A spectroscopic approach to imaging and quantification of cartilage lesions in human knee joints

Abstract

We have previously described a technology based on diffuse reflectance of broadband light for measuring joint articular cartilage thickness, utilizing that optical absorption is different in cartilage and subchondral bone. This study is the first evaluation of the technology in human material. We also investigated the prospects of cartilage lesion imaging, with the specific aim of arthroscopic integration. Cartilage thickness was studied ex vivo in a number of sites (n = 87) on human knee joint condyles, removed from nine patients during total knee replacement surgery. A reflectance spectrum was taken at each site and the cartilage thickness was estimated using the blue, green, red and near-infrared regions of the spectrum, respectively. Estimated values were compared with reference cartilage thickness values (taken after sample slicing) using an exponential model. Two-dimensional Monte Carlo simulations were performed in a theoretical analysis of the experimental results. The reference cartilage thickness of the investigated sites was 1.60 ± 1.30 mm (mean ± SD) in the range 0-4.2 mm. Highest correlation coefficients were seen for the calculations based on the near-infrared region after normalization to the red region (r = 0.86) and for the green region (r = 0.80).

The Contribution of Bone and Cartilage to the Near-Infrared Spectrum of Osteochondral Tissue

“…40 The influence of thickness on cartilage spectra has also been investigated in the visible and short-wave NIR spectral region. 55–58 Intensities and RGB coordinates from visible images usefully predicted cartilage thickness below 1.5 mm (RMSEP 0.28 mm), although prediction efficacy was reduced for samples between 1.5 mm and less than 2.5 mm thick. 55 …”

Non-destructive electromechanical assessment (Arthro-BST) of human articular cartilage correlates with histological scores and biomechanical properties

“…Multiple research groups have invented devices to assess cartilage function during arthroscopic surgery 2e6 . Methods involving ultrasound biomicroscopy 7 , arthroscopic ultrasound imaging 8 , optical reflection spectroscopy 9 , pulsed laser irradiation 10 or near-infrared spectroscopy 11 have been proposed. Two devices obtained FDA regulatory clearance (Artscan™ 200 Arthroscopic Cartilage Stiffness Tester and Actaeon™ Probe), while the Artscan was only briefly commercialized.…”

Cartilage analysis by reflection spectroscopy

“…The reflected light was transmitted via reflection probe and fiber to the VIS spectrometer (LR1 V.2.1, ASEQ Instruments, Canada, spectral range 200-1100 nm) respectively the NIR spectrometer (TIDAS S-1000 MS-T50/16, J&M Analytik AG, Germany, spectral range 1100-2100 nm). The relative reflection spectra were calculated by the formula [3] (1)…”