Ultrasonography Detects Erosive Joint Changes Associated With Septic Arthritis

Persistence of Doppler signal and a thickened synovial tissue at 3 months are associated with a poor clinical outcome in patients with septic arthritis.

Nearly half of patients with septic arthritis with poor functional outcome who underwent ultrasonography (US) showed decreased synovial thickness at 3 months compared to baseline, according to recent research presented at the American College of Rheumatology 2016 annual meeting.1 

Emeline Gaigneux, from the Rheumatology Unit at Nantes University Hospital in Nantes, France, and colleagues evaluated 34 patients (mean age = 63.7 years, 70.6% men) with a native joint infection treated in three hospitals between January 2014 and July 2015.

At baseline, 4 days, 15 days and 3 months, the researchers analyzed patients using an US exam, which included evaluating Power Doppler, synovial membrane thickness measurement, and periarticular tissue involvement. The researchers also performed baseline and 3-month x-rays. At 3 months, patients were evaluated using the short form 36 (SF-36) score and range of motion tests.

The researchers found 24 patients (70.6%) with septic arthritis had pre-existing joint disease, with 19 patients (55.9%) having septic knee arthritis. Of these patients, 15 (44.1%) had Staphylococcus Aureus implicated as the main source of septic arthritis. After diagnosis, there were 12 patients (35.3%) who underwent joint lavage time (mean time = 4.2 days) and there were 2 cases (5.9%) of synovectomy.

Regarding ultrasonography results, 96.4% of cases has US-evident synovitis at baseline, 100% of cases had US-evident synovitis at 15 days, while 77.8% of cases showed synovitis at 3 months (P = .051). Synovial thickness increased by 17.3% at 4 days from baseline, and increased by 20% at 15 days from baseline (P =.015); however, synovial thickness significantly decreased by 31.5% at 3 months (P = 0.015).

At baseline, Doppler signal was present in 64.3% of cases, 66.7% of cases at 4 days and 61.3% at 15 days, but significantly decreased to 25.9% of cases (P = .04) at 3 months. At 3-month follow-up, 20 patients (58.8%) showed lower range of motion and joint limitation  associated with synovial thickness increase between baseline and 3 months (P = .024) as well as a persistent Doppler signal at 15 days (P = .033) and 3 months (P = .024).

“[Patients with] septic arthritis have a poor functional outcome in more than half of the cases. US synovitis remains present at 3 months in most patients but with a significant decrease in synovial thickness compared to baseline,” Dr Gaigneux and colleagues stated.  

“Doppler signal persists in a quarter of the cases at [month 3]. Persistence of Doppler signal and a thickened synovial tissue at 3 months are associated with a poor clinical outcome.”

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  1. Gaigneux E, Cormier G, Merot O, et al. Ultrasonography Changes during the Course of Septic Arthritis Are Associated with Functional Outcome. Presented at: ACR/ARHP Annual Meeting; November 11-16, 2016; Washington D.C. Abstract #1003.

This article originally appeared on Rheumatology Advisor