When Fusing from the Thoracolumbar Junction to L5-S1, How Much Lordosis is Ideal?

Information provided by

Y.J. Kim, M.D.

Washington University Medical Center

Keith Bridwell, MD

Orthopaedic Surgeon

Washington University School of Medicine

Lawrence G. Lenke, MD

The Jerome J. Gilden Professor of Orthopedic Surgery

Co-Chief Pediatric & Adult Spinal, Scoliosis & Reconstructive Surgery

Abstract from the SRS 2005 Annual Meeting

Summary: This study determined the optimal sagittal spinal balance after adult long(> 5 vertebrae) lumbar instrumentation and fusion (out of 66 patients with 2-15.8 year follow-up). The angle of lumbar lordosis at 6 weeks post operation should be at least 30° larger than that of thoracic kyphosis because of the average 20° angle differences between lumbar lordosis and thoracic kyphosis for optimal global sagittal balance in addition to 10° spontaneous increase in thoracic kyphosis at final follow up.

Purpose: To determine the optimal time dependent sagittal spinal balance following adult lumbar deformity instrumentation and fusion from the distal thoracic spine to L5- S1.

Methods: A radiographic assessment of 66 adult lumbar deformity patients (average age 51.7 years) who underwent long (> 5 vertebrae) segmental posterior spinal instrumentation and fusion from the thoracolumbar spine to the L5- S1 with a minimum 2-year follow up (average 4.5 years) was analyzed. The optimal sagittal balance was defined as the distance from C7 plumb to superior posterior endplate of S1 2.0 cm or less.

Results: The preoperative lumbar lordosis angle (T12-S1) of 32° +19.5° increased to 50°+15.5° at postoperative 6 weeks, and then to 48°+16.0° at final follow-up. The preoperative thoracic sagittal Cobb angle was 27° +17.7° between T5 and T12 (37°+16.7° at final follow-up, average increase 10°+10.8°). The angle differences between the optimal sagittal balance group (n=35, C7 plumb <2CM ) and poor sagittal balance group (n="31," C7 plumb> 2cm) at final follow-up are: The angle differences between lumbar lordosis and thoracic kyphosis, -20°+13.4° vs -1° +21.0° (p <0 .0001), lumbar lordosis angle -52° +13.4° vs -44° +17.6° (p="0.023)." and thoracic kyphosis angle, 32°+14.6° 43° +16.6°

Conclusion: One has to anticipate a time dependent increase of thoracic kyphosis (T5-T12) of approximately 10° following long lumbar fusion/instrumentation. The ideal sagittal Cobb difference between lumbar lordosis (T12-S1) and thoracic kyphosis (T5-T12) for optimal sagittal balance is 20°, as is shown in this study. The ultimate difference should be 30° to anticipate the subsequent increase in kyphosis that is expected to occur above the instrumented fusion from the thoracolumbar junction to L5- S1.

Updated on: 12/10/09