shoulder joint dysfunction. This could lead to the development of rehabilitation protocols aimed specifically at redressing such dysfunction.

Adolescent↗
PubMedDate not supplied

MR imaging of rotator cuff tears: is there a diagnostic benefit of shoulder exercise prior to imaging.

The purpose of this study was to determine if shoulder exercise prior to MR imaging accentuates findings related to rotator cuff tears. In 32 consecutive patients undergoing MR imaging to evaluate the rotator cuff, after routine MR examination, the joint was moved by active or passive exercise (circumduction, including abduction, if possible) in an attempt to redistribute any joint fluid. The exercise was performed according to pain tolerance and for no longer than 4 minutes. The coronal oblique fast spin-echo T2-weighted images of these patients performed before exercise were reviewed by consensus agreement of two musculoskeletal radiologists who were blinded to clinical information. The appearance of the rotator cuff tendons and the distribution of fluid in the glenohumeral joint were determined. The identical postexercise MR images then were placed alongside the corresponding preexercise MR images, and a direct comparison of findings was made with regard to any change in the appearance of the rotator cuff or joint fluid by consensus opinion of the same two radiologists. Five patients (five shoulders) could not perform exercise because of pain. In the remaining 27 patients (27 shoulders), changes in the location of joint fluid were seen when the preexercise and postexercise images were reviewed together, the diagnosis of partial rotator cuff tear (n = 8) was changed to normal in two cases, and the diagnosis of partial tear was made with more confidence in one case. The diagnoses of normal rotator cuff (n = 16) and complete rotator cuff tear (n = 3) were unchanged. Eight patients had arthroscopy; in each of these, the preexercise and postexercise images showed similar results, and proved to be correct surgically (six normal, one partial rotator cuff tear, and one complete rotator cuff tear). Although postexercise MR images show changes in the distribution of joint fluid when compared to preexercise images, the diagnostic benefits of the postexercise images in the analysis of the rotator cuff appear to be limited.

Exercise↗
PubMedDate not supplied

Mode of failure for rotator cuff repair with suture anchors identified at revision surgery.

Rotator cuff tears are a common cause of shoulder pain and dysfunction. After surgical repair, there is a significant re-tear rate (25%-90%). The aim of this study was to determine the primary mode of mechanical failure for rotator cuffs repaired with suture anchors at the time of revision rotator cuff repair. We prospectively followed 342 consecutive torn rotator cuffs, repaired by a single surgeon using suture anchors and a mattress-suturing configuration. Of those shoulders, 21 (6%) subsequently underwent a revision rotator cuff repair by the original surgeon, and 1 underwent a second revision repair. Intraoperative findings, including the mode of failure, were systematically recorded at revision surgery and compared with the findings at the primary repair. In addition, 81 primary rotator cuff repairs had a radiographic and fluoroscopic evaluation at a mean of 37 weeks after repair to assess for any loosening or migration of the anchors. At revision rotator cuff repair, the predominant mode of failure was tendon pulling through sutures (19/22 shoulders) (P <.001). Two recurrent tears occurred in a new location adjacent to the previous repair, and one anchor was found loose in the supraspinatus tendon. The mean size of the rotator cuff tear was larger at the revision surgery (P =.043), the tendon quality ranked poorer (P =.013), and the tendon mobility decreased (P =.002), as compared with the index procedure. The radiographs and fluoroscopic examination showed that all 335 anchors in 81 patients were in bone. Rotator cuff repairs with suture anchors that underwent revision surgery failed mechanically by three mechanisms, the most common of which was tendon pulling through sutures. This suggests that the weak link in rotator cuff repairs with suture anchors and horizontal mattress sutures, as determined at revision surgery, is the tendon-suture interface.

Adult↗
PubMed2004

Matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase mRNA levels are specifically altered in torn rotator cuff tendons.

