Hilibrand and colleagues measured how often new radiculopathy or myelopathy arises at a level next to a previous anterior cervical fusion, which levels are most affected, and whether multilevel fusion raises that risk.
Consecutive single‑surgeon series of 374 patients with 409 anterior cervical arthrodeses for spondylosis, 1973 to 1992, followed up to 21 years.
The authors hypothesized that adjacent‑level disease would be more likely after a multilevel fusion than after a single‑level fusion.
Methods
Design
Retrospective cohort of a consecutive series
Operations 1973 to 1992
Data source
One institution, one senior surgeon
Patients
374 patients, 409 anterior cervical arthrodeses
Spondylosis with radiculopathy, myelopathy or both
180 male, 194 female
Mean age 51 (17 to 83)
9 deaths within 6 months excluded
Exposure
338 discectomy and arthrodesis (modified Robinson‑Smith)
71 subtotal vertebrectomy with strut graft
Single‑level vs multilevel arthrodesis
Follow-up
Up to 21 years
Outcomes
Yearly rate of new adjacent‑level disease
Prevalence over follow‑up
Kaplan‑Meier disease‑free survival
Risk by motion segment
Key Findings
Survivorship analysis predicted that 25.6% of patients (95% CI 20 to 32%) would develop symptomatic adjacent‑segment disease within 10 years of surgery.
New disease appeared at a steady average of 2.9% per year (95% CI 1.6 to 4.2%, range 0.0 to 4.8%) over the first decade.
Against the authors' hypothesis, adjacent disease followed 12% of 256 multilevel fusions vs 18% of 153 single‑level fusions (OR 0.64, 95% CI 0.55 to 0.75, p < 0.001).
More advanced radiographic degeneration at the adjacent level at surgery was linked to earlier symptoms, with mean onset over 7 years for grade I vs under 2 years for grade IV (r² = –0.985).
Of 46 affected patients followed at least 2 years after onset, 13 improved without surgery and 27 had anterior decompression and arthrodesis at the adjacent level.
Of those 29 adjacent‑level reoperations, 11 had excellent, 10 good and 8 fair results at latest follow‑up.
Board pearl
Symptomatic adjacent‑segment disease means new radicular or myelopathic signs traceable to a level next to the fusion, as opposed to radiographic degeneration alone.
Authors' conclusion
Symptomatic adjacent-segment disease may affect more than one-fourth of all patients within 10 years after an anterior cervical arthrodesis. A single-level arthrodesis involving the fifth or sixth cervical vertebra and preexisting radiographic evidence of degeneration at adjacent levels appear to be the greatest risk factors for new disease. Therefore, we believe that all degenerated segments causing radiculopathy or myelopathy should be included in an anterior cervical arthrodesis. Although our findings suggest that symptomatic adjacent-segment disease is the result of progressive spondylosis, patients should be informed of the substantial possibility that new disease will develop at an adjacent level over the long term.
Hilibrand and colleagues measured how often new radiculopathy or myelopathy arises at a level next to a previous anterior cervical fusion, which levels are most affected, and whether multilevel fusion raises that risk.
Consecutive single‑surgeon series of 374 patients with 409 anterior cervical arthrodeses for spondylosis, 1973 to 1992, followed up to 21 years.
The authors hypothesized that adjacent‑level disease would be more likely after a multilevel fusion than after a single‑level fusion.
Methods
Design
Retrospective cohort of a consecutive series
Operations 1973 to 1992
Data source
One institution, one senior surgeon
Patients
374 patients, 409 anterior cervical arthrodeses
Spondylosis with radiculopathy, myelopathy or both
180 male, 194 female
Mean age 51 (17 to 83)
9 deaths within 6 months excluded
Exposure
338 discectomy and arthrodesis (modified Robinson‑Smith)
71 subtotal vertebrectomy with strut graft
Single‑level vs multilevel arthrodesis
Follow-up
Up to 21 years
Outcomes
Yearly rate of new adjacent‑level disease
Prevalence over follow‑up
Kaplan‑Meier disease‑free survival
Risk by motion segment
Key Findings
Survivorship analysis predicted that 25.6% of patients (95% CI 20 to 32%) would develop symptomatic adjacent‑segment disease within 10 years of surgery.
New disease appeared at a steady average of 2.9% per year (95% CI 1.6 to 4.2%, range 0.0 to 4.8%) over the first decade.
Against the authors' hypothesis, adjacent disease followed 12% of 256 multilevel fusions vs 18% of 153 single‑level fusions (OR 0.64, 95% CI 0.55 to 0.75, p < 0.001).
More advanced radiographic degeneration at the adjacent level at surgery was linked to earlier symptoms, with mean onset over 7 years for grade I vs under 2 years for grade IV (r² = –0.985).
Of 46 affected patients followed at least 2 years after onset, 13 improved without surgery and 27 had anterior decompression and arthrodesis at the adjacent level.
Of those 29 adjacent‑level reoperations, 11 had excellent, 10 good and 8 fair results at latest follow‑up.
Board pearl
Symptomatic adjacent‑segment disease means new radicular or myelopathic signs traceable to a level next to the fusion, as opposed to radiographic degeneration alone.
Authors' conclusion
Symptomatic adjacent-segment disease may affect more than one-fourth of all patients within 10 years after an anterior cervical arthrodesis. A single-level arthrodesis involving the fifth or sixth cervical vertebra and preexisting radiographic evidence of degeneration at adjacent levels appear to be the greatest risk factors for new disease. Therefore, we believe that all degenerated segments causing radiculopathy or myelopathy should be included in an anterior cervical arthrodesis. Although our findings suggest that symptomatic adjacent-segment disease is the result of progressive spondylosis, patients should be informed of the substantial possibility that new disease will develop at an adjacent level over the long term.