Should long-segment cervical fusions be routinely carried into the thoracic spine? A multicenter analysis

Although recommendations for caudal "end level" in posterior cervical reconstruction remain highly variable, the benefits of routine extension of posterior cervical fusions into the thoracic spine remain unclear.

We compared clinical and radiographic outcomes in patients in whom posterior fusions ended in the cervical spine versus those in whom the fusion was extended into the thoracic spine.

A multicenter retrospective analysis of prospectively followed patients was carried out.

A total of 177 adult spine patients undergoing three or more levels of posterior cervical fusions for degenerative disease from January 2008 to May 2013 comprised the patient sample.

Cervical lordosis, C2-C7 sagittal plumbline, T1 slope, visual analog scale (VAS), Oswestry Disability Index (ODI), rate of pseudarthrosis, length of hospital stay (LOS), estimated blood loss (EBL), and operating room [OR] time were the outcome measures.

We assembled a multicenter (four sites) radiographic and clinical database of patients who had undergone three or more levels of posterior cervical fusions for degenerative disease from January 2008 to May 2013 with at least 2 years of postoperative (post-op) follow-ups. Patients were divided into two groups: Group 1 (fusion ending in the cervical spine) and group 2 (fusion extending into the thoracic spine). All radiographic measurements were performed by an independent experienced clinical researcher.

Group 1 and Group 2 had 104 and 73 patients, respectively. Mean EBL for Group 2 was significantly higher than Group 1. Mean OR time and LOS were comparatively higher for Group 2 than Group 1 but were not statistically significant (p>.05). Mean cervical lordosis improved postoperatively in both groups. There were no statistically significant differences in change or maintenance of mean cervical lordosis (2 weeks vs. 2 years post-op) between the two groups (p>.05). Similarly, the change in mean C2-C7 sagittal plumbline and T1 slope was not statistically significantly different between the two groups or with follow-up(p>.05). Clinically, significant improvements in VAS and ODI were noted in both groups from preop to final follow-up, but the difference between groups was not statistically significant. Although the rate of pseudarthrosis was significantly higher in Group 1 (21.2%) than in Group 2 (10.96%), there were no statistically significant differences in adjacent segment degeneration or revision surgery rates between the groups.

Both groups had similar clinical and radiographic outcomes. Extension of a posterior cervical fusion into the thoracic spine leads to lower pseudarthrosis rate, whereas stopping in the cervical spine yields lower EBL, OR time, and LOS, demonstrating that there are different benefits for each approach. However, although the optimal end-level remains debatable, there are scenarios in which upper thoracic extension should be considered. At this point, we recommend extension of surgery in smokers and other patients at increased risk for pseudarthrosis as well as in patients with anatomical limitations to strong C7 bone anchorage.