Aging and Exercise Effects on Bone and Tissue (collaboration with Dr. Maya Styner)
Developing Shape Analysis Software (collaboration with Kitware)
Idiopathic Scoliosis in Children (collaboration with Dr. James Sanders)
Barbed Surgical Sutures (collaboration with Dr. Martin King)
In collaboration with Dr. Maya Styner, UNC School of Medicine
With age, bone tends to become more brittle, increasing the risk of sudden fracture under moderate to high loads. On the other hand, regular exercise with interspersed periods of rest stimulates bone formation, strengthening bone and reducing the likelihood of fracture. Unfortunately, habitual exercise is most common in youth and young adults, so the degree to which exercise benefits the elderly remains unclear. This project aims to determine the interaction effects of aging and exercise on the bending properties and tissue elastic modulus of mouse femora. Using a combined imaging and mechanical testing approach, we will not only examine the mechanical performance of bones in both exercising and non-exercising groups, but bone geometric and material properties as well to determine precisely how exercise may affect aging bone.
In collaboration with Kitware, Inc.
For any given bone, various surface features such as bumps, ridges, grooves, and knobs may not appear important at first glance, but this could not be farther from the truth. Each facet of a bone plays a vital role, be it an attachment point for muscle, a joint contact surface, reinforcement to improve load-bearing function, or a combination of multiple roles. This holds true even below the bone surface. Interior features such as the size and shape of trabecular bone structures, marrow cavities, and growth plates can strongly influence various functions of bone. Many bone pathologies are likewise associated with changes to bone shape features. Therefore, shape analysis, a method for determining the size, shape, and position of distinct bone features, has great potential for versatile applications. In this project, we are testing a web-based, open-source bone shape analysis pipeline by quantifying differences between models for healthy and diseased bone created from 3D medical images. By comparing the statistical significance of these differences with standard metrics, we aim to show that our accessible pipeline is as effective as standard analyses performed with costly, specialized equipment.
Image: 3D model of a mouse knee segmented to identify anatomical shape features: tibia – light green, femur epiphysis – purple, femur growth plate – dark green, femur metaphysis – red, femur diaphysis – yellow, femur intracortical space – pink
In collaboration with Dr. James Sanders,
UNC School of Medicine Department of Orthopaedics
Idiopathic scoliosis in children presents as abnormal curvature of the spine that tends to initiate in late childhood or adolescence without any definite cause. Once a curve begins to form, it may worsen over time and in severe cases, mobility loss, pain, and restriction of lung volume may occur. Despite the cause remaining unknown, this project aims to investigate the role of the nucleus pulposus, a gel-like tissue typically in the center of the intervertebral disc. We are creating 3D models of scoliotic spines from MRI images to characterize deviation of the nucleus pulposus away from the center of the intervertebral disc and towards the convex side of the curve. This deviation may affect load transfer between vertebrae, which may impact vertebral growth as bone development and maintenance is strongly regulated by mechanical stimuli. In the second phase of this project, we will perform finite element analyses on the same 3D spine models to investigate patterns of stress and strain experienced by the vertebrae while supporting standing loads. Through this combination of techniques, we will determine whether deviation of the nucleus pulposus may be part of a positive feedback loop culminating in the progressive worsening of spinal curvature.
Image: Coronal view showing sideways spinal curvature. Nucleus pulposi are circled, and color coded to show the degree of in-plane deviation: green – not deviated, yellow – slightly deviated, red – highly deviated
In collaboration with Dr. Martin King, College of Textiles, NC State
Barbed surgical sutures are knotless sutures approved by the US FDA in 2004 that have been used in wound closure in various fields, including dermatology, urology, and orthopaedics. However, many aspects of these sutures need to be explore further, including the material selection and performance of various polymers used for these sutures and the extension of usage to tissue repair surgeries. We are characterizing the anchoring performance and tissue engagement of barbed surgical sutures manufactured from various polymers and are evaluating the performance of these sutures in tendon repair using animal models.
Publications and Presentations:
- Huang Y, Cadet ER, King MW, Cole JH. Comparison of the mechanical properties and anchoring performance of polyvinylidene fluoride and polypropylene barbed sutures for tendon repair. Under Review.
- Cong H, Ruff GL, Cole JH, Tokarz DA, Roe SC, Liu W, King MW (2018) In vivo comparison of polydioxanone and polyhydroxyalkanoate barbed surgical sutures in a rat model. Society for Biomaterials Annual Meeting, Atlanta, GA, April 11-14, Podium #202.
- Cong H*, Ruff GL, Cole JH, King MW (2017) Hydrolytic degradation of polydioxanone barbed and non-barbed sutures. International Conference on Medical Textiles and International Forum on Biomedical Textile Materials, Shanghai, China, May 17-19, podium. *Outstanding Oral Presentation Award