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J Korean Soc Spine Surg. 2005 Jun;12(2):123-131. Korean. Original Article.
Ahn YJ , Lee CS , Kim JH , Jeong KI , Kim YT .
Department of Orthopedic Surgery, Asan Medical Center, College of Medicine, Ulsan University, Seoul, Korea.
Department of Orthopedic Surgery, National Police Hospital, Seoul, Korea.

STUDY DESIGN: A prospective study of the accuracy of thoracic pedicle screws inserted in scoliotic patients. OBJECTIVES: To evaluate and present a practical, safe and accurate method for thoracic pedicle screw insertion in the surgical treatment of scoliosis using the posteroanterior c-arm fluoroscopy rotating method. SUMMARY OF LITERATURE REVIEW: Previous studies have emphasized the clinical importance, yet difficulty, of accurate thoracic pedicle screw insertion in scoliotic patients. Three-dimensional alterations in the pedicle orientation of scoliotic patients makes the accurate insertion challenging. No reports exist on the accuracy and benefits of posteroanterior c-arm fluoroscopy, which is rotated to allow visualization from en face, in real patients. MATERIALS AND METHODS: A total of 350 thoracic pedicle screws were inserted in 29 patients, including 24 with idiopathic scoliosis, using the posteroanterior (PA) c-arm rotation method. The smallest patient weighed 14 kg, and the next smallest 17 kg. The average preoperative curve was 60.9 degrees(range, 45 degrees~101 degrees). CT scans were taken, postoperatively, in the transverse and sagittal sections to evaluate the pedicle screw placement. RESULTS: The mean preoperative curve of 60.9 degrees was corrected to 15.4 degrees(range, 3 degrees~45 degrees) in the coronal plane, a correction of 74.7%. A mean of 12.1 thoracic screws were inserted per patient. On analysis of the postoperative CT scans, 39(11.1%) of the 350 screws penetrated the medial or lateral pedicle cortices, 8(2.3%) into the medial cortex and 31(8.9%) into the lateral cortex, by mean distances of 3.3 and 3.6 mm, respectively. No screws penetrated the inferior or superior cortices in the sagittal plane, but 16(4.6%) penetrated the anterior cortex. No neurological or vascular complications were encountered, and none of the screws required subsequent replacement. CONCLUSIONS: Thoracic pedicle screw insertion in scoliotic patients, using a posteroanterior c-arm rotation method, allows the en face visualization of both pedicles by rotating the c-arm to compensate for rotational deformity, which makes it a practical, simple and safe method.

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