Biomedical subjects

V J Raso

Publications and source records attributed to V J Raso.

At least 19 recordsLinked to original sources

PubMed2005

Atypical shoulder muscle activation in multidirectional instability.

OBJECTIVE: Surface and intramuscular electromyography was used to investigate shoulder muscle activity in subjects with multidirectional instability (MDI). METHODS: Subjects (seven MDI, 11 control) performed repetitive shoulder abduction/adduction, flexion/extension and internal/external rotation movements on an isokinetic dynamometer. The activity of the deltoid, infraspinatus, supraspinatus, latissimus dorsi, and pectoralis major muscles were recorded using double-differential surface and intramuscular fine-wire electrodes. A repeated measures analysis of variance evaluated group differences in the amplitude, onset, termination and duration of the muscle activity. RESULTS: Significant activation parameter differences for the supraspinatus, infraspinatus, posterior deltoid and pectoralis major muscles were found in the subjects with MDI. The rotator cuff and posterior deltoid muscles demonstrated abbreviated periods of activity when performing internal/external rotation, despite activation amplitudes that were similar to the controls. In contrast, the activation of the pectoralis major differed from the control group in both the amplitude and time domains when performing shoulder extension. CONCLUSIONS: MDI is associated with atypical patterns of muscle activity that occur even when highly constrained movements are used to elicit the activity. SIGNIFICANCE: In addition to glenohumeral hyperlaxity, the results suggest that dysfunctional neuromuscular control of the rotator cuff is also a contributing factor to the pathoetiology of MDI.

Adult↗

PubMed2005

Examination of the failure properties of the anterior cruciate ligament during the estrous cycle.

The purpose of this study was to determine whether the mechanical properties of the rat anterior cruciate ligament (ACL) vary when tested in vitro at different stages of the estrous cycle. Sixty female rats were allocated to four groups according to their stage of the estrous cycle: diestrus (n=16), proestrus (n=17), estrus (n=13) and metestrus (n=14). Right hindlimbs were harvested for mechanical testing and left hindlimbs were harvested for immunohistochemical staining to confirm the presence of the estrogen receptor. Results from the first relaxation test showed a significant difference between the estrus and proestrus stage, which was not observed in a second subsequent relaxation test. Likewise, no significant differences were found when comparing failure load and stiffness between the different stages of the estrous cycle. These results suggest that normal physiological fluctuations in estrogen during the estrous cycle did not alter the failure properties of the rat ACL.

Animals↗

PubMed2004

Stiffness characteristics of hamstring tendon graft fixation methods at the femoral site.

In ACL reconstruction, stiffness and strength of a tendon graft complex are important features for knee stability and rehabilitation. The fixation between tendon and bone is known to be one of the weakest components of the graft complex. We examined the tensile load-displacement characteristics of looped semitendinosus tendons in a porcine femoral tunnel. Two groups of six cadaveric semitendinosus tendons and porcine femurs were tested, secured with either an aperture or non-aperture fixation method. Constructs were tested at 1 mm/s until failure in a materials testing machine, which allowed force and displacement data to be recorded. The non-aperture fixation group was significantly less stiff for the first 4 mm of displacement and had significantly higher ultimate failure loads. Provided that adequate ultimate strength can be achieved, stiffness properties of a tendon graft will be improved by using aperture fixation in femoral-site ACL reconstruction.

Animals↗

PubMed2004

Using magnetic resonance imaging to characterize pedicle asymmetry in both normal patients and patients with adolescent idiopathic scoliosis.

