Crossing the Cervicothoracic Junction in Cervical Arthrodesis Results in Lower Rates of Adjacent Segment Disease Without Affecting Operative Risks or Patient-Reported Outcomes

Abstract

Study Design: Retrospective cohort study. Objective: To evaluate the risks and benefits of crossing the cervicothoracic junction (CTJ) in cervical arthrodesis. Summary of Background Data: Whether the CTJ should be crossed in cervical arthrodesis remains up for debate. Keeping C7 as the distal end of the fusion risks adjacent segment disease (ASD) and can result in myelopathy or radiculopathy. Longer fusions are thought to increase operative risk and complexity but result in lower rates of ASD. Materials and Methods: Patients undergoing cervical spine fusion surgery ending at C7 or T1 with ≥1-year follow-up were included. To evaluate operative risk, estimated blood loss (EBL), operative time, and length of hospital stay were collected. To evaluate patient-reported outcomes (PROs), Neck Disability Index (NDI) and SF-12 questionnaires (PCS12 and MCS12) were obtained at follow-up. Revision surgery data were also obtained. Results: A total of 168 patients were included and divided into a C7 end-of-fusion cohort (NC7=59) and a T1 end-of-fusion cohort (NT1=109). Multivariate regression analysis adjusting for age, sex, race, surgical approach, and number of levels fused showed that EBL (P=0.12), operative time (P=0.07), and length of hospital stay (P=0.06) are not significantly different in the C7 and T1 end-of-fusion cohorts. Multivariate regression of PROs showed no significant difference in NDI (P=0.70), PCS12 (P=0.23), or MCS12 (P=0.15) between cohorts. Fisher analysis showed significantly higher revision rates in the C7 end-of-fusion cohort (7/59 for C7 vs. 2/109 for T1; odds ratio, 6.4; 95% confidence interval, 1.2–65.1; P=0.01). Conclusions: Crossing the CTJ in cervical arthrodesis does not increase operative risk as measured by blood loss, operative time, and length of hospital stay. However, it leads to lower revision rates, likely because of the avoidance of ASD, and comparable PROs. Thus, crossing the CTJ may help prevent ASD without negatively affecting operative risk or long-term PROs.

Biomechanical Analysis of Multilevel Posterior Cervical Spinal Fusion Constructs

“…Prior clinical studies have shown conflicting results when comparing the extent of multilevel PCF constructs 4–7,16–20. Osterhoff et al5 showed no difference in radiographic outcomes in a retrospective analysis comparing posterior constructs ending at C7 versus T1 and T2.…”

Should cervicothoracic junctions be avoided in long cervical posterior fusion surgery? Analysis of clinical and radiologic outcomes over two years

“…Some studies 10,34,35 have shown that crossing the CTJ prevents kyphotic collapse, ongoing neck pain, and symptomatic adjacent segment degeneration. According to the results of this study, CTJ should be avoided if possible; if CTJ must be included, fusion extension up to T2-4 can be considered.…”

“…In this study, DJK and kyphosis occurred because of the destruction of the unique mechanical structure and muscle degeneration at the CTJ after the extension of fusion to C7/T1, which is thought to exacerbate postoperative neck pain (Figure 5). Some studies 10,34,35 have shown that crossing the CTJ prevents kyphotic collapse, ongoing neck pain, and symptomatic adjacent segment degeneration. According to the results of this study, CTJ should be avoided if possible; if CTJ must be included, fusion extension up to T2-4 can be considered.…”

Surgical challenges in posterior cervicothoracic junction instrumentation

“…A hypothesized protective effect of the extension of the construct across the CTJ is thought to rely on a more rigidity provided by inclusion of the thoracic spine. Conversely, a construct ending at C7 make the involved cervical segments act as a single column leaning over the rigid thoracic spine with only a single interposed disc, thus subjected to signi cant mechanical stress that may result in early disc degeneration [24]. In a biomechanical study Cheng et al [7] reported that in posterior cervical instrumentations, the intradiscal pressure of the lower adjacent disc was signi cantly lower for instrumentations that crossed the CTJ.…”

“…The published 'in vivo' studies however provide contrasting evidences. Articles by Schroeder et al [41], Ibaseta et al [24] and Fayed et al [15] found that posterior cervical constructs ending at C7, have increased risks of adjacent segment disease, while Huang et al [22] and Lee et al [32] found no signi cant increase in adjacent segment disease when stopping the construct at C7. At the same time, instrumentations that cross the CTJ have been reported to be associated with increased operative times and intraoperative blood loss [15,22].…”