Posterior extradural transpedicular monolateral odontoidectomy (PETMO): a technical note

Craniovertebral junction (CVJ) instability with irreducible basilar invagination (BI) and retroflexed odontoid poses a significant surgical challenge. Standard anterior decompression techniques—transoral or endoscopic transnasal—carry notable morbidity. Posterior approaches are rare and often invasive. We report the first clinical use of a purely posterior, extradural, transpedicular, monolateral odontoidectomy (PETMO) as a novel alternative in selected cases. A 67-year-old woman with progressive myelopathy due to irreducible BI and os odontoideum underwent PETMO with occipitocervical fixation. The odontoid and os odontoideum were resected en bloc via a right C2 transpedicular corridor using an ultrasonic bone dissector. Intraoperative neurophysiological monitoring and micro-Doppler were employed. The patient showed steady neurological improvement, regaining independent ambulation at 1-year follow-up. Postoperative imaging confirmed complete resection, effective cervicomedullary decompression, and CVJ realignment. PETMO offers a feasible posterior alternative for anterior CVJ decompression in selected patients with irreducible pathology and ligamentous insufficiency. It avoids the aerodigestive tract and minimizes neural and vascular manipulation. Though technically demanding, PETMO expands the surgical options for CVJ management and merits further investigation.