The role of the piezoelectric knife in accelerating bone healing
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BACKGROUND: Piezoelectric surgery (PIEZO) uses ultrasonic vibration to cut hard tissue without damaging adjacent soft tissues. Our previous studies indicated that PIEZO enhanced bone turnover compared to a conventional rotary bur (BUR) in rat tibia wounds by inducing the regional acceleratory phenomenon (RAP). PIEZO induced osteocyte apoptosis without damaging blood vessels during Day 1, 3 and 7 of rat tibia healing. We hypothesized that PIEZO increased bone turnover by activation of osteocyte apoptosis with a controlled inflammatory response. This study evaluated early morphological changes in tibial defects caused by either PIEZO or BUR. MATERIALS & METHODS: We created surgical defects in tibia by either PIEZO or BUR in 9–10-week-old Sprague-Dawley rat tibias (n=4). We evaluated tissue responses by using H&E, Masson’s Trichrome and TRAP stains on Day 1, 3 & 7 after surgery. The surgical defect beneath the soft tissue was located using Computed Tomography (CT). RESULTS: On postoperative Day 1, there was no significant blood vessel change or cellular extravasation in the PIEZO group. In contrast the BUR group had extravasation of leukocytes and increased blood vessels' size. On Day3, there was no significant inflammation or morphological changes to blood vessels in the PIEZO group. Empty lacunae adjacent to the defect area suggested osteocyte apoptosis. In the BUR group, blood vessels returned to an average size and the leukocyte population was reduced and bone adjacent to the lesion was unaffected, and intact osteocytes were in the lacunae. On Day 7 there was increased in osteoclastic activity in Piezo compared the BUR group. CONCLUSION: These results suggested that PIEZO induced osteocyte apoptosis, increased bone turnover with a controlled inflammatory response and protected the bone blood vessel network.