Interspinous Spacers for Spinal Stenosis Part 2

Dr. Manfrè reviews his technique for interspinous spacer placement. He uses local anesthesia which he administers with a spinal needle. He adjusts the angulation and entry point using CT, then inserts the guide wire. When he has it positioned between two spinous processes, and when the wire abuts the facet, this is the end point of the guide wire. He then uses soft tissue dilators through a 5mm incision before placing a spacer over the spacer delivery system. He usually places 8-12mm spacers, occasionally using 14mm spacers.

One of the main pitfalls that happens when placing spacers is oversizing. Dr. Manfrè believes that this is a more common phenomenon in open surgical decompression due to patient placement in the operating room. Patients are often placed prone with a pillow beneath their abdomen to flex the lumbar spine and aid in exposure and insertion of spacers. However, this causes measurements to be greater than they are in natural spine mechanics.

Next, we discuss the historical idea that interspinous spacers induce an unnatural lumbar kyphosis. New research suggests this is not the case. In fact, spacers restore the natural alignment of the spine without inducing kyphosis. Additionally, in patients with stenosis at multiple levels, the addition of a spacer at the worst level improves the morphology of the entire spine. He usually only places one spacer for his patients, and rarely will place two. New unpublished research by Dr. Manfrè on upright MRI shows that spacers placed for patients with spinal stenosis cause expansion of the dural sac by up to 70% by the next day. What’s more, in patients with both stenosis and listhesis, placement of a fusion spacer to correct both the stenosis and the instability result in disappearance of listhesis on MR the day after the procedure.