Comparison of pre- and postoperative orbital volume using three dimensional CT imaging in zygoma fracture patients

The aims of this study were (1) to assess the difference between the volume of the traumatized and non-traumatized orbit, (2) to determine the critica l change in orbital volume that will result in enophthalmos, and (3) to ana lyze the correlation between volume discrepancy and clinical outcome in max illofacial trauma patients. Twenty-seven surgically managed patients with a fracture of the orbitozygomatic complex were included in this study. Preop erative and postoperative volume measurements of both orbits were compared, using software whose accuracy was confirmed in a preliminary experimental study in dry skulls. The correlation between volume discrepancy and clinica l enophthalmos was statistically assessed before and after surgery. Preoper atively, there was an increase in orbital volume in 26 of 27 cases, with a range of 0.04-6.02 cc compared with the intact orbits. The mean volume diff erence between the orbits was 3.01+/-1.64 cm(3) in the preoperative period, and this decreased to 1.02+/-1.29 cm(3) following operation (P<0.01). Five patients (19%) showed clinical enophthalmos with a mean volume difference of 4.77+/-0.18 cm(3) preoperatively. Clinical enophthalmos persisted postop eratively in only one of five enophthalmic patients, in whom the volume dis crepancy was greater than 4 cm(3). Our data suggested that the technique de scribed here is an easy and accurate method of assessing the volume of the orbit. Orbital volume measurement may help the surgeon to predict volume to be restored and to avoid probable complications.