History

Surgery on the lower-third of the face may be performed to reconstruct congenital or acquired deficits or to enhance facial aesthetics. These goals can be accomplished by any combination of bony osteotomies or ostectomies, alloplastic augmentation, skin resurfacing or redraping, and/or soft tissue fill. While soft tissue operations of the face are described elsewhere in this text and orthognathic movements of the midface and mandible are beyond the scope of this chapter, we will highlight autologous genioplasty. Obwegeser provided the first detailed description of bony chin surgery in 1957. The osseous genioplasty, however, was not popularized until 1964 when Converse reported the horizontal osteotomy of the mandible to reposition the genial segment. Since then, chin surgery has become a common aesthetic procedure that can complement other procedures such as rhinoplasty, rhytidectomy, or platysmaplasty.

Although improvements in alloplastic materials developed in the 1970s and 1980s have led many surgeons to choose alloplastic chin augmentation, the osseous genioplasty should not be overlooked. The osseous genioplasty remains a versatile operation that can address a wide variety of chin deformities ranging from microgenia to macrogenia to chin asymmetry. Moreover, osseous genioplasty avoids alloplastic materials and the attendant complications that can occur with a long-term foreign body in situ. This chapter will detail the technical aspects of osseous genioplasty.

Physical evaluation

While the neoclassical artistic paradigm recommends that the lower-third of the face be divided into equal thirds – the upper lip, the lower lip, and the chin – such rules are only of limited utility in surgical planning. One of the principal errors a surgeon can make in assessing the lower-third of the face is to limit evaluation to the chin only – particularly the bony component of the chin. Rather, not only must the aesthetics of the chin be balanced in relation to the facial structure, but it is necessary to take into consideration the stature and sex of the patient as well. When evaluating the chin, a systematic approach to the physical examination is helpful. For example, when honing in on the lower third of the face, a step-by-step evaluation from nose to chin should include the lower midface, nasolabial folds, upper and lower lip relationship, incisor tooth show, labiomandibular fold, lower lip eversion and inclination, height and depth of the labiomental fold, chin pad thickness, static soft tissue ptosis, and dynamic chin pad motion with smile.

Large-format frontal, oblique, basilar, and lateral photographs in repose and animation are essential. Posteroanterior and lateral cephalograms, as well as a panoramic X-ray, can also be helpful. Any evaluation of the lower third of the face should also include the following points:

In a youthful midface, the superior border of the triangular shaped malar fat pad lies along the orbital rim and extends laterally to the zygomas (Fig. 35.1). The lateral border can be identified by drawing a line from the lateral canthus to the lateral commissure. The malar fat pad is located beneath the skin and subcutaneous fat, but it is superficial to the superficial muscular aponeurotic system (SMAS). It is fibrous and fatty, and it is readily distinguishable from the overlying subcutaneous fat. With advancing age, the malar fat pad descends inferiorly and medially. Ptosis of the malar fat pad empties the midface and accentuates tear-trough and nasolabial folds. To a lesser extent, this displacement also results in the formation of labiomandibular folds (marionette lines) and jowls.