Poster 199 Vibration Elastography to Assess the Effect of Dry Needling on Myofascial Trigger Points in Patients Affected by Myofascial Pain Syndrome

Disclosures: S. Gingrich, No Disclosures: I Have No Relevant Financial Relationships to Disclose. Case Description: A 72-year-old woman presented to an outpatient clinic for severe left medial knee and proximal left leg pain which she begannoticingwhile shoppingwithout any preceding trauma. Two daysprior toher symptoms’onset, shehadbeenanticoagulated for atrial fibrillation with rivaroxaban. Physical examination of the left leg revealed antalgic gait with significant edema, extensive ecchymosis, medial knee joint line tenderness and a large knee effusion. The dorsalis pedis pulses and neuromuscular examination were normal. Setting: Outpatient clinic. Results or Clinical Course: Emergent lower limb venous duplex studies were negative for thrombosis. A left knee musculoskeletal ultrasound showed a large complex effusion interspersed with hypoechoic and isoechoic signal. Arthrocentesis yielded only approximately 2 cc of sanguinous fluid. Subsequent left knee MRI showed a complex joint effusion with low T1 and variable T2 signal intensities consistent with coagulated blood product. After discussion with the patient’s primary care physician, rivaroxaban was discontinued in favor of warfarin. The patient has not had a repeat hemarthrosis after changing her anticoagulant. Discussion: Spontaneous atraumatic hemarthroses are known to occur during warfarin anticoagulation. Such incidents are often, though not always, attributed to supratherapeutic dosing. This case, to our knowledge, is the first reported incident of spontaneous atraumatic hemarthrosis occurring during appropriately dosed rivaroxaban anticoagulation. Conclusions: Oral direct thrombin and factor Xa inhibitors such as rivaroxaban and dabigatran differ from vitamin K antagonists such as warfarin in that their anticoagulative activity is typically unmonitored. This raises the possibility of inducing a spontaneous bleeding event such as hemarthrosis in individuals who could be more sensitive to such medications. Thus, as our case demonstrates, hemarthrosis should be considered in the differential diagnosis of any orally anticoagulated patient presenting with a knee effusion regardless of the anticoagulant used.