Forefoot Deformity in Rheumatoid Arthritis: A Comparison of Shod and Unshod Populations

The causality between rheumatoid arthritis and postural deformities: bidirectional Mendelian randomization study and mediation analysis

Background

To better understand the preventive or therapeutic clinical interventions that may be supported by the association between rheumatoid arthritis (RA) and postural deformities including hallux valgus, flat foot, and scoliosis, this study was conducted using Mendelian randomization (MR) analysis. It aimed to investigate whether RA is causally associated with postural deformities in European populations.

Methods

Summary-level data on RA and postural deformities were obtained from the IEU OpenGWAS project and Finngen database, respectively. LDSC regression analysis was conducted to assess the genetic correlation between these diseases. The inverse variance weighting (IVW) method was employed as the primary approach for two-sample MR analyses to evaluate causality. Supplementary methods included MR-Egger, maximum likelihood, weighted median, and cML-MA. To test for potential horizontal pleiotropy, we performed the MR-Egger intercept test, cML-MA, and secondary analyses after excluding confounders. Additionally, mediation analyses were conducted using two-step MR.

Results

The IVW method revealed RA to be causally associated with hallux valgus (OR 1.132, 95% CI 1.087-1.178, P < 0.001) and flat foot (OR 1.197, 95% CI 1.110-1.291, P < 0.001). Among postural deformities, hallux valgus was causally associated with flat foot (OR 1.823, 95% CI 1.569-2.119, P < 0.001) and scoliosis (OR 1.150, 95% CI 1.027-1.287, P < 0.05). No significant horizontal pleiotropy was detected. Moreover, mediation analyses indicated that hallux valgus mediates the effect of RA on flat foot (mediation effect 0.024, 95% CI 0.005-0.044, P < 0.05), with a mediation proportion of 41.31%.

Conclusion

These findings indicate a potential causal association between genetically predicted RA and both hallux valgus and flat foot. Furthermore, hallux valgus serves as a mediator in the pathway from RA to flat foot. This underscores the importance of early screening and preventive treatment of foot deformities in RA patients. Further research is necessary to determine the applicability of these findings in non-European populations.

Signaling pathways in rheumatoid arthritis: implications for targeted therapy

Rheumatoid arthritis (RA) is an incurable systemic autoimmune disease. Disease progression leads to joint deformity and associated loss of function, which significantly impacts the quality of life for sufferers and adds to losses in the labor force. In the past few decades, RA has attracted increased attention from researchers, the abnormal signaling pathways in RA are a very important research field in the diagnosis and treatment of RA, which provides important evidence for understanding this complex disease and developing novel RA-linked intervention targets. The current review intends to provide a comprehensive overview of RA, including a general introduction to the disease, historical events, epidemiology, risk factors, and pathological process, highlight the primary research progress of the disease and various signaling pathways and molecular mechanisms, including genetic factors, epigenetic factors, summarize the most recent developments in identifying novel signaling pathways in RA and new inhibitors for treating RA. therapeutic interventions including approved drugs, clinical drugs, pre-clinical drugs, and cutting-edge therapeutic technologies. These developments will hopefully drive progress in new strategically targeted therapies and hope to provide novel ideas for RA treatment options in the future.

Morpho-structural characteristics of feet in patients with rheumatoid arthritis: A cross sectional study

Objective: The aim of this study was to evaluate and classify the types and incidences of foot deformities in patients with Rheumatoid Arthritis (RA). Methods: A cross-sectional study with convenience sample was obtained of 220 patients with foot pain and RA classification criteria (approved by the American College of Rheumatology and the European League against Rheumatism in 2010). A series of outcomes were assessed to measure the morphological characteristics of the feet. The Foot Posture Index (FPI), the Manchester Scale of Hallux Valgus and the Nijmegen classification of forefoot disorders were assessed. Results: The most common foot posture according to the FPI assessment are the pronated position in the left foot (32.7% of participants) and the neutral position in the right foot (34.1% of participants). The disease progression causes more developed and serious foot deformities. 1.82% of patients present a severe level of Hallux Valgus before 10 years of disease evolution whereas 4.09% of patients present a severe level of Hallux Valgus after 10 years of disease evolution. Conclusions: The most common foot type in patients with RA is the pronated foot type with deformities in the MTP joints without Hallux Valgus. However, a percentage of patients with RA presents supinated foot type. The evolution of the disease shows some morphological changes in terms of patient's feet. The presence of more developed foot deformities is increased, such us Hallux Valgus or MTP joints deformity (Grade 3 in the Nijmegen classification scale).