BACKGROUND: Rotator cuff tears are a cause of pain and disability in the shoulder. The molecular changes associated with rotator cuff tearing are unclear. A subset of matrix metalloproteinases and tissue inhibitors of metalloproteinase, which are involved in extracellular matrix remodeling and degradation, were evaluated. HYPOTHESIS: There would be an increase in the mRNA level of specific matrix metalloproteinase and a decrease in the mRNA level of specific tissue inhibitors of metalloproteinase in rotator cuff tendon tissue obtained from patients with rotator cuff tears. STUDY DESIGN: Controlled laboratory study. METHODS: Tissue was obtained from 10 patients undergoing rotator cuff repair for full-thickness rotator cuff tears. Also, tissue was obtained from cadaveric specimens with no gross evidence of rotator cuff tearing. Reverse transcription polymerase chain reaction was performed for the collagenases (MMP-1, MMP-8, MMP-13), the stromelysins (MMP-3, MMP-10, MMP-11), and the tissue inhibitors of metalloproteinase (TIMP-1, TIMP-2, TIMP-3, TIMP-4). Western blotting was performed to confirm the mRNA changes demonstrated in collagenase-3 (MMP-13). RESULTS: There was a significant increase in collagenase-3 (MMP-13) mRNA levels, a decrease in stromelysin-1 (MMP-3) mRNA levels, and a decrease in tissue inhibitor of metalloproteinase-2, -3, and -4 mRNA levels. Western blotting demonstrated an increase in the active form of collagenase-3 (MMP-13) in rotator cuff tendon tears. CONCLUSIONS: The mRNA levels of specific matrix metalloproteinases and tissue inhibitors of metalloproteinase are altered in torn rotator cuff tendons. CLINICAL RELEVANCE: With the known action of the matrix metalloproteinases and tissue inhibitors of metalloproteinase in extra-cellular matrix remodeling, these findings suggest that their roles in remodeling of rotator cuff tears should be further investigated.

Aged↗
PubMed2003

Accuracy of ultrasound imaging of the rotator cuff in shoulders that are painful postoperatively.

BACKGROUND: Evaluation of the rotator cuff in a shoulder that has been persistently painful postoperatively could be challenging. Magnetic resonance imaging has been the preferred imaging method, but accuracy rates have been lower for those shoulders than for shoulders that have not been operated on; also, magnetic resonance imaging is susceptible to suture anchor artifact. The purpose of this study was to evaluate the diagnostic accuracy of ultrasound for evaluating the rotator cuff in shoulders that are painful postoperatively. METHODS: The records of forty-four consecutive patients who had undergone both a high-resolution ultrasound examination and subsequent shoulder arthroscopy were retrospectively reviewed. Thirty-four patients underwent rotator cuff repair at the time of the arthroscopy, and ten had subacromial decompression or another procedure without cuff repair. The results of the ultrasound examination were compared with the intraoperative findings of the arthroscopic examination (the "gold standard"). RESULTS: Ultrasound led to a correct diagnosis for forty of the forty-four patients. Twenty-two recurrent rotator cuff tears and twenty-two intact rotator cuffs were found at surgery. Ultrasound correctly identified twenty of the twenty-two rotator cuff tears (true-positive results) and twenty of the twenty-two intact rotator cuffs (true-negative results). Two intact cuffs were identified as having a full-thickness tear (false-positive results), and two cuffs with a full-thickness rotator cuff tear were identified as being intact (false-negative results). The sensitivity and specificity of ultrasound for identifying rotator cuff integrity postoperatively were 91% and 86%, respectively. The accuracy was 89%. CONCLUSIONS: Ultrasound is a highly accurate imaging study for evaluating the integrity of the rotator cuff in shoulders that have undergone an operation. Its accuracy for operatively treated shoulders appears to be comparable with that previously reported for shoulders that had not been operated on.

Adult↗
PubMed1994

[Results of the surgical repair of the rotator cuff. Radio-clinical correlation].

