Intra-Operative Navigation Assisted Surgery with 2-Dimention Planning for Orbital Wall Fracture Reconstruction, Benefit and Limitation

Background

Correction of enophthalmos in reconstruction of orbital wall fractures depends on intra-operative judgement by direction observation. Intra-operative navigation assistance could provide more precise guidance to “how exophthalmos of the orbit” after reconstruction of orbital wall, than observation only by raw eye.  Pre-operative planning is a key procedure of this technique. Theoretically, 3-dimention planning is more precise, but may not be available for every institute due to limited facility. We performed navigation assisted surgery by pre-operative 2-dimention planning and evaluated the clinical outcome and benefit.

 

Patients and methods

From April 2015 to January 2018, six patients undergone navigation assisted surgery for reconstruction of orbital wall fracture, with pre-operative 2-dimention planning, including 4 for combined orbital floor and medial wall fractures, and 2 for orbital floor fracture alone. Four of them were cases of secondary reconstruction. We input unformatted DICOM images into Medtronic StealthStation® Surgical Navigation System, and made the planning by the built-in planning software. On axial view, we firstly identified and drew the vertical midline from nose tip to center of cervical spine. Then, we made horizontal lines at top of the normal side orbit, extended to the fractured side, perpendicular to the midline, at the middle of the whole orbit. Points of the predicted position of the top of orbit at the fractured side was marked, in same distance opposite to the normal side. In secondary reconstruction cases, this predicted point was marked 1mm higher than the top of the orbit of the normal side. Then we performed reduction and reconstruction of the orbital wall fracture. Titanium mesh was used for orbital wall reconstruction, and was adjusted under assistance of navigation system. Medpor® was used for further orbital content reconstruction and correction of enophthalmos in secondary cases, and was adjusted with guidance of the predicted point (to reach the predicted point after inserting the Medpor®). Clinical result was evaluated by photographing of facial appearance, post-operative CT scan, and measurement of exophthalmometer.

 

Results

The 2-dimention planning of predicted reduction point was easy by drawing the vertical and horizontal lines. The predicted points of top of the orbit were compatible by intra-operative direct inspection in all cases. Post-operative exophthalmometer showed less than 1mm enophthalmos in injured eye in primary cases, and satisfied correction of enophthalmos in secondary cases (three cases less than 1mm post-op enophthalmos, and one case less than 2mm). Post-operative photographing showed satisfied appearance. CT scan revealed acceptable position of orbit and the titanium mesh.

 

Conclusions

For limited facility, navigation assisted surgery by 2-dimention planning for orbita wall reconstruction might be an alternative of 3-dimention planning. Optimal result could be reached with less cost and easier planning. However, it may not be as precise as 3-dimention planning and may have limitation in patients with more complicated fractures.