Study Design: This is a retrospective study
Objectives: This study compared the clinical outcomes of posterior lumbar interbody fusion (PLIF) using hydroxyapatite blocks
with PLIF using a metal or poly-ether-ether-ketone (PEEK) cage.
Summary of the Literature Review: There are few reports on the clinical outcomes of PLIF using a hydroxyapatite block for
treating lumbar degenerative disease.
Materials and Methods: The 27 PLIF cases (62 units, HA block) that were followed up for 1-year were compared with 13 cases
using a metal cage and 13 cases using a PEEK cage. Pedicle screw fixation was performed for all the cases. If the local bone is
deficient, then an additional bone graft with autogeous iliac bone or bone substitute was used. The visual analog scale(VAS) for
low back pain and radiating pain, the Oswestry disability index (ODI), the intervertebral height and the halo sign around the
cages and pedicle screws were comparatively analyzed.
Results: The mean VAS score for low back pain before PLIF and using the HA block, the metal cage and the PEEK cage was
7.5, 8.3 and 6.2, respectively, and this was 3.3, 2.9 and 4.8 after PLIF (P< 0.05 with using the HA block and the metal cage
(Wilcoxon test). The mean VAS score for radiating pain before PLIF was 7.9, 8.3 and 8.5, respectively, and the VAS score was
3.5, 3.1 and 3.9, respectively, after PLIF (P< 0.05 for all cases, Wilcoxon test). For the ODI, the means before PLIF were 60.3, 51.2
and 53.8, respectively, and they changed to 30.5, 24.9 and 29.7, respectively, after PLIF (P< 0 .05 for all cases, Wilcoxon test).
On the X-ray images, there was no halo sign greater than 2 mm near the pedicle screws or greater than 1 mm near the cages
and no breakage of the HA block. No additional bone graft was needed for the PLIF using the HA block and local bone. There was no statistically significant differences among the groups (P > 0.05, One-way ANOVA).
Conclusion: PLIF using a HA block showed improvements, including the back pain, and the ODI was satisfactory and this
didn’t fall below those ODIs of using metal or PEEK cages. Although a HA block may have higher tendency to break, there
was no breakage at the 1-year follow up.