Study: Consider Lyme Disease In Patients with Water on the Knee

According to a new literature review, spontaneous knee effusion, or “water on the knee,” should be considered a primary identifying symptom of Lyme disease even in patients without the telltale bull’s eye rash indicative of the disease.

Early identification of the disease is especially important since prompt treatment with antibiotics during the disease’s beginning stages can prevent the development of more severe symptoms.
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However, early symptoms of the disease are not always present, and can develop slowly over the course of 30 days after exposure.

For this reason, it is important to consider Lyme disease in the differential diagnosis as a potential cause of spontaneous knee effusion, particularly in areas where the disease is common.

“Half of patients do not recall a tick bite or observe a rash, and early symptoms are not always detected when a physician diagnoses a knee effusion,” researchers said.

“One of the most notable differentiating factors is, while septic or arthritic knees usually come with significant pain, knee effusions caused by Lyme disease are often very large, not activity-related, and mostly pain-free.”

The review is published in the Journal of the AAOS.

Reference:
Matzkin E, Suslavich K, Curry EJ, et al. Lyme disease presenting as a spontaneous knee effusion. J Am Acad Orthop Surg. 2015;23(11)674-682.