Infrared Fiber Optic Probe Evaluation of Degenerative Cartilage Correlates to Histological Grading

Background: Osteoarthritis (OA), a degenerative cartilage disease, results in alterations of the chemical and structural properties of tissue. Arthroscopic evaluation of full-depth tissue composition is limited and would require tissue harvesting, which is inappropriate in daily routine. Fourier transform infrared (FT-IR) spectroscopy is a modality based on molecular vibrations of matrix components that can be used in conjunction with fiber optics to acquire quantitative compositional data from the cartilage matrix. Purpose: To develop a model based on infrared spectra of articular cartilage to predict the histological Mankin score as an indicator of tissue quality. Study Design: Comparative laboratory study. Methods: Infrared fiber optic probe (IFOP) spectra were collected from nearly normal and more degraded regions of tibial plateau articular cartilage harvested during knee arthroplasty (N = 61). Each region was graded using a modified Mankin score. A multi-variate partial least squares algorithm using second-derivative spectra was developed to predict the histological modified Mankin score. Results: The partial least squares model derived from IFOP spectra predicted the modified Mankin score with a prediction error of approximately 1.4, which resulted in approximately 72% of the Mankin-scored tissues being predicted correctly and 96% being predicted within 1 grade of their true score. Conclusion: These data demonstrate that IFOP spectral parameters correlate with histological tissue grade and can be used to provide information on tissue composition.