STABILITY OF FRONTO-ORBITAL ADVANCEMENT IN NONSYNDROMIC BILATERAL CORONAL SYNOSTOSIS - A QUANTITATIVE 3-DIMENSIONAL COMPUTED TOMOGRAPHIC STUDY

Fronto-orbital dysmorphology in nonsyndromic bilateral coronal synosto sis includes frontal flattening, supraorbital recession, and ocular gl obe protrusion. Surgical advancement of the supraorbital region (''ban deau'') is performed to correct these deformities. A retrospective ana lysis of 10 consecutive patients with nonsyndromic bilateral coronal s ynostosis was performed to assess the effect of two types of bandeau f ixation at the nasion. The advanced bandeau was fixed medially at the nasion with a calvarial bone graft and polyglycolic acid sutures (bone graft/suture group, five patients) or with a microplate (plate group, five patients) and bilaterally at pterion with calvarial bone grafts and polyglycolic acid sutures (all patients). The cranio-orbital dysmo rphology and the surgical results were studied using pre-, peri-, and post-operative three-dimensional computed tomographic (CT) data. Refor mation, manipulation, editing, and quantitative measurements of the CT data were performed on a computer workstation and Analyze imaging pro gram. Four measurements were performed to evaluate the fronto-orbital morphology: the length:width ratio of anterior cranial fossa, ventral globe index, cornea position, and supraorbital rim lag. The ventral gl obe index assessed the degree of eyeball protrusion out of the orbital cavity. Measurements of the cornea position and supraorbital rim lag were performed on the longitudinal orbital projections of the CT data Six normal skull CT scans were available for same measurement and comp arison. Measurements of the preoperative frontoorbital dysmorphology i n bilateral coronal synostosis were significantly different from those of normal subjects. One year after the surgery, the length:width rati o of the anterior cranial fossa was normalized in both groups. The ven tral globe index was improved but not normalized in both groups, where as the cornea position and supraorbital rim lag were improved in the b one graft/suture group but were normalized in the plate group. Based o n the quantitative data, the surgical outcomes in the plate group were significantly better than those in the bone graft/suture group. Major relapse of surgical advancement in the bone graft/suture group seemed to occur in perioperative period. In summary, at 1 year postoperative ly, the bandeau advancement improved but did not entirely normalize th e fronto-orbital dysmorphology of nonsyndromic bilateral coronal synos tosis in either group. We conclude that plate rigid fixation at the na sion provides superior stability for bandeau advancement compared with bone graft/suture fixation.