Pedicle Morphology of the Lumbar Vertebra in Thais

Abstract Background : A detail knowledge of the lumbar pedicle morphology is necessary  for the treatment of lumbar instability by spinal fusion with posterior spinal fusion  in order to avoid risk complication with adjacent vital structure and  fracture of pedicle cortex. Objective : To determine the morphological parameters of the lumbar vertebra of Thais. Design: Descriptive study based on numerical survey. Setting: Bone Collection Unit, Department of Anatomy, Faculty of Medicine, Chiangmai University, Thailand Subjects: Human skeleton  L1-5 pedicles from Thai skeletons, 29 males and 21 females between 35 and 85 years of age. Material and Methods: Horizontal and vertical pedicle diameter, pedicle length, pedicle axis point and transverse angle of L1-5 pedicle were determined and recorded. Result: Results show that the largest horizontal pedicle diameter and transverse angle were found at L5 vertebra.   The vertical pedicle diameter and sagittal angle were found at L1 vertebra.   The longest pedicle was L3 vertebra.  L1-L4 pedicle axis point  were found  superior to the midtrasverse process while L5 pedicle axis point was found inferior to the midtransverse process.    Difference in  horizontal and vertical pedicle diameter and pedicle length  between male and female were found to be statistically significant,  whereas pedicle axis point and transverse angle were not different between two groups. Conclusion : Morphological parameters of the L1-5 lumbar pedicle provide the useful information for treatment of lumbar instability by spinal fusion    The present study revealed that horizontal and vertical pedicle diameter and pedicle length were statistically different between male and female,  whereas pedicle axis point and transverse angle were not different between two groups. Key words: lumbar morphology,  lumbosacral instability, spinal fusion