Internal calvarial bone distraction in rabbits with experimental coronal suture immobilization.

Correction of craniosynostosis involves removal of the coronal suture to allow for expansion of the developing brain and normal craniofacial growth. Frequently, however, the site reossifies, restricts growth, and requires additional surgery. The present study was designed to assess the effects of an internal, subperiosteal calvarial distractor on suturectomy site patency and compensatory craniofacial growth changes in an experimental rabbit model of coronal suture synostosis. In the present study, 43 1 1/2-week-old rabbits were used. Amalgam markers were placed across the frontonasal, coronal, and anterior lambdoidal sutures in all animals. Twenty-nine rabbits underwent bilateral coronal suture immobilization using methyl methacrylate. Fourteen rabbits were left untreated and served as sham controls. At 6 weeks of age, the immobilized rabbits were divided into three groups: (1) immobilized (controls), (2) suturectomy, and (3) suturectomy and distraction. The distractors were activated percutaneously at an average of 0.6 mm/week for 5 weeks (3 mm total). Lateral head radiographs were taken at 1 1/2, 6, 12, and 18 weeks of age. Results revealed that, by 6 weeks of age, animals with coronal suture immobilization exhibited significantly (p < 0.01) reduced growth across the coronal suture, resulting in shorter and inferiorly rotated cranial vaults compared with sham controls. By 12 weeks of age, rabbits with distraction returned to normal (sham control) coronal suture marker separation, whereas rabbits with immobilized sutures and suturectomy only showed significantly reduced marker distances. Rabbits with distraction also exhibited greater anterior cranial base lengths compared with the other experimental groups.(ABSTRACT TRUNCATED AT 250 WORDS)