Identifying compositional and structural changes in spongy and subchondral bone from the hip joints of patients with osteoarthritis using Raman spectroscopy

Abstract

Raman microspectroscopy was used to examine the biochemical composition and molecular structure of extracellular matrix in spongy and subchondral bone collected from patients with clinical and radiological evidence of idiopathic osteoarthritis of the hip and from patients who underwent a femoral neck fracture, as a result of trauma, without previous clinical and radiological evidence of osteoarthritis. The objectives of the study were to determine the levels of mineralization, carbonate accumulation and collagen quality in bone tissue. The subchondral bone from osteoarthritis patients in comparison with control subject is less mineralized due to a decrease in the hydroxyapatite concentration. However, the extent of carbonate accumulation in the apatite crystal lattice increases, most likely due to deficient mineralization. The alpha helix to random coil band area ratio reveals that collagen matrix in subchondral bone is more ordered in osteoarthritis disease. The hydroxyapatite to collagen, carbonate apatite to hydroxyapatite and alpha helix to random coil band area ratios are not significantly changed in the differently loaded sites of femoral head. The significant differences also are not visible in mineral and organic constituents' content in spongy bone beneath the subchondral bone in osteoarthritis disease.

Decomposition of in vivo spatially offset Raman spectroscopy data using multivariate analysis techniques

“…[29,30] Thus, the two measures of bone composition that have been associated with osteoarthritis, osteoporosis and osteogenesis imperfecta, the phosphate-to-carbonate ratio and the mineral-to-collagen ratio, were the central focus of the study. [7][8][9][10] The phosphateto-carbonate ratio was accurately reconstructed by all three analyses, each having errors of 2% or less. The phosphate-tocarbonate ratio is easier to resolve than the mineral-to-collagen ratio since the phosphate and carbonate bands are unique to the target layer (bone) and so are less affected by being covered with a layer of skin/soft tissue.…”

“…For example, it has been shown that excised subchondral bone from osteoarthritic hip joints can have decreased mineral-to-collagen ratio (~15%) and decreased phosphate-to-carbonate ratio (~20%). [7] It has also been shown that excised subchondral bone from osteoarthritic knee joints can have increased mineral-to-collagen ratio (~3%) and decreased phosphate-to-carbonate ratio (~6%). [8] Studies of excised bone from patients who had suffered osteoporotic fracture of the femur suggest that the bone in their femoral neck has an increased mineral-to-collagen ratio (~30%) [9] and studies of excised bone from mutant mice models of osteogenesis imperfecta suggest the mineral-to-collagen ratio is increased (~20%).…”

Polarization control of Raman spectroscopy optimizes the assessment of bone tissue

“…36 Given low instrument polarization and results from less polarization sensitive carbonate and Amide III bands, analysis of bone from osteoarthritic patients on different load bearing surfaces can be interpreted as a largely compositional effect. 53 Phase mismatch of ν1 Phosphate/CH 2 [see Figs. 2 and 6(e)] may have contributed to biomechanical correlation due to use of a commercial confocal system, 24 thereby indicating a Table 3 Paired phase difference between selected Raman peak ratios and overall variance of peak ratios were estimated for bone and tooth rotation using the unaltered polarization instrument.…”

Raman spectroscopy: techniques and applications in the life sciences

“…In some of these situations, ratios of Raman bands can be useful indicators. Buchwal et al used Raman band ratios as indicators of bone structure and composition [467] while Li et al used band ratios to measure the effects of maleic acid on human sperm [468].…”