INTRODUCTION: This study was undertaken to evaluate the functional results of rotator cuff tear repair. MATERIAL AND METHODS: This retrospective study concerned 108 shoulders operated with a minimal follow up of 1 year (mean 5.5 years). The average age of this masculine population was 55 years. The rotator cuff tear involved: 39 times the supra-spinatus, 59 times the supra-spinatus and infra-spinatus, 6 times the supra and infra-spinatus and the teres minor, 4 times the supra-spinatus and superior part of the sub-scapularis. All these patients were reviewed using the Constant's score. The functional results were compared with an ultrasonographic study and a radiographic protocol including 5 views. Muscle strength was measured objectively with the aid of an isokinetics testing (Cybex II). RESULTS: The results were satisfactory concerning pain (67 per cent did not suffer anymore) daily activity (78 per cent experienced a slight disability) and mobility (92 per cent of the patients had an anteflexion > 120 degrees and 82 per cent an external rotation > 40 degrees). Concerning strength, the results were variable and related to the posterior extension of the tear. Most of the patients complained of weakness (mean objective deficit of strength = 25 per cent), specially a disability during repetitive over head activities. The radiographic protocol analysed the humeral head position (16 per cent of spontaneous acromio-humeral interval narrowing on the standard X Ray and 43 per cent of dynamic narrowing on Leclercq view). The spontaneous narrowing was correlated with a severe omarthrosis and a re-rupture of the rotator cuff. All these re-ruptures involved an infraspinatus lesion. Dynamic narrowing, with an acromial interval < 7 mm, were seen in 71 per cent of the patients with posterior extension of the rotator cuff tear explaining the poor final result; the ultrasonographic assessment found a thinning (75 per cent of patient) and a heterogeneity in the infraspinatus even after repair. We found 14 re-ruptures and 6 ultrasonographic disorganised structures. DISCUSSION: A well preserved external rotation and a centred head gave good result because they were associated with the integrity of the infra-spinatus, essential to the muscular balance of the rotator cuff and necessary for the dynamic and static centering of the humeral head. In 71 per cent of the cases, the suture of the posterior cuff tear did not allow a good dynamic position of the humeral head. A spontaneous narrowing (static view) of the acromio-humeral interval was in relation with a re-rupture which evolved to omarthrosis. A dynamic narrowing with a Leclercq radiograph was associated with a functional deficit after rotator cuff repair. CONCLUSION: Humeral head stabilisation, supplied by posterior muscles of the rotator cuff, is essential in prevention of omarthrosis and in recovery of good strength. In several specific cases, we think that the transfer of an external rotator muscle, with a good humeral head stabilization action, may restore strength.

Acromion↗
PubMed2005

Using the axis of rotation of polar navigator echoes to rapidly measure 3D rigid-body motion.

An improved technique to prospectively correct three-dimensional rigid-body motion using polar spherical navigator (pNAV) echoes is presented. The technique is based on acquiring pNAVs of an object in a baseline and rotated position and determining the axis of rotation (AOR) between data sets, thereby reducing 3D rotations to a 2D, planar rotation. Finding the AOR is simplified by prerotating the baseline trajectory, which forces the axis to lie within a specific polar region of a spherical shell in k-space. Orbital navigator echoes are interpolated from the pNAV data in planes orthogonal to the AOR and cross-correlated to determine the 2D rotation. The rotation about the AOR is used in conjunction with its orientation to calculate the overall 3D rotation. The pNAV-AOR technique was tested for its precision, accuracy, and processing speed in detecting compound rotations and translations of varying magnitude. In comparison to the spherical navigator echo technique, the pNAV-AOR technique is noniterative, fast, and independent of rotation magnitude and direction. At low SNR, the technique can detect compound rotations to 0.5 degrees accuracy in an estimated 100 msec, indicating that prospective 3D rigid-body motion correction may be feasible with this technique.

Humans↗
PubMed1991

Human perception of horizontal trunk and head rotation in space during vestibular and neck stimulation.

