title: Near Infrared Spectroscopic Mapping of Functional Properties of Equine Articular Cartilage.
abstract: Mechanical properties of articular cartilage are vital for normal joint function, which can be severely compromised by injuries. Quantitative characterization of cartilage injuries, and evaluation of cartilage stiffness and thickness by means of conventional arthroscopy is poorly reproducible or impossible. In this study, we demonstrate the potential of near infrared (NIR) spectroscopy for predicting and mapping the functional properties of equine articular cartilage at and around lesion sites. Lesion and non-lesion areas of interests (AI, N = 44) of equine joints (N = 5) were divided into grids and NIR spectra were acquired from all grid points (N = 869). Partial least squares (PLS) regression was used to investigate the correlation between the absorbance spectra and thickness, equilibrium modulus, dynamic modulus, and instantaneous modulus at the grid points of 41 AIs. Subsequently, the developed PLS models were validated with spectral data from the grid points of 3 independent AIs. Significant correlations were obtained between spectral data and cartilage thickness (R2= 70.3%, p < 0.0001), equilibrium modulus (R2= 67.8%, p < 0.0001), dynamic modulus (R2= 68.9%, p < 0.0001) and instantaneous modulus (R2= 41.8%, p < 0.0001). Relatively low errors were observed in the predicted thickness (5.9%) and instantaneous modulus (9.0%) maps. Thus, if well implemented, NIR spectroscopy could enable arthroscopic evaluation and mapping of cartilage functional properties at and around lesion sites.
authors.affiliation: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland. jaakko.sarin@uef.fi.|Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland. jaakko.sarin@uef.fi.
authors.forename: Jaakko K
authors.initials: JK
authors.lastname: Sarin
authors.affiliation: Department of Physics and Mathematics, University of Eastern Finland, Joensuu, Finland.
authors.forename: Michael
authors.initials: M
authors.lastname: Amissah
authors.affiliation: Department of Equine Sciences, Utrecht University, Utrecht, Netherlands.
authors.forename: Harold
authors.initials: H
authors.lastname: Brommer
authors.affiliation: School of Veterinary Medicine, Veterinary Teaching Hospital, University of Helsinki, Helsinki, Finland.
authors.forename: David
authors.initials: D
authors.lastname: Argüelles
authors.affiliation: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.|Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Töyräs
authors.affiliation: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.|Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.|Department of Electrical and Computer Engineering, Elizade University, Ondo, Nigeria.
authors.forename: Isaac O
authors.initials: IO
authors.lastname: Afara
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000293:injuries / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D006736:Horses; D007596:Joints / Q000293:injuries / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D013055:Spectrophotometry, Infrared
keywords: Biomechanical; Indentation; Partial least squares (PLS) regression; Spectroscopy