Background Recently there have been studies showing the presence of inflammatory joint activity in patients with systemic lupus erythematosous (SLE) without musculoskeletal symptoms. The predictive value of these findings remains unknown. On the other hand, there is a proportion of healthy patients where synovitis can be demonstrated as a result of recent mechanical overexertion.
Objectives The aim of this study is to compare the sonographic findings of SLE patients without joint symptoms with healthy people.
Methods An ultrasonographic study (USS) was performed, using a linear probe for soft tissues (5-12 MHz), to 15 patients newly diagnosed with SLE and 44 healthy subjects matched for age and sex. The areas studied were: back of the wrist, 2nd and 3rd metacarpophalangeal joint (MCP) and 2nd and 3rd flexor tendon. The studies were performed in the nondominant hand. We determined the presence of synovitis, tenosynovitis and tendinosis and measured the thickness of the flexor tendons. Dichotomous variables were analyzed using the chi-square test and numerical variables through the Student t test.
Results Controls were matched with SLE patients of the same sex and age with a maximum difference of ± 3 years. SLE patients came from a cohort previously used in another study with no less than 5 years follow-up. Controls were healthy volunteer patients from the osteoporosis clinics or patients with localized non-inflammatory diseases outside the field of USS. Carpal sinovitis was seen in 33,3% of SLE patients and 27,2% of controls (p<0,05); metacarpophalangeal (MCP) synovitis was seen in 33,3% of SLE patients and 13,6% of controls (p<0,05); carpal tenosynovitis was seen in 40% of SLE patients and 13,6% of controls (p<0,05). The height of the synovial capsule of the carpal joint was 3,67±0,21 in SLE patients and 2,99±0,30 in the control group (p<0,001); Thickness of the extensor sheath was 2,99±0,42 in SLE patients and 2,49±0,36 in the control group (p<0,05); height of the capsule of the 2nd MCP joint was 3,19±0,27 in SLE patients and 3,04±0,19 in the control group (p>0,05); height of the capsule of the 3rd MCP joint was 2,91±0,52 in SLE patients and 2,54±0,32 in the control group. In order to compare MCP capsules height we assay a corection using the lenght of the major axis of the joint. The fixed height of the 2nd MCP was 0,461±0,121 and 0,406±0,098 (SLE/controls) (p<0,001); the fixed height of the 3rd MCP was 0,445±0,200 and 0,3642±0,117 (p<0,001).
Conclusions Our results suggest that the population of SLE patients without joint symptoms present sonographic findings suggestive of joint inflammation and tendon involvement that can not be explained by the acceptable changes that can be found in disease-free population, however, interpretation of their evolutionary significance has not been clarified.
The role of time since diagnosis in the development of synovitis or tendinosis, or corticoids in the development of tendinosis may be revealed with studies with larger amounts of patients.
Disclosure of Interest None Declared