Premature fusion of the coronal suture was produced in 9-day-old rabbits by immobilization of the suture area bilaterally with methyl-cyanoacrylate adhesive. The effects of suture fusion and its surgical release on suture growth and on skull morphology were evaluated by radiographic cephalometry. Immobilization resulted in significant changes in the angular dimensions in the vault toward an anteroposterior shortening. No permanent deformity was observed in the angular relationship between the cranial base and the facial skeleton. Craniectomy at 30 days, when a skull deformity had been established, resulted in rapid separation of the bones at the suture site which returned the deformed skull to a normal configuration by 90 days of age. Surgical removal of a normal suture in a control group also resulted in accelerated separation of the bones at the excised suture site, but it was less than after removal of an immobilized suture. The experimental data indicate that premature fusion of rapidly growing sutures results in consistent skull deformity. Early release of the fusion, when this is the primary abnormality, will result in spontaneous correction of the deformity.

Premature closure of a cranial suture results in skull deformation characterized by inhibited skull growth in a direction perpendicular to the course of the affected suture. Early surgical release of the closed suture results in a "normal" skull morphology. The present experimental study measured alterations in growth at the transverse cranial sutures that occurred following induced premature closure of the coronal suture and its subsequent release in New Zealand White rabbits. Using roentgenocephalometric methods, growth and morphometric changes were monitored at the frontonasal, coronal, and anterior lambdoid sutures following premature closure of the coronal suture at 9 days of age. The results indicated that premature closure of the coronal suture did not result in compensatory (increased) growth at the other transverse sutures of the vault. In fact, growth at these sutures was significantly reduced. This reduced growth at adjacent transverse sutures was not ameliorated by early surgical release of the fused suture.

Using radiocephalometric procedures, the authors examined the separate effects of suturectomy, periostectomy, and dural transection on the growing skull in young rabbits. When the coronal suture was surgically removed during normal growth, The freed frontal and parietal bones separated at a significantly accelerated rate. No accelerated separation was found when only the overlying periosteum and aponeurosis were transected. Furthermore, no additional separation was observed when the dura mater and falx cerebri were transected following suturectomy. Analysis of growth at the adjacent frontonasal and anterior lambdoid sutures suggested that the accelerated separation of bones after suturectomy was compensated for by reduced growth at these adjacent sutures. The result of these compensatory actions was that the total length of the skull remained unchanged. This study not only supports earlier observations that sutures grow in response to extrinsic separative forces but, significantly, that the suture tissue itself, rather than the dura or pericranium, acts as a restraint during normal translatory growth.

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