Compact Navigation-Assisted Transpedicular Approach Using Unilateral Biportal Endoscopy for Caudally Migrated Lumbar...

Severely migrated lumbar disc herniations are challenging to access using conventional interlaminar or transforaminal approaches, especially in revision cases. A transpedicular route provides direct access but raises concerns regarding accuracy, safety, and radiation exposure when fluoroscopy is required. In this Technical Note, we describe a transpedicular unilateral biportal endoscopic (UBE) approach assisted by a compact navigation system for a caudally migrated disc herniation, highlighting its feasibility and potential advantages.

A 73-year-old man with a history of L1/2 fusion and multilevel laminoplasty presented with severe low back pain, radicular leg pain, and weakness. Magnetic resonance imaging demonstrated a left L2/3 disc herniation that had migrated caudally to the lower border of the L3 pedicle. Based on these findings, a transpedicular UBE approach assisted by a compact navigation system was selected. After intraoperative computed tomography (CT) acquisition and automatic registration, real-time navigation accurately localized the left L3 pedicle and displayed the planned entry point and drilling trajectory relative to the patient's anatomy. Using a navigated drill, a pedicle entry point was created, and the transpedicular channel was prepared. Under UBE visualization, the medial pedicle wall was drilled to expose the L3 nerve root, enabling direct removal of the caudally migrated fragment. The procedure was completed safely with minimal blood loss and required only a single intraoperative CT, with no fluoroscopy. Postoperative CT confirmed an approximately 6-mm transpedicular bone window without pedicle fracture. The patient had immediate symptom relief and remained recurrence-free at 6 months.

This Technical Note demonstrates the feasibility of a transpedicular UBE approach assisted by compact navigation for complete removal of a severely caudally migrated lumbar disc herniation. The technique allowed accurate instrument guidance, effective decompression, and zero radiation exposure to the surgical team. Future studies are warranted to validate its long-term safety and broader applicability.