Rate and risk factors for pediatric cervical spine fusion pseudarthrosis: opportunity for improvement

Purpose Although the pediatric population typically has a high union rate, the cervical spine has a reputation for frequent pseduarthrosis, as high as 38% in some prior series. Our purpose was to examine the rate and risk factors for pseudarthrosis in pediatric cervical spine fusions. Methods Retrospective review of all patients with ≥ 2 years follow-up undergoing cervical spinal fusion between January 2004 and December 2019 at a tertiary pediatric hospital. Pseudarthrosis was defined as an absence of radiographic union as assessed by the attending surgeon for which revision surgery was performed. Results 64 patients (mean age: 8.4 ± 4.7 years) met inclusion criteria. Mean follow-up was 63.3 ± 41.4 months (range: 24–187 months). 28 fusions (44%) included the occiput. 41 patients (64%) had instrumentation, while 23 patients (36%) had uninstrumented fusions. 48 (75%) patients had a halo for a mean of 97.6 ± 49.5 days. The incidence of pseudarthrosis was as follows: overall = 8/64 (12.5%); posterior fusion = 14.8% (8/54); anterior fusions = 0% (0/4); and anteroposterior fusions = 0% (0/6). The rate of pseudarthrosis was over 8 times higher in fusions involving the occiput (occipitocervical fusion: 25.0%; 7/28 vs. cervical alone: 2.8%; 1/36; p = 0.02). Although not statistically significant, the rate of pseudarthrosis was 3 times higher in uninstrumented fusions (21.7%; 5/23) than instrumented fusions (7.3%; 3/41) ( p = 0.12). In patients with uninstrumented fusion to the occiput, pseudarthrosis rate was 35.7% (5/14), which was higher compared to those who did not (6.0%; 3/50) ( p = 0.01). Incidence of pseudarthrosis was similar in patients who received autograft (13.0%; 7/54) compared to allograft alone (10.0%; 1/10) ( p > 0.999). Conclusions The pseudarthrosis rate in pediatric cervical spine fusions remained high despite frequent use of halo immobilization and autograft. Patients with uninstrumented occipitocervical fusions are at particularly high risk with more than 1 in 3 developing a pseudarthrosis. Study design Retrospective, Comparative. Level of Evidence III.