#101 Prospective, Randomized, Multicenter Study Comparing the Clinical Outcomes of Two Minimally Invasive Interspinous Devices for the Treatment of Lumbar Spinal Stenosis

General Session: Lumbar Therapies Motion Preservation

Presented by: W. Bradley

Author(s):

W.D. Bradley (1)
P.G. Whang (2)

(1) Texas Back Institute, Denton, TX, USA
(2) Yale Department of Orthopaedics and Rehabilitation, New Haven, CT, USA

Abstract

Introduction: Lumbar spinal stenosis is a significant problem, often occurring in older patients. In this population, minimally invasive surgery may be particularly appealing if non-operative care fails to relieve symptoms. The purpose of this study was to compare the clinical outcomes of two lumbar minimally invasive interspinous implants used to treat symptomatic neurogenic claudication.

Methods: A total of 416 patients were enrolled and had an interspinous device implanted. Currently, 12-month follow-up data are available for 293 patients, 153 patients randomized to treatment with the SuperionĀ® device (Investigational group) and 140 treated with X-STOPĀ® (Control group). Primary selection criteria included lumbar spinal stenosis of at least moderate severity at 1 or 2 levels between L1 and L4, age of at least 45 years, persistent groin or lower extremity pain relieved by flexion, failure to gain relief after at least 6 months of non-operative care, no significant instability or spondylolisthesis greater than Grade I, and no previous lumbar spine surgery. Clinical outcome measures included Visual Analogue Scale (VAS) assessing back and leg pain, Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ), complications, and re-operations.

Results: The two groups were similar with respect to demographic characteristics. Intra-operative data are presented in Table 1. Incision length and blood loss were significantly less in the Investigational group and operative time was longer compared with the Control group.

The mean VAS scores for back pain as well as left and right leg pain all improved significantly in both groups by 6 weeks after surgery, and remained significantly improved throughout 12 month follow-up period (all p< 0.005; Figure 1). The ODI and ZCQ scores followed a similar pattern of significant improvement with no significant difference between groups. At no time point were there any significant differences between the groups for any of the outcomes measures.

At the 12-month follow-up, there was no significant difference in the re-operation rates for the two groups (5.9% Investigational vs. 4.3% Control).

Discussion: The results of this study provide further evidence that interspinous devices may bring about significant improvements in neurogenic claudication symptoms in appropriately selected patients. The Investigational Superion device was non-inferior to the X-STOP Control. The outcome data were stable and significant improvements were maintained according to multiple outcome measures. Follow-up of these patients will continue for 5 years to determine if these promising results continue to be present over time.

Table 1. Comparison of intra-operative data.

Figure 1. Mean ODI scores.