Sam McPhee (Edinburgh / GB), Lekha Koria (Leeds), Marlène Mengoni (Leeds), Marta Peña Fernández (Edinburgh / GB), Rainer Beck (Edinburgh / GB), Jonathan Shephard (Edinburgh / GB), Claire Brockett (Leeds), Uwe Wolfram (Clausthal-Zellerfeld)
Abstract-Text (inkl. Referenzen und Bildunterschriften)
Introduction: Osteoarthritis (OA) is a multifaceted joint disease primarily characterised by cartilage degeneration, causing pain and reduced mobility. Understanding the complex pathogenesis of OA is crucial for improving treatment strategies. Aside from cartilage changes, alterations in subchondral bone play a significant role in OA progression. While the macrostructural alterations are well documented, few studies explore the microscale mechanical properties of the constituent tissue. Our aim was to investigate whether microscale non-linear mechanical and compositional properties of OA subchondral bone differ from healthy bone.
Materials: Micropillars with an average height of 143.1 µm and taper angle of 12.3°, were extracted by picosecond laser ablation in the subchondral bone plate (BP) and trabeculae (TB) of distal tibia specimens resected from 3 cadaveric donors (ND) and 2 arthroplasty patients (OA). Micropillars were hydrated and compressed uniaxially with a cyclic loading profile to a depth of 15 µm. In silico micropillar compression was used to back-calculate the constituent elastic (E0) and yield (σ0-) properties of each pillar. We used power law regression to evaluate whether variables attributed to the mineral and collagen phases, measured by quantitative backscattered electron microscopy (qBEI) and Raman spectroscopy, could explain the variability of the mechanical properties.
Results & Conclusion: ND and OA pillars exhibited a median (IQR) E0 of 7.83 (2.94) GPa and 8.23 (2.78) GPa and σ0- of 49.09 (21.88) MPa and 54.00 (25.63) MPa. Only σ0- was significantly different between the ND and OA trabeculae pillars. Power law regression revealed that the mineral density measured by qBEI was the primary explanatory compositional variable for predicting E0 and σ0-. The results suggest that microscale mechanical properties are largely unaffected by the progression of OA, especially in the context of drastic morphological changes that occur in late-stage OA.