Middle-aged and older patients commonly present with neurogenic claudication, the classic nerve-related radiating leg and buttock pain caused by lumbar spinal stenosis. Imaging will typically show degenerative factors, including the narrowing of the midline sagittal spinal canal and possibly also narrowing between the facet superior articulating process, the posterior vertebral margin and nerve root canal.
The narrowing and compression of spinal stenosis is believed to cause leg, buttock and groin pain for about 1.2 million Americans. Those who experience mild or moderate symptoms typically have pain that is relieved in flexion, when they sit or walk bent forward, such as while leaning on a supermarket cart.
Some patients do well with conservative treatment of their condition. For those who do not gain relief from several months of a physical therapy regimen and/or pain medications, surgery is often the next option. Until recently, that often meant a laminectomy, or decompression, to remove the bone and soft tissue pressing on nerves and sometimes a spinal fusion procedure as well.
At Abington Memorial Hospital, we are now participating in a clinical trial of a device that offers a potential alternative to traditional spinal surgery for moderate lumbar spinal stenosis. Instead of the large incision and tissue removal of a laminectomy, we use a minimally invasive technique and one-centimeter incision to insert the Superion ™ Interspinous Spacer (ISS) from VertiFlex® Inc. The device, which is not yet approved by the FDA, is available only on study in the United States at about two dozen sites, including Abington. The Superion ISS is already in use in Europe and South America, and has been implanted in more than 950 patients worldwide.
The current clinical trial being conducted at Abington compares the safety and effectiveness of the Superion ISS to the X-STOP® Interspinous Process Distraction® Device, an FDA-approved device. Because the study is randomized, patients do not know which device they have received until after surgery. However, regardless of which arm they are assigned to, patients participating in the trial will receive one of the two interspinous devices. They will not receive either a laminectomy or fusion.
Designed to act as a support column, the Superion ISS is implanted between the spinous processes to open the passageways through which the nerve roots travel from the lumbar spine to the legs. The small device, about the size of a quarter, gives us the potential to stabilize the affected location, relieve patients’ chronic leg pain and enable them to move without significant restriction while preserving their natural anatomy. If indicated, two devices can be implanted to support two levels. The device is titanium-based, so it is not likely to pose limitations on post-operative studies, such as MRIs.
To be eligible for the study, patients (male or female) must be 45 years or older, with a diagnosis of moderate degenerative lumbar spinal stenosis and symptoms that have been unresponsive to conservative care for at least six months. Patients will be excluded if they have significant peripheral neuropathy, morbid obesity, osteoporosis, insulin-dependent diabetes mellitus, prior surgery of the lumbar spine, or other criteria that may be assessed upon examination. The study and devices are not appropriate for patients with severe spinal stenosis.
The study will help us determine whether patients will see a dramatic reduction in their physical limitations and greatly improve their abilities to walk or stand for long periods with a significant lessening of pain. These benefits can help restore them to more active and independent lives, which is what we hope for all of our patients.
Guy A. Lee, MD is Co-director, Orthopaedic Residency Program, Orthopaedic Surgery at Abington Memorial Hospital. To refer a patient, please call Abington Memorial Hospital’s Human Motion Institute at 215-830-8700, extension 3121.