Biomedical subjects

Keith M Bagnall

Publications and source records attributed to Keith M Bagnall.

3 recordsLinked to original sources

PubMed2006

Pedicle growth asymmetry as a cause of adolescent idiopathic scoliosis: a biomechanical study.

Over the last century the neurocentral junction (NCJ) has been identified as a potential cause of adolescent idiopathic scoliosis (AIS). Disparate growth at this site has been thought to lead to pedicle asymmetry, which then causes vertebral rotation and ultimately, the development of scoliotic curves. The objectives of this study are (1) to incorporate pedicle growth and growth modulation into an existing finite element model of the thoracic and lumbar spine already integrating vertebral body growth and growth modulation; (2) to use the model to investigate whether pedicle asymmetry, either alone or combined with other deformations, could be involved in scoliosis pathomechanisms. The model was personalized to the geometry of a nonpathological subject and used as the reference spinal configuration. Asymmetry of pedicle geometry (i.e. initial length) and asymmetry of the pedicle growth rate alone or in combination with other AIS potential pathogenesis (anterior, lateral, or rotational displacement of apical vertebra) were simulated over a period of 24 months. The Cobb angle and local scoliotic descriptors (wedging angle, axial rotation) were assessed at each monthly growth cycle. Simulations with asymmetrical pedicle geometry did not produce significant scoliosis, vertebral rotation, or wedging. Simulations with asymmetry of pedicle growth rate did not cause scoliosis independently and did not amplify the scoliotic deformity caused by other deformations tested in the previous model. The results of this model do not support the hypothesis that asymmetrical NCJ growth is a cause of AIS. This concurs with recent animal experiments in which NCJ growth was unilaterally restricted and no scoliosis, vertebral wedging, or rotation was noted.

Adolescent↗

PubMed2005

Evaluating MRI as a technique for visualizing the neurocentral junction.

STUDY DESIGN: Magnetic resonance imaging (MRI) of the neurocentral junction (NCJ) was correlated with gross anatomic and histologic sections acquired at the same position. OBJECTIVES: To determine the composition of the MRI of the NCJ and to explore the long-standing discrepancy between the ages of closure of the NCJ as determined by anatomic and imaging studies. SUMMARY OF BACKGROUND DATA: Disparate growth at the site of the NCJ has been implicated as a potential cause of adolescent idiopathic scoliosis since the early 1900s. Although anatomic studies have refuted this theory by maintaining that the NCJ closes before the age of 10 years, recent MRI studies have suggested that the NCJ remains open until adolescence. METHODS: One hundred fourteen porcine NCJs in various stages of development were visualized using MRI. Gross anatomic and histologic sections were acquired at the same position as MRI for correlation. RESULTS: The presence or absence of NCJ cartilage was represented by the presence or absence of a line on MRI. However, the NCJ image overestimated the width of the NCJ cartilage in the anteroposterior direction during development. As the NCJ underwent the process of closure, the NCJ image underestimated the extent of closure in the medial-lateral direction. CONCLUSIONS: Although MRI underestimated the extent of NCJ closure, MRI accurately showed whether cartilage was present or absent at the NCJ site. MRI determination of the age of NCJ closure appears reliable, and further exploration of the asymmetric growth hypothesis is required.

Aging↗

PubMed2004

The addition of manual lymph drainage to compression therapy for breast cancer related lymphedema: a randomized controlled trial.

PURPOSE: The purpose of this investigation was to compare the reduction in arm lymphedema volume achieved from manual lymph drainage massage (MLD) in combination with multi-layered compression bandaging (CB) to that achieved by CB alone. METHODS AND MATERIALS: Fifty women with lymphedema (mean age of 59 years +/- 13 years) were randomly assigned to 4 weeks of combined MLD/CB or CB alone. The primary study endpoint was the reduction in arm lymphedema volume, which was determined by water displacement volumetry and measurement of circumference. Independent assessors, blinded to subject treatment assignment, performed the outcome measurements. RESULTS: Arm lymphedema volume decreased significantly after 4 weeks irrespective of treatment assignment (p < 0.001). Individuals with mild lymphedema receiving combined MLD/CB had a significantly larger percentage reduction in volume compared to individuals with mild lymphedema receiving CB alone, and compared to individuals with moderate or severe lymphedema receiving either treatment. CONCLUSION: These findings indicate that CB, with or without MLD, is an effective intervention in reducing arm lymphedema volume. The findings suggest that CB on its own should be considered as a primary treatment option in reducing arm lymphedema volume. There may be an additional benefit from the application of MLD for women with mild lymphedema; however, this finding will need to be further examined in the research setting.

Adult↗