What precaution should be observed when using ultrasound near bony prominences?

What precaution should be observed when using ultrasound near bony prominences?

• A. Avoid bony prominences (may develop hot spots)
• B. Increase contact pressure on bony prominences
• C. Place the transducer directly on bone with no gel
• D. Only treat over bone if there is scar tissue

Answer: (A)

Ultrasound energy is absorbed and heats tissues, and bone takes up energy more readily than soft tissue. When a transducer is near a bony prominence, there is less soft tissue between the source and bone, so heat can localize at the periosteum and underlying bone, creating hot spots. This makes the area prone to burns or discomfort, even with what seems like low settings. Because of this risk, the safe approach is to avoid placing the transducer directly over bony prominences and instead treat over adjacent soft tissue, use lower intensity or pulsed delivery if proximity to bone is unavoidable, keep the head moving, and ensure proper gel coupling to maximize even energy distribution. The other options either increase risk (more pressure over bone can raise heating, or direct bone contact without gel can alter energy transfer and raise local temperature) or are not general precautions for all patients (treating over bone only if there is scar tissue).

Ultrasound energy is absorbed and heats tissues, and bone takes up energy more readily than soft tissue. When a transducer is near a bony prominence, there is less soft tissue between the source and bone, so heat can localize at the periosteum and underlying bone, creating hot spots. This makes the area prone to burns or discomfort, even with what seems like low settings. Because of this risk, the safe approach is to avoid placing the transducer directly over bony prominences and instead treat over adjacent soft tissue, use lower intensity or pulsed delivery if proximity to bone is unavoidable, keep the head moving, and ensure proper gel coupling to maximize even energy distribution.

The other options either increase risk (more pressure over bone can raise heating, or direct bone contact without gel can alter energy transfer and raise local temperature) or are not general precautions for all patients (treating over bone only if there is scar tissue).