Gustavo Juliani Faller

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

OBJECTIVE Use 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 METHODS This 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. RESULTS The 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. CONCLUSION In this animal model, cranial expansion by linear craniectomy followed by bioabsorbable spring placement was feasible and well tolerated by adjacent tissues.

Experimental comparative study of the histotoxicity of poly(lactic-co-glycolic acid) copolymer and poly(lactic-co-glycolic acid)-poly(isoprene) blend

Current treatments of craniosynostosis rely on the application of metal springs for cranial bone deviation. However, those metal springs demand a second surgical procedure for their removal. An attractive alternative would be the substitution of metal for bioresorbable polymers in the composition of the springs. The addition of poly(isoprene), PI, to poly(lactic-co-glycolic acid), PLGA, produces a polymeric blend with partial miscibility and distinct mechanical behavior that may benefit the patient recover. It is necessary to compare the histotoxicity of PLGA/PI to that presented by PLGA. In order to verify the histological behavior of the blend, 46 male Wistar rats (Rattus norvegicus, albino strain) underwent implantation of PLGA or PLGA/PI in the skull and were allocated into subgroups by timing of euthanasia (15, 30, 60, or 90 days). After euthanasia, the skull was removed and the histotoxicity was assessed histopathologically. The PLGA/PI blend showed greater histotoxicity in animals euthanized at 60 days, although in this period the histotoxicity of the PLGA/PI blend was similar to that of the PLGA copolymer at 15 days. Despite the instability of histological response, presented in different periods of observation, the results obtained in long-term show that the material has high potential for studies in craniosynostosis treatment.

Neonatal Mandibular Distraction Osteogenesis Reduces Cleft Palate Width and Lengthens Soft Palate, Influencing Palatoplasty in Patients With Pierre Robin Sequence.

AbstractThe aim of this study was to evaluate the influence of neonatal mandibular distraction osteogenesis (MDO) on cleft dimensions and on early palatoplasty outcomes in patients with Pierre Robin Sequence (PRS). In a prospective cohort study that enrolled 24 nonsyndromic patients with PRS, 12 submitted to the MDO group and 12 patients not treated (non-MDO group), the authors compared patients for cleft palate dimensions through 7 morphometric measurements at the moment of palatoplasty and for early palatoplasty outcomes. At palatoplasty, the MDO group presented a significant shorter distance between the posterior nasal spines (PNS–PNS, P < 0.001) and between uvular bases (UB–UB, P < 0.001), representing a reduction in cleft palate width. They also had significant soft palate lengthening represented by a larger distance between UB and retromolar space (UB–RM, P < 0.001) and UB and PNS (UB–PNS, P = 0.014). Their UB moved away from the posterior wall of the nasopharynx (UB–NPH, P < 0.001). The MDO group had a length of operative time significantly shorter (P < 0.001) and no early palatoplasty complications compared with the non-MDO group. In conclusion, MDO acted as an orthopedic procedure that reduced cleft palate width and elongated the soft palate in patients with PRS. These modifications enabled a reduction of around 11% in the length of operative time of palatoplasty (P < 0.001).