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Does the Levasseur-Merrill Retractor Provide Reliable In Vivo Guidance for the Intraoral Vertical Ramus Osteotomy?
Li Hsing J Loh1, Rae L Sesanto1, Kaylie A Catlin1
1Resident, Department of Oral & Maxillofacial Surgery, University of Alabama at Birmingham, Birmingham, Alabama.
Summary
The Levasseur-Merrill retractor (LMR) did not consistently position the intraoral vertical ramus osteotomy (IVRO) safely, leading to frequent inferior alveolar foramen (IAF) violations. However, long-term neurosensory deficit (NSD) was rare and linked to full bony canal breaches.
Area of Science:
- Oral and Maxillofacial Surgery
- Neurosurgery
- Anatomy
Background:
- The Levasseur-Merrill retractor (LMR) is intended to guide intraoral vertical ramus osteotomy (IVRO) placement, aiming to protect the inferior alveolar nerve.
- Accurate IVRO placement is crucial for preventing neurosensory deficits (NSD).
Purpose of the Study:
- To evaluate the precision of IVRO placement using the LMR during surgery.
- To assess the risk of neurosensory deficit (NSD) associated with LMR-assisted IVRO.
Main Methods:
- A prospective case series involving 26 subjects (42 operated sides) who underwent IVRO by a single surgeon.
- Analysis of postoperative cone beam computed tomography (CBCT) images to measure IVRO proximity to the inferior alveolar foramen (IAF).
- Subjective assessment of NSD using 2-point discrimination, sharp/dull touch, and von Frey filaments at 6 months postoperatively.
Main Results:
- The LMR did not consistently achieve the desired 7 mm distance from the mandibular posterior border, with frequent violations of the IAF (61.9%).
- Full bony canal violation occurred in 4.8% of operated sides.
- Neurosensory deficit (NSD) at 6 months was observed only in the sides with full bony canal violation.
Conclusions:
- The LMR's ability to consistently guide IVRO placement away from the IAF is questionable.
- While IAF violation is common, significant long-term NSD is infrequent and appears primarily associated with complete bony canal breach.
