Urinary N-Telopeptide Can Predict Pseudarthrosis After Anterior Cervical Decompression and Fusion: A Prospective Study

Study Design: Prospective cohort study.

Objective: To examine preoperative urinary cross-linked n-telopeptide (uNTx) and assess for association with fusion rates in patients undergoing single and multi-level anterior cervical decompression and fusion (ACDF).

Summary Of Background Data: Although high rates of fusion have been reported for ACDF, the risk of pseudarthrosis remains substantial. An established marker of bone turnover, uNTx may prove useful as a predictor of fusion.

Methods: Patients undergoing primary ACDF with allograft/plating technique from 2015 to 2017 by a single surgeon were consecutively enrolled and preoperative uNTx was collected. Patients undergoing revision, with creatinine >1.2, and with improperly-collected uNTx were excluded. Demographics, laboratory values, and fusion status were assessed at 6 months, 1 year, and 2 years postoperatively.

Results: Of the 97 patients enrolled, 69 met inclusion criteria. Of included cases, 41%, 33%, 18%, and 8% underwent 1-, 2-, 3-, and 4-level ACDF, respectively. Overall, fusion rates were 37.3%, 70.9%, and 95.3% at 6 months, 1 year, and 2 years, respectively. uNTx was higher in the fusion group (31.1 vs. 22.2, P = 0.001) at 6 months and 1 year (30.0 vs. 21.0, P = 0.006), with no difference at 2 years. No differences were identified in the proportion of smokers, immunomodulatory agents, corpectomies, or fusion levels between groups. Multivariate regression analysis demonstrated that uNTx is an independent predictor of fusion (odds ratio, OR, 1.124, P = 0.003). Both groups experienced improvements in NDI and VAS neck pain at 6 months with no significant differences noted between groups. Of 16 patients with pseudarthrosis at 1 year, 2 underwent posterior cervical fusion for symptoms.

Conclusion: Preoperative uNTx was greater in patients with successful ACDF fusion compared with patients with pseudarthrosis at 6 months and 1 year. A negative correlation was found between preoperative uNTx and motion on dynamic imaging. These results suggest that uNTx could serve to identify patients at risk for pseudarthrosis after ACDF.

Level Of Evidence: 3.