Elsevier

The Spine Journal

Volume 21, Issue 9, Supplement, September 2021, Pages S158-S159
The Spine Journal

P38. A novel fusion classification system for the advent of bioactive interbody implants

https://doi.org/10.1016/j.spinee.2021.05.246Get rights and content

BACKGROUND CONTEXT

Historically, intervertebral fusion and biologically-mediated stability required bone bridging exclusively. The advent of bioactive interbody devices, which allow for appositional integration of bone at the endplate-implant interface, demands an evolution in our radiographic assessment of such fusion processes. Specifically, acknowledgement that endplate bone adhesion to the surface of these implant confers stability, and potentially an effective ‘fusion’, warrants strong consideration within a new classification scheme.

PURPOSE

We present a novel interbody fusion classification system that addresses inadequacies if traditional grading schemes in order to accommodate the integration capability of bioactive intervertebral cages.

STUDY DESIGN/SETTING

Classification System Reliability Survey.

PATIENT SAMPLE

A total of 37 surgeon respondents.

OUTCOME MEASURES

Intraclass correlation coefficients for inter- and intra-rater reliability assessments.

METHODS

A novel grading system for intervertebral fusion was developed by the authors (Figure) and included fusion consolidation through and/or around the intervertebral device, as well as the apposition of bone to the surface of the implants (ingrowth/ongrowth). Ten patient cases with 1year CT scans were selected for the survey, including coronal and sagittal reconstruction views which were provided to the respondents. Surveys were administered twice >2weeks apart and with cases in differential order. Intraclass Correlation Coefficient (ICC) was used to calculate inter and intrarater reliability.

RESULTS

A total of 51 spine surgeons participated, with 37 of them completing surveys on two separate occasions. For the entire cohort, ICC inter-rater reliability (95% CI) average was 0.618 (0.435-0.834; p<0.001), while the intra-rater reliability average was 0.778 (SD=0.211). Four respondents had outlier intra-rater reliability scores averaged 0.259. When removing those 4 respondents (10.8% of the respondents), and analyzing the more consistent 90% of the respondents, ICC inter-rater reliability average was 0.628 (0.445-0.841; p=<0.001), and intra-rater reliability average was 0.831 (SD=0.125).

CONCLUSIONS

Our novel CT-based interbody fusion classification system demonstrated substantial inter-rater reliability, and excellent intra-rater reliability when applied to a spectrum of real cases. Future assessment of interbody fusions should consider utilization of this new system in order to address the important contribution of appositional ongrowth/ingrowth, along with traditional bone healing through and around devices.

FDA DEVICE/DRUG STATUS

This abstract does not discuss or include any applicable devices or drugs.

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