Interspinous process devices in the lumbar spine.

A growing number of interspinous process devices have been introduced to the lumbar spine implant market. Implant designs vary from static spacers to dynamized devices. Furthermore, they are composed of a range of different materials including bone allograft, titanium, polyetheretherketone, and elastomeric compounds. The common link between them is the mechanical goal of distracting the spinous processes to affect the intervertebral relationship. In contrast, the purported clinical goals are more variable, ranging from treatment of degenerative spinal stenosis, discogenic low back pain, facet syndrome, disk herniations, and instability. Though some clinical data exist for some of these devices, defining the indications for these minimally invasive procedures will be crucial. Indications should emerge from thoughtful consideration of data from randomized controlled studies.