Facial feminization surgery (FFS) is largely a bony reductive approach to reshaping the face. Reversing the male facial skeletal features focuses on the prominences of the forehead, brow bones, chin and jaw angles. The techniques to do so are well known and widely used. Such facial bone reshaping is largely an art form in that the amount of bony reduction done and trying to ensure its symmetry is up to the expertise and ‘eye’ of the surgeon. Surgeons may acquire 3D facial scan preoperatively and review them but, unlike orthognathic surgery, do not take measurements and determine the details of the surgical plan based on them.
Virtual surgical planning (VSP) is an established preoperative planning technology that has been a major advance in orthognathic surgery and in some uncommon cases of bony genioplasty. The three dimensional planning it provides and methods to try and ensure that the execution of the proposed surgical plan is achieved has established it as a superior tool to conventional paper cephalometric tracings. Its application to other facial bony reshaping procedures, such as facial feminization surgery, is appealing but untested as of yet.
In the November 2019 issue of Plastic and Reconstructive Surgery an article on this topic was published entitled ‘Osseous Transformation with Facial Feminization Surgery: Improved Anatomical Accuracy with Virtual Planning’. In this paper the authors performed a cadaveric study comparing virtual vs non-virtual surgical planning on male cadaveric heads for the procedures of brow bone reduction by outer table frontal sinus setback, lateral brow reshaping, jaw angle reduction and bony genioplasty. Study parameters included operative time, avoidance of adjacent structure injury (safety) and accuracy. (presurgical planned vs actual result)
Their cadaveric results showed that virtual frontal sinus setback surgery was significant faster (19 vs 44 minutes), safer (zero intracranial violation) and 97% accurate. For jaw angle reduction virtual planning improved safety (zero nerve injury) and accuracy. (95% vs 58%)
It is hard to argue that any form of comprehensive presurgical planning of facial surgery does not have some merit. The question is not whether it has merit but the significance of its merit. What are its costs and how much better is it than skill and experience? For brow bone reduction by outer table bony removal and setback, there should never be a circumstance where intracranial penetration occurs. Bone removal may be faster by providing confidence in the bone cuts but the actual reshaping of the bone and its replacement is the most time consuming part of the procedure in my hands. Lateral brow reshaping is full thickness bone reshaping where a guide may increase the degree of symmetry but would not make its performance faster.
Where I find a cutting guide could be useful is in jaw angle reduction. Staying below the intrabony course of the inferior alveolar nerve is not an issue but getting symmetry of the bone cuts is…and many patients do not have symmetric bony jaw angles. It is also a procedure that is performed in a more restrictive operative field with an angled view to the osteotomy line. Even in the East where jaw angle reduction is a commonly perform procedure in non-transgender patients the concept of cutting guides has bee advocated for both accuracy and safety.
Dr. Barry Eppley