Do lordotic cages provide better segmental lordosis versus non-lordotic cages in lateral lumbar interbody fusion (llif)?

STUDY DESIGN: Retrospective Comparative Radiographic Review. OBJECTIVE: To evaluate the radiographic changes brought about by lordotic and nonlordotic cages on segmental and regional lumbar sagittal alignment and disc height in LLIF. SUMMARY OF BACKGROUND DATA: The effects of cage design on operative level segmental lordosis in posterior interbody fusion procedures have been reported. However, there are no studies comparing the effect of sagittal implant geometry in lateral lumbar interbody fusion (LLIF). METHODS: This is a comparative radiographic analysis of consecutive LLIF procedures performed with use of lordotic and non-lordotic interbody cages. Forty patients (61 levels) underwent LLIF. Average age was 57 years (30-83). Ten-degree lordotic PEEK cages were used at 31 lumbar interbody levels, and non-lordotic cages were used at 30 levels. The following parameters were measured on pre- and post-operative radiographs: segmental lordosis, anterior and posterior disc heights at operative level; segmental lordosis at supra- and subjacent levels; and overall lumbar (L1-S1) lordosis. Measurement changes for each cage group were compared using paired t-test analysis. RESULTS: The use of lordotic cages in LLIF resulted in a significant increase in lordosis at operative levels (2.8°; P=0.01), whereas non-lordotic cages did not (0.6°; P=0.71) when compared to pre-operative segmental lordosis. Anterior and posterior disc heights were significantly increased in both groups (P<0.01). Neither cage group showed significant change in overall lumbar lordosis (lordotic P=0.86 vs. non-lordotic P=0.25). CONCLUSION: Lordotic cages provided significant increase in operative level segmental lordosis compared to non-lordotic cages although overall lumbar lordosis remained unchanged. Anterior and posterior disc heights were significantly increased by both cages, providing basis for indirect spinal decompression.