A prospective evaluation of ultrasound as a diagnostic tool in acute microcrystalline arthritis.

The performance of ultrasound (US) in the diagnosis of acute gouty (MSU) arthritis and calcium pyrophosphate (CPP) arthritis is not yet well defined. Most studies evaluated US as the basis for diagnosing crystal arthritis in already diagnosed cases of gout and few prospective studies have been performed. One hundred nine consecutive patients who presented an acute arthritis of suspected microcrystalline arthritis were prospectively included. All underwent an US of the symptomatic joints(s) and of knees, ankles and 1(st) metatarsopalangeal (MTP) joints by a rheumatologist "blinded" to the clinical history. 92 also had standard X-rays. Crystal identification was the gold standard. Fifty-one patients had MSU, 28 CPP and 9 had both crystals by microscopic analysis. No crystals were detected in 21. One had septic arthritis. Based on US signs in the symptomatic joint, the sensitivity of US for both gout and CPP was low (60% for both). In gout, the presence of US signs in the symptomatic joint was highly predictive of the diagnosis (PPV = 92%). When US diagnosis was based on an examination of multiple joints, the sensitivity for both gout and CPP rose significantly but the specificity and the PPV decreased. In the absence of US signs in all the joints studied, CPP arthritis was unlikely (NPV = 87%) particularly in patients with no previous crisis (NPV = 94%). X-ray of the symptomatic joints was confirmed to be not useful in diagnosing gout and was equally sensitive or specific as US in CPP arthritis. Arthrocenthesis remains the key investigation for the diagnosis of microcrystalline acute arthritis. Although US can help in the diagnostic process, its diagnostic performance is only moderate. US should not be limited to the symptomatic joint. Examination of multiple joints gives a better diagnostic sensitivity but lower specificity

Efficacy of anakinra in acute hydroxyapatite calcification-induced joint pain: A retrospective study of 23 cases.

Hydroxyapatite (HA) crystal calcifications in or around the joint can induce acute flares with severe pain. A previous pilot study suggested that the interleukin-1β (IL-1β) inhibitor anakinra was effective. The goal of this observational study was to confirm these results in a larger set of patients and to report on the long-term follow-up. Flare was defined as acute pain for<10 days. Calcification in or around a joint (rotator cuff: 15/23 patients) was confirmed by conventional radiography and/or ultrasonography (US). Anakinra 100mg daily was administered subcutaneously for 1 to 3 consecutive days. Clinical data collected before the injection and on days 3 and 21 included pain score on a visual analog scale (VAS, 0-10cm) and C-reactive protein (CRP) level. When available, US baseline and follow-up findings were compared. Long-term follow-up data were collected from patient charts and/or after a phone call. 23 patients (15 males, mean [SD] age 58 [11] years) were included. Baseline mean (SD) VAS pain was 7.7 (1) cm and CRP level was elevated in half of the patients. After therapy, mean (SD) VAS pain score decreased rapidly in the first 3 days to 1.6 (1.4) cm (P<0.001) and remained stable for 3 weeks at 1.8 (2.1) cm. US assessment revealed decreased Doppler intensity but no significant change in size of calcifications. No significant side effects were noted. After long-term follow-up (median duration 24 months), half of the patients still had some chronic pain, but only 4 experienced acute relapse. This study suggests that IL-1β inhibition may be an efficient therapeutic approach for acute HA flare, with a good safety profile