Transconjunctival Versus Endoscopic-Assisted Orbital Reconstruction: A Human Cadaver Study on the Predictability of Implant Position

Complex orbital fractures are associated with potential functional and cosmetic post-traumatic impairment. Adequate reconstruction is crucial for a satisfactory surgical outcome and therefore anatomical alignment of the orbital boundary is essential. However, the surgeon’s error may affect the final effect of treatment by incorrect positioning of the implant, which can result in poor clinical outcome. The endoscope can be used as a tool for additional visualization of the orbit through a transantral approach. The goal of this study is to evaluate whether endoscopic guidance is beneficial for optimal implant placement and could serve as a convenient alternative for intra-operative imaging and navigation. The transconjunctival reconstruction (TCR) with and without endoscopic assisted reconstruction (EAR) is compared in human cadaveric model.

Computed tomography scans were obtained in 10 cadaveric heads. Complex orbital fractures were created in all 20 orbits. Two OMF surgeons, experienced in the field of orbital reconstruction, performed the orbital reconstructions with preformed orbital titanium mesh plates. CT-scans were performed at baseline (with intact orbits), after creation of the orbital defects and postoperatively. The ideal implant location had been planned digitally on the pre-operative scan beforehand. Implant placement accuracy was evaluated by comparing the planned implant location with the location of the implant on the post-operative scan. The rotations (roll, pitch, yaw) and translations in x, y and z direction between the planned implant and resulting implant position were calculated. A paired t-test was used to compare translation and rotation. The inter- and intraoperator variability was tested on 10 orbits by using the intraclass correlation coefficient (ICC).

There were no statistically significant differences (P> 0.05) in the implant dislocation (translation and/or rotation) between the TCR and EAR group (table 1). The intra- and interoperator variability showed inconsistency for translation and rotation in both the conjunctival and endoscope group.

Theoretically, an endoscope in combination with the transconjunctival approach creates a better visualization of the bony defect of the orbital floor and the posterior ledge as suggested in previous studies. Although consistency is low, the TCR en EAR groups show similar results suggesting that additional visualisation is not increasing the reproducibility of the implant placement. In our study none of the implants was positioned below the posterior ledge. The main concern is adequate implant positioning and prevention of rotation of the implant. The EAR showed no significant improvement for this matter. The drawbacks of the use of the endoscope are an additional incision intra-orally and prolonged operating time (15 minutes extra surgery time on average). Endoscopic assisted orbital reconstruction may be helpful for visualization of the orbital defect, especially for educational purposes, but lacks the advantage for better anatomical reconstruction in complex orbital defects.

References

Hundepool AC, Willemsen MAP, Koudstaal MJ, van der Wal KGH. Open reduction versus endoscopically controlled reconstruction of orbital floor fractures: a retrospective analysis. Int J Oral Maxillofac Surg. 2012;41(4):489-93

Polligkeit J, Grimm M, Peters JP, Cetindis M, Krimmel M, Reinert S. Assessment of indications and clinical outcome for the endoscopy-assisted combined subciliary/transantral approach in treatment of complex orbital floor fractures. J Craniomaxillofac Surg. 2013;41(8):797-802

Table 1 Implant position transconjunctival vs. endoscopic assisted approach

 

	Conjunctival			Endoscope
	Mean	SD		Mean	SD		P-value
Translation	4.98mm	2.19mm		4.18mm	2.06mm		p=0.19
Pitch	-1.29°	3.05°		-0.25°	3.65°		p=0.24
Yaw	17.81°	10.91°		14.53°	11.88°		p=0.14
Roll	-9.81°	9.09°		-7.12°	5.65°		p=0.19