Vertebral Fracture Versus Degenerative Spine Disease: The Effect of Cervical Fusion Indication on Risk of Pseudarthrosis.

STUDY

DESIGN

Retrospective cohort study.

OBJECTIVE

To provide quantitative data regarding long-term complications of cervical fusion based on surgical indication.

SUMMARY OF BACKGROUND DATA: Pseudarthrosis, or failure to obtain solid bony fusion, is a potential complication of cervical fusion surgery responsible for 45%-56% of revisions. This study aims to determine whether the underlying indication for surgery influences the risk of non-union or revision.

METHODS

The TriNetX Research Network was queried for adults older than or equal to ≥18 years undergoing primary cervical fusion for fracture or degeneration. Cohorts were constructed for posterior (PCF) and anterior (ACF) fusion at C1-C7 levels, and fusions spanning cervicothoracic (CT) or occipitocervical (OC) junctions. Risk factors, demographic, and surgical variables were controlled by propensity matching. Analysis examined pseudarthrosis risk at 1-5 years and revision within 5 years after surgery.

RESULTS

There were 2009 patients each in the matched PCF cohorts and 2077 in the matched ACF cohorts. In PCF cohorts, degenerative patients had higher pseudarthrosis risk (P<0.001; RR: 1.95, 95% CI: 1.51-2.53) and revision rates (P<0.001; RR: 2.83, 95% CI: 1.88-4.28) compared with fracture patients. Similarly, degenerative patients showed increased pseudarthrosis risk (P=0.001; RR: 1.52, 95% CI: 1.18-1.97) and revision rates (P=0.001; RR: 2.29, 95% CI: 1.37-3.80) in ACF cohorts. CT cohorts each included 4300 patients, whereas OC cohorts included 725 patients each. Pseudarthrosis risk was higher in degenerative CT (P<0.001; RR: 2.39, 95% CI: 1.97-2.90) and OC cohorts (P=0.008; RR: 1.67, 95% CI: 1.14-2.45). Revision risk was greater in degenerative OC patients (P=0.014; RR: 2.06, 95% CI: 1.15-3.71), but no significant association was found in CT patients (P=0.15).

CONCLUSIONS

These results indicate that degenerative disease is associated with a higher risk of pseudarthrosis and revision after cervical fusion than is vertebral fracture. We hypothesize that the pathophysiology of degenerative disease may influence bone formation.

LEVEL OF EVIDENCE: Level 3-non-randomized, controlled cohort study.