Literature Review: Utility of Bedside Sonography to Distinguish Soft Tissue Abnormalities from Joint Effusions in the Emergency Department

Published in Journal of Ultrasound Medicine, 2010
Authors: Srikar Adhikari, MD, RDMS, Michael Blaivas, MD, RDMS

This week I am going to discuss this article instead of an ultrasound case from the ED.  I thought the article was interesting and has important clinical significance.  Please view the article for associated pictures and figures.  -Christina Natoli, PA Fellow    

Introduction:

The purpose of this study was to determine the utility of bedside sonography to differentiate soft tissue abnormalities from joint effusions. Musculoskeletal complaints are very common in emergency departments making up 13.8% of 110 million ED visits in 2004. The differential diagnosis of joint effusions is very diverse including arthritis (septic, osteoarthritis, rheumatoid), hemarthosis, bursitis cellulites, abscesses and hematoma, many of which require different management. Traditionally, ED physicians have relied on joint aspiration to identify the presence or absence of an effusion; however, this approach is very invasive. The use of bedside ultrasound can aide in deciding whether aspiration needs to be done, to request additional diagnostic imaging or consultation or to manage with conservative measures.

Methods:

This article is a retrospective review of patients presenting with pain, erythema or swollen join over a 1 year period at 2 urban EDs. Scans were only done by 4 ultrasound credentialed ED physicians. All patients in the study underwent a physical exam before the sonogram and then the sono was performed by ED physician sonologists who were not involved in the clinical management of the patient. The effect on the management plan was recorded as: no effect, a new aspiration procedure, or elimination of an aspiration procedure. The sonographic protocol included scanning the symptomatic joint and surrounding soft tissue in 2 planes. To differentiate an effusion from cartilage, graded compression was used and the anechoic area was followed along the entire length of the bone. The contralateral joint was also viewed for comparison.  Continuous data are presented as means with SDs and dichotomous data are presented as percent frequencies of occurrence with 95% confidence intervals.  Statistical level of significance used was P < .05

Results:  

Total of 54 patients were identified over a 1 year period. 22/54 of patients had joint effusions via ultrasound. In total, sonography altered management in 35/54 patients. To break down the alteration in management specifically: joint aspiration was planned in 39/54 cases before ultrasound; however, after ultrasound only 20 of these underwent joint aspiration, and in the group where the ED physician believed a joint aspiration needed to be done, sonography changed the management in 27/39 cases. There was statistically significant difference in treatment plans after ultrasound.

Conclusion:

This study shows that sonography can alter the treatment of patients significantly. More than 50% of joint aspirations were avoided in the study group. Also, ultrasound detected joint effusions in approximately 50% of patients in whom aspiration was not planned by the treated ED physician.

Limitations:

  • Retrospective study
  • No protocol for ultrasound evaluation
  • The presence or absence of an effusion in ultrasound was not confirmed by another imaging study or joint aspiration in all cases.
  • Selection bias - not all patients with red, swollen joints where part of the study if the ultrasound physician was not on duty.
  • Small sample size

Key points from the article:

  • Differential diagnosis of a swollen painful joint is extensive including septic arthritis, crystal arthropathy, hemarthosis, cellulitis, abscesses, hematoma which all require different management and plans. 
  • Clinical criteria alone is not adequate in differentiating these conditions.
  • Ultrasound is rapid, sensitive, portable, noninvasive
  • Ultrasound is important to aid in fluid aspiration and to avoid injury to surrounding structures
  • By distinguishing soft tissue abnormalities from joint effusions, a substantial number of potentially traumatic and unnecessary aspiration attempts can be eliminated
  • Ultrasound findings can expedite the diagnosis and management of septic arthritis.