This prospective study evaluated the outcomes of 27 patients who underwent a 2-level axial lumbar interbody fusion with a minimum 2-year follow-up. Clinical outcomes were measured using the Visual Analog Scale for back and leg pain and Oswestry Disability Index. Radiographic evaluation included standing x-rays, flexion-extension x-rays, and CT scans to assess fusion. The results demonstrated good clinical outcomes with reduced back pain and disability. However, radiographic evaluation found pseudarthrosis in 7 patients, and 3 patients required reoperation. Therefore, while this technique provided pain relief, the fusion rate was insufficient and complications were observed in some patients. Larger and longer-term studies are still needed to draw definitive conclusions

1. Results and complications after 2-level axial lumbar
interbody fusion with a minimum 2-year follow-up
Marchi L., Oliveira L., Coutinho E., Pimenta L.
J Neurosurg Spine
17:187-192, 2012
Cristian Gragnaniello
20-9-2012
Journal Club Critical Appraisal
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4. Significance/context and importance
of the study
• The study was done as there are no studies
evaluating 2 level axialif
• It is original
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5. Hypothesis or Objectives
• To report on the outcome of 27 patients
treated with 2 level AxiaLIF in a prospective
nonrandomized fashion.
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6. Internal Validity
• Ethics committee approval
• Participants – no selection bias as they were
consecutive patients
• Baseline data are reported and indications for
surgery are clearly stated
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7. • Design – prospective nonrandomized
• Interventions – outcomes were measured
with methods sound for lumbosacral spine
surgery (VAS for back and leg pain) and ODI
• Neurological examination and complications
are also reported
• Radiological evaluation was performed using
standing anteroposterior and lateral plain
radiographs, lateral flexion and extension
radiographs, and CT scans with sagittal and
coronal acquisitions.
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8. • The intervertebral disc height was measured
and expressed as an average of the sum of
the measurements at the anterior and
posterior regions of the disc. The disc space
height was normalized with the
anteroposterior diameter of the upper
vertebral body.
• Segmental lordosis values were obtained as
the angle between lines tangent to the
superior endplate of the superior vertebra and
the inferior endplate of the inferior vertebra.
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9. • Solid fusion was defined as less than 5° of
angular motion, the absence of radiolucent
lines covering at least 50% of the implant
surfaces, and the presence of continuous
trabecular bone growing through the disc
space.
• Bridging bone was defined as any bone
formation or incomplete bony ingrowth
between the endplates of the vertebral
bodies.
• Images were evaluated by 4 spine surgeons.
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10. Statistical analysis
• Student t-tests were used for comparing
variables, with a level of significance of 95%
(p < 0.05).
• Good internal validity as t-test is best used
when comparing 2 sets of data or a nominal
variable and a measurement variable
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11. Participant Flow Chart (if relevant)
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12. Conclusions: External Validity or
Generalisability
• All clinically important outcomes were
considered
• The likely treatment benefits ARE NOT worth
the potential harms and costs
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13. Presentation of Paper
• Well written paper, good economy of words,
paper well organized, probably better analysis
of results/complications needed
• Figures and tables are appropriate and
summarizing key points
• Bibliography is sound
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14. Table Summary
Objective Evaluate TranS1 fusion at 2 levels
Design Internal validity OK
Participants Internal validity OK, small series but seen the results it
would be surprising if it was bigger
Funding TranS1 BAD
Interventions OK
Results Results
Outcome Results
Conclusions External validity OK
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15. Conclusion
• Future, next steps: more laboratory testing
needed, probably too soon to push the
technique to 2 levels
• TranS1 for 2 levels is biomechanically not
sound
• Application to my practice: I would not
propose it to my patients
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