at was subjected to NIR spectroscopic probing were carefully extracted for histological evaluation based on Mankin score. After dehydration and paraffin embedding, two serial 5 μm sagittal sections obtained at 100 μm intervals from non-weight-bearing and weight-bearing regions, were cut from the joints and stained with safranin O--fast green. For Safranin-O/Fast Green staining, the paraffin-embedded sections were counterstained with Haematoxylin before being stained with 0.02% aqueous Fast Green for 4 min (followed by 3 dips in 1% acetic acid) and then 0.1% Safranin-O for 6 min. The slides were then dehydrated and mounted with crystal mount medium. OA severity in the joints was evaluated according to the modified Mankin histological grading system^[@CR6]^, and Mankin score was assigned for each sample location by three independent assessors. The Mankin score assesses structural integrity (0--6 points), cellularity (0--3 points), matrix staining (0--4 points), and tidemark integrity (0--1 points), with a maximum score of 14 points. The final score for each sample location was determined as the most severe histological change observed in multiple sections. In the case where the scores were different among the assessors, the highest Mankin score was selected. The inter-assessor agreement was assessed using the kappa (κ) coefficient, a chance-corrected estimate of agreement. κ values of 1.00--0.81 indicate excellent agreement, 0.80--0.61 substantial agreement, 0.60--0.41 moderate agreement, 0.40--0.21 fair agreement and 0.20--0.00 slight agreement^[@CR28]^.

Biochemical quantitation of GAG content {#Sec7}
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Sulphated GAG (sGAG) assay was performed based on a protocol provided in the Blyscan sulfated Glycosaminoglycan assay kit (Biocolor Life Science Assays; Labtek, West Ipswich, QLD, Australia). sGAG content was measured at a wavelength of 595 nm by a microplate spectrophotometer (Benchmark Plus, Tacoma, WA, USA). Three measurements were obtained and repeatability