Comparison of outcomes for posterior lumbar interbody fusion (PLIF) between spinal block bullet and fusion cages

Jiann Her Lin, Tong Han Tsai, Yung Hsiao Chiang, Hao Yiang Wu, Chung Ching Hsia, Guann Juh Chen, Ming Ying Liu

Research output: Contribution to journalArticlepeer-review


Background: Spinal block bullet cages are considered interbody spacers rather than providing a scaffold, into which osteoinductive or osteoconductive materials could be placed. On the other hand, hollow fusion cages provide interbody fusion through osteoinductive or osteoconductive materials placed inside them. While posterior lumbar interbody fusion (PLIF) with spinal block bullet cages is thought to achieve less fusion than that with fusion cages, there are no reports of previous investigation. We compared the PLIF outcomes between the two different cages. Methods: A series of patients (n=25) with lumbar disc diseases or degenerative lumbar spondylolisthesis were retrospectively reviewed; Group 1 (n=11) underwent PLIF with bullet cages and Group 2 (n=14) with fusion cages at a single level. Both groups received internal fixation with transpedicular screws and rods at the same level. Rostral adjacent level mobility, segmental motion, ratio of disc height, and foramen area in the fusion level were studied on the follow-up X-ray images. Fusion success was defined as segmental stability and absence of radiolucency at the cage - end plate interface. Visual analogue pain score (VAS) and the SF-8™ health survey (SF-8) were used to access the clinical outcome. Results: The duration of follow-up was 25.9±10.65 months in Group 1 and 19.57±13.22 months (p=0.22) in Group 2. Group 1 subjects achieved the same results as those in Group 2 in segmental motion (Groups 1, 2=1.40±0.71°, 1.81±0.94°; p=0.28), ratio of disc height (Groups 1, 2=0.3±0.03, 0.29±0.07; p=0.89), foramen area (Groups 1, 2=1.30±0.28cm 2, 1.18±0.33cm 2; p=0.36), and rostral segmental motion (Groups 1, 2=6.43±4.08°, 8.89±4.84°; p=0.201). Moreover, there was no statistical difference between both groups in VAS (Group 1, 2=2.72±1.13, 3.1±0.96; p=0.44) and SF-8 (Group 1, 2=16.54±2.93, 15.1±2.37; p=0.19). Conclusion: According to our study, the spinal block bullet cages achieved the same radiological parameters and clinical outcomes for PLIF as the fusion cages.

Original languageEnglish
Pages (from-to)193-198
Number of pages6
JournalJournal of Medical Sciences (Taiwan)
Issue number5
Publication statusPublished - 2008
Externally publishedYes


  • Bullet cage
  • Fusion cage
  • Posterior interbody fusion
  • Segmental motion

ASJC Scopus subject areas

  • General Medicine


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