THE GROWTH OF THE LUMBAR VERTEBRAL CANAL

Study Design. This study examines the growth and development of the lumbar spinal canal with emphasis on early life. Objective. Changes in dimensions of the canal were investigated throughout life. Summary of Background Data. Seven hundred and fifteen lumbar vertebrae were examined from the Spitalfield Collection of Skeletons at the Natural History Museum, London. Methods. Unmagnified silhouette pictures were taken of the canals with a specially designed photographic box. Computerized image analysis provided the accurate measurements. Results. Regarding the midsagittal diameter and the cross-sectional area, the cranial four lumbar vertebrae were already fully matured in infants. At L5 there was significant increase up to 4 years of age when the midsagittal diameter was even larger then in the adult. The interpedicular diameter significantly increased at L1 until 10 years of age, at the other levels until adulthood, as did the perimeter at L4 and L5 until 14 years of age. The shape of the canal was assessed by measuring the circularity, the 'trefoilness' and the situation of the centroid. The first measurement significantly decreased with age, the trefoilness increased until adulthood, and the centroid of the canal approached the vertebral body. In spines with spina bifida occulta the lumbar canal was significantly larger proximal to the lesion than in the unaffected spines. Conclusion. The lumbar spinal canal exhausts its growth potential by infancy as regards the midsagittal diameter and the cross-sectional area. Thus, in the case of delayed development, it is not capable of catch-up growth.