Crossing the Cervicothoracic Junction in Multilevel Cervical Arthrodesis: A Systematic Review & Meta-Analysis

Optimizing Surgical Strategy for Cervical Spinal Deformity: Global Alignment and Surgical Targets

Cervical spinal deformity (CSD) is a complex condition characterized by abnormal curvature and cervical spine alignment. It can lead to a multitude of symptoms, including chronic pain, neurological deficits, and functional impairments, severely impacting an individual's health-related quality of life (HRQoL). Surgical intervention is often necessary to address the deformity and alleviate symptoms, but optimal surgical strategies remain a topic of ongoing research and debate. This narrative review aims to provide an in-depth overview of the surgical management of CSD, focusing on optimizing patient outcomes and enhancing readers' understanding of the complexities involved. We begin by discussing the importance of preoperative assessment, including comprehensive radiographic evaluation and careful consideration of the global spinal alignment. The relationship between the cervical spine and the reciprocal changes that occur are explored to guide surgeons in their decision-making process. Furthermore, we delve into the selection of fusion levels, emphasizing the significance of identifying the primary driver of deformity. We review the current literature on optimal alignment targets and strategies to optimize surgical planning. By providing a comprehensive analysis of the surgical management of CSD, this review aims to enhance the readers' knowledge and assist surgeons in making informed decisions when planning and executing surgical interventions. Understanding the intricacies of CSD correction and the latest advancements in the field can ultimately improve patient outcomes and enhance HRQoL for individuals suffering from this challenging condition.

Effect of Cervicothoracic Junction LIV Selection on Posterior Cervical Fusion Mechanical Failure: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and Meta-analysis.

OBJECTIVE

Analyze and summarize literature evaluating the role of C7, T1, and T2 lowest instrumented vertebra (LIV) selection in posterior cervical fusion (PCF) and if this affects the progression of mechanical failure and revision surgery.

SUMMARY OF BACKGROUND DATA

Literature evaluating mechanical failure and adjacent segment disease in the setting of PCF at or nearby the cervicothoracic junction (CTJ) remains limited with studies reporting conflicting results.

MATERIALS AND METHODS

Two reviewers conducted a detailed systematic review using EMBASE, PubMed, Web of Science, and Google Scholar on June 28, 2021, for primary research articles comparing revision and complication rates for posterior fusions ending in the lower cervical spine (C7) and upper thoracic spine (T1-T2). The initial systematic database yielded 391 studies, of which 10 met all inclusion criteria. Random effects meta-analyses compared revision and mechanical failure rates between patients with an LIV above the CTJ and patients with an LIV below the CTJ.

RESULTS

Data from 10 studies (total sample=2001, LIV above CTJ=1046, and LIV below CTJ=955) were meta-analyzed. No differences were found between the 2 cohorts for all-cause revision [odds ratio (OR)=0.75, 95% CI=0.42-1.34, P<0.0001] and construct-specific revision (OR=0.62, 95% CI=0.25-1.53, P<0.0001). The odds of total mechanical failure in the LIV below CTJ cohort compared with the LIV above CTJ cohort were significantly lower (OR=0.38, 95% CI=0.18-0.81, P<0.0001).

CONCLUSION

The results show patients with PCFs ending below the CTJ have a lower risk of undergoing total mechanical failure compared with fusions ending above the CTJ. This is important information for both physicians and patients to consider when planning for operative treatment.

LEVEL OF EVIDENCE

Level I.

What does degeneration at the cervicothoracic junction tell us? A kinematic MRI study of 93 individuals

PURPOSE

Current decision-making in multilevel cervical fusion weighs the potential to protect adjacent levels and reduce reoperation risk by crossing the cervicothoracic junction (C7/T1) against increased operative time and risk of complication. Careful planning is required, and the planned distal and adjacent levels should be assessed for degenerative disc disease (DDD). This study assessed whether DDD at the cervicothoracic junction was associated with DDD, disc height, translational motion, or angular variation in the adjacent superior (C6/C7) or inferior (T1/T2) levels.

METHODS

This study retrospectively analyzed 93 cases with kinematic MRI. Cases were randomly selected from a database with inclusion criteria being no prior spine surgery and images having sufficient quality for analysis. DDD was assessed using Pfirrmann classification. Vertebral body bone marrow lesions were assessed using Modic changes. Disc height was measured at the mid-disc in neutral and extension. Translational motion and angular variation were calculated by assessing translational or angular motion segment integrity respectively in flexion and extension. Statistical associations were assessed with scatterplots and Kendall's tau.

RESULTS

DDD at C7/T1 was positively associated with DDD at C6/C7 (tau = 0.53, p < 0.01) and T1/T2 (tau = 0.58, p < 0.01), with greater disc height in neutral position at T1/T2 (tau = 0.22, p < 0.01), and with greater disc height in extended position at C7/T1 (tau = 0.17, p = 0.04) and at T1/T2 (tau = 0.21, p < 0.01). DDD at C7/T1 was negatively associated with angular variation at C6/C7 (tau = - 0.23, p < 0.01). No association was appreciated between DDD at C7/T1 and translational motion.

CONCLUSION

The association of DDD at the cervicothoracic junction with DDD at the adjacent levels emphasizes the necessity for careful selection of the distal level in multilevel fusion in the distal cervical spine.