The vestibular signal of head motion in space must be complemented by a neck signal of the trunk-to-head excursion in order to provide the individual with information on trunk motion in space. This consideration led us to study psychophysically the role of vestibular-neck interaction for human self-motion perception. Subjects (Ss) were presented with passive horizontal rotations of their trunk and/or head (sinusoidal rotations, f = 0.025 - 0.4 Hz) in the dark for vestibular and neck stimulation, as well as for combinations of both. Ss' perception was evaluated in terms of gain (veridical perception of stimulus magnitude, G = 1), phase, and detection threshold. (1) Perception of trunk rotation in space. During vestibular stimulation (whole-body rotation) and neck stimulation (trunk rotation with the head kept stationary) the frequency-transfer characteristics underlying this perception were very similar. The gain fell short; it was only about 0.7 at 0.4 and 0.2 Hz stimulus frequency and was further attenuated with decreasing frequency. In contrast, the phase was close to that of actual trunk position. The gain attenuation was found to be a function of the peak angular velocity of the stimulus, a fact, which we related to a 'velocity threshold' of the order of 1 deg/s. During the various vestibular-neck combinations used, Ss' perception was again erroneous, reflecting essentially the sum of its two non-ideal constituents. However, there was one noticeable exception; during the combination 'head rotation on stationary trunk', Ss veridically perceived their trunk as stationary (compatible with the notion that the sum yielded 'zero'). (2) Perception of head rotation in space. During vestibular stimulation, Ss' estimates showed the same non-ideal gain-vs.-frequency characteristics as described above for the trunk. Neck stimulation induced an illusion as if the head had been rotated in space. This neck contribution was such that, when it was combined with its vestibular counterpart during head rotation on stationary trunk, the perception became almost veridical. On closer inspection, however, this neck contribution was found to reflect the sum of two components; one was the non-ideal neck signal contributing to the perception of 'trunk in space', the other was an almost ideal neck signal of head-on-trunk rotation. (3) The results could be described by a simple model. In this model, the erroneous vestibular signal 'head in space' is primarily used to create an internal representation of 'trunk in space'.(ABSTRACT TRUNCATED AT 400 WORDS)

Head↗
PubMed1993

Rotation of the cervical spinal column: a computed tomography in vivo study.

The functional anatomy of the spinal column has mainly been studied in the cadaver. The aim of our study was to determine in vivo the normal axial rotation of the cervical column using computed tomography (CT). Sixty subjects, divided into decades from 20 to 80 years of age were studied. The CT protocol comprised an axial cut at the level of the skull base (C0) and at each vertebral level in the neck, in the neutral position (with the nasal septum vertical) and during rotation of the head. To reduce the exposure to irradiation the subjects were divided into two groups: 40 were studied from C0 to the fifth cervical vertebra (C5) with unilateral rotation at C0 of 10 degrees, 20 degrees and 40 degrees (20 rotations to the left and 20 to the right), and 20 subjects were studied from C0 to the first thoracic vertebra (T1) with a maximum rotation at C0 to left and right. The angular position of a vertebra was defined as the anteroposterior axis with reference in the neutral position to the axis of C0, and in rotation was related to its original axis. At each vertebral level the mean angle of rotation and its standard deviation were calculated (n = 30) for the successive intermediate and maximum rotations at C0 level. The rotation of the cervical spine took place mainly at two levels: 58% between C1 and C2 and 24% between C3 and C6. The pairs of vertebrae C0/C1 and C2/C3 provided functional couples where the rotation was minimal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

The three-dimensional vestibulo-ocular reflex evoked by high-acceleration rotations in the squirrel monkey.

The aim of this study was to determine if the angular vestibulo-ocular reflex (VOR) in response to pitch, roll, left anterior-right posterior (LARP), and right anterior-left posterior (RALP) head rotations exhibited the same linear and nonlinear characteristics as those found in the horizontal VOR. Three-dimensional eye movements were recorded with the scleral search coil technique. The VOR in response to rotations in five planes (horizontal, vertical, torsional, LARP, and RALP) was studied in three squirrel monkeys. The latency of the VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) was 5.8+/-1.7 ms and was the same in response to head rotations in all five planes of rotation. The gain of the reflex during the acceleration was 36.7+/-15.4% greater than that measured at the plateau of head velocity. Polynomial fits to the trajectory of the response show that eye velocity is proportional to the cube of head velocity in all five planes of rotation. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain did not change with frequency (0.74+/-0.06, 0.74+/-0.07, 0.37+/-0.05, 0.69+/-0.06, and 0.64+/-0.06, for yaw, pitch, roll, LARP, and RALP respectively). The VOR gain increased with head velocity for sinusoidal rotations at frequencies > or =4 Hz. For rotational frequencies > or =4 Hz, we show that the vertical, torsional, LARP, and RALP VORs have the same linear and nonlinear characteristics as the horizontal VOR. In addition, we show that the gain, phase and axis of eye rotation during LARP and RALP head rotations can be predicted once the pitch and roll responses are characterized.

Acceleration↗
PubMed2005

Reproduction of ON-center and OFF-center self-rotations.

