Subchondral bone micro-architectural alterations in osteoarthritis: a synchrotron micro-computed tomography study

Area of Science:

• Orthopedics and Rheumatology
• Bone Biology
• Medical Imaging

Background:

• Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage breakdown and subchondral bone alterations.
• Micro-computed tomography (micro-CT) using synchrotron radiation offers high resolution for analyzing bone micro-architecture.

Purpose of the Study:

• To evaluate the three-dimensional (3D) micro-architecture of subchondral trabecular (Tb) bone in osteoarthritis (OA).
• To compare bone micro-architecture in OA subchondral bone with and without cartilage, and with osteoporosis (OP) bone.

Main Methods:

• Subchondral bone from femoral heads of OA cases (with and without cartilage) and OP cases were analyzed using micro-CT.
• Key parameters measured included bone volume fraction (BV/TV), Tb thickness (TbTh), Tb spacing (TbSp), Tb number (TbN), connectivity, degree of anisotropy (DA), and degree of mineralization (DM).

Main Results:

• Significant differences in BV/TV and morphological parameters were observed between OA subchondral bone lacking cartilage (OAc-) and osteoporosis (OP) samples.
• Connectivity was higher in OAc- compared to OAc+ and OP samples.
• Degree of mineralization (DM) was significantly lower in OAc- and OAc+ compared to OP samples.

Conclusions:

• Subchondral bone changes in OA are predominantly observed in advanced stages with cartilage loss.
• These findings suggest that subchondral bone alterations are secondary to cartilage deterioration in OA, rather than a primary pathogenic mechanism.
• Longitudinal studies are recommended for more definitive conclusions.