Study Design. Epidemiological analysis using CTs.
Objective. To investigate the true incidence of lumbar spondylolysis in the general population in Japan.
Summary of Background Data. Although there have been several reports on the incidence of lumbar spondylolysis, they had some weakness. One of them concerns the subjects investigated, because the incidence of lumbar spondylolysis varies considerably, and some patients are asymptomatic. In addition, most of the past studies used plain radiograph films or skeletal investigation. Therefore, the past reported incidence may not correspond to that of the general population.
Methods. We reviewed the computed tomography (CT) scans of 2000 subjects (age: 20–92 years) who had undergone abdominal and pelvic CT on a single multidetector CT scanner for reasons unrelated to low back pain. We reviewed them for spondylolysis, spondylolytic spondylolisthesis, and spina bifida occulta (SBO) in the lumbosacral region. The grade (I–IV) of spondylolisthesis was measured using midsagittal reconstructions.
Results. Lumbar spondylolysis was found in 117 subjects (5.9%). Their male-female ratio was 2:1. Multiple-level spondylolysis was found in 5 subjects (0.3%). Among these 117 subjects, there were 124 vertebrae with spondylolysis. Of them, 112 (90.3%) corresponded to L5, and 26 (21.0%) had unilateral spondylolysis.
SBO was found in 154 subjects. Of them, 25 had spondylolysis (16.2%), whereas, in 1846 subjects without SBO, 92 had spondylolysis (5.0%). The incidence of spondylolysis among the patients with SBO was significantly higher than that in subjects without SBO (Odd ratio was 3.7-fold).
Of 124 vertebrae with spondylolysis, 75 (60.5%) showed low-grade (Meyerding grade I or II) spondylolisthesis, and no subject presented high-grade spondylolisthesis. Spondylolisthesis was found in 74.5% of the subjects with bilateral spondylolysis, and in 7.7% of those with unilateral spondylolysis.
Conclusion. The incidence of lumbar spondylolysis in the Japanese general population was 5.9% (males: 7.9%, females: 3.9%).
To investigate the true incidence of lumbar spondylolysis in the general population, we reviewed the computed tomography scans of 2000 subjects who had undergone abdominal and pelvic computed tomography for reasons unrelated to low back pain. The incidence of lumbar spondylolysis in the Japanese general population was 5.9% (males: 7.9%, females: 3.9%).
From the Departments of *Orthopedics and †Radiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
Acknowledgment date: February 18, 2009. Revision date: March 17, 2009. Acceptance date: March 17, 2009.
The manuscript submitted does not contain information about medical device(s)/drug(s).
Other funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Supported by JOA-Subsidized Science Project Research 2006-2.
Address correspondence and reprint requests to Natsuo Yasui, MD, 3–18–15 Kuramoto-cho, Tokushima 770–8503, Japan; E-mail: firstname.lastname@example.org