A Different Type of Tennis Elbow: Spontaneous Septic Arthritis of the Elbow in a Previously Healthy 40-Year-Old Male.

Septic arthritis of the elbow is a serious and uncommon condition, particularly in immunocompetent individuals and those without risk factors. We present the case of a 40-year-old previously healthy male who developed spontaneous elbow septic arthritis after initiating a recreational tennis regimen. He presented with progressive elbow pain, loss of extension, and swelling, but lacked fever or any systemic findings suggestive of infection on arrival. Point-of-care ultrasound (US) revealed an elbow effusion, which then prompted US-guided arthrocentesis in the emergency department. Synovial fluid analysis demonstrated 57,000 white blood cells with 99% polymorphonuclear cells. Additionally, the Gram stain was positive for Gram-positive cocci in clusters, confirming the presence of intraarticular infection. The patient was admitted for surgical joint washout and IV antibiotics. He was able to complete a course of IV and then oral antibiotics and had a full functional recovery at six months. This case highlights the utility of bedside US in recognizing joint effusions and guiding arthrocentesis, even in patients without typical risk factors or signs and symptoms of systemic illness.