Focal bone abnormality as a complication of ultrasound diathermy: a report of eight cases.

Purpose: To review the magnetic resonance (MR) imaging findings in eight patients who developed marrow lesions after undergoing physiotherapy with use of ultrasound diathermy.

Materials And Methods: The authors retrospectively reviewed the medical charts and MR images of eight patients (six women and two men aged 22-69 years) who received ultrasound diathermy treatment for a variety of soft tissue injuries involving primarily the knee, shoulder, and wrist. All patients underwent MR imaging without the use of intravenous gadolinium-based contrast material. The institutional review board approved the study, and the requirement to obtain informed consent was waived.

Results: MR imaging of all patients revealed subcortical rim or arc lesions with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, without involvement of the deeper aspect of the bone marrow. The imaging features of the lesions were similar to those of focal osteonecrosis. Follow-up MR imaging performed in three patients approximately 2-3 months after cessation of ultrasound therapy revealed resolution of the bone lesions. Symptoms resolved in all patients.

Conclusion: This study demonstrated that ultrasound diathermy may produce an osseous injury. The abnormality itself was usually mild and transient, with apparent full recovery after termination of therapy.