Neurospine.  2018 Sep;15(3):194-205. 10.14245/ns.1836192.096.

Diagnosing Pseudoarthrosis After Anterior Cervical Discectomy and Fusion

  • 1Department of Orthopedic, Changzheng Hospital, Second Military Medical University, Shang Hai, China.
  • 2Orthopaedic Surgery, Columbia University Medical Center, The Spine Hospital, New York-Presbyterian Healthcare System, New York, NY, USA.


Radiographic confirmation of fusion after anterior cervical discectomy and fusion (ACDF) surgery is a critical aspect of determining surgical success. However, there is a lack of established diagnostic radiographic parameters for pseudoarthrosis. The purpose of this study is to summarize the findings of previous studies, review the advantages and disadvantages of frequently employed diagnostic criteria, and present our recommended protocol of fusion assessment. This study identified randomized controlled trials, case-control studies, and prospective and retrospective cohort studies reporting on spinal fusion and how successful fusion after ACDF. Among the 39 articles reviewed, bridging bone across the operated levels on static radiographs was the most commonly used criteria to confirm fusion (31 of 39, 79%). Dynamic flexion-extension radiographs were used to assess for interspinous movement (ISM) (22 of 39, 56.4%) and change in Cobb angle (12 of 39, 30.8%). Computed tomography (CT) based findings (21 of 39, 53.8%) were employed in ambiguous cases with improved sensitivity and specificity. Reconstructed CT scans were used to assess for intragraft bridging bone and extragraft bridging bone (ExGBB). ExGBB were proved to have the highest diagnostic sensitivity and specificity for pseudoarthrosis detection when compared to all other radiographic criteria. The ISM < 1 mm on dynamic flexion-extension radiographs had high diagnostic sensitivity and specificity as well. After our reviewing, we recommend using dynamic lateral flexion-extension cervical spine radiographs at 150% magnificationin which the interspinous motion < 1 mm and superjacent interspinous motion ≥4 mm confirms fusion. In ambiguous cases, we recommend using reconstructed CT scans to evaluate for ExGBB.


Anterior cervical spine surgery; Anterior cervical discectomy and fusion; Anterior cervical arthrodesis surgery; Cervical spine fusion; Fusion; Pseudarthrosis

MeSH Terms

Case-Control Studies
Cohort Studies
Prospective Studies
Retrospective Studies
Sensitivity and Specificity
Spinal Fusion
Tomography, X-Ray Computed
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