Novel Landmark for Cervical Pedicle Screw Insertion Point from Computed Tomography-Based Study

STUDY DESIGN: Cross-sectional study. PURPOSE: The purpose of this study was to evaluate a novel landmark for the cervical pedicle screw insertion point. OVERVIEW OF LITERATURE: To improve the accuracy of pedicle screw placement, several studies have employed the lateral mass, lateral vertical notch, and/or inferior articular process as landmarks; however, we often encounter patients in whom we cannot identify accurate insertion points for pedicle screws using these landmarks because of degenerative changes in the facet joints. The superomedial edge of the lamina is less affected by degenerative changes, and we hypothesized that it could be a new landmark for identifying an accurate cervical pedicle screw insertion point. METHODS: A total of 327 consecutive patients, who had undergone neck computed tomographic scanning for determination of neck disease in our institute, were included in the study. At first, the line was drawn parallel to the superior border of the pedicle in the sagittal plane and parallel to the vertical body in the coronal plane. The line was moved downward in 1-mm increments to the inferior border of the pedicle. We determined whether the line passing through the superomedial edge of the lamina (termed the “N-line”) was located between the superior and inferior borders of the pedicle in the sagittal plane. RESULTS: The percentages of N-lines located between the superior and inferior borders of the pedicle were 100% at C3, 100% at C4, 99% at C5, 96% at C6, and 97% at C7. The lower cervical spine has the higher N-line location. CONCLUSIONS: The N-line was frequently located at the level of the pedicle of each cervical spine in the sagittal plane. The superomedial edge of the lamina could be a new landmark for the insertion point of the cervical pedicle screw.

Short-Term Clinical Result of Cortical Bone Trajectory Technique for the Treatment of Degenerative Lumbar Spondylolisthesis with More than 1-Year Follow-Up

STUDY DESIGN: Retrospective follow-up study on the result of surgical treatment for patients with degenerative lumbar spondylolisthesis (DLS) using cortical bone trajectory (CBT) technique. PURPOSE: To evaluate the capability of CBT to manage patients with DLS. OVERVIEW OF LITERATURE: CBT is a recently advocated, novel, less-invasive technique of lumbar pedicle screw, which provides enhanced screw purchase by maximizing the thread contact with higher density bone surface. Despite the frequent use of CBT technique in the lumbar spine surgery, little is known of the capability of this technique to manage patients with DLS. METHODS: Thirty two consecutive patients (5 males, 27 females) surgically treated with single-level DLS in our institute using CBT were included. All patients were followed up at least 12 months (mean 24 months). Their clinical and radiological features were measured. RESULTS: Good leg pain relief was achieved in all patients. The mean postoperative percentage slip demonstrated significant reduction with significant neurological recovery when compared with preoperative percentage slip, and it was maintained until the latest follow-up. Loss of correction of more than 3 mm during the follow-up period was observed in 3 cases. Surgical site infection was observed in one case; however, pull-out of PSs or neurological deterioration was not found. No patient needed additional surgery during the follow-up period. CONCLUSIONS: These preliminary results confirmed that CBT is useful for the treatment for patients with DLS. This technique allows good reduction of spondylolisthesis and neurological improvement.

Navigated Pin-Point Approach to Osteoid Osteoma Adjacent to the Facet Joint of Spine

Osteoid osteoma (OO) is a benign osteoblastic tumor. Its curative treatment is complete removal of the nidus, where intraoperative localization of the nidus governs clinical results. However, treatment can be difficult since the lesion is often invisible over the bony surface. Accordingly, establishment of an ideal less invasive surgical strategy for spinal OO remains yet unsettled. We illustrate the efficacy of a computed tomography (CT)-based navigation system in excising OO located adjacent to the facet joint of spine. In our 2 cases, complete and pin-point removal of the nidus located close to the facet joint was successfully achieved, without excessive removal of the bone potentially leading to spinal instability and possible damage of nearby neurovascular structures. We advocate a less invasive approach to spinal OO, particularly in an environment with an available CT-based navigation system.