STUDY DESIGN: Morphometric analysis of vertebrae from normal patients and patients with adolescent idiopathic scoliosis. OBJECTIVES: To use magnetic resonance imaging to assess pedicle asymmetry in normal patients and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development and to determine if patients with adolescent idiopathic scoliosis exhibited a consistent vertebral morphology. SUMMARY OF BACKGROUND DATA: To date, most studies of vertebral morphology in adolescent idiopathic scoliosis have produced conflicting data, especially on pedicle length, and have been conducted on patients in the late stages of scoliosis development, which may affect the patterns of vertebral morphology detected. Magnetic resonance imaging enables in vivo assessment of curves during development and permits improved acquisition of transverse images. METHODS: Magnetic resonance images of 76 pedicles from 8 normal patients and 80 pedicles from 10 patients with adolescent idiopathic scoliosis were examined retrospectively. Recorded parameters included pedicle lengths, pedicle widths, pedicle areas, pedicle perimeters, and lamina lengths. The extent and direction of asymmetry in vertebrae from normal patients and patients with adolescent idiopathic scoliosis were determined and compared. RESULTS: Normal patients displayed significant neural arch asymmetry, with the left sided measurements being greater. Patients with adolescent idiopathic scoliosis also displayed significant neural arch asymmetry; however, the longer pedicle was not consistently on the convexity or the concavity. CONCLUSIONS: The baseline used to assess adolescent idiopathic scoliosis vertebral morphology must take into consideration the extent and direction of normal vertebral asymmetry. The pattern of vertebral asymmetry seen inadolescent idiopathic scoliosis may depend on the specific cause of the disorder, with no consistent pattern evident when data from different causes are pooled together.

Adolescent↗

PubMed2002

MRI characteristics of the neurocentral synchondrosis.

BACKGROUND AND OBJECTIVES: The neurocentral synchondrosis (NCS) is a cartilaginous growth plate that since the early 1900s has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS). Previous studies have focused only on the closure age without characterizing normal NCS development. Using MRI, the normal development of the NCS image can be characterized, and the stages preceding the disappearance of this image can be specified. METHODS: A total of 405 NCSs were visualized in 11 normal pediatric patients using T1 and T2 transverse and sagittal MRI views. The images were correlated and the variety of images recorded to categorize the NCS into developmental stages. RESULTS: The development of the NCS was categorized into five developmental stages. The image of the NCS became absent in a specific pattern along the vertebral column, first in the cervical region (age 6), then in the lumbar region (age 12), and finally in the thoracic region (age 14). CONCLUSION: The normal development of the NCS at the level of individual vertebrae and also along the vertebral column as a whole was determined using MRI. These patterns of development are valuable and necessary to evaluate the role of the NCS in pathological conditions.

Adolescent↗

PubMed2002

Using three-dimensional difference maps to assess changes in scoliotic deformities.

The three-dimensional nature of scoliosis, coupled with changes due to natural history or treatment, is often difficult to quantify and visualise. A difference map was developed to compare the sequential surface topography of subjects over their treatment period. Three-dimensional surface maps representing patients' trunk surfaces were captured with a laser scanner. Patient surface maps from two clinic visits were matched using a manual best-fit technique that accounted for growth and positioning. The surfaces were subtracted, generating a colour-coded three-dimensional difference map displaying the surface changes. The difference maps were compared with known clinical measures, indicating good agreement (78% specific) with the clinical parameters in detecting change. Full agreement or agreement with the clinical parameters occurred in the surgical, brace and no treatment groups: 76%, 80% and 85%, respectively. A difference index (average of the absolute value of differences on a point-by-point basis) was calculated from the difference map, enabling quantification of change. The difference index, with zero being a perfect match, averaged 5 +/- 1 for repeated measures 7 +/- 2 for subjects deemed to have no change, 9 +/- 2 for subjects with slight change, and 14 +/- 2 for subjects with significant change. The difference map showed the extent and location of changes and is a useful tool for assessing surface topography changes.

Adolescent↗

PubMed2002

Evaluation of a laser scanner for surface topography.

