Background In the last decade, the role of musculoskeletal ultrasound in investigating monosodium urate deposition is rapidly evolving since various findings have been described as specific for gout.
Objectives The goal of this study was to investigate the frequency of gout-specific ultrasonography (US) findings in a selected cohort of manual workers with hyperuricemia and various musculo-skeletal complaints being admitted to a rehabilitation unit because of high risk of occupational disability.
Methods In order to eliminate any experimental bias, an examiner blinded study (regarding the clinical and lab assessment of patients) of 12 joints was performed using standardized US examinations of 58 individuals undergoing an inpatient rehabilitation program with diverse musculo-skeletal complaints. Ultrasonographic findings were described and gout-specific changes, for example the double contour sign and tophi, were assessed. These results were then combined with the data of the patients' medical history (diagnosis gout vs. non-gout) as well as the laboratory values of hyperuricemia (HU).
Results 58 patients (mean age of 54,5 yrs) with hyperuricemia (serum uric acid levels >7mg/dL/420mmol/L) and musculo-skeletal problems were included in the study. 27/58 (46,5%) had a previous history of gout attacks. In 12 of 27 (44%) patients with a history of gout, this diagnosis was not at all documented by the admitting physician. Only 6 of 27 (22%) gout patients currently received a urate-lowering treatment.
In total, 676 joints in 58 patients were examined by ultrasound. The pathological finding most often found in joints with gout was the double contour sign (44/324 joints; 13,6%). However, the DC sign was also documented in 29 of 372 joints (7,8%) in patients with (asymptomatic) HU.
In patients with gout, the ultrasound showed pathological findings in 67/324 joints (20,7%). In 26/39 (66,7%) previously affected joints, gout-specific sonographic indications were found by the blinded investigator. With regard to the MTP, sonographic pathologies were also detectable in 16 of 22 (73%) MTP joints on the contralateral, which were the asymptomatic joints, prior to testing.
Conclusions The clinical diagnosis of gout was underreported and undertreated in our selected patient population implicating that gout is still not considered to be a severe disease leading to joint destruction. Nevertheless, structural ultrasonographic gout-specific signs/changes were often found in these patients with gout, particularly in joints affected by attacks, however often also in the corresponding, contralateral, and clinically unaffected joint. Interestingly, patients with hyperuricemia without typical clinical signs of gout showed sonographic features in different joints implicating an as yet “silent” precipitation of urate crystals. As the examined cohort represents patients with a variety of longstanding musculo-skeletal complaints and is at high risk, it seems to be worth further research for gout-specific findings, especially for patients with hyperuricemia.
Disclosure of Interest None declared