Two-year clinical outcomes of a multicenter randomized controlled trial comparing two interspinous spacers for treatment of moderate lumbar spinal stenosis

Vikas V Patel, Peter G Whang, Thomas R Haley, W Daniel Bradley, Pierce D Nunley, Larry E Miller, Jon E Block, Fred H Geisler, Vikas V Patel, Peter G Whang, Thomas R Haley, W Daniel Bradley, Pierce D Nunley, Larry E Miller, Jon E Block, Fred H Geisler

Abstract

Background: Interspinous spacers are a minimally invasive surgical alternative for patients with lumbar spinal stenosis (LSS) unresponsive to conservative care. The purpose of this prospective, multicenter, randomized, controlled trial was to compare 2-year clinical outcomes in patients with moderate LSS treated with the Superion(®) (Experimental) or the X-Stop(®), a FDA-approved interspinous spacer (Control).

Methods: A total of 250 patients with moderate LSS unresponsive to conservative care were randomly allocated to treatment with the Experimental (n = 123) or Control (n = 127) interspinous spacer and followed through 2 years post-treatment. Complication data were available for all patients and patient-reported outcomes were available for 192 patients (101 Experimental, 91 Control) at 2 years.

Results: Zurich Claudication Questionnaire (ZCQ) Symptom Severity and Physical Function scores improved 34% to 36% in both groups through 2 years (all p < 0.001). Patient Satisfaction scores at 2 years were 1.8 ± 0.9 with Experimental and 1.6 ± 0.8 with Control. Axial pain decreased from 59 ± 26 mm at baseline to 21 ± 26 mm at 2 years with Experimental and from 55 ± 26 mm to 21 ± 25 mm with Control (both p < 0.001). Extremity pain decreased from 67 ± 24 mm to 14 ± 22 mm at 2 years with Experimental and from 63 ± 24 mm to 18 ± 23 mm with Control (both p < 0.001). Back function assessed with the Oswestry Disability Index similarly improved with Experimental (37 ± 12% to 18 ± 16%) and Control (39 ± 12% to 20 ± 16%) (both p < 0.001). Freedom from reoperation at the index level was 84% for Experimental and 83% for Control (log-rank: p = 0.38) at 2 years.

Conclusions: Both interspinous spacers effectively alleviated pain and improved back function to a similar degree through 2 years in patients with moderate LSS who were unresponsive to conservative care.

Trial registration: NCT00692276.

Figures

Figure 1
Figure 1
(A) A/P and (B) lateral radiographic image showing a properly placed Superion Interspinous Spacer.
Figure 2
Figure 2
Improvement in ZCQ symptom severity scores through 2 years post-treatment. Values are mean ± 95% CI.
Figure 3
Figure 3
Improvement in ZCQ physical function scores through 2 years post-treatment. Values are mean ± 95% CI.
Figure 4
Figure 4
ZCQ patient satisfaction scores through 2 years post-treatment. Values are mean ± 95% CI.
Figure 5
Figure 5
Improvement in axial pain severity through 2 years post-treatment. Values are mean ± 95% CI mm.
Figure 6
Figure 6
Improvement in extremity pain severity through 2 years post-treatment. Values are mean ± 95% CI mm.
Figure 7
Figure 7
Improvement in back function through 2 years post-treatment.Values are mean ± 95% CI.

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