Advanced Three-Dimensional Technologies in Craniofacial Reconstruction.

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Describe the evolution of three-dimensional computer-aided reconstruction and its current applications in craniofacial surgery. 2. Recapitulate virtual surgical planning, or computer-assisted surgical simulation, workflow in craniofacial surgery. 3. Summarize the principles of computer-aided design techniques, such as mirror-imaging and postoperative verification of results. 4. Report the capabilities of computer-aided manufacturing, such as rapid prototyping of three-dimensional models and patient-specific custom implants. 5. Evaluate the advantages and disadvantages of using three-dimensional technology in craniofacial surgery. 6. Critique evidence on advanced three-dimensional technology in craniofacial surgery and identify opportunities for future investigation. SUMMARY: Increasingly used in craniofacial surgery, virtual surgical planning is applied to analyze and simulate surgical interventions. Computer-aided design and manufacturing generates models, cutting guides, and custom implants for use in craniofacial surgery. Three-dimensional computer-aided reconstruction may improve results, increase safety, enhance efficiency, augment surgical education, and aid surgeons' ability to execute complex craniofacial operations. Subtopics include image analysis, surgical planning, virtual simulation, custom guides, model or implant generation, and verification of results. Clinical settings for the use of modern three-dimensional technologies include acquired and congenital conditions in both the acute and the elective settings. The aim of these techniques is to achieve superior functional and aesthetic outcomes compared to conventional surgery. Surgeons should understand this evolving technology, its indications, limitations, and future direction to use it optimally for patient care. This article summarizes advanced three-dimensional techniques in craniofacial surgery with cases highlighting clinical concepts.

Extending the Reach of Craniofacial Free Flaps Using the Descending Branch of the Lateral Circumflex Femoral Vessels.

SUMMARY: Craniofacial free tissue transfer is sometimes complicated by insufficient pedicle length and/or paucity of recipient vessels. A saphenous vein graft can be used to reach the high-flow, large-caliber vessels of the neck, but because of the vein's taper and thick wall, there is often a mismatch. Following the principle of like-for-like, the authors prefer the descending branch of the lateral circumflex femoral vessels to achieve a more anatomical pedicle extension for free tissue transfer in complex craniofacial reconstruction. The authors' experience using the descending branch of the lateral circumflex femoral pedicle extender from 2010 to 2019 was reviewed. Indications, patient characteristics, reconstruction site, flap type, pedicle length, recipient vessels, and vascular complications were noted. The authors reviewed two strategies for implementation of the pedicle extender: in some cases, the flap was first transferred and allowed to perfuse on the descending branch of the lateral circumflex femoral vessels in the thigh, and then transferred to the recipient vessels (double-ischemia transfer); and in other cases, the flap and pedicle extender were transferred such that the flap underwent a single period of ischemia (single-ischemia transfer). The descending branch of the lateral circumflex femoral pedicle extender was used in 17 craniofacial cases. Indications included tumor, trauma, osteoradionecrosis, and congenital. Double-ischemia transfer was used in eight cases and single-ischemia transfer in nine. The longest pedicle extender in the series was 15 cm. Arterial thrombosis occurred in one case. This case series demonstrates that the descending branch of the lateral circumflex femoral pedicle extender is a viable option for complex craniofacial free tissue transfer cases. It provides ample length and excellent vessel match, following the like-for-like principle. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Multilineage somatic activating mutations in HRAS and NRAS cause mosaic cutaneous and skeletal lesions, elevated FGF23 and hypophosphatemia.

Pathologically elevated serum levels of fibroblast growth factor-23 (FGF23), a bone-derived hormone that regulates phosphorus homeostasis, result in renal phosphate wasting and lead to rickets or osteomalacia. Rarely, elevated serum FGF23 levels are found in association with mosaic cutaneous disorders that affect large proportions of the skin and appear in patterns corresponding to the migration of ectodermal progenitors. The cause and source of elevated serum FGF23 is unknown. In those conditions, such as epidermal and large congenital melanocytic nevi, skin lesions are variably associated with other abnormalities in the eye, brain and vasculature. The wide distribution of involved tissues and the appearance of multiple segmental skin and bone lesions suggest that these conditions result from early embryonic somatic mutations. We report five such cases with elevated serum FGF23 and bone lesions, four with large epidermal nevi and one with a giant congenital melanocytic nevus. Exome sequencing of blood and affected skin tissue identified somatic activating mutations of HRAS or NRAS in each case without recurrent secondary mutation, and we further found that the same mutation is present in dysplastic bone. Our finding of somatic activating RAS mutation in bone, the endogenous source of FGF23, provides the first evidence that elevated serum FGF23 levels, hypophosphatemia and osteomalacia are associated with pathologic Ras activation and may provide insight in the heretofore limited understanding of the regulation of FGF23.

Resorption of PDLLA plates as a nidus for recurrent langerhans cell histiocytosis.

Resorbable plating systems have been adapted into routine use for craniofacial reconstruction in children. After implantation in some patients, the area around the plates can develop palpable and visible fibrous capsules, with underlying bone resorption and a significant foreign-body giant cell reaction. The reaction is usually self-limited. We report a case in which Langerhans cell histiocytosis was resected, and then recurred at the sites of resorbing plate and screw placement in association with a foreign-body giant cell reaction.

The reliability and advantages of the sentinel vein as a microsurgical recipient vessel.

Free flaps to the scalp, calvaria, and anterior and middle cranial fossae are typically transferred to the superficial temporal artery and vein. Occasionally the superficial temporal vein is unsuitable for microvascular anastomosis. In such cases, we have had success using the sentinel vein, a perforating vein located in the anterior aspect of the deep temporal fat pad. This article describes the pertinent anatomy, our clinical experience, and the advantages of the sentinel vein as a microsurgical recipient vessel.

Contemporary concepts for the bilateral cleft lip and nasal repair.

The bilateral cleft lip and nasal deformity presents a complex challenge for repair. Surgical techniques continue to evolve and are focused on primary anatomic realignment of the tissues. This can be accomplished in a single-stage or two-stage repair early in infancy to provide a foundation for future growth of the lip and nasal tissue. Most cleft surgeons currently perform a single-stage repair for simplifying patient care. Certain institutions utilize presurgical orthopedics for alignment of the maxillary segments and nasal shaping. Methods for the bilateral cleft lip repair are combined with various open and closed rhinoplasty techniques to achieve improved correction of the primary nasal deformity. There is recent focus on shaping the nose for columellar and tip support, as well as alar contour and alar base position. The authors will present a new technique for closure of the nasal floor to prevent the alveolar cleft fistula. Although the alveolar fistula is closed, alveolar bone grafting is still required at the usual time in dental development to fuse the maxilla. It is paramount to try and minimize the stigmata of secondary deformities that historically have been characteristic of the repaired bilateral cleft lip. A properly planned and executed repair reduces the number of revisions and can spare a child from living with secondary deformities.

External doppler monitoring of free flaps through negative pressure dressings.

The negative pressure dressing is a highly effective modality for coverage and bolstering of skin grafts in the early postoperative period. In the situation of a skin graft over a free flap, the surgeon might be inclined to avoid this modality out of concern that the dressing would deleteriously effect flap survival or impede flap monitoring. This case series supports the safety of the negative pressure dressing and demonstrates a technical modification that permits external Doppler monitoring of the flap through the dressing. Thus, this technique provides an ideal environment for skin graft healing while maintaining the ability to monitor the flap in a straightforward manner and also simplifies nursing care.