The use of focused ultrasound and highintensity focused ultrasound (HIFU) is common in physical therapy and medical procedures. The ultrasound produces heat and can be used to treat several diseases. We report a case of a 49-year-old male that had a knee injury after mild trauma. The patient started physical therapy sessions to treat the injury. Ipsilateral calf claudication started a few hours after the focused ultrasound was used to heat the popliteal area progressing to symptoms of acute arterial occlusion in two weeks. We started anticoagulation and confirmed popliteal thrombosis with duplex scan and computed tomography. The 5 years follow up showed good clinical recovery and recanalization of the artery. This case reminds us that the focused ultrasound should not be considered harmless and life-threatening complications may occur. The inadvertent heating of neighboring structures and recanalization of the heated vessel may happen.