Temporal progression of subchondral bone alterations in OA models involving induction of compromised meniscus integrity in mice and rats: A scoping review

Femoral neck shape and trabecular bone microarchitecture association with hip osteoarthritis - Results from the QUALYOR study

OBJECTIVES

Hip osteoarthritis (OA) is a major public health concern. The determinants of hip OA, however, are not as well understood as those of other OA sites, such as the knee. In recent years, the role of subchondral bone in the pathogenesis of OA has been emphasized but data are lacking for hip OA. Therefore, we aimed to determine which bone characteristics were associated to hip OA.

METHODS

We made a cross-sectional analysis of 1537 postmenopausal women included in the QUALYOR prospective cohort. At baseline, we measured areal BMD by DXA at the lumbar spine and the hip, volumetric BMD and geometry by hip quantitative computerized tomography (QCT) using the Bone Investigational Toolkit (BIT) software, as well as microarchitecture at the distal radius and tibia by high-resolution peripheral quantitative tomography (HR-pQCT). We built a hip OA score (CT OA score) with images from the hip QCT, based on the depiction of the four major signs of osteoarthritis: subchondral bone sclerosis, joint space narrowing, osteophytes and subchondral cysts. The severity of each of these four signs was graded as absent, mild, moderate or severe (semi-quantitative score ranging from 0 to 3 for each sign). The absence of hip OA was defined as CT score equal to 0, mild hip OA as CT score between 1 and 4 and moderate to severe hip OA as CT score>4. Women with and without hip OA were compared using t tests and multivariable modeling.

RESULTS

The mean age was 65.9 (±6.7) years and the mean body mass index was 24.6 (±3.6) kg/m2. Among these 1537 women, 601 had an OA score of 0, 756 between 1 and 4 (mild OA) and 180 greater than 4 (severe OA). Women with hip osteoarthritis had lower trabecular total hip vBMD (125 vs. 129mg/cm3, P<0.01). Cortical hip vBMD did not differ between women with and without hip OA (966.5 vs. 963.5mg/cm3, P n.s). Patients with hip OA also had larger femoral neck volume (11.55 vs. 11.27mm3, P<0.001). The BIT analysis showed greater bone resistance to bending (cross-sectional moment of inertia [CSMI] min with 6.03 vs. 5.6cm4 and section modulus [Z] polar with 7.98 vs. 7.59cm3, P<0.05) at the femoral neck in patients with mild hip OA and even greater in women with severe hip OA. Patients with hip OA had significantly higher trabecular area measured at the radius by HR-pQCT (205.11 vs. 192.61mm2, between group difference 12.50 95% CI [8.15-16.86] P<0.01), lower trabecular number at the tibia (1.57/μm vs. 1.63/μm, between group difference -0.06 95% CI [-0.09 to -0.03] P<0.001) and higher trabecular spacing at the tibia (0.58 vs. 0.56μm, between group difference 0.02 95% CI [0.011-0.038] P<0.005). Cortical parameters were not different in patients with hip OA compared to controls.

CONCLUSION

Women with hip OA have larger femoral neck and lower trabecular bone parameters, suggesting a sizeable role of hip bone geometry and remodeling in the pathophysiology of hip OA.

Pyroptosis for osteoarthritis treatment: insights into cellular and molecular interactions inflammatory

Osteoarthritis (OA) is a widely prevalent chronic degenerative disease often associated with significant pain and disability. It is characterized by the deterioration of cartilage and the extracellular matrix (ECM), synovial inflammation, and subchondral bone remodeling. Recent studies have highlighted pyroptosis-a form of programmed cell death triggered by the inflammasome-as a key factor in sustaining chronic inflammation. Central to this process are the inflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18), which play crucial roles mediating intra-articular pyroptosis through the NOD-like receptor protein 3 (NLRP3) inflammasome. This paper investigates the role of the pyroptosis pathway in perpetuating chronic inflammatory diseases and its linkage with OA. Furthermore, it explores the mechanisms of pyroptosis, mediated by nuclear factor κB (NF-κB), the purinergic receptor P2X ligand-gated ion channel 7 (P2X7R), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and hypoxia-inducible factor-1α (HIF-1α). Additionally, it examines the interactions among various cellular components in the context of OA. These insights indicate that targeting the regulation of pyroptosis presents a promising therapeutic approach for the prevention and treatment of OA, offering valuable theoretical perspectives for its effective management.

Osteoarthritis year in review 2024: Biology

Osteoarthritis (OA) research is a fast-growing and extremely wide field, in which a substantial increase in knowledge has been achieved over the last year. It covers many different topics, however, a PubMed search using the terms 'osteoarthritis' and 'biology' resulted in only a limited number of studies that were published between April 2023 and April 2024. In order to identify OA-relevant studies that focus on mechanistic studies of biological processes at the tissue, cellular, and molecular level, the following keywords were included as search terms: tissue interactions, single cell sequencing, transcriptomics, extracellular matrix, signaling, ion channels, and pain. The final selection of publications presented in this 'year in review' was influenced by the personal preferences of the authors, and eventually three larger key themes emerged: 1) Joint tissue interactions covering meniscus, subchondral bone, fat tissue, synovium, and synovial fluid. 2) Degeneration of the cartilage extracellular matrix and generation of bioactive fragments. 3) Receptors, ion channels, signaling pathways, and cellular metabolism. Many of the studies summarized here identified novel potential targets for OA treatment, and promising results were already obtained addressing these targets in different animal models. It will be exciting to see which findings can be translated into future clinical studies and eventually lead to novel treatment approaches for human OA.