BACKGROUND: Midface augmentation is commonly used to improve the appearance of concave faces and to achieve balance in the facial contour. It can also be an adjunct to orthognathic or reconstructive surgery. However, an inherent risk of midface augmentation is injury to the infraorbital nerve where it exits the infraorbital foramen (IOF). This can result in significant morbidity, including loss of sensation to the midface, nasal sidewall, upper lip, and lower eyelid. OBJECTIVES: The authors identify a safe zone of dissection in the midface for subperiosteal placement of infraorbital, paranasal, malar, and submalar implants, which avoids injury to the infraorbital nerve. METHODS: Given the popularity of transconjuctival and intraoral access to the midface skeleton, the authors identified relevant bony and dental landmarks from radiographic images and measured distances between the IOF and these landmarks. Forty-four computed tomography scans of adult hemifaces were used to accurately locate the IOF in relation to the anatomic landmarks. RESULTS: Most often, the IOF's location correlated with the second premolar on a vertical axis. The average distance between the IOF and the infraorbital rim, piriform aperture, tip of the second premolar cusps, and lateral orbital rim was approximately 8.61, 17.43, 41.81, and 25.93 mm (respectively) in men and 8.25, 15.69, 37.33, and 24.21 mm (respectively) in women. CONCLUSIONS: A safe zone of dissection for midface augmentation has been identified, which differs from previous findings. Awareness of this zone may help clinicians locate the IOF and avoid injury to the nerve.
BACKGROUND: Midface augmentation is commonly used to improve the appearance of concave faces and to achieve balance in the facial contour. It can also be an adjunct to orthognathic or reconstructive surgery. However, an inherent risk of midface augmentation is injury to the infraorbital nerve where it exits the infraorbital foramen (IOF). This can result in significant morbidity, including loss of sensation to the midface, nasal sidewall, upper lip, and lower eyelid. OBJECTIVES: The authors identify a safe zone of dissection in the midface for subperiosteal placement of infraorbital, paranasal, malar, and submalar implants, which avoids injury to the infraorbital nerve. METHODS: Given the popularity of transconjuctival and intraoral access to the midface skeleton, the authors identified relevant bony and dental landmarks from radiographic images and measured distances between the IOF and these landmarks. Forty-four computed tomography scans of adult hemifaces were used to accurately locate the IOF in relation to the anatomic landmarks. RESULTS: Most often, the IOF's location correlated with the second premolar on a vertical axis. The average distance between the IOF and the infraorbital rim, piriform aperture, tip of the second premolar cusps, and lateral orbital rim was approximately 8.61, 17.43, 41.81, and 25.93 mm (respectively) in men and 8.25, 15.69, 37.33, and 24.21 mm (respectively) in women. CONCLUSIONS: A safe zone of dissection for midface augmentation has been identified, which differs from previous findings. Awareness of this zone may help clinicians locate the IOF and avoid injury to the nerve.
Authors: Matthew J Zdilla; Aaron W Koons; Michelle L Russell; Kelsey R Mangus; Kaitlyn N Bliss Journal: J Craniofac Surg Date: 2018-03 Impact factor: 1.046