MRI Bone Abnormality of the Knee following Ultrasound Therapy: Case Report and Short Review

Abstract

Ultrasound (US) therapy in sports and medical pathologies is widely used by many physiotherapists and sports medicine clinicians; however, data regarding their potential side effects remain rare. We report a case of a 21-year-old woman with iliotibial band (ITB) syndrome treated with a physiotherapy session combined with US therapy. She had twenty 7 min US sessions on the knee, for 3 months (US at 1 Mhz with an intensity between 1 and 2 W/cm²). Due to persistence of the ITB syndrome's symptomatology after the 3 months of physiotherapy sessions, an MRI (magnetic resonance imaging) was carried out and revealed osteonecrosis-like bone abnormalities on the external femoral condyle, the external tibial plateau, and the proximal fibula. In view of these lesions, the ultrasonic therapy was stopped, and a repeat MRI demonstrated the progressive disappearance of these imaging abnormalities one year after the last US (ultrasound) treatment. In light of this case, we propose here a short review of reported osseous "osteonecrosis" abnormalities associated with US therapies.

Keywords: MRI; bone abnormality; ultrasound therapy.

Figure 1

MRI: 1 month before the first US therapy. DP FS MRI image in frontal (a) and sagittal (b) section demonstrating a single (13 × 14 × 16 mm) lesion under the epiphyseal cortex of the lateral femoral condyle with peripheral border in hyper-intensity, highlighted with white arrows.

Figure 2

MRI: 1 month after the last US therapy. DP FS MRI image in sagittal (a) and frontal (b,c) sections demonstrating signal abnormalities under the epiphyseal cortex with hyper-intensity in the peripheral border: 21 × 20 × 12 mm lesion on the femur, 16 × 18 × 15 mm on the tibia, and 10 × 9 × 9 mm on the proximal fibula, highlighted with white arrows.

Figure 3

Standard X-rays: 4 months after the last US therapy. AP (a) and lateral view (b) showing no bone lesion.

Figure 4

MRI: 6 months after the end of US therapy. DP FS MRI image in frontal (a) and sagittal (b) sections showing a reduction in lesions of the lateral femoral condyle, lateral tibial plateau, and head of the fibula with a sinuous cortical-to-cortical necrotic-like demarcation border in DP FS hypersignal 6 months after the US stopped. An 11 × 11 × 8 mm lesion remained on the femur and a 14 × 14 × 8 mm lesion on the tibia, but there was complete disappearance on the fibula. Arrows show lesion.

Figure 5

MRI: 11 months after the last US therapy. DP FS MRI image in frontal (a) and sagittal (b) sections showing remaining bone abnormality. At the last follow-up, only a single lesion persisted on the femur of 8 × 9 × 5 mm. arrows show lesion.