Level Selection in Posterior Cervical Fusion: The Clinical Impact of Junctional Crossing.

Abstract

Retrospective cohort. Determine the impact of posterior cervical fusion (PCF) construct on outcomes. Current literature suggests a lower instrumented vertebra (LIV) caudal to the cervico-thoracic junction (CTJ) is protective against hardware failure. However, the impact of a LIV beyond the CTJ in combination with an upper instrumented vertebra (UIV) extending to the upper cervical junction is unclear. Patients undergoing PCF for degenerative pathology from 2010 to 2022 were identified. The primary independent variable was PCF construct, regarding the upper (C2-C3 segment) and lower (C7-T1 segment) cervical junctions. Patients were categorized into those with: neither junction crossed (NJX), one junction crossed (OJX), or both junctions crossed (BJX). Outcomes were reoperations, hardware failure, and PROs. Regression models controlled for age and BMI. Four hundred forty-three patients were included; mean age was 62.3±10.1 and 268 (60.5%) were male. Of these, 88 (19.9%) patients had BJX, 139 (31.4%) OJX, and 216 (48.8%) NJX. Reoperation: OJX patients had significantly more reoperations (10.8%) than BJX (3.4%, P=0.045) and NJX (4.2%, P=0.015) patients, with no difference between BJX and NJX patients (P=0.758). OJX increased risk for reoperation versus NJX (HR=2.61, 95% CI=1.13-6.00, P=0.024) and BJX (HR=3.87, 95% CI=1.10-13.60, P=0.035). Hardware failure: NJX patients had significantly less hardware failure (6.5%) than BJX (17.2%, P=0.004) and OJX (19.7%, P<0.001) patients, with no difference between BJX and NJX patients (P=0.645). OJX (OR=3.85, 95% CI=1.90-7.79, P<0.001) and BJX (OR=3.19, 95% CI=1.44-7.03, P=0.004) increased the odds of hardware failure versus NJX. PROs: NJX patients reported less 3-month NDI% (29.4±17.9 vs. 34.2±15.1, P=0.008; 35.1±18.6, P=0.043) than OJX and BJX patients, with no difference in other PROs. OJX patients had greater rates of reoperation than BJX and NJX patients, as well as greater rates of hardware failure than NJX patients. Surgeons may consider constructs with a UIV that crosses C2-C3 and LIV that crosses the CTJ, or a construct that crosses neither.