Computer-aided Planning and Execution in Facial Gender Surgery: Approaches, Concepts, and Implementation.

Facial gender surgery (FGS) involves major surgical modification of the craniofacial soft tissues and skeleton. Computer-aided surgery (CAS) has improved precision and accuracy of osteotomies and decreased operative time in complex reconstructive craniofacial surgery. FGS is a natural application for CAS because the procedures are not only technically challenging but also demand a high standard of aesthetic results. Planning FGS cases virtually enables better and more reproducible results through simulated surgical planning and precise execution of osteotomies in surgical fields with limited exposure. We describe our experience with CAS in FGS for each of the facial thirds to introduce new concepts for conceptual planning of osteotomy design and patient-specific implants.

Comparing calvarial transport distraction with and without radiation and fat grafting.

The purpose of this study is to: a) assess transport distraction to reconstruct cranial defects in radiated and non-radiated fields b) examine adipose grafting's effect on the bony regenerate and overlying wound, and c) elucidate sources of bone formation during transport distraction osteogenesis. Twenty-three male New Zealand white rabbits (3 months; 3.5 kg) were used, 10 non-irradiated and 13 irradiated (17 treatment, 6 control) with a one-time fraction of 35 Gy. A 16 × 16 mm defect was abutted by a 10 × 16 mm transport disc 5 weeks after irradiation, and 11 animals were fat grafted at the distraction site. Latency (1 day), distraction (1.5 mm/day), and consolidation (4 weeks) followed. Fluorochromes were injected subcutaneously and microCT, fluorescence, and histology assessed. In distracted animals without fat grafting, bone density measured 701.87 mgHA/ccm and 2271.95 mgHA/ccm in irradiated and non-irradiated animals. In distracted animals with fat grafting, bone density measured 703.23 mgHA/ccm and 2254.27 mgHA/ccm in irradiated and non-irradiated animals. Fluorescence revealed ossification emanating from the dura, periosteum, and transport segment with decreased formation in irradiated animals. Transport distraction is possible for cranial reconstruction in irradiated fields but short-term osseous fill is significantly diminished. Adipose grafting enhances wound healing in previously irradiated fields but does not enhance ossification.

Evaluation of cranial bone transport distraction with and without adipose grafting.

Transport distraction osteogenesis (DO) can be used to autologously reconstitute calvarial defects. The purpose of this study is to histomorphologically interrogate osteogenic formation during cranial transport distraction using a novel device. We also evaluate the effect of fat grafting on the regenerate and soft-tissue stability during distraction. This study was approved by Yale IACUC. Ten male New Zealand white rabbits (3 mo; 3.5 kg) were used (8 treatment, 2 control). A 16 × 16 mm defect was created abutted by a 10 × 16 mm transport disc. The device was fixated anterioposteriorly. Four animals were fat-grafted using 2 mL of subdermal intrascapular fat deposited along the distraction site. Latency (1 d), active distraction (12-14 d) (1.5 mm/d), and consolidation (4 wk) followed. Calcein and xylene orange fluorochromes were injected subcutaneously during and post-distraction to mark sites of bone formation. Following sacrifice, osteogenesis was assessed using microCT, histology, and fluorescence. Treatment animals demonstrated regenerate bone between distracted segments on microCT. MicroCT analysis of non-fat-grafted and fat-grafted animals revealed a mean density of 2271.95 mgHA/ccm and 2254.27 mgHA/ccm (P = 0.967), respectively, and defect bone versus total volume (BV/TV) of 0.0999 and 0.0766 (P = 0.5979), respectively. Controls had minimal reossification. Histologically, mean densities measured 43.63% and 8.19%, respectively. Fluorescence revealed ossification from the callus as well as from dura and periosteum in the cranial defect. Transport distraction is effective to reconstruct critically sized rabbit calvarial defects. Regenerate bone arises predominantly from the callus with contribution from surrounding dura and periosteum. Adipose grafting is well tolerated but does not enhance osseous regeneration.