Does the presence of the fibronectin-aggrecan complex predict outcomes from lumbar discectomy for disc herniation?

Publication date: February 2019

Source: The Spine Journal, Volume 19, Issue 2

Author(s): Micah W. Smith, Agnes Ith, Eugene J. Carragee, Ivan Cheng, Todd F. Alamin, S. Raymond Golish, Kyle Mitsunaga, Gaetano J. Scuderi, Matthew Smuck

Abstract

Background context

Protein biomarkers associated with lumbar disc disease have been studied as diagnostic indicators and therapeutic targets. Recently, a cartilage degradation product, the fibronectin-aggrecan complex (FAC) identified in the epidural space, has been shown to predict response to lumbar epidural steroid injection in patients with radiculopathy from herniated nucleus pulposus (HNP).

Purpose

Determine the ability of FAC to predict response to microdiscectomy for patients with radiculopathy due to lumbar disc herniation

Study design/setting

Single-center prospective consecutive cohort study.

Patient sample

Patients with radiculopathy from HNP with concordant symptoms to MRI who underwent microdiscectomy.

Outcomes measures

Oswestry disability index (ODI) and visual analog scores (VAS) were noted at baseline and at 3-month follow-up. Primary outcome of clinical improvement was defined as patients with both a decrease in VAS of at least 3 points and ODI >20 points.

Methods

Intraoperative sampling was done via lavage of the excised fragment by ELISA for presence of FAC. Funding for the ELISA was provided by Cytonics, Inc.

Results

Seventy-five patients had full complement of data and were included in this analysis. At 3-month follow-up, 57 (76%) patents were "better." There was a statistically significant association of the presence of FAC and clinical improvement (p=.017) with an 85% positive predictive value. Receiver-operating-characteristic (ROC) curve plotting association of FAC and clinical improvement demonstrates an area under the curve (AUC) of 0.66±0.08 (p=.037). Subset analysis of those with weakness on physical examination (n=48) plotting the association of FAC and improvement shows AUC on ROC of 0.81±0.067 (p=.002).

Conclusions

Patients who are "FAC+" are more likely to demonstrate clinical improvement following microdiscectomy. The data suggest that the inflammatory milieu plays a significant role regarding improvement in patients undergoing discectomy for radiculopathy in lumbar HNP, even in those with preoperative weakness. The FAC represents a potential target for treatment in HNP.

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