Crossing the Cervico-Thoracic Junction in Long Posterior Cervical Fusions Reduces Caudal Adjacent Segment Pathology

Study Design: Retrospective case control. Objectives: The purpose of this study is to compare clinical outcomes and rates of symptomatic caudal adjacent segment pathology (ASP) in posterior cervical fusions (PCF) constructs with end-instrumented vertebrae in the cervical spine (EIV-C) to PCF constructs that end in the proximal thoracic spine (EIV-T). Methods: Retrospective review of 1714 consecutive cervical spinal fusion cases was done. Two groups were identified: 36 cervical end-instrumented vertebra patients (age56 +/- 10 yrs) and 53 thoracic EIV patients (age 57 +/- 9 yrs). Symptomatic ASP was defined as revision surgery or nerve root injection (or recommended surgery or injection) at the adjacent levels. Results: EIV-C patients had a significantly higher rate of caudal-level symptomatic ASP requiring intervention compared with EIV-T patients (39% vs 15%, p = 0.01). The development of caudal-level ASP was highest at C7 (41%), followed by C6 (40%). The overall complication rate and surgical revision rates, however, were similar between the groups. Neck Disability Index outcomes at 2 years postop were significantly better in the EIV-T group (24.5 vs. 34.0, p = 0.05). Conclusions: Long PCF that cross the C-T junction have superior clinical outcomes and reduced rates of caudal breakdown, at the expense of longer fusions and higher EBL, with no increase in the rate of complications. Crossing the C-T junction affords protection of the caudal adjacent levels without adding significant operative time or morbidity.