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Results and complications after 2-level axial lumbar

interbody fusion with a minimum 2-year follow-upMarchi L., Oliveira L., Coutinho E., Pimenta L.

J Neurosurg Spine

17:187-192, 2012

Cristian Gragnaniello20-9-2012

Journal Club Critical Appraisal

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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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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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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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• 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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• 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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• 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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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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Participant Flow Chart (if relevant)

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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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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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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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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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