Study Design. Computed tomography–based anatomical study.
Objective. To study the secular changes in lumbar spinal canal dimensions.
Summary of Background Data. Development of symptomatic lumbar spinal stenosis, among other factors, is related to the dimensions of the bony canal. The canal reaches its adult size early on in life. Several factors, including protein intake, may influence its final dimensions. As with increases in human stature from improvements of socioeconomic conditions, we hypothesized that adult bony canal size has also grown larger in recent generations.
Methods. This study analyzes computed tomographic reconstructions from 184 subjects performed for either trauma (n = 81) or abdominal pathologies (n = 103) and born either between 1940 and 1949 (n = 88) or 1970 and 1979 (n = 96). The cross-sectional area of the bony canal was digitally measured at the level of the pedicle (i.e., at a level not influenced by degenerative changes) for each lumbar vertebra. Intra- and interobserver reliability was assessed.
Results. Intra- and interobserver measurement reliability were excellent (interclass correlation coefficient = 0.87) and good (interclass correlation coefficient = 0.61), respectively. Contrary to our hypothesis, the 1940–1949 generation patient group exhibited larger lumbar canals at all levels as compared with the 1970–1979 group. Statistically this difference was highly significant (P < 0.001) and particularly pronounced in the trauma subgroup.
Conclusion. Given that human stature evolution has stabilized and adult height is established during the first 2 years of long bone growth, it is possible that antenatal factors are responsible for this surprising finding. Maternal smoking and age may be possible explanations. This finding may have significant implications. An increasing number of patients may emerge with lumbar spinal stenosis as degenerative changes develop, putting a strain on health resources. Further studies in different population groups and countries will be important to further confirm this trend.
Level of Evidence: 3
We studied cross-sectional area of the lumbar spine at pedicle level in 2 different groups of patients using computed tomography. The groups were born either in the 1940–1949 or the 1970–1979 periods. We found highly statistically significant differences; the younger subjects having smaller canals at pedicle level. This difference could be secondary to maternal age and smoking habit changes.
*Department of Orthopedics, Centre Hospitalier Universitaire Vaudois (CHUV), and the University of Lausanne, Lausanne, Switzerland and Spine Unit, Clinic Cecil, Lausanne, Switzerland
†Medical School, University of Lausanne, Lausanne, Switzerland
‡Burier Gymnasium, La Tour-de-Peilz, Switzerland; and Departments of
¶Orthopedics, Centre Hospitalier Universitaire Vaudois (CHUV) and the University of Lausanne, Lausanne, Switzerland.
Address correspondence and reprint requests to Constantin Schizas, MD, FRCS, Neuro-orthopaedic Spine Unit, Clinique Cecil, Lausanne, Switzerland; E-mail: firstname.lastname@example.org
Acknowledgment date: October 14, 2013. First revision date: April 25, 2014. Second revision date: May 12, 2014. Acceptance date: May 20, 2014.
The manuscript submitted does not contain information about medical device(s)/drug(s).
No funds were received in support of this work.
Relevant financial activities outside the submitted work: grants.