Background Peripheral enthesitis has been repeatedly described like the primary lesion in all forms of spondyloarthritis (SpA), and it may occur at any enthesis in SpA, though it is most common in the entheses of the lower limbs. Ultrasonography (US) has proved to be a highly sensitive and noninvasive tool, to assess the presence of enthesitis

Objectives To estimate the prevalence and the US abnormalities of enthesitis in patients with SpA, compared to a control group.

Methods We have consecutively included 40 patients with established SpA, including 30 patients with ankylosing spondylitis (AS), 8 patients with psoriatic arthritis (RP) and two patients with arthritis-associated with Crohn's disease. Control populations consisted of 20 patients with mechanical low back pain (MBP). Ultrasound (US) in B mode and power Doppler (PD) was performed at Achille tendon (AT) and plantar fascia (PF).

Results The study sample included 40 control patients (4 male- 16 female) with a mean (SD) age of 51.05 (11.45) years (range 32–73) and mean duration of disease 8.40 (range 5–81) years.

SpA subtypes were: ankylosing spondylitis 30; psoriatic arthritis 8; arthritis-associated inflammatory bowel disease (AIBD) 2. 47.5% of entheses were tender at clinical examination. Axial form was found in 36 cases (90%) and peripheral form in 4 cases (10%).

In SpA patients, a total of 109/160 (68.12%) of the entheseal sites were abnormal compared with 27/80 (33.75%) in controls, which was statistically significantly fewer than in the SpA group for AT (p=0.000) and PF (p=0.023). Abnormal vascularization in the cortical bone insertion was found in 47 cases (29.375%) versus 4 cases in control group with a significant correlation. We also found a significant correlation for decreased echogenicity and bone erosions. No major variation in the proportion of abnormal entheses identified by US examination was observed between different forms of SpA.

US abnormalities were not correlated to the duration of the disease in patients with SpA, and there was no significant difference between US findings and either ESR, CRP, BASDAI score or BASFI score. We also, found no significant correlation between entheseal US abnormalities and the anti-TNF medications used among the SpA patients.

Conclusions Ultrasonography can be useful for detecting subclinical enthesitis in SpA patient and the enthesis US score can be useful for improving the diagnostic of SpA.

References

1. Balint PV, Kane D, Wilson H. Ultrasonography of entheseal insertions in the lower limb in spondyloarthropathy. Ann Rheum Dis 2002;61:905–10.

2. D'Agostino MA, Said-Nahal R, Hacquard-Bouder C. Assessment of peripheral enthesitis in the spondyloarthropathies by ultrasonography combined with power Doppler: a cross-sectional study. Arthritis Rheum 2003;48:523–33.

References

Disclosure of Interest None declared