Risk factors for atlantoaxial dislocation in rheumatoid arthritis: A comparative study.

BACKGROUND: The objective of the study was to assess clinical and imaging features of rheumatoid arthritis associated with atlantoaxial dislocation (RA-AAD) in comparison to RA without AAD (RA-C) and to identify the associated factors to AAD. METHODS: This was a retrospective comparative study including RA patients over 18 years old. The control group of RA-C was matched according to age (±2 years), gender, and RA duration (±2 years). General data, RA characteristics, AAD features, and treatment modalities were recorded. Statistical analysis was performed to determine the predictive factors of AAD. RESULTS: A total of 120 patients were included (78 RA-AAD and 42 RA-C); sex-ratio was 0.15. Mean age was 58.55 ± 9.14 years (RA-AAD) versus 60.43 ± 10.78 years (RA-C), (p = 0.31). Regarding RA features, RA-AAD patients have significantly a higher rheumatoid factor (RF) rate (p = 0.002), extra-articular manifestations (p = 0.009) especially osteoporosis (p < 10-3 ), eye involvement (p = 0.02), coxitis (p < 0.0001), Disease Activity Score (DAS28) (p < 10-3 ), and global health status scale (HAQ) (p = 0.003). X-ray analysis showed pathologic PADI (<14 mm) in 51.6% of cases. The AADI was pathological (>3 mm) in 100% of patients with the following distribution: 67.9% between (3-6 mm) and 23.3% between (6-9 mm). Atlantoaxial dislocation (AAD) was presumed anterior (85.4%), lateral (7.3%) and rotatory (7.3%). The abnormalities observed on magnetic resonance imaging (MRI) were: C1-C2 synovitis (61%), confirmed AAD (34.1%) and basilar impression (4.9%). AAD diagnosed by cervical MRI was anterior in 89.8% of cases, lateral (5.3%) and with a double ascending and anterior component in 4.9% of cases. An immobilisation with a type C4 cervical collar was indicated for all the patients and five of them had boluses of corticosteroid (methylprednisolone 1 g/day) for three consecutive days. C1-C2 arthrodesis by trans-articular screwing was performed in four patients with neurological signs or pathological measurements on cervical MRI. The outcome was favourable in 100% of cases after surgical treatment with improvement in neck pain and neurological condition within a mean decline of 4 ± 3 years [1-7]. Multivariate analysis identified coxitis, osteoporosis, high baseline DAS28, and a high rate of RF positivity as predictive factors of AAD. CONCLUSION: Our results confirmed that predictive factors of AAD were related to higher disease activity and structural damage. These modifiable factors may be prevented by tight control, early treatment, and educating RA patients to improve treatment adherence.

ZnFe2O4-chitosan magnetic beads for the removal of chlordimeform by photo-Fenton process under UVC irradiation.

A simple protocol was proposed for the preparation of magnetic chitosan beads ZnFe2O4-CS via a co-precipitation method. The use of synthesized magnetic ZnFe2O4-CS beads as catalyst for the heterogeneous photo-Fenton treatment of chlordimeform insecticide (CDM) was evaluated. The photo-Fenton experiments were carried out with different synthesized catalysts by varying the molar ratio Zn/Fe in chitosan beads, the catalyst concentration and pH. Under optimal conditions using 1 g of ZnFe2O4-CS beads with a molar ratio Zn/Fe = 0.35 and at pHinitial = 3, a real wastewater doped with 20 mg L-1 of CDM was treated and complete removal of the insecticide was achieved after 7 min with a total TOC removal after 2 h of treatment. The generated carboxylic acids and ions during the photo-Fenton process were identified and quantified. The stability of the photocatalytic activity of the best catalyst in terms of pollutant removal, ZnFe2O4-CS(0.35) beads with a molar ratio Zn/Fe equal to 0.35, was satisfactory validated by four consecutive cycles. This optimal catalyst was characterized, before and after use, by Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy, X-Ray Powder Diffraction and Vibrating Sample Magnetometry analysis.