Low Endurance Testing of a Spinous Process Spacer

Lumbar neurogenic claudication secondary to spinal stenosis causes narrowing of the spinal canal that contributes to extremity lower back pain. Lumbar extension, as seen in standing and walking, exacerbates symptoms by decreasing the foraminal height, width, and area, whereas flexion, as seen in sitting, improves symptoms by increasing the cross-sectional area of the foramen. Interspinous process devices have been developed to treat symptomatic lumbar stenosis [1]. The device is placed between the spinous processes and serves to limit the amount of extension that can occur beyond a neutral alignment. The objective of this study was to perform low endurance cyclic tests on the In-Space spinous process spacer (Synthes Spine) to assess fixation and containment in a human cadaveric spine model in vitro. The device was cyclically tested under an alternating sequence of combined loading conditions using a new protocol developed on a robotic based spinal testing system (Spine Robot).