125 - Unilateral Pedicle Screw Fixation Following Lateral Lumbar Interbody F...

#125 Unilateral Pedicle Screw Fixation Following Lateral Lumbar Interbody Fusion without Plate Fixation: A Preliminary Report

MIS Techniques and Outcomes

Poster Presented by: M. Al-Masieh

Author(s):

J.Y. Du (1,2)
M. Al-Maaieh (1)
A. Aichmair (1)
R.C. Huang (1)

(1) Hospital for Special Surgery, Orthopedic Spine Service, New York City, NY, United States
(2) Weill Cornell Medical College, New York City, NY, United States

Abstract

Background: Lateral Lumbar Interbody Fusion (LLIF) is a minimally invasive technique that accesses and fuses the anterior vertebral column of the lumbar spine. The LLIF approach preserves the anterior and posterior longitudinal ligaments and uses a fusion cage that spans the apophyseal vertebral ring bilaterally, which improves stability. Due to these factors, less invasive supplemental fixation may be allowed.

Purpose: To assess the clinical outcomes of patients with unilateral pedicle screw instrumentation following LLIF without anterior plate fixation.

Methods: A retrospective review was performed of all patients with unilateral pedicle screw fixation following LLIF without anterior plate fixation between March 2006 and December 2012 from a single institution/ single surgeon. Demographic, comorbidity, clinical, peri-operative, and complication data were assessed. Student's paired t-test was performed to compare pre- and post-operative Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Short Form-12 (SF-12).

Results: A total of 22 patients were included. Average age of patients at surgery was 60.4±11.9 years (range: 32-78 years), with 13 males and 9 females. Diagnoses prompting surgery were spondylolisthesis with central stenosis (n=18), degenerative disc disease with foraminal stenosis (n=3), and scoliosis with stenosis (n=1). LLIF was performed through a left-sided approach in 19 cases and a right-sided approach in 3 cases, with use of recombinant human bone morphogenic protein-2 (rhBMP-2) in 8 cases. For the posterior portion of the surgery, hemilaminotomy was performed in 11 cases, and posterolateral fusion was performed in all cases, with rhBMP-2 usage in 8 cases. Unilateral pedicle screw instrumentation was performed on the right side in 12 cases and on the left side in 10 cases. Average operation time was 204.9±39.6 minutes (range: 143-295 minutes). Estimated blood loss was 195.5±109.0cc (range: 50-500cc). No patients received a transfusion. There were no intra-operative complications. Average length of post-operative hospital stay was 4.5±2.6 days (range: 2-12 days). One patient experienced transient L2, L4 traction neuropathy. One patient required revision decompression laminotomy. At final follow-up (average 416.9.4±273.7 days after surgery), there was significant improvement in VAS (p< 0.01),

ODI (p< 0.001), and SF-12 physical component (p< 0.001), but not for SF-12 mental component (p=0.52).

A sub-analysis was performed to compare the clinical outcomes of patients with both unilateral pedicle screw fixation and anterior plate fixation following LLIF (n=12) to patients with only unilateral pedicle screw fixation following LLIF (n=22). Using unpaired student's t-tests, patients with both unilateral pedicle screw fixation and anterior plate fixation were found to have significantly higher duration of surgery (p=0.002) than patients with only unilateral pedicle screw fixation following LLIF, with no significant differences in VAS, ODI, and SF-12 clinical indices between groups. There were two cases of vertebral compression fracture in patients with both unilateral pedicle screw fixation and anterior plate fixation following LLIF.

Conclusions: We report a series of patients treated with unilateral pedicle screw fixation following LLIF. Significant clinical improvement suggests that unilateral pedicle screw fixation may be adequate for supplemental stabilization following LLIF. Use of anterior plate fixation increased operative time without improving clinical outcomes and may lead to significant risk of vertebral compression fracture.