The ZMF: Is it a reliable intraoperative guide for the IOF?

Intraoperative localization of the inferior orbital fissure (IOF) is necessary when making an osteotomy across the zygomatic bone while performing an orbito-zygomatic craniotomy. The zygomatico-facial foramen (ZMF) may serve as good reference point for locating the IOF. In this study, the position of the ZMF was assessed and its location in relation to the IOF was measured in 78 skulls. The ZMF was present in 83.3% of the skulls and when present, was related to the lateral end of the IOF in all cases. The mean distance of the ZMF from the IOF was 15.6 mm, and the mean distance between the ZMF and the fronto-zygomatic suture was 25.9 mm. In skulls where the ZMF was absent, the mean distance of the inferior orbital rim (at the level of IOF) from the fronto-zygomatic suture (20.7 mm) could be used for determining the position of the IOF. The IOF could thus be located approximately 15-16 mm medial to the ZMF in the same transverse plane. The location of the ZMF could also be used as a landmark for determining the inferior limit of the orbito-zygomatic craniotomy.