Rheumatoid shoulder assessed by ultrasonography: prevalence of abnormalities and associated factors

Introduction The shoulder involvement in rheumatoid arthritis (RA) is common. It can be subclinical and compromise the function of the upper limb. Musculoskeletal ultrasonography can detect subclinical abnormalities in rheumatoid shoulder. Our aim was to assess the prevalence of ultrasound abnormalities in rheumatoid shoulder, and investigate their association with different parameters. Methods Cross-sectional study including 37 patients with RA, meeting the ACR/EULAR 2010 classification criteria, who were enrolled during a month. A questionnaire with sociodemographic, clinical and laboratory data was filled in for all patients. Ultrasound evaluation was performed by a single experienced operator. For each patient, both of shoulders were evaluated. Results Mean age was 50 years with female predominance. Median disease duration of RA was 7.5 years. All patients had a seropositive form of RA. Mean clinical DAS28 was 5.1. Mean HAQ was 1.2. Thirty-one (83.8%) patients had involvement of the shoulder: unilateral in 9(24.3%) cases and bilateral in 22(59.5%) cases. Synovitis was found in 16(43.2%) patients with Doppler in 4 (10.8%) cases. Sub-acromial bursitis was noted in 14 (37.8%) cases and the effusion in 20 (54.1%). Synovitis was noted especially in elderly individuals (p: 0.01). The Doppler was visualized in elderly patients (p: 0.01), with a shorter disease duration (p: 0.02) and with a high SDAI (p: 0.006). US inflammatory findings in anterior recess of glenohumeral joint were linked to a higher synovial index (p: 0.03) and a higher level of rheumatoid factor (p: 0.01). Conclusion 59.5% of our RA patients had bilateral involvement of the shoulder which was related to the disease activity. Ultrasound should be a systematic tool to look for the involvement of this joint in RA patients.


Introduction
Shoulder involvement is frequent during the natural history of Rheumatoid Arthritis (RA). Several structures can be targeted by the disease; especially the glenohumeral joint but also periarticular structures. Only a small proportion of patients has clinically detectable shoulder tenderness and swelling, whereas up to 5% of patients after 2 years and 96% after 12 years show erosive damage at the shoulder [1,2]. Thus, clinical evaluation of shoulder does not offer an accurate assessement of this joint [3]. Moreover, conventional radiography ascertains tardily the diagnosis. Owing to the necessity of early treatment in RA patients before the damage occurrence [4], musculoskeletal (MS) ultrasonography (US) has a great role in detecting subclinical abnormalities in rheumatoid shoulder in order to achieve a low disease status and eventually remission. It has proved to be a valid tool in the assessment of inflammatory arthritis, including RA, and to be more sensitive than clinical examination in such joints as rheumatoid shoulder. Also, it has shown a good correlation with clinical and biologic parameters [5,6]. The aim of the present study was to evaluate the prevalence of abnormalities in rheumatoid shoulder, and to investigate their association with the clinical and laboratory measures.   was not evaluated since abnormalities at this region are frequently seen even in healthy subjects and might not reflect RA involvement.

Statistical analysis
All statistical calculations were done by computer using SPSS software (SPSS, Inc., Chicago, IL, USA). Quantitative variables were expressed as means ± SD or as medians and interquartile range, depending on their distribution. For categorical variables, the percentages of patients in each category were calculated.
Categorical variables were analysed using chi-squared tests, quantitative variables were analysed using the unpaired t-test for normally distributed ones, and Mann-Whitney U-test for nonnormally distributed ones. The significance set was fixed at a p value of equal to or less than 0.05.

Conclusion
Ultrasound allows the differentiation between degenerative shoulder lesions and signs of disease activity in RA and identifies a subgroup of patients with higher disease activity that could benefit from a more aggressive treatment approach. Further studies are needed to investigate these findings.
What is known about this topic  All joints can be affected during the natural history of Rheumatoid Arthritis (RA);  Clinical evaluation and conventional radiography remain insufficient for assessing several structures;  Musculoskeletal ultrasonography has a great role in detecting subclinical abnormalities in rheumatoid joints in order to achieve a low disease status and eventually remission.

What this study adds
 This study tries to assess the prevalence of abnormalities in rheumatoid shoulder by ultrasonography and to identify risk factors associated with.

Competing interests
The authors declare no competing interest.
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Authors' contributions
All authors have read and agreed to the final version of this manuscript and have equally contributed to its content and to the management of the case.

Acknowledgments
We are really grateful because we managed to achieve this study which couldn't be completed without the effort and co-operation from our group members. I sincerely thank all my co-authors for the guidance and encouragement in finishing this research. I also would like to express my gratitude to my colleagues for the support to spend some times with me to fill in the questionnaires. Table 1: Baseline characteristics of patients