Low intensity pulsed ultrasound (LIPUS) has been shown to accelerate bone healing, although the healing mechanisms are not yet fully understood. One hypothesis involves the role of weak bone piezoelectricity. In cases of fractures, bioabsorbable materials such as poly-L-lactic acid (PLLA), which also exhibit piezoelectric properties, are used for fixation. This study investigated whether combining PLLA with LIPUS could further enhance bone regeneration. Rat tibiae with small artificial bone defects were divided into three groups: Control (defect only), US only (daily LIPUS treatment), and PLLA + US (PLLA film inserted near the defect plus LIPUS). After 2 weeks, bone mineral density (BMD) around the defect was analyzed using X-ray CT. Compared to the control group, the volume of soft callus (BMD: 100–300 mg/cm³) increased by 2.1% in the US only group and by 10.4% in the PLLA + US group. These results suggest that both LIPUS and PLLA contribute to enhance bone formation, and their combination may shorten the healing period.
Murakami et al. (Wed,) studied this question.