A Minolta VIVID 700 portable non-contact 3D laser scanner was evaluated on 15 subjects with idiopathic scoliosis. The 3D map was compared to two structured light pattern (lines and dots) techniques to determine the reliability, ease of use, speed, and quality. The parameters used for the clinical assessment of scoliosis were measured twice for the Minolta and light projection systems. The edges of the image and areas where occlusion typically occur were examined. The absolute distance in calculated depth between adjacent points was examined to determine errors. The Minolta system and the dot pattern produced regular grids of points. The light projection pattern produced an irregular grid, with more resolution along the video line and less resolution between projected lines, resulted in a somewhat jagged appearance of the surface map. The Minolta system was less sensitive to edge effects, occlusion, and sharp transitions of depth. The comparison of clinical parameters showed good results between repetitions but moderate results between techniques.

Adolescent↗

PubMed2002

Image coding technique for 3-D back reconstruction.

This work investigated the use of coded-line patterns to improve image correspondence and 3D reconstruction. The objective was to define an optimum structured light pattern to facilitate the construction of topographic maps of the trunks of scoliosis patients. The system consisted of stereo CCD television cameras, a slide projector to create the coded-line pattern and a computer with video acquisition card. The optimum pattern in terms of generating correct results with minimum computing time was a line pattern consisting of 6 groupings of 3-level grey lines. This chosen pattern was investigated using known 3D objects to determine the effectiveness, resolution and computational time to correlate stereo images. The selected structured light pattern consisted of a repeated pattern of white (W), grey (G) and black (B) lines. Each line was 4mm wide on the back surface. The pattern consisted of 6 groups of 3 lines, WBG WGB GWB GBW BGW BWG. Using known 3D models of a section of a cylinder, a plate with steps and a ramp-like object; the coded line system was tested under typical clinical lighting conditions. For the 3D test objects, errors in correspondence occurred in 2-4 % of stereo pixels. The processing time varied from 10-12 minutes. The 3D resolution obtained was 4mm.

Back↗

PubMed2002

Intra-operative measurement of vertebral bone strength.

A significant complication of surgical correction of the deformed spine is pull out of the vertebral hooks or screws. This complication can be partly attributed to poor bone stock. Currently, there are few methods available for surgeons to assess the mechanical strength and stiffness of the vertebra, and even fewer methods that provide in-vivo measurements. An "upbiter" is often used to form a seat in the lamina for the hook. A typical upbiter was modified and instrumented with strain gauges to investigate the feasibility of determining the forces and displacements needed to cut through laminar bone during surgical procedures. The calibration showed that the system was repeatable and could highly correlated with applied force (R2=0.98) and displacement (R2=0.99) with resolutions of 0.72 N and 0.40 mm respectively. This system was tested on three females, on lamina ranging from T4 to T12 regions. The average maximum force for bone failure was at 470+/-128N.

Biomechanical Phenomena↗

PubMed2002

Computer modelling of hooks for use as intra-operative force sensors.

There are a number of forces applied during scoliosis surgery, the magnitude and direction of which remains unknown. There is little literature concerning the in vivo distribution of forces along the spine. Computer modelling (ANSYS) was used to investigate the possibility of using an instrumented hook to intra-operatively measure the antero-posterior and distraction/compression forces applied by the surgeon during corrective scoliosis surgery. Three hook designs were evaluated based on specific design criteria. ANSYS provided the preliminary analysis to determine the strain distribution in these hooks. One design, the "membrane" design, was selected and a prototype was manufactured. Preliminary tests demonstrate that this prototype will be able to differentiate between the four major forces applied during the surgical correction.

Biomechanical Phenomena↗

PubMed2002

Assessing changes in three dimensional scoliotic deformities with difference maps.

