408 - Evaluation of Lumbar Lordosis in Patients Treated with the AxiaLIF 2 L...

#408 Evaluation of Lumbar Lordosis in Patients Treated with the AxiaLIF 2 Level Implant and Posterior Instrumentation

MIS Techniques and Outcomes

Poster Presented by: W. Tobler

Author(s):

W.D. Tobler (1)
N. Anand (2)
M.A. Melgar (3)
T.J. Raley (4)
R.J. Nasca (5)

(1) University of Cincinnati, Neurosurgery, Cincinnati, OH, USA
(2) Cedars Sinai Medical Center, Los Angeles, OH, USA
(3) Tulane University, Neurosurgery, New Orleans, LA, USA
(4) Advanced Spine and Pain, Arlington, VA, USA
(5) Orthopedic and Spine Surgery, Wilmington, VA, USA

Abstract

Introduction: There is concern that using an axial rod coupled with distraction may lead to a loss of segmental (L4-S1) and total (L1-S1) lumbar lordosis in patients undergoing lumbosacral fusions. In order to evaluate this hypothesis, we reviewed prospectively collected data from four clinical sites on 53 patients that underwent a lower lumbar fusion at L4-L5 and L5-S1 using the presacral approach.

Methods: Two-level fusions were performed in 53 patients (mean age: 52 years) and 106 levels for persistent back pain, mainly due to degenerative disc disease), after at least 6 months of failed nonoperative treatment. The AxiaLIF 2 L and 2 L plus system (TranS1 Wilmington, NC) and supplemental posterior fixation with pedicle and facet screws was used. Patients were positioned on a Jackson table to maintain lordosis with hips and knees in extension. The AxiaLIF rod trajectory was started in the posterior third of the sacrum and directed to the anterior third of the L4 vertebral body. Variable amounts of distraction were applied to the AxiaLIF rod as well to the pedicle based instrumentation. Pedicle screws were used in 29 patients, facet screws in 15, and 9 had a combination of pedicle and facet screws. Lordosis measurements were made using the Cobb method on preoperative and postoperative standing lateral radiographs. The Cobb angle of the L4-S1 segment was determined by placing a line along the superior end plate of L4 and the superior end plate of S1. The Cobb angle of the L1 to S1 segment was measured along the superior end plate of L1 and the superior end plate of S1. Change in lordosis from pre-treatment to post-treatment is reported as median and range. Mean follow-up was 29 months.

Results: Forty-five (85%) patients were rated as excellent or good using Odom's criteria. Fusion, determined by CT scans and flexion and extension radiographs with bridging bone from end-plate to end plate, was identified in 99 (93%) of the 106 interspaces treated. Median change in segmental lordosis from L4-S1 was -1.3 degrees (range: -16 to 9 degrees). Median change in total lordosis measured from L1 to S1 was 0 degrees (-27 to 12 degrees). Ten (19%) patients had ≥10 degrees loss of lordosis from L1 to S1 following surgery. These patients were hyperlordotic prior to surgery with a median preoperative lordosis of 60 degrees (range: 47 to 70 degrees).

Conclusion: The two-level AxiaLIF rod and posterior instrumentation results in high fusion rates with no significant change in either segmental L4-S1 or total L1 to S1 lumbar lordosis.