In self-rotation reproduction tasks, subjects appear to estimate the displacement angle and then reproduce this angle without necessarily replicating the entire temporal velocity profile. In contrast, subjects appear to reproduce the entire temporal velocity profile during linear motion stimulating the otoliths. To investigate what happens during combined rotation and translation, we investigated in darkness the central processing of vestibular cues during eccentric rotation. Controlling a centrifuge with a joystick, nine healthy subjects were asked to reproduce the angle of the previously imposed rotation. Rotations were either ON-center, or 50 cm OFF-center with inter-aural centripetal acceleration. Rotation duration was either variable (proportional to the traveled angle), or constant. We examined whether the stimulation of the otoliths during OFF-center rotation changes self-rotation reproduction, and whether rotation duration is processed differently by the nervous system with and without otolith stimulation. As postulated, the subjects indeed reproduced more closely the stimulus velocity profile when OFF-center. But the primary result is that the additional supra-threshold linear acceleration cues, measured by the otoliths, did not improve performance. More specifically, to our surprise, the ability to reproduce rotation angle degraded slightly in the presence of additional information from the otolith organs, with the linear acceleration cues appearing to interfere with the reproduction of movement duration.

Acceleration↗
PubMed2005

[Rotational stability in intraocular lenses with C-loop haptics versus Z haptics in cataract surgery. A prospective randomised comparison].

The aim of the study was to compare the rotational stability of intraocular lenses (IOLs) with C-loop haptics and those with Z haptics. A total of 50 patients with cataracts were prospectively randomised in equal numbers using a design equivalent to IOL MS 612 S (C-loop haptic) and MS 6120 (Z haptic, both HumanOptics, Erlangen). Complete ophthalmological examinations were performed including assessment of the IOL rotation after 1 day, 1 month and 3 months postoperatively. The significances between the groups were evaluated using the Wilcoxon test. The Fisher exact test was used for the primary finding of the study (rotation of at least 10 degrees ). The IOL group with the C-loop haptics showed a median lens rotation of 0 degrees on the first day and 2 degrees clockwise after 1 month and 3 months. In the Z haptic group, there was no median rotation in the IOL group. Moreover, the range of IOL rotation of the C-loop haptics was broader (3 months postoperatively: maximum in the C-loop haptics: 21 degrees with 15.5 degrees in the Z haptics). There was no significant difference at any time. At 3 months postoperatively, 32% of the C-loop haptic IOL and 16% of the Z haptic IOL rotated at least 10 degrees (P=0.32). In 59% of the IOL with C-loop haptics, the direction of the rotation was clockwise. This was 40% for the IOL with Z haptics (P=0.33). At 3 months postoperatively, both IOLs demonstrated good rotational stability with a low mean deviation from the target axis. IOLs with Z haptics showed a tendency to greater rotational stability than C-loop haptics but without any significant difference. There was no significant difference in visual rehabilitation.

Cataract Extraction↗
PubMed1989

Bubble cycling as the explanation of the promotion of ultrasonic cavitation in a rotating tube exposure system.

The cavitation-promotion effect of rotating a sample tube during ultrasound exposure is not yet fully understood. Cavitation-induced hemolysis was observed in 0.5% hematocrit suspensions of erythrocytes exposed for 5 min at 37 degrees C. For 1.61 MHz unfocused exposure an apparent threshold of 4 W/cm2 spatial-peak intensity was obtained for hemolysis in a 72 rpm rotating exposure chamber which was made of dialysis tubing. If the tube was not rotated, then no hemolysis was observed up to 16 W/cm2. Creation of standing waves in the sample by using a thick-walled culture tube, or by placing a styrofoam reflector behind the dialysis tube did not change the apparent threshold. Focused 1.45 MHz exposure gave the same apparent threshold in a rotating dialysis tube, but this increased to about 128 W/cm2 for the nonrotating case. When the focused ultrasound was turned on for half a rotation and off for half, results were similar to those for a nonrotating CW case, while on-off cycles synchronized to a quarter rotation gave results similar to the rotating CW case. A plausible explanation of the rotation effect, given these results, is that rotation brings bubbles on the rear wall, where the beam exits the tube, back around to the front again, where the bubbles may then re-nucleate the suspension, and thereby promote cavitation bioeffects in the rotating tube.

Animals↗
PubMed1996

Vestibulo-ocular reflex of the squirrel monkey during eccentric rotation with centripetal acceleration along the naso-occipital axis.

