Are Congenital Cervical Block Vertebrae a Risk Factor for Adjacent Segment Disease? A Retrospective Cross-Sectional CT and MR Imaging Study

Adjacent segment disease (ASDI) is a well-described complication of spinal fusion surgery that may ultimately lead to spinal stenosis and repeated surgical intervention. Although congenital block vertebrae also present with degenerative changes in the adjacent segments, this has not yet been systematically investigated. The aim of this study was to assess the presence and degree of ASDI in congenital cervical block vertebrae. Methods: A total of 51 patients with congenital vertebral fusion in one cervical segment were analysed in this IRB-approved retrospective cross-sectional study using available CT/MR imaging. Exclusion criteria were prior spinal surgery and the presence of additional hereditary abnormalities. We assessed the severity of degenerative changes using a sum score. The sum score for adjacent and non-adjacent segments was then divided by the highest possible degeneration score, which resulted in a ratio of severity for adjacent and remaining segments (ranging from 0 to 1). Results: Overall, 35 of 51 patients (68.6%) showed evidence of ASDI, and 34 of 51 patients (66.7%) also showed degenerative changes in the remaining segments. The severity score was significantly higher (p = 0.025) in the segments adjacent to the congenital block vertebrae (mean value 0.307) compared to the non-adjacent segments (mean value 0.188). Conclusions: Our results suggest that ASDI is also caused by congenital block vertebrae of the cervical spine.

Placement of Unilateral Cortical Bone Trajectory Screws in Previously Instrumented Pedicle without Removal of Existing Hardware for Adjacent Segment Disease

Adjacent segment disease (ASD) in the lumbar spine is a possible consequence in segments adjacent to a fusion. As the number of lumbar fusions in the United States increases, the rates of ASD will continue to climb. There are several treatment options for ASD with open decompression and extension of the fusion being common. However, need for exposure and removal of existing instrumentation can lead to increased operative times resulting in increasing blood loss and infection risk. The purpose of this paper is to describe a case report for unilateral cortical trajectory screw instrumentation, allowing for posterior instrumentation without having to remove the existing pedicle screws in the setting of ASD. Our technique can be done with standard c-arm fluoroscopy without the need for navigation.

Comparison of adjacent segment disease after minimally invasive versus open lumbar fusion: a minimum 10-year follow-up

OBJECTIVE The object of this study was to compare, after a long-term follow-up, the incidence and features of adjacent segment disease (ASDis) following lumbar fusion surgery performed via an open technique using conventional interbody fusion plus transpedicular screw fixation or a minimally invasive surgery (MIS) using a tubular retractor together with percutaneous pedicle screw fixation. METHODS The authors conducted a retrospective chart review of patients with a follow-up period > 10 years who had undergone instrumented lumbar fusion at the L4–5 level between January 2004 and December 2010. The patients were divided into an open surgery group and MIS group based on the surgical method performed. Baseline characteristics and radiological findings, including factors related to ASDis, were compared between the two groups. Additionally, the incidence of ASDis and related details, including diagnosis, time to diagnosis, and treatment, were analyzed. RESULTS Among 119 patients who had undergone lumbar fusion at the L4–5 level in the study period, 32 were excluded according to the exclusion criteria. The remaining 87 patients were included as the final study cohort and were divided into an open group (n = 44) and MIS group (n = 43). The mean follow-up period was 10.50 (range 10.0–14.0) years in the open group and 10.16 (range 10.0–13.0) years in the MIS group. The overall facet joint violation rate was significantly higher in the open group than in the MIS group (54.5% vs 30.2%, p = 0.022). However, in terms of adjacent segment degeneration, there were no significant differences in corrected disc height, segmental angle, range of motion, or degree of listhesis of the adjacent segments between the two groups during follow-up. The overall incidence of ASDis was 33.3%, with incidences of 31.8% in the open group and 34.9% in the MIS group, showing no significant difference between the two groups (p = 0.822). Additionally, detailed diagnosis and treatment factors were not different between the two groups. CONCLUSIONS After a minimum 10-year follow-up, the incidence of ASDis did not differ significantly between patients who had undergone open fusion and those who had undergone MIS fusion at the L4–5 level.