Change of the orbital volume ratio in pure blow-out fractures depending on fracture location.

The purposes of this study were to observe bony orbital volume (OV) changes in pure blow-out fractures according to fracture location using a facial computed tomographic scan and to investigate whether the OV measurements can be used as a quantitative value for the evaluation of the surgical results of the acute blow-out fracture.Forty-five patients with unilateral pure blow-out fracture were divided into 3 groups: inferior (group I), inferior medial (group IM), and medial (group M) orbital wall fracture. The OV and the orbital volume ratio (OVR) were prospectively measured before and 6 months after surgery with the use of 3-dimensional computed tomographic scans, and the Hertel scale was measured with a Hertel exothalmometer.The preoperative OVR increased to the greatest extent in group IM, and the mean preoperative OVR was 121.46. The mean preoperative OVR in group I was significantly higher than that of group M (P = 0.005). The OV and OVR revealed a statistically significant decrease after the surgery (P = 0.000). The Hertel scale improved from -1.04 mm before the surgery to -0.78 mm after the surgery, but no significant difference was observed (P = 0.051).The OVR was useful as a quantitative value to evaluate pure blow-out fractures, compared with that of the Hertel scale. Fracture location-associated OVR studies are needed to make volume guidelines of blow-out fracture surgery.