Introduction: Fracture of the femoral stem is an infrequent event in the follow-up to a total hip arthroplasty (THA). The authors describe the case of a patient exposed to continuous application of ultrasound therapy that led to detachment of the stem-cement interface, followed by fatigue fracture of the femoral stem and the need for revision surgery. The aim of this report is to point out the possibility of undesirable effects in the use of therapeutic ultrasound in areas with underlying orthopedic implants.

Case Report: A 66-year-old male patient with a previous diagnosis of psoriatic arthritis, underwent bilateral total hip arthroplasty five years ago due to avascular necrosis of femoral head after use of corticosteroids. After the appearance of an intermitent aching pain over the lateral aspect of the hip (greater trochanter) trochanteric bursitis with insertional tendinopathy of the left gluteus minimus was diagnosed and physical therapy treatment was indicated along with non opioid analgesics. Inadvertently, he received local applications of continuous ultrasound during 23 sequential sessions over a period of 30 days, and presented sudden worsening of the pain. Radiographically, there was a fatigue fracture of the femoral stem. The treatment instituted was revision of the femoral component.

Conclusion: The case describes a direct association between the use of ultrasound and fatigue fracture of the metallic material. The authors warn of the possibility of an undesirable effect of therapeutic ultrasound when applied repeatedly on a site with an underlying cemented orthopedic implant.

Keywords: Aseptic loosening, Hip arthroplasty, Ultrasound