Restoration of Segmental Lordosis and Related Factors in Interbody Fusion for Degenerative Lumbar Disease

ABSTRACT

STUDY DESIGN: A retrospective study. OBJECTIVES: To analyze restoration of segmental lordosis and factors related to interbody fusion and the fusion rate with degenerative lumbar disease. SUMMARY OF LITERATURE REVIEW Few studies have addressed the restoration of segmental lordosis and factors related to interbody fusion for degenerative lumbar disease. MATERIALS AND METHODS: Records of 43 patients treated by anterior lumbar interbody fusion (ALIF) or posterior lumbar interbody fusion (PLIF) surgery from 2011 to 2013 were reviewed. ALIF used a metal cage with a 10degrees lordotic angle and PLIF used a metal cage with an 8degrees lordotic angle. Preoperative, postoperative, and at least 1 year outcomes were analyzed from radiographs. As a related factor, segmental flexibility, disc height, osteophytes, vaccuum disc, hypertrophic facet, spondylolisthesis, and endplate violation were analyzed. We also analyzed the bony union rate. RESULTS: The segmental lordotic angle was 4.67degrees before surgery, improved to 10.43degrees after surgery, and was 9.32degrees at the final follow-up. Comparing between the ALIF and PLIF at the L3-4 level in a similar number of patients revealed 7.24degrees and 4.61degrees restoration after ALIF and PLIF surgery, postoperatively. The difference was statistically significant (p=0.011). Segmental flexibility had a statistically significant positive correlation (p=0.013). Lower disc height and osteophytes limited restoration of segmental lordosis, but vaccuum disc was restored well after interbody fusion. Bony union was achieved in 92.8% of the cases. CONCLUSIONS: Intebody fusion, especially ALIF surgery, results in acceptable restoration of segmental lordosis. Even with narrowed disc space or osteophytes, remained segmental flexibility is an important factor of segmental lordosis restoration.