Topographical difference maps were used to compare the trunk surfaces of subjects over the course of their treatment. Three-dimensional points representing the trunk surfaces were aligned accounting for growth and positioning. A goodness-of-fit score was calculated and a color map used to display trunk surface changes. Fifty-one successive subjects were assessed with difference maps. Two subjects each had 10 repetitions taken on the same day to assess reliability. A blinded observer used a five-point scale that extended from full agreement to full disagrment to judge the maps according to the extent and location of changes. The observations were compared to clinical measures mapped onto the same scale by another blinded observer. Goodness of fit for repeated measures averaged 5 +/- 1, for subjects deemed to have no change 7 +/- 2, for subjects with slight change 9 +/- 2, and 14 +/- 2 for subjects with significant change. Judges were in full agreement or in agreemnt with forty of the fifty-one subjects (78%) and in slight disagreement with the remaining eleven. When the cohort was subdivided in surgical, brace and no treatment groups, the judges were in full agreement or in agreement 76%, 80%, and 85% respectively. The difference map provides a qualitative and quantitative measure of how the trunk surface has changed as a whole.

Adolescent↗

PubMed2002

Local energy as a measure of back symmetry in scoliosis.

The Cobb angle has been the most commonly used method in measuring the severity of scoliosis and its progression. However, in recent years a number of researchers have chosen to monitor scoliosis by examining the severity of the surface deformity resulting from the scoliosis. Each of these approaches has been limited by errors introduced in manual location of landmarks. Scoliosis results in an asymmetry of the back. It would be very desirable to have a computer-based method of measuring this asymmetry. This paper investigates the use of wavelets and the concept of local energy to measure asymmetry associated with scoliosis. The local energy model uses wavelet theory to obtain information about shading and boundaries of objects in an image. Edges and sharp discontinuities are areas of high local energy in an image. Features such as scapular prominence, shoulder edges, waist creases and other anomalies that contribute to the scoliotic back asymmetry have high local energy. A preliminary study was completed to determine if this approach was applicable to measurement of back asymmetry. Two-dimensional local energy images were created from photographs of the backs of patients with scoliosis. The local energy was integrated across each image and a left-to right line of symmetry was calculated. This line of symmetry was then correlated with the scoliotic score developed by our group. This technique shows promise of providing an automatic method of measuring scoliosis progression.

Back↗

PubMed2002

Development of the neurocentral junction as seen on magnetic resonance images.

The neurocentral junction (NCJ) is a cartilaginous growth plate in the vertebra that has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS) since the early 1900s. Studies to date have focused on the age of closure without characterizing normal NCJ development. Using MRI, the normal development of the NCJ image can be determined and the stages preceding the disappearance of the NCJ image can be characterized. 405 NCJs from 11 pediatric patients were examined using MRI and the various images were categorized. NCJ development encompassed five stages, with a specific pattern of absence of the NCJ image noted in each vertebra and in the vertebral column as a whole. The image of the NCJ first became absent in the cervical region (age 6), then in the lumbar region (age 12) and finally in the thoracic region (age 14). These patterns of development serve as a baseline to evaluate NCJ pathology in conditions such as adolescent idiopathic scoliosis (AIS).

Adolescent↗

PubMed2002

The components of the magnetic resonance image of the neurocentral junction.

The neurocentral junction (NCJ) is a cartilaginous growth plate located between the vertebral centrurn and the neural arch. In characterizing the age of closure of this growth plate, anatomic studies have suggested that the NCJ closes before age 10, whereas MRI studies have suggested that the NCJ does not fuse until adolescence In this study, gross anatomic and histologic sections were correlated with MR images to determine the components of the NCJ image. The NCJ image appeared as a thick white line that was shown to encompass the cartilage of the growth plate, the surrounding woven bone and a portion of the trabecular bone of the vertebra. Although the MR pixels were too large to completely resolve the tissues that surround the growth plate, MRI was shown to be a valuable technique of visualizing the NCJ cartilage and further MRI studies of the human NCJ are needed.

Age Factors↗

PubMed2002

Is the Boston brace mechanically effective in AIS?

