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.