Abstract
Osteoporosis (OP) and Osteoarthritis (OA) are two of the most common musculoskeletal diseases in the ageing population. This study aimed at a comprehensive comparison of subchondral bone and cartilage changes between OP and OA, in order to better understand their commonalities and differences and provide new information on the pathological process of OA.Femoral heads with OP (N=7) and OA (N=31) were collected from patients undergoing arthroplasty surgeries. Osteochondral plugs were extracted from different regions of the femoral heads according to the severity of cartilage degradation assessed by a new macroscopic and a modified OARSI microscopic grading system. Plugs were scanned by micro-computed tomography and it was shown that subchondral bone with early cartilage degradation in OA was similar to those in OP in terms of both microarchitecture and matrix mineralisation, in both subchondral plate and trabecular bone. In contrast, subchondral bone in OA with advanced cartilage degradation was sclerotic and hypo-mineralised. These data indicate that subchondral bone remodelling in OA is a biphasic process and at an early stage it may have similar features to those seen in OP. Moreover, subchondral trabecular bone was more mineralised than the subchondral plate in both OP and OA, and the relationships among trabecular bone volume fraction, material density, and apparent density were similar in OP and different stages of OA.
Chondrocytes expressing MMP13 and ADAMTS4 were located mainly in the upper zone(s) of cartilage in both OP and OA as shown by immunohistochemistry. The percentage of degradative chondrocytes in different zones of cartilage in OA exhibited a significant variation with the severity of cartilage degradation. The percentage was significantly lower in OP in all zones compared to various stages of OA, but exhibited greater heterogeneity. The correlations between expression of degradative enzymes by chondrocytes and subchondral bone properties in OP and OA were statistically significant for only a few parameters examined, and the correlations were generally weak. Based on these data a novel model of cartilage degradation in OA was proposed, in which biochemical disruption is more important in early stages while mechanical wear is critical in advanced stages.
| Date of Award | 2 Dec 2021 |
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| Original language | English |
| Awarding Institution |
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| Sponsors | China Scholarship Council |
| Supervisor | Ashley Blom (Supervisor) & Mohammed Sharif (Supervisor) |