On "A New Evaluation Method for Lumbar Spinal Instability ..." Kasai et al. Phys Ther. 2006;86:1661-1667.

After performing a critical analysis on the article by Kasai et al, (1) we had some comments we would like PTJ and the authors to consider.

Typically, studies of this type include a table of subject demographics, such as height, weight, body mass index, and so on. This information allows readers to determine the applicability of a test to their own patient population. The publication of this information would be helpful.

The concept of lumbar instability remains controversial, with widely varying levels of definition and clinical relevance in the medical literature. In fact, Groopman (2) argued that "spinal instability" is a term used to justify an operation. Kasai and colleagues (1) attempted to define instability based on the widest of 3 proposed radiographic standards reported in the literature. It is unclear whether these radiographic measures reflect clinical signs and symptoms of lumbar instability, or what use they have in patient management.

Despite this fact, the investigators concluded that "... the data from the PLE [passive lumbar extension] test for subjects with lumbar degenerative diseases can be very useful for determining treatment strategy, that is, whether to provide conservative treatment with a corset or to perform procedures such as spinal fusion." (1) A "corset" is more suggestive of a Civil Warera undergarment than a 21st century musculoskeletal management strategy. Because this article was published in our professional journal, we were struck by the absence of any reference to current best evidence on the management of lumbar instability, (3) which includes physical therapy intervention as an appropriate management strategy. We are excited about the new changes in PTJ, and, in keeping with the quality of the Journal and what it represents to our profession, we would welcome the addition of this information in an author response.

Kevin Baker, Jason Rodeghero, Hanni Cowley, Albert Bone

K Baker, PT, MSR, FAAOMPT, [e-mail]

J Rodeghero, PT, DPT, OCS, MTC, ATC

References

(1) Kasai Y, Morishita K, Kawakita E, et al. A new evaluation method for lumbar spinal instability: passive lumbar extension test. Phys Ther. 2006;86:1661-1667.

(2) Groopman J. A knife in the back: is surgery the best approach to chronic back pain? New Yorker. April 8, 2002.

(3) O'Sullivan PB, Phyty GD, Twomey LT, Allison GT. Evaluation of specific stabilizing exercises in the treatment of chronic low back pain with radiologic spondylolysis or spondylolisthesis. Spine. 1997;22:2959-2967.

[DOI: 10.2522/ptj.2007.87.6.812.1]

Author Response

We have reported the passive lumbar extension test to be an effective method, with high sensitivity and specificity, on the basis of the results of this test after radiological classification of the subjects into lumbar spinal instability--positive and lumbar spinal instability--negative groups. (1) Our results indicate that, for patients with positive lumbar spinal instability, wearing a corset (the term "bracing" may be more suitable) or spinal fusion to stabilize the spine may be an effective intervention to improve clinical symptoms such as low back pain, because lumbar spinal instability is likely to be strongly related to these clinical symptoms.

In our study, height, body weight, and body mass index (mean [+ or -] SD) for the lumbar spinal instability--positive and lumbar spinal instability-negative groups were 159.2 [+ or -] 7.9 cm and 162.3 [+ or -] 8.4 cm, 57.2 [+ or -] 10.3 kg and 58.3 [+ or -] 11.7 kg, and 22.5 [+ or -] 4.1 and 22.1 [+ or -] 4.4, respectively. There was no significant difference between the 2 groups, although the lumbar spinal instability-positive group had slightly lower values for height and body weight than the lumbar spinal instability-negative group, because the lumbar spinal instability-positive group had a slightly higher male:female ratio than the lumbar spinal instability-negative group.

In 1985, Kirkaldy-Willis (2) organized a symposium on lumbar spinal instability, with several articles published in Spine. In the more than 20 years since then, many studies of spinal biomechanics have been performed, with an accumulation of various clinical findings; however, no consensus has yet been reached on the definition, classification, clinical symptoms, and evaluation methods for lumbar spinal instability. The reasons may stem from the existence of instability that is accompanied by radiologic evidence and clinical symptoms, instability that is not accompanied by radiologic evidence but that is accompanied by clinical symptoms, and so on. Imaging examinations are valuable in some cases but not in all, resulting in confusing discussion among specialists. The evaluation methods for lumbar spinal instability that have been reported by Hicks et al (3) include painful arc in flexion, instability catch sign, painful catch sign, Gower sign, posterior shear test, prone instability test, apprehension sign, passive accessory intervertebral motion test, and passive physiological intervertebral motion test. The presence of so many tests for lumbar spinal instability suggests the ambiguity surrounding this disorder.

At present, functional (flexion-extension) radiography of the lumbar spine seems to be the most practical method for the evaluation of lumbar spinal instability. Therefore, we believe that it is important to conduct a patient interview for clinical symptoms such as pain and a clinical examination for patients who have radiographically apparent instability to accumulate scientifically reliable evidence. From this point of view, we have conducted a study of the passive lumbar extension test, which yielded the conviction that this test can be of some help for the diagnosis and management of lumbar spinal instability. (1)

Yuichi Kasai, Koichiro Morishita, Eij Kawakita, Tetsushi Kondo, Atsumasa Uchida

Y Kasai, MD, is Associate Professor, Department of Orthopaedic Surgery, Mie University Graduate School of Medicine, Tsu City, Mie Prefecture, Japan. Address all correspondence to Dr Kasai at: [e-mail]. mie-u.ac.jp.

References

(1) Kasai Y, Morishita K, Kawakita E, et al. A new evaluation method for lumbar spinal instability; passive lumbar extension test. Phys Ther. 2006;86:1661-1667.

(2) Kirkaldy-Willis WH. Presidential symposium on instability of the lumbar spine. Spine. 1985;10:245.

(3) Hicks GE, Fritz JM, Delitto A, Mishock J. Interrater reliability of clinical examination measures for identification of lumbar segmental instability. Arch Phys Med Rehabil. 2003;84:1858-1864.

[DOE 10.2522/ptj.2007.87.6.812.2]