Spontaneous Rupture of Multiple Tendons in the Lower Extremity Following the Diagnosis of Lyme Disease.

Over a time frame of less than 1 year, a 23-year-old competitive horseback rider experienced a midsubstance tear of both the tibialis anterior and extensor hallucis longus tendons without inciting injury. It was after the second spontaneous tear that the patient's recent diagnosis of Lyme disease became the likely culprit. Often, patients with chronic Lyme disease present with an elaborate clinical picture that can mimic many more common diagnoses such as septic arthritis, transient synovitis, ligamentous sprain, and various other traumatic injuries. With the pathognomonic erythema migrans rash reported to be present less than 50% of the time in late-stage infections, the diagnosis of Lyme disease can often be difficult, with a high rate of underdiagnosis. It is important that Lyme disease be included in the differential diagnosis of spontaneous tendon pathology, especially for physicians practicing in highly endemic areas. The treatment is relatively simple and successful-especially for an acute infection-and it is important to initiate treatment promptly to prevent disability.