Anne J. Yoon

Abstract

The purpose of this study was to characterize and analyze the heterotopic bone regenerate which formed following implantation of recombinant human bone morphogenetic protein-2 (rhBMP-2) and to determine by epi-illumination, x-ray photometry and histology, if there is increased and sustained osteogenic potential present with distraction osteogenesis of this heterotopic bone. While many previous studies have documented the osteogenic potential of BMP-2, no study to date has shown the results of application of force on this ectopic bone. Our study included three control rats (non-expansion) and six experimental rats (expansion). Of the control rats, #76 (a pilot study rat) had already been processed by the previous investigator for histology and was not available for the quantitative analysis.

For our study epi-illumination analysis and plain radiography was completed prior to histological processing. Digital photos of each sample were taken and color-mapped using Adobe Illustrator CS software to mark the presence of bone (pink) and the metal cage struts (green). These were then analyzed using Image J 1.40g NIH free software program. Histology was then completed using standard H&E. Micro-CT images taken for this study were used solely for visualization and orientation and not for any analysis purposes. The Wileoxon-Mann-Whitney rank sum test was used at the significance level of a=0.05 and no statistically significant differences were found between the groups due to the small sample size (n=2). While the results of this study from a quantitative standpoint were not significant due to the fact that the sample size was reduced from experimental complications, our study demonstrates the potential for increased and sustained osteogenesis in subjects undergoing induced ectopie distraction osteogenesis.

Through epi-illumination and plain radiography we were able to show that the underlying muscle provided an added stimulus for osteogenesis as the majority of the novel bone growth was along the periphery of the cage adjacent to the muscle regardless of whether expansion occurred. However the samples undergoing distraction also had moderate amounts of osteogenesis in the center (between the distraction cages) though this bone was not as dense as the peripherally formed bone. Histology revealed that while the majority of the hone was formed via the intramembranous pathway while endochondral and/or transchondroid bone formation (as proposed in previous studies) was also identified in a few of the samples in localized areas. In addition the much of the bone was immature woven bone in irregular trabeeulae interspersed with dense cellular fibrovascular connective tissue, with areas of more mature bone and marrow cavities at the peripheries. Follow-up studies should include: increased time periods prior to cage removal, a modified cage design with increased surface area adjacent to the muscle, a different cage material to circumvent the difficulties encountered during both the Miero- CT visualization and histological processing and an increased sample size.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Orthodontics and Dentofacial Orthopedics

School

School of Dentistry

First Advisor

Paul McMillan

Second Advisor

V. Leroy Leggitt

Third Advisor

Kenneth Wright

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2008

Date (Title Page)

9-2008

Language

English

Library of Congress/MESH Subject Headings

Osteogenesis, Distraction -- dissertations; Bone Morphogenetic Protein; Bone Regeneration -- physiology; Bone Transplantation; Rats.

Type

Thesis

Page Count

xi; 53

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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