Minimally Invasive Robot-Guided Dual Cortical Bone Trajectory for Adjacent Segment Disease

Here we present a novel application of cortical bone trajectory (CBT) fixation utilizing robotic guidance in a previously instrumented spine with a traditional pedicle screw (PS), obviating the need for a larger posterior incision, reducing the risk of infection, muscular dissection, and likely decreasing hospital length of stay. A 60-year-old woman with prior left L3-L4 extreme lateral interbody fusion and unilateral percutaneous PS placed at L3 to L5 presented with progressive bilateral lower-extremity pain and diminished sensation in the S1 dermatome secondary to adjacent segment disease (ASD). The patient underwent an L5-S1 anterior lumbar interbody fusion for indirect decompression and restoration of segmental lordosis. After the first stage was completed, she was turned prone for posterior percutaneous instrumentation. Given prior instrumentation at L3-L5 on the left side, a robot planning software was used to plan a cortical bone screw on the left L5 pedicle. A left S1 PS was then planned with the screw head aligning with the left L5 cortical bone screw. Instrumentation was then placed percutaneously using the robot bilaterally without issue. Intraoperative fluoroscopic imaging demonstrated accurate placement of PS, and postoperative computed tomography demonstrated the excellent positioning of all PSs. This report is the first documented case of a robotically placed CBT screw placed in the same pedicle as a prior traditional PS for ASD. This method expands the surgical options for ASD to include robotic percutaneous placement of posterior instrumentation at the same level as previous instrumentation.