Novel placement of cortical bone trajectory screws in previously instrumented pedicles for adjacent-segment lumbar disease using CT image-guided navigation

Object. Symptomatic adjacent-segment lumbar disease (ASLD) after lumbar fusion often requires subsequent surgical intervention. The authors report utilizing cortical bone trajectory (CBT) pedicle screw fixation with intra-operative CT (O-arm) image-guided navigation to stabilize spinal levels in patients with symptomatic ASLD. This unique technique results in the placement of 2 screws in the same pedicle (1 traditional pedicle trajectory and 1 CBT) and obviates the need to remove preexisting instrumentation. Methods. The records of 5 consecutive patients who underwent lumbar spinal fusion with CBT and posterior interbody grafting for ASLD were retrospectively reviewed. All patients underwent screw trajectory planning with the O-arm in conjunction with the StealthStation navigation system. Basic demographics, operative details, and radiographic and clinical outcomes were obtained. Results. The average patient age was 69.4 years (range 58-82 years). Four of the 5 surgeries were performed with the Minimal Access Spinal Technologies (MAST) Midline Lumbar Fusion (MIDLF) system. The average operative duration was 218 minutes (range 175-315 minutes). In the entire cohort, 5.5-mm cortical screws were placed in previously instrumented pedicles. The average hospital stay was 2.8 days (range 2-3 days) and there were no surgical complications. All patients had more than 6 months of radiographic and clinical follow-up (range 10-15 months). At last follow-up, all patients reported improved symptoms from their preoperative state. Radiographic follow-up showed Lenke fusion grades of A or B. Conclusions. The authors present a novel fusion technique that uses CBT pedicle screw fixation in a previously instrumented pedicle with intraoperative O-arm guided navigation. This method obviates the need for hardware removal. This cohort of patients experienced good clinical results. Computed tomography navigation was critical for accurate CBT screw placement at levels where previous traditional pedicle screws were already placed for symptomatic ASLD.