General Session: Adult Spinal Deformity
Presented by: N. Anand - View Audio/Video Presentation (Members Only)
N. Anand(1), B. Khandehroo(1), J. Cohen(1), R. Cohen(1), E. Baron(1), S. Kahwaty(1)
(1) Cedars-Sinai Medical Center, Spine Center, Los Angeles, CA, United States
Introduction: Current CMIS techniques for spinal deformity correction are dependent on interbody fusion achieved via placement of lateral interbody cages. Cages with an increased angle of lordosis are being advocated to improve segmental lordosis to achieve better sagittal alignment. This study was designed to assess if the actual segmental lordosis was the same as the lordosis of the cage and what factors made a difference.
Methods: This is a retrospective study of 65 consecutive patients who underwent lateral interbody fusion using lordotic cages as part of CMIS correction of scoliosis from May 2012 to July 2015. At L5-S1 an ALIF was done. Standing radiographs at pre-op and 6weeks post-op were reviewed to identify the position of the cage in the intervertebral space and the amount of segmental lordosis achieved.
Results: A total of 218 cages were placed through the tubular lateral transpsoas approach. Placement of the cage in the posterior 3rd of the intervertebral space led to lower segment lordosis compared to middle or anterior 3rd placement(p< 0.05) (Figure 1). However, there was no statistically significant difference in the segmental lordosis between the anterior 3rd and the middle 3rd positions. Additionally, It was also noticed (Figure 2) that 6, 10 and 12 degree cages create more segmental lordosis (p< 0.05) when they were placed in lower lumbar intervertebral levels (L4-L5) compare to those placed in higher lumbar region(L1-L2). For 12degree cage it was 15.7 degrees (8.5-25 degrees) at L4-L5, 12.7 degrees (7.9-19.6 degrees) at L3-L4, 12.4 degrees (7.3-18.8 degrees) at L2-L3 and 10.8degrees (4.6- 17.5 degrees) at L1-L2 (p< 0.05).The actual lordosis of the cage did have a significant impact (p< 0.05) on the amount of segmental lordosis achieved. The 20 degree cage achieved a mean segmental lordosis of 19, compared to 13.8degrees for the 12degree cage, 12.6degrees for the 10degree cage, and 8.2degrees for the 6degree cage.
Conclusions: The lordosis of the cage does have an impact on segmental lordosis achieved during lateral interbody fusion procedures. Our study does demonstrate that placement of the cage and the level it is being placed are also significant factors in the amount of segmental lordosis achieved. The achieved segmental lordosis was notably more when a cage was placed in lower lumbar intervertebral levels (L4-L5). Additionally, cages placed in the posterior 3rd of the intervertebral space had a significantly worse segmental lordosis compared to those places in the anterior or middle 3rd.