Background/Purpose:

Sympathetic joint effusion (SJE) or sympathetic synovial effusion (SSE) is a rheumatologic entity that has not been well defined in the medical literature. It is a non-inflammatory synovial fluid collection that is associated with infection or inflammation of an adjacent anatomic structure. The epidemiology and clinical characteristics of SJE/SSE are largely unknown. This knowledge gap has led to a lack of recognition and misdiagnosis by clinicians. Our study aimed to determine incidence, demographic information, and describe the clinical characteristics and potential triggering conditions for this presumptive reactive phenomenon.

Methods:

We conducted a study of patients >18 years of age hospitalized at Temple University Hospital (TUH) between January 31, 2010 and December 10, 2016 who underwent diagnostic arthrocentesis for painful effusions. Individuals with synovial fluid white blood cell count (WBC) in the normal range of 200 WBC/mm3 or less were included. Patients with non-inflammatory range synovial fluid of 200-2,000 WBC/mm3 were excluded to limit confounders. Demographic and clinical data of 72 patients were included for detailed analysis.

Results:

SJE/SSE was seen in 80/882 hospitalized patients (incidence of 9%). Seventy-two patients fulfilled inclusion criteria for detailed chart review. Demographic information revealed: male 46/72 (64%), female 26/72 (36%), African-American 38/72 (53%), Caucasian 16/72 (22%), Hispanic 10/72 (14%), undefined and other 8/72 (11%). Onset was typically acute, with 45/72 (63%) of patients developing symptoms within six days of arthrocentesis. All patients (100%) with SJE/SSE presented with painful effusion, and a minority had physical findings of warmth 23/72 (32%) or erythema 12/72 (17%). Interestingly, nearly a third of patients 21/72 (29%) were misdiagnosed with crystal or septic arthritis based solely on clinical exam, and empiric treatment was often administered prior to arthrocentesis. The most commonly affected joint was the knee 61/72 (85%), followed by the elbow 5/72 (7%), shoulder 3/72 (4%) and hip 3/72 (4%). Identifiable pathology in the affected limb was found in 29/72 (40%) of patients. Infection was the most common etiology, found in 17/29 (59%) of patients, and included cellulitis, abscess, osteomyelitis, septic bursitis, myositis, and necrotizing fasciitis. The majority of cases of SJE/SSE 23/29 (79%) were associated with concomitant infection, DVT or intramuscular hematoma in the affected limb which required specific therapeutic interventions.

Conclusion:

Sympathetic joint effusion or sympathetic synovial effusion (SJE/SSE) is relatively common in hospitalized patients. SJE/SSE may be a sentinel sign for a more serious disorder affecting the same limb. Clinicians should maintain a heightened index of suspicion for SJE/SSE. A search for underlying infection, venous thrombosis, and intramuscular hematoma in the affected limb is warranted when encountering acute painful joint effusion with normal range synovial fluid WBC count.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sympathetic-joint-effusion-in-an-urban-hospital/