Dynamic spring-mediated cranioplasty in a rabbit model.

Since the beginning of craniofacial surgery, there has been an ongoing search for surgical techniques to enhance outcome while, at the same time, decreasing the invasiveness of the surgical treatment of craniofacial deformities. The purpose of this study was to test a recently reported minimally invasive treatment modality, the dynamic spring, in a rabbit calvarial model for efficacy and safety. Specifically, the results of spring cranioplasty on skull growth, the underlying brain, and adjacent bone were to be assessed. The study population consisted of 36 7-week-old New Zealand white rabbits. The rabbits were divided into four treatment groups (9 rabbits each): control, sham surgery, stainless steel springs, and memory metal springs. Postoperative analysis included weekly radiographs to evaluate movement of amalgam markers placed at standardized locations. Additionally, 16 rabbits (4 from each group) were killed at 14 days after surgery, and postmortem histological analysis was done. The remaining rabbits were followed until they were adults and were then killed and similarly analyzed. No morbidity or mortality occurred in the immediate perioperative period secondary to the surgery. Postmortem histological analysis of all study animals revealed no intracranial, subcutaneous, or skin infections and no technical complications related to the surgery. Statistical analysis using ANOVA and pair-wise comparisons between treatment groups revealed a statistically significant difference (P < 0.05) between the marker movement in the spring groups versus the sham and control groups. There were no significant differences between the sham and control groups or between the two spring groups. In conclusion, this study confirms the efficacy and safety of the dynamic spring in a rabbit model.