Case Presentation: A 39-year-old Air Force veteran was admitted to the US Department of Veterans Affairs Boston Healthcare System (VABHS) for evaluation of recurrent, painful right knee effusions. On presentation, his vital signs were stable, and the examination was significant for a right knee with a large effusion and tenderness to palpation without erythema or warmth. His white blood cell count was 12.0 cells/L with an erythrocyte sedimentation rate of 23 mm/h and C-reactive protein of 11.87 mg/L. He was in remission from alcohol use but had relapsed on alcohol in the past day to treat the pain. He had a history of IV drug use but was in remission. He was previously active and enjoyed long hikes. Nine months prior to presentation, he developed his first large right knee effusion associated with pain. He reported no antecedent trauma. At that time, he presented to another hospital and underwent arthrocentesis with orthopedic surgery, but this did not lead to a diagnosis, and the effusion reaccumulated within 24 hours. Four months later, he received a corticosteroid injection that provided only minor, temporary relief. He received 5 additional arthrocenteses over 9 months, all without definitive diagnosis and with rapid reaccumulation of the fluid. His most recent arthrocentesis was 3 weeks before admission.
►Lauren E. Merz, MD, MSc, Chief Medical Resident, VABHS: Dr. Jindal, what is your approach and differential diagnosis for joint effusions in hospitalized patients?
►Shivani Jindal, MD, MPH, Hospitalist, VABHS, Instructor in Medicine, Boston University School of Medicine (BUSM): A thorough history and physical examination are important. I specifically ask about chronicity, pain, and trauma. A medical history of potential infectious exposures and the history of the present illness are also important, such as the risk of sexually transmitted infections, exposure to Lyme disease or other viral illnesses. Gonococcal arthritis is one of the most common causes of nontraumatic monoarthritis in young adults but can also present as a migratory polyarthritis.1
It sounds like he was quite active and liked to hike so a history of tick exposure is important to ascertain. I would also ask about eye inflammation and back pain to assess possible ankylosing spondyarthritis. Other inflammatory etiologies, such as gout are common, but it would be surprising to miss this diagnosis on repeated arthocenteses. A physical examination can confirm monoarthritis over polyarthritis and assess for signs of inflammatory arthritis (eg, warmth and erythema). The most important etiology to assess for and rule out in a person admitted to the hospital is septic arthritis. The severe pain, mild leukocytosis, and mildly elevated inflammatory markers could be consistent with this diagnosis but are nonspecific. However, the chronicity of this patient’s presentation and hemodynamic stability make septic arthritis less likely overall and a more indolent infection or other inflammatory process more likely.
►Dr. Merz: The patient’s medical history included posttraumatic stress disorder (PTSD) and antisocial personality disorder with multiple prior suicide attempts. He also had a history of opioid use disorder (OUD) with prior overdose and alcohol use disorder (AUD). Given his stated preference to avoid opioids and normal liver function and liver chemistry testing, the initial treatment was with acetaminophen. After this failed to provide satisfactory pain control, IV hydromorphone was added.