Dynamic Spring-Mediated Cranioplasty in a Rabbit Model

Abstract

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.

Skull Expansion by Spring-Mediated Bone Regeneration

“…The use of rabbits that did not present synostosis was not a limitation for cranial expansion under the expanding action of springs, corroborating reports from the literature (Ten Cate, Freeman et al 1977;Persing, Morgan et al 1991;Gewalli, Guimaraes-Ferreira et al 2001;David, Gewalli et al 2002;Davis, Windh et al 2008;Davis, Windh et al 2009). Tanaka et al published a study analyzing the local response to spring placement at the interparietal suture in healthy rats.…”

“…Rabbits have been widely used as experimental model in studies of behavior of cranial sutures, intracranial pressure, craniometric variations, evolution of fixation materials, and distraction of craniofacial structures (Mabbutt and Kokich 1979;Persson, Roy et al 1979;Alberius and Selvik 1983a;Alberius, Selvik et al 1986;Persing, Babler et al 1986;Alberius, Malmberg et al 1990;Smith, Mooney et al 1996;Singhal, Mooney et al 1997;Losken, Mooney et al 1998;Mooney, Siegel et al 1999;Wendy, Fellows-Mayle et al 2000;Gewalli, Guimaraes-Ferreira et al 2001;Putz, Smith et al 2001;Abreu 2002;David, Gewalli et al 2002;Gosain, Santoro et al 2002;David, Proffer et al 2004;Guimarães-Ferreira, Miguéns et al 2004;Cooper, Singhal et al 2006;Cardoso, Cançado et al 2007;Davis, Windh et al 2008;Davis, Windh et al 2009). Cerebral growth curve of rabbit specimens is similar to those of newborn human children: craniofacial growth in rabbits is accelareted immediately after birth, progressively decreasing from two to thirty-four weeks of age (Alberius, Selvik et al 1986;Abreu 2002).…”

The Atkinson Morley's Hospital joint neurosurgical – maxillofacial procedures: Cranioplasty case series 1985–2003

“…Alternative modalities for reconstruction include gene therapy and introduction of bone morphogenetic proteins (Chim and Schantz, 2005;Springer et al, 2005), smart biomaterials ''interacting'' with morphogenetic proteins and/or growth factors (Chim and Schantz, 2005) or stimulating osteoconduction and osteogenesis with or without the addition of autologous osteoblasts (Henkel et al, 2005), antibiotic-impregnated implants and dynamic cranioplasty with the use of distraction osteogenesis techniques (David et al, 2002).…”

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

“…The hardware used for fixation or manipulation of the affected bone segments has included titanium plates, nylon and steel wire, and absorbable polymer implants. More recently, metal springs have been employed (Persing et al, 1986;Lauritzen et al, 1998;David et al, 2002;Guimaraes-Ferreira et al, 2002;Ferreira et al, 2006;Lauritzen et al, 2008;McIntosh et al, 2008).…”

“…Distraction osteogenesis with metal springs as a treatment for congenital cranial deformities yields outcomes comparable to those of established techniques (Persing et al, 1986;Lauritzen et al, 1998Lauritzen et al, , 2008David et al, 2002;Davis et al, 2009b). Springs combine the advantages of distraction with significant reductions in tissue elevation, dural manipulation, operative time, blood loss, and length of stay; furthermore, as they are exclusively internal, springs decrease the risk of infection and obviate the need for manual progressive distraction Lauritzen et al, 2008).…”