Correction of coronal suture synostosis using suture and dura mater allografts in rabbits with familial craniosynostosis

Objective: Resynostosis following surgical correction of craniosynostosis i s a common clinical correlate. Recent studies suggest that the dura mater i s necessary to maintain suture patency. It has also been hypothesized that dura mater from synostotic individuals may provide aberrant biochemical sig nals to the osteogenic fronts of the calvaria, which result in premature su ture fusion and subsequent resynostosis following surgery. This study was d esigned to test this hypothesis by surgically manipulating the coronal sutu re and dura mater in rabbits with familial craniosynostosis to prevent post surgical resynostosis. Design: Craniofacial growth and histomorphometric data were collected from 129 rabbits: 72 normal controls end 57 rabbits with bilateral coronel sutur e synostosis (15 unoperated on controls; 13 surgical controls; 9 dura mater transplant only; 10 suture transplant only; and 10 suture end dura mater t ransplant). At 10 days of age, all rabbits had radiopaque amalgam markers p laced on either side of the coronel, frontonasal, and anterior lambdoidal s utures. At 25 days of age, 42 synostosed rabbits had a 3 to 5-mm wide coron al suturectomy. Coronal sutures and/or underlying dura mater allografts wer e harvested from same-aged, wildtype, isohistogenic central rabbits and tra nsplanted onto the dura mater of synostosed host rabbits. Serial radiograph s were taken at 10, 25, 42, and 84 days of age, and the suturectomy sites w ere harvested at 84 days of age in 44 rabbits and serially sectioned for hi stomorphometric examination. Results: Results revealed that cranial vault growth was significantly (p < .05) improved following surgical release of the fused coronel suture compar ed with synostosed rabbits who were not operated on but was still significa ntly different (p < .05) from that of normal control rabbits. By 84 days of age, significant (p < .05) differences were noted in calvarial suture mark er separation, cranial vault shape indices, and cranial base angles between rabbits with and without dura mater allografts, probably as a result of re synostosis of the suturectomy site or suture-only allografts. Qualitative h istological examination revealed that at 84 days of age rabbits with suture and dura allografts had patent coronal sutures, suture-only allografts had fused coronal sutures with extensive endosteal hyperostosis, dura mater-on ly allografts had some new bone in the suturectomy site that resembled rudi mentary osteogenic fronts, end suturectomy controls had extensive endosteal bone formation and resynostosis of the suturectomy site. Significantly (p < .05) more bone was found in the suturectomy sites of rabbits without dura mater allografts compared with rabbits with dura mater allografts. Conclusions: Results support the initial hypothesis that normal dura mater allografts will maintain suture or suturectomy site patency end allow unres tricted craniofacial growth. However, it is still unclear whether the dura mater from normal rabbits was providing biochemical signals to the transpla nted sutures or suturectomy sites or simply acting as a barrier to prevent abnormal biochemical signals from the dura mater of synostosed rabbits from reaching the calvaria. The clinical and therapeutic implications of these procedures are discussed.