Interspinous Spacing Devices

KEY FACTS

Terminology

• Synonyms: Interspinous posterior decompression, interspinous distraction device, interspinous spacer device (ISD), interspinous implant

• Dynamic stabilization alters movement & load transmission of spinal motion segment without fusion of segment

• Interspinous spacing device places stenotic segment in slight flexion while preventing extension

Imaging

• Radiographs & CT helpful to evaluate interspinous location

  • Assess for fractures

Pathology

• Lumbar neurogenic claudication symptoms are exacerbated during extension, relieved during flexion

  • Dimensions of canal & foramen ↑ in flexion, ↓ in extension

  • Facet loading ↑ during extension, ↓ during flexion

Clinical Issues

• ISD helpful for treatment of spinal stenosis with neurogenic claudication

  • Causes focal flexion at applied level, resulting in increased canal & foramen dimensions

• Complications

  • ISD malposition, migration, dislocation, spinous process fracture

• Indications

  • Lumbar stenosis ± facet joint hypertrophy & subarticular recess stenosis, foraminal stenosis

  • 1- to 2-level lumbar stenosis from L1-L5 in patients with at least moderate impairment in function

• Patients anatomy may influence outcomes

  • Decreased accessible distance between laminospinous plane and tip of spinous process

• Osteoporosis is contraindication