General Internal Medicine Question 39

Answer & Critique

Correct Answer: A

Educational Objective: Manage prepatellar bursitis.

Key Point

Bursal fluid aspiration should be performed for both therapeutic and diagnostic purposes in all patients who present with prepatellar bursitis.

The most appropriate next step in management of this patient is to aspirate the bursal fluid collection for diagnostic and therapeutic purposes. Bursal fluid aspiration and analysis should be performed in all patients who present with prepatellar bursitis. Aspiration is necessary to definitively distinguish the cause of prepatellar bursitis (namely, trauma, gout, and infection). Gram stain and culture of the bursal fluid should be obtained and analyzed for leukocyte count and for the presence of crystals. An extremely elevated leukocyte count (>50,000/µL [50 × 109/L]) should raise suspicion for septic bursitis, although a lower count does not entirely eliminate this possibility.

Compression is indicated only after bursal fluid aspiration has been performed. Dressings should be worn for 24 to 48 hours, and patients should be advised to avoid applying direct pressure to the bursa. Once the compression dressing is removed, patients should be advised to wear a neoprene sleeve.

Glucocorticoid injection into the fluid collection is not indicated for patients presenting with acute prepatellar bursitis. Instead, glucocorticoid injection should be reserved for chronic prepatellar bursitis that has a noninfectious cause or that is postinfectious (negative cultures have been obtained after antibiotic administration).

Imaging, either with plain radiography or ultrasonography, is not usually required for the diagnosis of prepatellar bursitis. Plain radiography may show soft-tissue swelling on lateral views but rarely aids in establishing the correct diagnosis. Ultrasonography will show a fluid collection but will not help identify the cause. Therefore, plain radiography or ultrasonography is not indicated in this patient.

Bibliography

Baumbach SF, Lobo CM, Badyine I, Mutschler W, Kanz KG. Prepatellar and olecranon bursitis: literature review and development of a treatment algorithm. Arch Orthop Trauma Surg. 2014 Mar;134(3):359-70. PMID: 24305696

This content was last updated in January 2016.

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