L-58-062-09-fig02.tif
Fig. 1 Sagittal T2-weighted MRI study showing severe lumbar spinal stenosis. Reproduced from Daffner SD, Wang JC: The pathophysiology and nonsurgical treatment of lumbar spinal stenosis. Instr Course Lect 2009;58:657-668.

AAOS Now

Published 5/1/2011
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A. Nick Shamie, MD

Lumbar spinal stenosis: The growing epidemic

Lumbar spinal stenosis (LSS) is a common condition that occurs in the aging spine of individuals beyond their fifth decade of life (Fig. 1). Most patients who undergo surgical intervention for LSS are in their sixth and seventh decades of life.

The incidence of LSS in the United States has been estimated at 8 percent to 11 percent of the population. As the “baby boomers” age, an estimated 2.4 million Americans will be affected by LSS by 2021. With the first wave of baby boomers just qualifying for Medicare, this condition will undoubtedly have an impact on government healthcare spending. The adjusted rate of lumbar stenosis surgery per 100,000 Medicare beneficiaries was 137.4 in 2002 and 135.5 in 2007; these numbers are expected to double in the coming years due to the increased numbers of older adults.

The current accepted treatment algorithm for LSS begins with nonsteroidal anti-inflammatory drugs and narcotics, physical therapy, and pain management modalities such as epidural steroid injections. Over the long term, 15 percent of patients will improve with nonsurgical modalities, and 70 percent will continue to experience neurogenic claudication. Therefore, most patients with LSS will, in time, require surgical intervention for a more definitive treatment.

Pain management
Current trends suggest that the numbers of pain medicine prescriptions and interventional pain management procedures are increasing. From 1997 to 2005, the cost of pharmaceuticals, outpatient procedures, and inpatient procedures for treatment of neck and back pain increased by 171 percent, 74 percent, and 25 percent respectively. Although the cost of pharmaceuticals and outpatient procedures (mostly interventional pain procedures) have increased more than the cost of surgical procedures, media reports continue to focus on surgery as a contributor to increasing costs.

Oversight on the amount of prescription medication used or interventional procedures performed on patients with LSS is limited. Furthermore, most spine surgeons don’t perform lumbar epidurals themselves; when they refer patients to pain management colleagues, surgeons lose control of the treatment regimen for patients.

Many patients who are fearful of surgical intervention are resorting to nonsurgical modalities for temporary relief, irrespective of the often limited results. The media has also been very critical of the number and types of spinal surgeries being performed in the United States. Most articles focus on surgeons who perform unnecessary surgeries with costly spinal implants and undoubtedly have an impact on patients’ decision-making.

Other interventions
Numerous studies have shown that surgical intervention has a higher success rate in treating LSS compared with nonsurgical modalities. SPORT (Spine Patient Outcomes Research Trial), a large prospective randomized clinical trial, compared surgical and nonsurgical treatment for LSS. Although the statistical methods used to analyze the data were criticized, SPORT clearly showed that surgery is superior to nonsurgical treatment of LSS at 2 years. But this does not necessarily mean that nonsurgical modalities should not be offered or that surgery should be the first line of treatment for LSS.

Most surgeons would agree that epidural injections provide some benefits for patients. A subset of patients may even obtain long-term relief and avoid surgery. In addition, the patient and the surgeon will learn more about each other during a period of conservative treatment. If a more conservative approach is unsuccessful, patients are more comfortable considering their surgical options. Three to six months of nonsurgical care prior to surgical intervention is standard for the treatment of LSS.

Taking care of spinal stenosis patients requires a comprehensive approach utilizing the expertise of surgeons, pain management specialists, physical therapists, and others. However, at times, differences in philosophy can be found between the surgeons and other specialists taking care of these patients. As an example, when a pain specialist was recently asked how many times a procedure could be repeated if the patient’s pain returns, he answered, “Ad infinitum.” Compare this philosophy with orthopaedic principles that support using progressive treatment modalities that not only relieve symptoms but also permanently address the condition. Surgeons should therefore ask patients to return for a follow-up after one or two epidural steroid injections or few session of physical therapy to maintain communication and assess progress.

