Near Infrared Spectroscopic Mapping of Functional Properties of Equine Articular Cartilage.

The research study evaluates the use of near infrared (NIR) spectroscopy in predicting and mapping the functional properties of horse joint cartilage, particularly around areas of injury. Conventional methods of assessing cartilage injuries can have poor reproducibility, so this new approach could potentially enhance the accuracy of diagnosis and monitoring.

Methodology

• The researchers procured sections of equine joints, with both normal and injured areas, totaling 44 different zones of interest (AI).
• These AI zones were then split into grids, and this resulted in 869 individual grid points, from which spectroscopic readings could be taken.
• The researchers collected the NIR spectra – a form of light that can penetrate the surface of the tissue – from these grid points.
• Following data collection, a statistical technique called partial least squares (PLS) regression was used to find potential correlations between the spectroscope readings and the thickness, equilibrium modulus (a measure of the cartilage stiffness when in a state of stress equilibrium), dynamic modulus (measure of stiffness under conditions of changing stress), and instantaneous modulus (a measure of stiffness at a given instant) at the grid points of 41 AIs.
• The PLS models were then validated by using them to predict the properties of independent AIs.

Results

• Significant correlations were found between the spectral data and each of the cartilage properties measured. Particularly, the thickness (70.3%), equilibrium modulus (67.8%). dynamic modulus (68.9%), and instantaneous modulus (41.8%).
• When the models were used to predict the properties of the independent test samples, they exhibited relatively low error rates for thickness (5.9%) and instantaneous modulus (9.0%).

Conclusion

• The study shows that near infrared spectroscopy has the potential to be used in the assessment and mapping of functional properties, such as thickness and stiffness, of articular (joint) cartilage, particularly around areas of injury.
• This would be a significant advance over traditional arthroscopic (a minimally invasive procedure used to examine and treat damage within the joint) methods of evaluation, which have been found to be less reliable.