arthritis 2013 july 1
Determining the properties and integrity of subchondral bone in the developmental stages of osteoarthritis (OA), especially in a form that can facilitate real-time characterization for diagnostic and decision-making purposes, is still a matter for research and development. This paper presents relationships between near infrared (NIR) absorption spectra and properties of subchondral bone obtained from 3 models of osteoarthritic degeneration induced in laboratory rats via: (i) menisectomy (MSX); (ii) anterior cruciate ligament transaction (ACL); and (iii) intra-articular injection of mono-ido-acetete (1 mg) (MIA), in the right knee joint, with 12 rats per model group (N = 36). After 8 weeks, the animals were sacrificed and knee joints were collected.
A custom-made diffuse reflectance NIR probe of diameter 5mm was placed on the tibial surface and spectral data were acquired from each specimen in the wavenumber range 4 000 – 12 500 cm-1. After spectral acquisition, micro computed tomography (micro-CT) was performed on the samples and subchondral bone parameters namely: bone volume (BV) and bone mineral density (BMD) were extracted from the micro-CT data.
Statistical correlation was then conducted between these parameters and regions of the near infrared spectra using multivariate techniques including principal component analysis (PCA), discriminant analysis (DA), and partial least squares (PLS) regression. Statistically significant linear correlations were found between the NIR absorption spectra and subchondral bone BMD (R2 = 98.84%) and BV (R2 = 97.87%).
This non-destructive and fast evaluation technique provides a means of detecting, qualifying and quantifying changes in subchondral bone composition during OA development in rats, and this has the potential for clinical appraisal and real-time evaluation of subchondral bone health during joint surgery.