Sagittal alignment assessment after short-segment lumbar fusion for degenerative disc disease.

Greater SS, greater PI, and a PI-LL mismatch greater than 10° are associated with failed bony fusion, while ASD is related to a greater difference between the pre-operative and post-operative values of PT. Neither the type nor the size of cage seem to have a significant impact on either solid bony fusion, nonunion, or ASD rates. Thus, we recommend on the study of patients' sagittal alignment in the pre-operative setting even when treating patients with short-segment lumbar interbody fusion.