451 - Radiographic and Clinical Outcomes in Extreme Lateral Interbody Fusion...

#451 Radiographic and Clinical Outcomes in Extreme Lateral Interbody Fusion: An Interim Analysis

MIS Techniques and Outcomes

Poster Presented by: A. Tohmeh

Author(s):

A.G. Tohmeh (1)
M. Tohmeh (1)
B. Watson (2)
X.J. Zielinski (2)

(1) Northwest Orthopaedic Specialists, Spokane, WA, USA
(2) Inland Imaging, Spokane, WA, USA

Abstract

Introduction: The minimally-disruptive lateral transpsoas approach for anterior lumbar interbody fusion (XLIF) is increasingly used as an alternative to open direct anterior lumbar interbody fusion. Additional radiographic and clinical results are needed to fully assess XLIF outcomes. The purpose of this study was to examine mid-term clinical and radiographic results of patients having undergone a minimally-disruptive approach for anterior lumbar interbody fusion.

Methods: 93 patients were treated with XLIF from February 2008 to June 2011. Patients were included in the study with at least 12 months clinical follow-up and radiography evaluated by a third-party radiologist.

Mean patient age was 59.5 years, BMI was 28.8, and 44% of patients were female. Comorbidities included smoking (11%), diabetes (16%), heart disease (20%), and prior lumbar spine surgery (62%). Prior surgeries included simple decompressions (64%) and instrumented fusions (36%). Patients were treated at an average of 1.6 XLIF levels (total 149 levels) from T10-L5 for a variety of degenerative lumbar conditions. The most common level treated was L4-5 (72%) and 18% of patients underwent a direct posterior decompression. Supplemental fixation was used in all patients.

Results: Average follow-up was 19 months (range 12-36). Mean total anesthesia time was 143 mins with mean operating (skin-to-skin) time being 99 mins. Mean blood loss was 102 cc per case (including supplemental instrumentation), and length of hospital stay (LOS) was 2.9 days (range 1-6 days) with one (1.4%) intraoperative complication (dural tear). Back and leg pain improved 64% and 51% from preoperative to last follow-up, with a 49% improvement seen in ODI. Quality of life improved 61% from 41.5 to 67.1 at last follow-up. At last follow-up, 92% of patients reported being either very or somewhat satisfied with their outcome, while 86% would either definitely or likely re-do the surgery, had their outcome been known in advance.

Postoperative radiography revealed cage tilting on lateral views in 15% of levels, with a mean tilt of 12° at one year postoperative. No cage migrations were observed. Any amount of superior or inferior endplate subsidence was seen in 23% and 44% of cases, respectively. In cases with subsidence, the average subsidence distance as a percentage of the height of the intervertebral implant for superior and inferior endplates was 29% for both. Disc height increased 108% immediately postoperative and settled at an average increase of 66% at 1 year. Foraminal height similarly increased by 32% postoperatively and was 20% at 1 year.

Complete fusion was observed in 91% of levels with 8% showing ongoing fusion at one year. No revisions for pseudoarthrosis occurred.

Conclusions: Mid-term results of XLIF in the treatment of degenerative lumbar conditions show significant improvements in pain, disability and quality of life. Despite some radiographic settling, substantial increases in disc and foraminal height were seen with a high rate of interbody fusion without pseudoarthrosis. Additionally, 92% of patients reported being satisfied with their outcome and 86% would choose to undergo the procedure again. Subsequent analyses from this series include expanding the patient sample as well as a comparison of 18mm versus 22mm cages, different fixations and biologics, and radiographic findings (specifically subsidence) as it impacts patient outcome.