Commentary & Perspective on
"A Comprehensive Study of Patients with Surgically Treated Lumbar Spinal Stenosis with Neurogenic Claudication"
by Yasutsugu Yukawa, MD, et al.

Commentary & Perspective by
Choll W. Kim, MD, PhD, and Steven R. Garfin, MD*,
Department of Orthopaedic Surgery,
University of California, San Diego, La Jolla, CA

Spinal stenosis is closely linked with advancing age. With the increasing age of the population, the prevalence of spinal stenosis and other comorbid conditions is expected to increase concurrently. Neurogenic claudication manifests with pain and weakness in the back and leg, causing difficulty in ambulation. Other diseases, including vascular claudication and degenerative joint disease as well as general physical deconditioning, may have a similar presentation. The combination of these factors among our elderly population will lead to a greater difficulty in performing the activities of daily living and self-care. Methods to identify the causes of decreased ambulatory ability are crucial in caring for this group of patients.

In an extension of a previous study involving thirty-two patients¹, Yukawa et al. evaluated the outcome of surgery in sixty-two patients with lumbar spinal stenosis and neurogenic claudication in a prospective, nonrandomized longitudinal study. All patients were assessed preoperatively with use of the Oswestry Disability Index and a visual analog pain scale. In addition, both treadmill and bicycle exercise testing provided more objective measures of disability. All sixty-two patients underwent posterior decompressive surgery, with most (74%) also having a posterolateral arthrodesis of the spine with instrumentation. Spinal arthrodesis was reserved for patients with preoperative spinal instability (defined as spondylolisthesis greater than or equal to 5mm in the sagittal plane or as any angular malalignment of greater than or equal to 10° between vertebrae in the coronal plane). All objective and subjective functional and pain assessments were repeated postoperatively at various intervals. The minimum follow-up was two years, and the average follow-up was 3.8 years (range, two to seven years). The main findings were that nearly all (93.5%) of the patients had a positive result on the treadmill exercise test preoperatively compared with 9.7% postoperatively, a significant improvement (p < 0.05). Yukawa et al. also made the following observations: treadmill testing was more sensitive to the patients' symptoms than was bicycle testing; the degree of stenosis seen on imaging studies did not correlate with the degree of disability; and patients treated with arthrodesis had better outcomes in comparison with those treated with decompressive surgery alone. The authors concluded that the treadmill test was a good tool for detecting neurogenic claudication and that surgical treatment for patients with a positive result on treadmill exercise testing led to significant improvement in pain and function (p < 0.05).

These results agree with those in numerous reports², which shows that surgical treatment of lumbar spinal stenosis provides substantial improvement in pain, function, and overall patient satisfaction. In a prospective, randomized study of a subset of thirty-one patients, Amundsen et al.³ showed that surgical decompression led to superior results. Although the method of evaluation was less rigorous than that used by Yukawa et al., they found that 92% of the patients who were treated surgically had a good result compared with 47% of the patients treated nonoperatively. In a prospective, randomized study involving patients with lumbar stenosis but without instability or deformity, Grob et al.⁴ further showed that arthrodesis provided no added benefit to patients who had undergone decompression surgery alone. However, if there was spinal instability, such as occurs with degenerative spondylolisthesis, Herkowitz and Kurz⁵ showed in their randomized, prospective study that arthrodesis used adjunctively afforded outcomes superior to those obtained with decompressive laminectomy alone. The findings by Yukawa et al. correspond well with those of these other prospective, randomized studies.

An important contribution of this work is the rigorous evaluation of function before and after surgery. The treadmill exercise testing provided a method of quantifying the patient's walking capacity. This outcomes measure could be an important tool for assessing the efficacy of various treatments. It is not, however, a useful diagnostic tool by itself. Many medical conditions can lead to a positive result on the treadmill exercise test. Vascular disease, arthritic conditions, and generalized weakness may also affect walking capacity. In this study, patients with peripheral vascular disease or severe cardiopulmonary or musculoskeletal conditions that would limit their exercise capacity during functional testing were excluded. Treadmill exercise testing may be a useful diagnostic tool only if used in conjunction with other measures, including bicycle exercise testing.

In summary, Yukawa et al. have described a rigorous, quantitative method of assessing disability due to spinal stenosis. The validity of their study is supported by previous work demonstrating that surgical treatment leads to significant improvements in patient satisfaction and overall health outcomes. Investigators who wish to assess alternative treatment modalities, such as controlled physical therapy programs, epidural steroid injections, and other surgical regimens (e.g., minimally invasive techniques) should consider including the treadmill exercise protocol in their pre- and post-treatment functional assessments.

*The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

References

1. Tenhula J, Lenke LG, Bridwell KH, Gupta P, Riew D. Prospective functional evaluation of the surgical treatment of neurogenic claudication in patients with lumbar spinal stenosis. J Spinal Disord. 2000;13:276-82.
2. Garfin SR, Rauschning W. Spinal stenosis. Instr Course Lect. 2001;50:145-52.
3. Amundsen T, Weber H, Nordal HJ, Magnaes B, Abdelnoor M, Lilleas F. Lumbar spinal stenosis: conservative or surgical management?: A prospective 10-year study. Spine. 2000;25:1424-35; discussion 1435-6.
4. Grob D, Humke T, Dvorak J. Degenerative lumbar spinal stenosis. Decompression with and without arthrodesis. J Bone Joint Surg Am. 1995;77:1036-41.
5. Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am. 1991;73:802-8.