Digital measurements of the anatomical parameters of pedicle-rib unit screw fixation in thoracic vertebrae of preschoolers / 中国组织工程研究

ABSTRACT

BACKGROUND: Pedicle screw internal fixation has been widely used in the lumbar spine, and fixed application in thoracic vertebra has gradually been accepted. Considering the narrow thoracic pedicle, especially at T3-T9, pedicle screw always punctures the cortex and important adjacent structures. To avoid serious complications, researchers developed the external pedicle approach from the costal transverse process joint and the costal vertebra joint to the vertebral body, and then others designed a similar screw entry method, which can provide enough safe paths as long as the ribs are not penetrated. At present, the existing studies mainly focus on the upper and middle thoracic vertebrae in adults. OBJECTIVE: To measure the anatomical parameters of pedicle-rib unit screw fixation in thoracic vertebrae of preschoolers, and to explore their developmental regularity and morphological characteristics at different age groups and sexes, so as to provide theoretical basis for clinical practice. METHODS: Sixty-seven preschoolers aged 7-12 years old without bone destruction, tumor, deformity, degeneration or fractures at the spine and no history of spine related surgery were selected. Three-dimensional reconstruction was conducted after spiral CT scanning. The morphological structure of pedicle-rib unit was observed. The transverse diameter, length, inclination angle and safety angle range of pedicle-rib unit screw were measured and analyzed statistically to investigate the feasibility of screw on anatomy. All guardians of the children signed the informed consents, and the study was approved by the hospital ethical committee. RESULTS AND CONCLUSION: (1) The transverse diameter of the thoracic pedicle-rib unit was increased with age, and decreased first and then increased with the increase of vertebral sequence. The transverse diameter in males was larger than in females at the same age. (2) The length of pedicle-rib screw channel was significantly different in different age groups (P < 0.05), which showed a significant increase with age and a trend of first increase and then decrease with the increase of vertebral sequence. (3) Pedicle-rib unit screw placement showed that safety angle range was 18°-25°, including maximum safety scope in T1, followed by T|0, minimum in T4 and T5. (4) Thus, security angle range of pedicle-rib unit screw in children is narrower than that in adults. Compliance with the adult standards in screw placement may cause severe nerve damage to the nerves and blood vessels, so preoperative individualized screw placement should be carried out according to the CT results.