Morphometric Evaluation of the Thoracic Vertebral Pedicle: A Cadaveric Study

The present study was conducted to provide base line data of the thoracic pedicle using macerated vertebrae bones. One hundred and eighty thoracic vertebrae were studied by direct measurements for linear dimensions of the Mid- Pedicle Width, Pedicle Length, and Pedicle Height in 15 human cadavers using a digital Vernier calliper with accuracy of 0.05mm. SPPSS ANOVA and Turkey Post Hoc multiple comparison tests were used to determine the significance of observed difference between the measured vertebrae dimensions, while Pearson's correlation analysis was used to determine the strength of the relationship. The significance level was set at 95%. Respectively, the highest and lowest mean values; for pedicle length (PL) was found at T12 (17.61±2.4mm) and T3 (14.59±2.09mm) respectively, at T12 (17.34±1.59mm) and T1 (9.78±0.99mm) respectively for pedicle height (PH); and at T12 (T12=11.26±2.78mm) and T4 (5.84±1.17mm) respectively for the mid-pedicle width (MPW). T1 and T12 vertebrae were observed to be significantly different from other vertebrae (P<0.05). Of the predictor variables evaluated for estimating pedicle dimensions, MPW had no significant correlation with PL (r=0.134; R2=0.02, P=0.07), MPW was averagely (+) correlated with PL (r=0.58; R2=0.34, P<0.01), while a week (+) correlation between the PL and PH was recorded (r=0.261; R2=0.07, P<0.01). The changes in measurement across the vertebrae can be explained on the basis of segmental musculoskeletal anatomy and biomechanical stress acting on different regions of the spine. Considering the mid-thoracic region, currently available screws used across the world for the thoracic region of adult spine may not be suitable for majority of the Nigerian population. Results of this study will play a key role in the design of other instruments; it will also assist in understanding spine pathologies; and in the management of spinal disorders in this part of the world.

Key Words: Cadavers, Dimensions, Morphometry, Spine, Thoracic pedicles