If injections do not bring relief, discussing next steps with the patient is important. Patients who are in severe pain often are willing to try any procedure that they are offered; a discussion with a surgeon is critically important, especially if surgical intervention can finally offer the patient definitive treatment for his or her neurogenic claudication from LSS.

Surgical intervention
But how successful is surgery for treatment of LSS, and what type of surgery is most effective? The controversy over spine surgery for treatment of “back pain” generally centers on fusion surgeries for treatment of discogenic back pain or back pain without buttock or leg pain. LSS patients rarely complain solely of back pain; their most common complaint is buttock and leg pain.

Decompression and laminectomy for treatment of LSS symptoms show consistently good to excellent results. The data from SPORT also support the benefits of surgery. The Maine Lumbar Spine Study shows that 80 percent of patients are happy with their surgical results 8 to 10 years after surgery.

The longer patients are followed, however, the less successful the results become. This is partly due to the progressive nature of spinal degeneration. The same vertebral level can progress with further foraminal stenosis (when the level is not fused) or symptomatic stenosis can develop in untreated levels.

This progression of disease is not unique to the spine and does not define treatment failure. For example, patients who have bypass grafts or stenting for coronary artery disease may have re-stenosis of the same vessels or additional coronary arteries following a successful surgery. It is, however, important to differentiate between “back pain” and LSS when discussing the results of spine surgery.

Fusion remains an important part of the spine surgeon’s armamentarium. When used judiciously with good indications, it offers patients significant benefits. Several studies have shown that patients undergoing laminectomy for treatment of LSS have better functional improvement when they have concomitant posterolateral fusion. Use of internal fixation increases fusion rates and further improves patient outcomes, especially when patients are followed long term (beyond
5 years postoperative).

When the main indication for performing spine surgery is to decompress the nerves in the spine, the results are good—whether or not fusion surgery is performed. Fusion is indicated when inherent instability, iatrogenic instability, or a need to correct a deformity exists. Inherent instability can be seen on preoperative dynamic films. Spine surgeons who attempt to decompress the nerves to the best of their ability often have to remove so much bone that the spine is rendered unstable and requires stabilization.

A more controversial goal of fusion surgery is to stop or retard the progression of degeneration at the operative level. This remains a controversial indication, with conflicting results.

Laminectomy surgery is not without its complications. Nerve injury, dural tears, and postoperative epidural hematoma resulting in paralysis have all been reported.

Elderly patients with LSS may be more attracted to less invasive surgeries such as the use of tubular retractors to target the stenotic level(s) with minimal injury to the surrounding soft tissues. This approach may speed recovery, but minimally invasive surgery should not equate to minimal treatment for the patient. If tubular retractors limit the surgeon’s visualization, resulting in inadequate decompression, the patients haven’t benefitted from the smaller incisions.

The most recent addition to the LSS treatment armamentarium are interspinous devices. These devices can be implanted with local anesthesia and without the need to remove bone or soft tissue. They pose no serious risk (nerve or dural injury) to the patient and are more effective than epidural steroid injections, with a 60 percent to 70 percent success rate at 4 years after implantation. Patient selection, however, is an important determinant of success.

Less invasive interspinous devices are being investigated. One such device is now in a clinical trial comparing its success to that of current devices on the market.

Conclusion
LSS will remain an important part of a spine surgeon’s surgical practice. With the growing elderly population, surgeons need to remain focused on the patient’s needs and their individualized indications for the various treatment options. A customized treatment plan for each patient provides optimal results. Technological advances enable some qualified patients to be treated with less invasive surgical options.

Disclosure information: Dr. Shamie—Seaspine; Medtronic; SI Bone; Biomet; Vertiflex; American College of Spine Surgery

A. Nick Shamie, MD, is a member of the AAOS Communications Cabinet and an associate professor at the University of California Los Angeles, specializing in spine surgery. He can be reached at shamiemd@ucla.edu