Interspinous spacer indications

Interspinous spacers limit extension at 1 or 2 levels (without fusion), preventing narrowing of the associated neural foramen, and may also off-load the facet joints and even the disc. “Success rate”: 63% at 2 years. This device may be used as a stand-alone.

Interspinous spacers are commonly used to treat lumbar spinal stenosis or facet joint arthritis. The aims of implanting interspinous devices are to unload the facet joints, restore foraminal height, and provide stability especially in extension but still allow motion ¹⁾.

Lumbar ID may have a potential beneficial effect in select group of patients with degenerative disease of the lumbar spine. However, further good quality trials are needed to clearly outline the indications for their use ²⁾.

Interspinous distraction of 8 mm is sufficient to replicate electrophysiological improvements obtained during full decompression even in severe single-level stenosis but not in multilevel disease. Interspinous distraction has therefore an immediately measurable neurophysiological effect. Level of Evidence: 4.³⁾.

see Adjacent segment degeneration

It has been introduced as a minimally invasive method of stabilizing two adjacent interspinous processes by augmenting an interbody cage in transforaminal interbody fusion. The ID is intended to replace the standard pedicle screw instrumentation used for posterior fixation ⁴⁾.

Different degrees of distraction of the interspinous processes lead to different load distribution on the intervertebral disc. The implant tested is not appropriate in cases of serious spinal stenosis because of the contradiction that, while over-distraction of the interspinous processes decreases the posterior annulus and the zygapophyseal joints load and distracts the intervertebral foramina, it leads to a marked increase in the load of the anterior annulus, which is recognized to accelerate disc degeneration ⁵⁾.