Morphometric Study of Pedicles of Lumbarnvertebrae – A Cross-Sectional Study

Abstract

Background and objectives The pedicles offer the strongest points of attachment to the spine. Most spinal instrumentation systems use screws for fixation placed into the pedicle. The screw design, details, biomechanics and implantation safety depend upon the anatomic constraints, especially the morphometry of pedicles. The objectives of the present study were to provide morphometrical data support for successful pedicle screw fixation and also to analyse the quantification of spinal stenosis directly relevant to Belgaum region. Methods Twenty five sets of normal, adult, dry lumbar vertebrae were studied for their dimensions ( height, width and length of the pedicles, mid-sagittal diameter and interpedicular distance ) with the help of Vernier caliper. The material for the study that is total of 125 lumbar vertebrae were obtained from 25 cadavers from the Department of Anatomy, Jawaharlal Nehru Medical College, Belgaum. The study was conducted during a period of one year from January 2007 to December 2007. Results The following readings ( Mean ± Standard Deviation) were obtained for different dimensions of lumbar vertebrae L 1 , L 2 , L 3 , L 4 and L 5 respectively. VIII  Height of the pedicle: 19.5 ± 2.89, 18.4 ± 3.74, 18.1 ± 3.21, 17.7 ± 2.51 and 18.7 ± 3.08.  Width of the pedicle: 10.7 ± 2.03, 12.8 ± 2.73, 13.4 ± 2.66, 14.9 ± 2.51 and 20.9 ± 3.36.  Length of the pedicle: 15.5 ± 2.69, 15.8 ± 2.75, 16.1 ± 2.91, 14.2 ± 2.84 and 13.6 ± 2.05.  Mid-sagittal diameter: 18.3 ± 2.86, 16.2 ± 3.26, 16.0 ± 3.32, 17.8 ± 3.12 and 18.1 ± 2.99.  Interpedicular distance: 22.5 ± 3.46, 22.9 ± 3.14, 24.8 ± 3.22, 24.9 ± 3.47 and 27.1 ± 4.01. Conclusions and interpretation The morphometrical data obtained in our study would be helpful for the surgeons dealing with the transpedicular fixation in selecting the largest fully threaded screw that can be safely accommodated by the pedicle. The data would also come handy to the clinicians dealing with the problem of low backache and in diagnosis of spinal stenosis. The present study concludes that, the different dimensions of the lumbar pedicle morphometry which have been studied would be of help for successful pedicle screw fixation with minimum post-operative complications and also for quantification of spinal stenosis, specifically relevant to this region of Belgaum city