Development and testing of an absorbable spring for cranial expansion in rabbits

ObjectiveUse of metal springs for treatment of craniosynostosis is gaining ground in the surgical armamentarium, as these springs simplify operative technique, help to avoid extended approaches, and thus minimize morbidity. Nevertheless, these devices have to be removed eventually. The purpose of this study was to perform cranial expansion with a fully integrated, biodegradable polymer spring in an animal model and to assess the efficacy of and histological reaction to this device.Material and methodsThis was an experimental, unblinded, prospective study. Twelve female New Zealand rabbits (Oryctolagus cuniculus) aged 6 weeks were randomly allocated to two groups. Control animals underwent linear craniectomy alone. Intervention animals underwent craniectomy with placement of a poly(lactic-co-glycolic acid)/polyisoprene (PLGA/PI) copolymer blend spring for cranial expansion transverse to the ostectomy. Expansion was measured radiographically over 12 weeks with amalgam markers. At the end of the experiment period, histological analysis was performed to quantify inflammatory reaction.ResultsThe copolymer blend springs had a mean strength of 4.2N. In the intervention group, cranial expansion at the frontal markers was 9.6–11.67 mm (significantly greater than in controls). Histological analysis showed minor inflammatory reactions.ConclusionIn this animal model, cranial expansion by linear craniectomy followed by bioabsorbable spring placement was feasible and well tolerated by adjacent tissues.