Characterization of LIPUS Parameters Suitable for Hip Bone Fracture

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Regenerative Medicine

Background:

• Hip bone fractures represent a significant clinical challenge, impacting mobility and quality of life.
• Ultrasound therapy, particularly low-intensity pulsed ultrasound (LIPUS), has emerged as a promising non-invasive treatment modality for bone healing.
• Optimizing LIPUS parameters, such as frequency and intensity, is crucial for maximizing therapeutic efficacy.

Purpose of the Study:

• To evaluate the efficacy of different low-intensity pulsed ultrasound (LIPUS) frequencies (0.5 MHz and 1.5 MHz) for promoting hip bone fracture healing.
• To determine the optimal LIPUS frequency and intensity for enhanced bone regeneration at the fracture site.
• To investigate the impact of acoustic attenuation in soft tissues on ultrasound intensity delivery.

Main Methods:

• Ex vivo acoustic attenuation measurements were performed using human cadaver and porcine tissues to assess ultrasound propagation.
• In vivo study involved 20 hip-fractured rabbits divided into control and LIPUS treatment groups (0.5 MHz and 1.5 MHz).
• A compensation method was employed to maintain a constant intensity of 30 mW/cm² at the fracture site, accounting for tissue attenuation.

Main Results:

• Ultrasound intensity significantly decreased with tissue depth; 1.5 MHz intensity dropped to 6.16 mW/cm² through 5.0 cm of tissue.
• The compensation method successfully maintained 30 mW/cm² intensity at the fracture site for both 0.5 MHz and 1.5 MHz groups.
• The 0.5 MHz LIPUS group demonstrated superior outcomes in bone histomorphometry, mechanical properties, and histological evaluation compared to the 1.5 MHz and control groups.

Conclusions:

• A LIPUS frequency of 0.5 MHz, delivered at a consistent intensity of 30 mW/cm² to the fracture site, is more effective for treating hip bone fractures.
• The findings suggest that 0.5 MHz LIPUS offers a promising therapeutic strategy for accelerating bone healing in hip fractures.
• Maintaining consistent ultrasound intensity at the fracture site through compensation methods is critical for effective LIPUS treatment.