Reoperation rates for symptomatic nonunions in posterior cervical (subaxial) fusions with and without bone morphogenetic protein in a cohort of 1158 patients

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Bone morphogenetic protein (BMP) was first approved in 2002 for use in single-level anterior lumbar fusions as an alternative to iliac crest grafts. Subsequent studies have concluded that BMP provides superior fusions rates and therefore reduces reoperations for nonunions. The purpose of this study was to determine the reoperation rates for symptomatic nonunions in posterior cervical (subaxial) spinal fusions with and without the use of BMP and to determine if the nonunion rates are statistically significantly different between the two groups.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Between January 2009 and September 2013, the authors identified 1158 posterior cervical spinal fusion cases in the subaxial spine (C2–7) from a large spine registry (Kaiser Permanente). Patient characteristics, diagnoses, operative times, lengths of stay, and reoperations were extracted from the registry. Reoperations for symptomatic nonunions were adjudicated via chart review. Logistic regression was conducted to produce estimates of odds ratios (OR) and 95% confidence intervals (CIs). Kaplan-Meier curves for the non-BMP and BMP groups were generated and compared using the log-rank test.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>In this cohort there were 1158 patients (19.3% with BMP) with a median follow up of 1.7 years (interquartile range [IQR] 0.7–2.9 years) and median duration to operative nonunion of 0.63 years (IQR 0.44–1.57 years). Kaplan-Meier curves showed no significant difference in reoperation rates for nonunions using the log-rank test (p = 0.179). In a subset of patients with more than 1 year of follow-up, 788 patients were identified (22.5% with BMP) with a median follow-up duration of 2.5 years (IQR 1.7–3.4 years) and a median time to operative nonunion of 0.73 years (IQR 0.44–1.57 years). There was no statistically significant difference in the symptomatic operative nonunion rates for posterior cervical (subaxial) fusions with BMP compared with non-BMP (1.1% vs 0.7%; crude OR 1.73, 95% CI 0.32–9.55, p = 0.527) for more than 1 year of follow-up.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>This study presents the largest series of patients using BMP in posterior cervical (subaxial) spinal fusions. Reoperation rates for symptomatic nonunions with more than 1 year of follow-up were found to be 1.1% with BMP and 0.7% without BMP. There was no significant difference in the reoperation rates for symptomatic nonunions with or without BMP.</jats:p></jats:sec>

The Posterior Use of BMP-2 in Cervical Deformity Surgery Does Not Result in Increased Early Complications: A Prospective Multicenter Study

“…14,15,18,19,25 The majority of these studies report a higher radiographic fusion rate with BMP, but there may not be a substantial difference in clinically significant nonunion—defined as pseudarthrosis requiring revision—between these groups. 18,19,25 This question of clinical significance is important and is particularly relevant to the subject of BMP. The Yale Open Data Access (YODA) Project, for example, found that the use of BMP likely leads to an increased risk of complications.…”

“…The use of BMP in the posterior cervical spine, however, has been recently examined in several retrospective studies without the airway complications reported with anterior use. 14 –18 These studies have shown rates of nonunion ranging from 0% to 10.3% with the majority showing an improvement fusion rates based on computed tomography imaging. Other authors, focusing on posterior BMP use at the cervicothoracic junction, found that the use of BMP did not result in a significantly different rate of symptomatic non-union requiring reoperation.…”

Reoperation rates for symptomatic nonunions in posterior cervicothoracic fusions with and without bone morphogenetic protein in a cohort of 450 patients

“…Again, we believe operative nonunion rates are useful and clinically relevant and can be used to compare BMP to non-BMP patients as we have shown in other studies. [20][21][22] We also acknowledge there are some limitations to our study. It is a retrospective study, which may have inherent selection biases.…”

“…In previous articles we have introduced the use of reoperation rates for nonunions as a possible outcome measure, combining both radiographic studies and clinical symptoms. [20][21][22] We believe this is an important outcome measure for both patients and health care payers and is worthy of adding to the literature. Hence, the objective of our study is to report the reoperation rates for symptomatic nonunions in a large cohort of patients with posterior cervicothoracic spine fusions from a spine registry and to compare these rates with and without the use of BMP.…”

Pseudarthrosis of the Cervical Spine

“…2 McAnany et al 2 conducted a meta-analysis of fusion rates after a known pseudarthrosis (not primary surgery), and fusion rates were higher after posterior surgery (97.1%) compared with anterior surgery (86.4%) in studies with a minimum follow-up of at least 6 months. In a large study from a multicenter health system, Guppy et al 31 evaluated 1158 patients undergoing all levels (1-5) of posterior cervical fusion, and the overall nonunion rate was ∼ 1.0%, with similar rates between non-BMP (0.7%) and BMP (1.1%) groups at a median follow-up of 1.7 years. Another retrospective series of 57 patients undergoing posterior cervical fusion by Dorward et al 32 reported a pseudarthrosis rate of 10.5%, though only 2 of 6 patients required revision surgery with a minimum of 2-year follow-up.…”