Lambrechts MJ, D'Antonio ND, Karamian BA, Toci GR, Sherman M, Canseco JA, Kepler CK, Vaccaro AR, Hilibrand AS, Schroeder GD. What is the role of dynamic cervical spine radiographs in predicting pseudarthrosis revision following anterior cervical discectomy and fusion?
Spine J 2022;
22:1610-1621. [PMID:
35568109 DOI:
10.1016/j.spinee.2022.04.020]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/23/2022] [Accepted: 04/26/2022] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT
Postoperative dynamic radiographs are used to assess fusion status after anterior cervical discectomy and fusion (ACDF) with comparable accuracy to computed tomography (CT) scans.
PURPOSE
To (1) determine if dynamic radiographs accurately predict pseudarthrosis revision in a cohort of largely asymptomatic patients who underwent ACDF, (2) determine how adjacent segment motion is affected by fusion status, and (3) analyze how clinical outcomes differ between patients with symptomatic and asymptomatic pseudarthrosis.
STUDY DESIGN
Retrospective cohort study.
PATIENT SAMPLE
Patients ≥ 18 years who underwent primary one- to four-level ACDF at a single institution over a 10-year period.
OUTCOME MEASURES
Interspinous motion on preoperative and postoperative flexion-extension radiographs and preoperative and postoperative Visual Analogue Scale for Neck Pain (VAS Neck) and Arm Pain (VAS Arm), Neck Disability Index (NDI), Modified Japanese Orthopaedic Association scale (mJOA), Mental and Physical Component Scores of the Short-Form 12 (SF-12) Health Survey (MCS-12 and PCS-12) METHODS: The difference in spinous process motion between flexion and extension radiographs was used to determine motion at each level of the ACDF construct. Pseudarthrosis was defined as ≥ 1 mm spinous process motion on dynamic radiographs. A receiver operating characteristic (ROC) curve was generated to predict the probability of surgical revision for pseudarthrosis based on millimeters of interspinous motion at each instrumented level. Patient reported outcome measures (PROMs) were used to assess the effect of pseudarthrosis on clinical outcomes. Alpha was set at p<.05.
RESULTS
A total of 597 patients met inclusion criteria including 1,203 ACDF levels. Of those, 215 patients (36.0%) were diagnosed with a pseudarthrosis on dynamic radiographs with 29 patients (4.9%) requiring pseudarthrosis revision. ROC analysis identified a "cutoff" value of 1.00 mm of interspinous process motion for generating an optimal area under the curve (AUC). The negative predictive value (NPV) was 99.6%, whereas the positive predictive value (PPV) was 13.7%. When analyzing adjacent segment motion, the Δ supra-adjacent interspinous process motion (ISM) was significantly lower for patients with a superior construct pseudarthrosis (-1.06 mm vs. 1.80 mm, p<.001), whereas the Δ infra-adjacent level ISM was significantly lower for patients with an inferior construct pseudarthrosis (-1.21 mm vs. 2.15 mm, p<.001). Patients with a pseudarthrosis not requiring revision had worse postoperative NDI (29.3 vs. 23.4, p=.027), VAS Neck (3.40 vs. 2.63, p=.012), and VAS Arm (3.09 vs. 1.85, p=.001) scores at 3 months, but not 1-year, compared with patients who were fused. Patients requiring pseudarthrosis revision had higher 1-year postoperative NDI (38.0 vs. 23.7, p=.047) and lower 1-year postoperative Δ VAS Arm (-0.22 vs. -2.97, p=.016) scores.
CONCLUSIONS
One-year postoperative dynamic radiographs have a greater than 99% negative predictive value for identifying patients requiring pseudarthrosis revision, but they have a low positive predictive value. Most patients with a pseudarthrosis remain asymptomatic with similar 1-year postoperative patient-reported outcomes compared with patients without a pseudarthrosis.
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