Objective:
Enophthalmos is a commonly seen scenario in the severe blow out fracture of orbit floor. It usually indicated surgical intervention if the height discrepancy is more than 2mm. Several surgical implant could be utilized including the traditional mesh plate, osteosynthesis plate, or the latest patient-specific implant(PSI). In some difficult condition, revision surgery is need to correct the suboptimal result. We would like to investigate the orbital volume change after the different implant placement in a revision case and see its relationship with the surgical outcome.

Material:
A 26-year-old female suffered from left orbital blow-out fracture with prominent enophthalmos. She underwent first surgery with Titanium mesh plate but the enophthalmos still persisted with minimal improvement. We thus designed a PSI implant by the mirroring method with posterior part 1mm augmentation. The delayed revision surgery with PSI was done later.

Method:
We use the Mimics software to calculate the orbit volume of the (1)healthy side, (2)post-Titanium mesh plate reconstructed, and (3)post-PSI reconstructed orbit. We would like to investigate how the volume change in these conditions respectively.

Result:
The volume of the healthy side orbit is 31857 mm3. The volume of the Titanium mesh plate reconstructed orbit is 30484 mm3 (95.7% of healthy side volume). The volume of the PSI reconstructed orbit is 28603 mm3.(89.7% of healthy side volume)

Conclusion:
Over correction of the orbit volume should be considered in a severe enophthalmos, especially in the group of delayed or revision surgery. The amount of the overcorrection needs further big data analysis. Using patient-specific implant may play important role in precise reduction of the orbital volume.