Imaging and Management of Cervical Fusion with Hardware

Imaging Modalities for Post-Operative Cervical Fusion Assessment

• The American College of Radiology recommends CT as the gold standard for assessment of spinal fusion and hardware integrity due to superior visualization of bony structures 1, 3
• CT offers significant advantages over radiographs in detecting adjacent segment degenerative disease following anterior cervical discectomy and fusion (ACDF), with a study of 690 patients showing CT altered treatment in 60% of patients with abnormal imaging and persistent symptoms 1
• The American College of Radiology suggests that recent advances in CT technology, including multiplanar reformats, metal artifact reduction techniques, and dose reduction protocols, have enhanced evaluation capabilities 1
• Dual-energy CT and photon counting CT show promise for decreasing metal artifact and increasing image sharpness in hardware evaluation, according to the American College of Radiology 1
• Metal artifact significantly limits assessment of the fused level and hardware on MRI, but MRI remains the most sensitive imaging test for detecting soft tissue abnormalities associated with neck pain, as stated by the American College of Radiology 4, 5
• MRI offers benefit in detecting adjacent level disease including disc herniations and nerve root impingement in post-surgical patients, with emerging MRI techniques for metal artifact reduction likely to increase the utility of MRI in postoperative cervical pain evaluation 3, 4
• The American College of Radiology notes that contrast enhancement is not routinely needed for anterior approach surgeries since the epidural space is rarely transgressed 3, 4

Hardware Types and Considerations

• The American Association of Neurological Surgeons recommends multiple strategies for interbody grafting, with Class II evidence supporting the use of autograft, allograft, and titanium cages 6, 7
• Autograft bone from iliac crest, allograft bone from cadaveric iliac crest or fibula, and titanium cages are all recommended options for creating arthrodesis after 1- or 2-level ACDF, according to the American Association of Neurological Surgeons 6, 7
• Alternative materials include polyetheretherketone (PEEK) cages and carbon fiber cages, which have shown fusion rates >50%, as reported by the American Association of Neurological Surgeons 6, 7

Post-Operative Management

• Initial post-operative assessment should include radiographs to evaluate hardware position, and for patients with persistent symptoms, CT is recommended as the primary modality to assess fusion status and hardware integrity, as suggested by the American College of Radiology 1, 2
• MRI without contrast is appropriate for evaluating adjacent segment disease and soft tissue complications, while MRI with and without contrast is the preferred imaging modality for suspected infection, according to the American College of Radiology 3, 4

Common Pitfalls and Caveats

• Degenerative findings on MRI are commonly observed in asymptomatic patients, leading to potential false-positive interpretations, with approximately 65% of asymptomatic patients 50-59 years of age having radiographic evidence of significant cervical spine degeneration, as noted by the American College of Radiology 5, 9
• Recombinant human bone morphogenic protein-2 (rhBMP-2) carries a complication rate of up to 23-27% compared with 3% for standard approaches and is not recommended for routine use, according to the American Association of Neurological Surgeons 6, 7
• Polymethyl-methacrylate (PMMA) is not recommended as a means to preserve interspace height after anterior discectomy as fusion generally does not occur, as stated by the American Association of Neurological Surgeons 6
• Failing to document pre-operative physical examination findings that correlate with imaging is a common clinical assessment pitfall, as reported by the American College of Radiology 8