InterLaminar Decompression and Instrumentation

Posted on September 21, 2017 | by Dr. Shim

Spinal stenosis is a very common problem afflicting many people after the age of 60. It should not be considered a disease, but rather a normal process of aging.

The degenerative cascade is the process by which the disk degenerates or collapses. Because of the collapse, the facet joints of the posterior spine rub abnormally against each other, causing the bone to enlarge. For my older patients, many of you will find that the joints of your fingers have enlarged over time. That is the same process. The bones rub against each other, causing wear of the cartilage. The bone responds to the pain on the cartilage by enlarging the surface area between the bones. This enlargement is the development of the widening bones. In the spine, this enlarging of the bones will cause pressure on the nerves that travel through the spine. That is the so called “bone spur”, pinching the nerve. In addition, as the disks collapse, the rims of the disk naturally bulge out. Some of the bulging can cause some narrowing of the space for the nerve. The final cause of spinal stenosis is secondary to the effects of the narrowing of the space by the disks. There are ligaments called the ligamentum flavum that are normally stretched between the bones of the spine. With narrowing of the disks, these ligaments are no longer stretched or taut. It will cause a shortening, and widening or hypertrophy of the ligament. This widened ligament can also contribute to the narrowing of the space for the nerve.

Degenerative spinal stenosis is usually a combination of the bone spurs, the narrowing of the disk, and the widening of the ligaments covering the spinal nerve.

Traditional treatments for spinal stenosis included activities modification, NSAID medications and exercise. Recent studies have not demonstrated a usefulness of epidural steroid injections for these patients, though many still request the injection.

Surgical options depend on many factors, and not all patients are candidates for surgery. In general, the main goal of surgery was to remove pressure on the nerves. In certain situations, there is an instability component that necessitates fusion along with removing pressure on the nerve.

In the past 10 years, there has been more and more interests in so called interspinous ligament devices. The rationale is that a device designed to stretch the ligaments, and restore some of the disk height may relieve the spinal stenosis pressure. The devices have had some success, but some patients will still require formal surgery to directly remove pressure on the nerve.

As these concepts evolved, an interlaminar device called the Coflex, from Paradigm spine has been studied for efficacy. The concept is relatively simple. A more traditional limited removal of bone and ligaments off the nerve is performed. then a U shaped device is placed in between the spinous processes, thus achieving some of the height restoration, facet off loading, and opening of the foramen. In addition, secondary to the more traditional laminectomy/laminotomy, the surgeon has direct visualization of the nerves being relieved of pressure.

In my experience, for the properly selected patient, this is a very reasonable option for patients with localized spinal stenosis and with low grade instability.

The procedure can be done on an outpatient basis for select patients. There is no fusion associated with this technique.