The vestibulo-ocular reflexes (VOR) are determined not only by angular acceleration, but also by the presence of gravity and linear acceleration. This phenomenon was studied by measuring three-dimensional nystagmic eye movements, with implanted search coils, in four male squirrel monkeys. Monkeys were rotated in the dark at 200 degrees/s, centrally or 79 cm off-axis, with the axis of rotation always aligned with gravity and the spinal axis of the upright monkeys. The monkey's position relative to the centripetal acceleration (facing center or back to center) had a dramatic influence on the VOR. These studies show that a torsional response was always elicited that acted to shift the axis of eye rotation toward alignment with gravito-inertial force. On the other hand, a slow phase downward vertical response usually existed, which shifted the axis of eye rotation away from the gravito-inertial force. These findings were consistent across all monkeys. In another set of tests, the same monkeys were rapidly tilted about their interaural (pitch) axis. Tilt orientations of 45 degrees and 90 degrees were maintained for 1 min. Other than a compensatory angular VOR during the rotation, no consistent eye velocity response was ever observed during or following the tilt. The absence of any response following tilt proves that the observed torsional and vertical responses were not a positional nystagmus. Model simulations qualitatively predict all components of these eccentric rotation and tilt responses. These simulations support the conclusion that the VOR during eccentric rotation may consist of two components: a linear VOR and a rotational VOR. The model predicts a slow phase downward, vertical, linear VOR during eccentric rotation even though there was never a change in the force aligned with monkey's spinal (Z) axis. The model also predicts the torsional components of the response that shift the rotation axis of the angular VOR toward alignment with gravito-inertial force.

Animals↗
PubMed2006

Manual rotation of the fetal occiput: predictors of success and delivery.

OBJECTIVE: The purpose of the study was to define predictors of successful rotation and rate of cesarean delivery after manual rotation of the fetal occiput from occiput posterior or transverse position. STUDY DESIGN: A retrospective cohort study comprised patients who underwent a trial of manual rotation of the fetal occiput from occiput posterior or occiput transverse position. Successful rotation was defined as delivery in the occiput anterior position. We examined maternal, fetal, and labor characteristics as predictors of both fetal position at delivery and cesarean delivery. RESULTS: Multiparity (odds ratio, 2.5; 95% CI, 1.5-3.8) and maternal age < 35 years (odds ratio, 2.0; 95% CI, 1.1-3.4) were associated with successful manual rotation of the fetal occiput. After successful rotation, the cesarean delivery rate was 2%, compared with 34% if the rotation failed (P < .001). Asian ethnicity, nulliparity, age > 35 years, labor induction, and epidural usage were associated with higher rates of cesarean delivery. CONCLUSION: After successful manual rotation of the fetal occiput, women had lower cesarean delivery rates than women with unsuccessful rotations. Multiparity and maternal age of < 35 years were associated with more successful rotations.

Adult↗
PubMed2004

Rotational deformity in malunited fractures of the distal radius.

PURPOSE: To evaluate rotational deformity in malunited fractures of the distal radius and its effect on forearm rotation. METHODS: Thirty-seven patients with a symptomatic malunion of the distal radius (25 with dorsal angulation and 12 with volar angulation) were assessed for rotational deformity of the distal fragment. Spiral computed tomographic scans were taken of both wrists. Rotational deformity was evaluated by comparing the radial torsion angle of the injured and uninjured sides according to Frahm. Multivariable regression analyses were used to identify the radiologic parameter that had the most important influence on forearm rotation. RESULTS: Of the 37 patients, 23 showed a rotational deformity of the distal radius. In both dorsally and volarly angulated malunions, pronation and supination deformities were identified. There was a tendency toward more pronation deformities with volar malunion. Volar angulated malunion with a rotational deformity of less than 10 degrees showed the smallest amount of forearm supination. Losses of pronation-supination did not correlate with the amount of rotational deformity. CONCLUSIONS: This study showed that rotational deformity is common with angulated malunions of the distal radius. The effect on forearm rotation should not be overestimated. Pretreatment computed tomographic scanning of both wrists to identify and measure malrotation of the distal radius may be helpful to improve the outcome after corrective osteotomy.

Adult↗