Analysis of Bone Microstructural Changes Using Raman Spectroscopy in Women with Varus Deformity of the Knee Joint in the Course of the Primary Osteoarthritis

The aim of this study was to determine the correlation between the level of deformation, the degeneration rate of the knee joint, and the change in the structure of the subchondral bone layer affected by osteoarthritis in women. The study included patients diagnosed with primary knee osteoarthritis, with varus of the joint, planned for surgical treatment in the form of knee arthroplasty. The patients underwent a clinical and radiological assessment using standard radiographs of the knee joints in the anterior–posterior and lateral positions, while the level of varus deformity of the joint was determined on the basis of measurement radiographs of the lower limbs. Cartilage and bone materials from the tibial plateau were collected from 30 patients during the surgical treatments; these were then processed and examined using the Raman spectroscopy technique at the Department of Optical Spectroscopy of the Poznań University of Technology using the Renishaw inVia micro-Raman system coupled with a confocal microscope. The obtained Raman scattering spectra were analyzed by measuring the individual band intensities, and the results in the form of the ratios of selected Raman bands assigned to selected chemical groups were expressed as the mineralization index. The patients were divided into two groups, the first with a joint varus range of 3–10 degrees and the second with a range of 11–30 degrees. The patients were also divided into four groups, depending on the osteoarthritis degree, using the Kellgren–Lawrence scale. The investigation indicated that there is a relationship between the level of deformation and degeneration of the knee joint, expressed in scales based on radiological examination, and the coefficient, which determines the changes in the bone microstructure. The results showed that a decrease in mineralization occurred in the medial and lateral condyles as the knee osteoarthritis progressed. This study confirmed that the Raman spectroscopy technique is a useful tool for further research regarding the pathogenesis and course of osteoarthritis and may have an impact on the early diagnosis and treatment of knee osteoarthritis.