Guided bone regeneration is a promising means for reconstructing bone defects in the cranium. The present study was performed to better define those factors that affect osteogenesis in the cranium. The authors studied a single animal model, investigating the contribution of the dura, the pericranium, and the adjacent calvarial bone in the process of calvarial regeneration in both mature and immature animals. Bilateral, 100-mm2, parietal calvariectomies were performed in immature (n = 16) and mature (n = 16) rabbits. Parietal defects were randomized to one of four groups depending on the differential blockade of the dura and/or the pericranium by expanded polytetrafluoroethylene membranes. Animals were humanely killed after 12 weeks, and histometric analysis was performed to quantitate the area of the original bone defect, new bone formation, and new bone density. Bone formation was quantified separately both at the periphery and in the center of the defects. Extrasite bone formation was also quantified both on the dural and on the pericranial sides of the barriers. Bone regeneration was incomplete in all groups over the 12-week study period, indicating that complete bone healing was not observed in any group. The dura was more osteogenic than the pericranium in mature and immature animals, as there was significantly more extrasite bone formed on the dural side in the double expanded polytetrafluoroethylene barrier groups. In both the dural and the double expanded polytetrafluoroethylene barrier groups, dural bone production was significantly greater in immature compared with mature animals. The dura appeared to be the source of central new bone, because dural blockade in the dural and double expanded polytetrafluoroethylene groups resulted in a significant decrease in central bone density in both mature and immature animals. Paradoxically, isolation of the pericranium in mature animals resulted in a significant reduction in total new bone area, whereas pericranial contact appeared to enhance peripheral new bone formation, with the control group having the greatest total new bone area. The present study establishes a model to quantitatively study the process of bone regeneration in calvarial defects and highlights differences in the contribution of the dura and pericranium to calvarial bone regeneration between infant and adult animals. On the basis of these findings, the authors propose that subsequent studies in which permeability of the expanded polytetrafluoroethylene membranes is altered to permit migration of osteoinductive proteins into the defect while blocking prolapse of adjacent soft tissues may help to make guided bone regeneration a realistic alternative for the repair of cranial defects.

Microsurgical breast reconstruction is a safe and highly effective technique. Complications tend to be minor and do not affect postreconstruction adjuvant therapy. Obesity is a major predictor of flap and donor-site complications, and these patients should be appropriately counseled. Similarly, neoadjuvant preoperative chemotherapy and prior abdominal surgery increase the rates of minor complications.

Distraction osteogenesis has been used increasingly for midfacial advancement in patients with syndromic craniosynostosis and in severe developmental hypoplasia of the midface. In these patients, the degree of advancement required is often so great that restriction of the adjacent soft tissues may preclude stable advancement in one stage. Whereas distraction is an ideal solution by which to gradually lengthen both the bones and the soft tissues, potential problems remain in translating the distraction forces to the midface. In these patients, severe developmental hypoplasia may be associated with weak union between the zygoma and the maxilla, increasing the chance of zygomaticomaxillary dysjunction when using internal devices that translate distraction force to the maxilla through the zygoma. Eight cases are reported in which either internal or external distraction systems were used for midface advancement following Le Fort III (n = 7) or monobloc (n = 1) osteotomies. Cases of patients in whom hypoplasia at the zygomaticomaxillary junction altered or impaired plans for midface distraction were reported from three host institutions. Seven patients had midface hypoplasia associated with syndromic craniosynostosis, and one patient had severe developmental midface hypoplasia. The distraction protocol was modified to successfully complete midface advancement in light of weakness at the zygomaticomaxillary junction in seven patients. Modifications included change from an internal to an external distraction system in two patients, rigid fixation and bone graft stabilization of the midface in one patient, and plate stabilization of a fractured or unstable zygomaticomaxillary junction followed by resumption of internal distraction in four patients. Previous infection and bone loss involving both malar complexes precluded one patient from being a candidate for an internal distraction system. Using a problem-based approach, successful advancement of the midface ranging from 9 to 26 mm at the occlusal level as measured by preoperative and postoperative cephalograms was undergone by all patients. Advantages and disadvantages of the respective distraction systems are reviewed to better understand unique patient characteristics leading to the successful use of these devices for correction of severe midface hypoplasia.