Which modality is commonly used when non-thermal tissue repair and inflammation modulation are desired?

• A. Continuous ultrasound
• B. Thermal diathermy
• C. Low-level laser therapy
• D. Pulsed ultrasound

Answer: (D)

Non-thermal tissue repair and inflammation modulation rely on mechanical and cellular signaling effects rather than heat. Pulsed ultrasound delivers energy in bursts with a low duty cycle, so it minimizes tissue heating and emphasizes mechanical phenomena like acoustic streaming and micro-cavitation. These mechanical cues can boost cellular activities involved in healing—fibroblast proliferation, collagen synthesis, and angiogenesis—and help modulate inflammatory mediators. That combination makes pulsed ultrasound a common choice when you want to promote repair and control inflammation without increasing tissue temperature.

Continuous ultrasound, by contrast, tends to raise tissue temperature, which is useful for analgesia and increasing tissue extensibility but not the non-thermal repair-focused effects here. Thermal diathermy heats tissue through electromagnetic energy, again producing thermal benefits rather than non-thermal signaling. Low-level laser therapy is another non-thermal option that uses light to affect cellular function, but it works through different mechanisms and is a separate modality from ultrasound.