Displacements of eyeball in orbital blowout fractures.

Thirty-two cases of orbital blowout fracture, excluding those of linear fracture with trap-door variety, were selected to study the changes of the eyeball position: posterior displacement or enophthalmos, medial and inferior displacement. Two-millimeter slices of computed tomographic scans were taken, and the eyeball positions were measured with the contralateral eye as a control. Intraorbital edema, if present, at least 10 days after injury had little effect on the position of the eyeball, nor was there any evidence to suggest the late onset of enophthalmos. Enophthalmos remains around 1 mm before total orbital enlargement reaches 2 ml in volume, thereafter increases proportionally with total orbital enlargement until 4 ml, then remains on a plateau. Enophthalmos increases proportionally with the increase of medial orbital wall enlargement when the inferior orbital wall enlargement is less than 2 ml. With inferior wall enlargement more than 2 ml, 3 to 4 mm of enophthalmos is seen irrespective of the increase of medial wall enlargement. The medial displacement of the eyeball increases proportionally with the increase of medial wall enlargement when inferior wall enlargement is less than 2 ml. The inferior displacement of the eyeball has little proportional relationship with medial or inferior wall enlargement when the former exceeds 2 ml. Relatively good proportional relationship is found between the enophthalmos and the medial displacement of the eyeball, but not between the enophthalmos and the inferior displacement of the eyeball.

Clinical application of a solid three-dimensional model for orbital wall fractures.

Orbital wall fractures have been diagnosed conventionally by plain X-rays, CT imaging, and more recently by three-dimensional CT imaging. However, it is not easy to know the three-dimensional appearances of orbital wall fractures. Anatomically precise reconstruction of the orbital wall is essential for the appearance and function of the eyes. Life-size solid models of fractured orbital walls and also solid models of bone grafts for the reconstruction were produced by milling polyurethane foam on the basis of CT data. These models are very valuable because they provide not only satisfactory understanding of the three-dimensional morphology, but the models at hand are the ideal guides during the operation, and the prefabricated bone grafts, based on the models make a complete surgical simulation.

How to fashion a TRAM flap in the presence of a lower midline laparotomy scar. An experimental study in rats.

The transverse rectus abdominis musculocutaneous (TRAM) flap cannot be used successfully in a patient with a pre-existing midline abdominal scar because the area distal to the scar undergoes circulatory failure leading to necrosis. To investigate the usefulness of various procedures to improve the circulation in such a flap, we studied the percentage area survival of experimental abdominal island flaps in five groups of rats with pre-existing midline scar treated by different procedures which depended on the source of blood used to supply the flap (control, arterial, venous, arteriovenous shunt, and delayed, n = 5 in each group). All flaps in the arterial group survived completely. The mean (SEM) percentages of the flaps that survived in the control (17(2)%) and venous (17(1)%) groups were significantly lower than those in the delayed (31(2)%) and arteriovenous shunt (67(6)%) groups (all, p < 0.01). These results indicate that preservation of arterial inflow by arterial anastomosis or arteriovenous shunt on the opposite side is important if the flap is to survive across the midline scar. Preservation of the vein in the opposite flap is not essential, because venous outflow is supposed to drain through the midline scar into the epigastric vein of the pedicle without any signs of congestion.