Usefulness of Nutrient Foramen of Lamina for Insertion of Thoracic Pedicle Screw

Yang, Jun Young; Lee, June Kyu; Song, Ho Sup

Abstract

PURPOSE
To determine the utility of the nutrient foramen on the lamina in thoracic pedicle screw fixation.
MATERIALS AND METHODS
This study investigated the nutrient foramina on the lamina from 4th to 8th thoracic vertebra after partial laminectomy of 7 cadaveric spines. A 2 mm steinmann pin was inserted as follows: Vertical insertion on the right nutrient foramen and a 10 degree caudad on the left nutrient foramen. Radiographs and CT were obtained and the relationships between steinmann pin and pedicle were analyzed.
RESULTS
There were 44 nutrient foramens (63%). Among them, 31 nutrient foramens (70%, 31/44) were on the right. On the lateral radiograph, the right pins were inserted to the upper end plate and the left pins were inserted within the vertebral body in T4 and T5. In T6, 7 and 8, the right pins were inserted lower than the upper end plate, and the left pins were inserted to the lower portion of the vertebral body. On the CT axial scan, medialization to 17 degrees from T4 to T7 and 5 degrees in T8 from the nutrient foramen was possible when the size of pedicle screw for humans is considered.
CONCLUSION
The nutrient foramens on the lamina of thoracic vertebra are useful for inserting the thoracic pedicle screw.