Quantification of arthritic bone degradation by analysis of 3D micro-computed tomography data

Area of Science:

• Orthopedics
• Rheumatology
• Biomedical Engineering

Background:

• Animal models are crucial for evaluating rheumatoid arthritis (RA) therapies.
• Quantifying bone degradation in RA models is essential for assessing treatment efficacy.

Purpose of the Study:

• To present quantitative measurements of bone degradation using the cortical bone profile in a glucose-6-phosphate isomerase (G6PI)-induced arthritis model.
• To investigate the effect of experimental arthritis on the cortical bone profile of metatarsals.
• To introduce and validate the cortical thickness gradient (CTG) as a novel measure for assessing bone changes in arthritis.

Main Methods:

• Micro-computed tomography (μCT) was used to image metatarsals from hind paws in three arthritis and one control experiment.
• Automated identification of orthogonal slices to metatarsals ensured measurement independence from animal positioning.
• Cortical thickness index (CTI) and the newly introduced cortical thickness gradient (CTG) were measured along the metatarsals.

Main Results:

• Both CTI and CTG were found to quantify arthritic progression.
• The cortical thickness gradient (CTG) demonstrated higher sensitivity in detecting arthritic changes compared to CTI.
• Arthritis significantly affected the cortical bone profile, as evidenced by changes in CTI and CTG.

Conclusions:

• The developed μCT method provides reliable quantification of bone degradation in experimental arthritis.
• The novel cortical thickness gradient (CTG) is a sensitive biomarker for assessing bone loss in rheumatoid arthritis models.
• This approach aids in the evaluation of therapeutic strategies for rheumatoid arthritis by providing precise measurements of bone degradation.