Spring-mediated skull expansion: overall effects in sutural and parasutural areas. An experimental study in rabbits

Abstract

PURPOSE: The use of springs in cranial expansion has proven to be effective in the treatment of craniosynostosis. Spring-mediated expansion has been studied both in the sagittal and in parasagittal regions, especially in scaphocephaly. A rabbit model was used in the present study to analyze the effects of springs on the cranial vault and sutures. METHODS: Thirteen 4-week-old New Zealand rabbits were divided into 4 groups: in group I, only amalgam markers were used as control; in group II, amalgam markers were used and sagittal suturectomy was performed; in group III, amalgam markers were used, a sagittal suturectomy was performed and an expansible spring was fitted in the interparietal region and in group IV, markers were used and linear parasagittal craniectomy was carried out with springs. Animals were sacrificed after 2, 4, 8 and 12 weeks. Radiological control and histological analysis were performed in the area of spring implantation. RESULTS: In the groups using springs distraction of the craniectomy borders was greater than in those that did not use springs. New bone formation was observed in all groups, and was faster in group II. Bone growth started from the borders and depth. Bone regeneration presented a similar histological pattern in the groups with spring in the sagittal and parasagittal region. CONCLUSION: The rabbit model proved to be adequate for the analysis proposed by the study. The use of springs in the groups with sagittal and parasagittal osteotomy led to a similar distraction of amalgam markers and both groups had similar ossification histological pattern.

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

“…Unlike in previous studies (Gewalli et al, 2001;David et al, 2002;Davis et al, 2009b;Dornelles et al, 2010;de Faria Valle Dornelles et al, 2011), expansion was greatest not at parietal bone markers but, rather, at frontal ones. This occurred at least partly because our craniectomy extended beyond the coronal suture and the implant was placed on top of it, thus distributing force more anteriorly.…”

“…In vitro strength measurements were similar to those of metal springs used in other studies (Gewalli et al, 2001;Sanger et al, 2007;Davis et al, 2009a, Dornelles et al, 2010de Faria Valle Dornelles et al, 2011). These measurements were obtained approximately 7 days before implantation.…”

“…Unlike in experimental protocols using a smaller (2015) 1e8 6 ostectomy and spring, there was no bone bridge formation; the defect was bridged by connective tissue alone (Persing et al, 1986;Gewalli et al, 2001;Davis et al, 2009a, Dornelles et al, 2010de Faria Valle Dornelles et al, 2011). There were major differences between the control and intervention groups in neovascularization, giant cells, and mature collagen production.…”

“…The mortality rate was high in the control and intervention groups. The high periprocedural mortality is likely attributable to the need for a wide craniectomy for implant placement, whereas the craniectomy used for metal spring placement is generally smaller (2 mm wide and bounded by the lambdoid and coronal sutures) (Persing et al, 1986;Gewalli et al, 2001;Davis et al, 2009a, Dornelles et al, 2010de Faria Valle Dornelles et al, 2011). Extension of craniotomy posterior to the lambdoid suture caused major intraoperative bleeding in all animals, which led to three immediate fatalities and one delayed death (two due to hypovolemic shock and two due to intracranial hemorrhage).…”

In vitro evaluation of poly (lactic‐co‐glycolic acid)/polyisoprene fibers for soft tissue engineering

“…Main treatment consists of osteotomy of these sutures and sequentially use of metallic springs for cranial expansion purposes . The idea of replacing the metallic springs with polymeric springs seeks the application of a material that will be better tolerated and posteriorly absorbed by the body, avoiding the need of a second surgical procedure to extract the device . Evaluating the cranial response in rats (Wistar) and rabbits (New Zealand), the springs made of PLGA/PI showed proper expansion of interbone space, biocompatibility with the bone environment and neovascularisation of areas surrounding the device …”