Background: The monobloc procedure has been criticized owing to its tendency for cerebrospinal fluid leak, relapse, infection, and incomplete ossification. Such risks have been decreased through gradual advancement of the monobloc via distraction osteogenesis. This cadaver study was undertaken to develop an endoscopic, ultrasonic monobloc osteotomy to further minimize risks and potentially improve outcomes.
Methods: Three fresh, adult human cadavers were used in this study. Endoscopic ultrasonic monobloc osteotomy was completed in all cadavers with 3 incisions hidden in the hair-bearing scalp. The incisions afforded access for small craniotomies through which the dura was dissected from the frontal bones. An ultrasonic scalpel and endoscope then traveled extradurally to osteotomize the frontal bones, temporal bones, sphenoid wings, and superior aspects of the orbits intracranially. Pterygomaxillary dysjunction was performed with conventional osteotomes intraorally.
Results: The endoscopic ultrasonic monobloc osteotomy was completed as a single fragment in all 3 cadavers. No additional incisions were required. Completeness of the osteotomy and integrity of the single fragment were evaluated by manual examination and endoscopic visualization of free movement at osteotomy sites. Osteotomy completion took less than 2.5 hours. Dura and periosteum surrounding all osteotomies remained intact, eliminating concern for injury to adjacent soft tissue. Careful placement of temporal incisions and craniotomies was critical to facilitate completion of osteotomies in a clinically safe manner.
Conclusions: We have demonstrated the feasibility of an endoscopic ultrasonic monobloc advancement technique in cadavers. The technique can be completed without a bicoronal incision while completely protecting all vital structures. The preservation of vascularity and periosteum afforded by this technique may provide improved outcomes and reduced complications.