Quantitative analysis of the orbital floor defect after zygoma fracture repair

Moderate-energy zygoma fractures result frequently in a posteromedially displaced bone fragment. Closed reduction using a force vector directed in an anterolateral direction frequently produces stable repair of these injuries. Exploration of the orbital floor (OF) is not routinely undertaken. However, as the zygoma forms a significant portion of the OF, realignment may create an unrecognized OF defect. Routine OF exploration may be unnecessary and carries the risks of eyelid malposition, scarring, and extraocular muscle injury. Our goal was to quantitatively describe the effect of zygoma reduction on OF defect size and identify predictors for floor exploration.

Retrospectively, patients with moderate energy zygoma fractures were identified. Fractures inadequately reduced on the postoperative computed tomography (CT) scan or those which underwent OF exploration were excluded. The sizes of preoperative and postoperative floor defects from CT scans were measured. Globe projection was measured. Statistical analysis was carried out using Student's t test.

Of 102 identified patients, 15 satisfied the inclusion criteria. The average pre- and postoperative OF defects measured 0.3 and 0.6 cm(2), respectively. This difference approached statistical significance, but was clinically insignificant except in 1 patient. Similarly, globe projection was clinically similar between the repaired and unaffected sides, except in the same patient.

In majority, repair of moderate energy zygoma fractures does not clinically significantly increase OF defect or produce enophthalmos. In patients with significant displacement of the zygoma at the level of OF with comminution of floor fragments, the reduction maneuver may create a critical size defect and we believe should be followed by floor exploration.