Development of a safer calvaria critical-sized defect model in rats using piezoelectric surgery
[um_loggedin show_lock=yes]Authors: Rafael Senos; Kurt D Hankenson
Affiliations: University of Michigan – Department of Orthopaedic Surgery
Introduction: Critical-size bone defects in rats are used to study bone regeneration in skull and long bone. For decades, trephines have been used to generate circular holes with no notable refinement the osteotomy technique. Piezoelectric equipment is increasingly used in human clinical oral and maxillofacial surgery, neurosurgery, traumatology, and orthopaedics, because the technique only cuts bone and avoids damaging sensitive soft tissues such as blood vessels, nerves, and muscle. In addition, piezoelectric instruments are reported to be easier for surgeons to handle than other osteotomy devices.
Hypothesis/Objectives: This study aimed to evaluate and compare the surgical technique and bone regeneration process between hand-drill trephine technique and piezoelectric equipment technique in a critical-size calvaria defect in rat model. We hypothesized that piezoelectric technique would produce reliable osteotomies.
Materials and Methods: Thirty Sprague Dawley male rats were divided into two groups for craniotomies in parietal bones: 1) CG (n=16) – 7.9mm diameter circular with trephine and 2) PSG (n=14) – 7.0mm side square using piezoelectric device. General notes were taken during surgical procedure and post-operative care; microCT and histology (H&E) were performed at 0d (n=2 per group), 45d (n=6 per group) and 75d (n=6 per group) after surgery.
Results: CG rats bled extensively during the osteotomy (more than 20min). Two rats (17%) of CG group died during immediately postoperative care. CG was performed in 27.5min (±4.5) per animal, while PSG in 38.5min (±9.4), which is statistically different. The amount of newly formed bone was similar between the two groups at 45d. No new additional bone was formed observed between 45 to 75d. MicroCT and histology showed that in four rats of CG the defect was not constrained to parietal bones, but also invaded frontal and interparietal bones.
Conclusions: Piezoelectric surgery appearsbe safer than trephine. Although regeneration rates were similar between groups, piezoelectric technique presented lessdeviation. Using the trephine it was difficult to not invade bones other than the parietal bone. This is significant because the various calvarial bones have differing rates of healing. Piezoelectric technique represents a refined and more reproducible technique in comparison to classic trephine approach for critical sized defect generation in rats.
Acknowledgements, Funding, and Conflicts of Interest: We thank MS Kaela Navarro and Veterinary Technologist Heather Defoe for technical support during surgeries and microCT analysis.
We also thank Michigan P30 Core Center Grant from NIH/NIAMS.[/um_loggedin]