Intraoperative Computed Tomography for Complex Midfacial and Orbital Trauma

Advanced intraoperative imaging provides the clinician the ability to have real-time feedback while navigating their way through complex surgical procedures.  Navigational systems have the benefit of allowing preoperative planning to be integrated into the intraoperative system; however, they do not account for the three-dimensional changes that occur in tissue volumes and positioning after surgical manipulation of the initial anatomy. This can lead to unexpected clinical inaccuracies.  Intraoperative computed tomography (CT) has been used in the neurosurgical arena for three-dimensional angiography.   Since the use of intraoperative CT allows for immediate evaluation, the use in Oral and Maxillofacial surgery for dealing with the complex anatomy of midfacial and orbital trauma may be beneficial. 

Inaccurate reduction of the zygomaticomaxillary complex (ZMC) can lead to increased orbital volume with resultant enopthalamos and facial asymmetry due to lack of malar projection.  Incorrect placement of orbital floor fixation can lead to hypoglobus, diplopia, continued entrapment of periorbital tissues, and increased posterior vertical orbital height.  These conditions are very difficult to address secondarily often requiring osteotomies, custom designed implants, and multiple procedures all with less than ideal outcomes.

Ten patients were selected who presented to the Vanderbilt University Emergency Department with complex midfacial and/or orbital trauma from July 2011 through February 2012.  All patients underwent surgical reconstruction of their injuries with the adjunctive use of intraoperative CT guidance.  All procedures and imaging were performed in the same operative suite utilizing the same Phillips Allura Xper FD20 CT unit.  Axial, coronal, and sagittal images were obtained and analyzed on each patient prior to procedure completion.

Objective analysis intraoperatively focused on the following outcome variables:  adequate reduction, comparison of bony symmetry to uninjured side, positioning of inferior rectus muscle, comparison of posterior vertical orbital height, and extraocular movements.

Subjective analysis postoperatively focused upon patient satisfaction with esthetics and function.

Etiology of injury included gunshot wounds, sporting accidents, assault, and motor vehicle collisions. Ten patients (9 male and 1 female), with a mean age of 39, ranged in age from 18 to 72.  Six of the patients had a ZMC fracture while all patients had an orbital fracture.  Intraoperative imaging was evaluated prior to completion of the procedure with no patients requiring alteration of their fixation. Based upon intraoperative imaging all patients had clinically acceptable: 1) bony symmetry and fracture reduction compared to the uninjured side; 2) horizontal position of the inferior rectus muscle; 3) posterior vertical orbital height when compared to uninjured side; 4) extraocular movements when forced duction tests were performed.

Subjectively all patients were satisfied with their outcomes functionally and esthetically with no reported diplopia.  One patient complained of continued left infraorbital nerve (V2) dysesthesia.

While intraoperative navigational systems can be helpful, we have found that the use of intraoperative CT predictably improves functional and esthetic outcomes of complex midfacial and orbital trauma.  The use of this technology also helps the overall reduction in health care costs by eliminating the need for reoperation in complex cases.

References:

1.  Pohlenz, Phillip, Felix Blake, Marco Blessmann, Ralf Smeets, Christian Habermann, Philipp Begemann, Rainer Schmelzle and Max Heiland. Intraoperative Cone Beam Computed Tomography in Oral and Maxillofacial Surgery using a C-Arm Prototype: First Clinical Experiences After Treatment of Zygomaticomaxillary Complex Fractures. J Oral Maxillofacial Surgery 67(3):515-521, 2009.

2.  Bell, R. Bryan, Markiewicz, MR. Computer-Assisted Planning, Stereolithographic Modeling, and Intraoperative Navigation for Complex Orbital Reconstruction: A Descriptive Study in a Preliminary Cohort. J Oral Maxillofacial Surgery. 67(12):2559-70, 2009.