The application of three-point loading is thought to be the essential basis for effective bracing of adolescent idiopathic scoliosis. Care is taken to ensure that active pressure pad is located to provide maximum support to the apex of the scoliosis while minimizing its lordosising effect. Paradoxically, while cited as an essential factor in the design of braces, there is no consensus as to the importance of such loading to the clinical effectiveness of braces. It may be that braces are effective but that they are effective for reasons unrelated to mechanics. There are few studies that link brace mechanics and change in spinal alignment. Optimal bracing for AIS requires a much better understanding of the role of the mechanical support of braces used to treat AIS. Sixteen subjects, 3 males and 13 females, were participated to this study to determine the correlation between quantity and quality of brace wear and treatment outcomes in AIS. This study showed that the target force levels set for the active pad in braces prescribed for the treatment of AIS vary considerably and that brace applies the desired load 25% of the prescribed time.

Adolescent↗

PubMed2002

Long-term follow-up of surgically treated AIS patients.

The aim of this study was to determine the long-term changes in spine and trunk alignment in patients who have undergone scoliosis surgery. Twenty-three (16F; 7M; at age of surgery 15.7 +/- 4.9 years) patients with adolescent idiopathic scoliosis agreed to participate and had posterior-anterior radiographs and surface topography prior to derotation surgery, within 6 months of surgery, at 2 years post-operatively and 5-10 years (mean follow-up period 6.11 +/- 1.6 years) after surgery. Cobb angles, surface trunk rotations, and cosmetic scores were measured at each visit. A questionnaire assessed back appearance and pain at the 5-10 year follow-up. The results of the questionnaire were compared to 25 patients with idiopathic scoliosis who had recently undergone surgery. A paired two-tailed Student's t-test with p=0.05 was used to compare the deformity between visits. The Cobb angle and cosmetic score improved after surgery while the change in trunk rotation was insignificant (p=0.37). Between the two-year and 5-10 year review, the Cobb angle, cosmetic score, and surface trunk rotation significantly increased. Self-perception of appearance and pain were similar to the control group. Surgical correction of scoliosis is not completely maintained during adulthood although the radiographic and surface deterioration does not appear to be clinically significant.

Adolescent↗

PubMed2001

Pineal transplantation after pinealectomy in young chickens has no effect on the development of scoliosis.

STUDY DESIGN: Three experimental groups and one control group of chickens underwent different surgical procedures to determine the effects of pineal gland transplantation on the development of scoliosis. OBJECTIVE: To determine whether transplantation of the pineal gland to the body wall musculature maintains serum melatonin levels at normal values and prevents the development of scoliosis. SUMMARY OF BACKGROUND DATA: Scoliosis occurs consistently after pinealectomy in young chickens. Many characteristics of this scoliosis are similar to those seen in patients with adolescent idiopathic scoliosis. It is not clear whether the underlying mechanism is dependent on reduced levels of serum melatonin or some other aspect of the extensive surgery. METHODS: Four groups of chickens were selected: normal chickens, pinealectomized chickens, chickens that underwent simple cutting of the pineal stalk, and chickens that underwent transplantation of the pineal gland into the body wall. Development of scoliosis was determined from measurement of the Cobb angle from weekly radiographs. RESULTS: All of the experimental groups showed the same levels of incidence and the same patterns of scoliosis development. Serum melatonin levels were reduced to nearly zero in all the experimental groups for the duration of the experiment. Scoliosis developed in none of the normal chickens. CONCLUSIONS: Neither transplantation of the pineal gland into the body wall musculature nor simple cutting of the pineal stalk was able to maintain normal levels of serum melatonin because both procedures reduced levels to nearly zero. The incidence and pattern of scoliosis development in these groups were the same as those for the pinealectomized group. Reduction of serum melatonin levels remains a prerequisite for scoliosis development in young chickens.

Animals↗

PubMed2001

The critical stage of pinealectomy surgery after which scoliosis is produced in young chickens.

STUDY DESIGN: Stages of the surgical procedure for pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. OBJECTIVES: To determine the critical stage of surgery for pinealectomy after which scoliosis develops in young chickens. SUMMARY OF BACKGROUND DATA: Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. METHODS: Five distinct stages in the pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. RESULTS: Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. CONCLUSIONS: Cutting the pineal stalk was identified as the critical stage of pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.

Animals↗