Interspinous Spacers in the Lumbar Spine

Recently, a new class of spinal devices called interspinous spacers (ISPs) has been introduced. A number of designs have been developed, which vary from non-compressible metallic spacers to compressible cushion-like devices. Following the path of other spinal devices, they are composed of materials ranging from allograft bone, titanium alloy, polyetheretherketone (PEEK), and elastomeric preparations. Though they are unique in their details, they share the common mechanical goal of effecting distraction between adjacent spinous processes, whereby they block intervertebral extension at that level. The proposed indications for ISPs include degenerative spinal stenosis, discogenic low-back pain, facet syndrome, disc herniations, and non-traumatic instability.