Safety and accuracy of pedicle screw placement in pediatric patients with spinal deformity

English Keywords:Ｐedicle screw  Ｐediatric  Ｓpinal deformity  Ｃomplication  Ｓpinal deformity

English Abstract:

  【Abstract】 Objective：To investigate the safety and accuracy of pedicle screw placement in pediatric scoliosis patients and its possible risk factors.Methods:Forty one consecutive cases from Feb. 2008 to Jul. 2008 undergoing posterior pedicle screw instrumentation were retrospectively reviewed.There were 15 girls and 26 boys，with a mean age of 5.4 years at surgery（range，2-10 years）.The diagnoses included congenital scoliosis （n=36），idiopathic scoliosis　（n=2），neuromuscular scoliosis（n=2），scoliosis associated with achondroplasia （n=1）.Free-hand pedicle screw placement was performed based on the anatomic landmark.Postoperative CT scans were performed in all cases.The extent of medial，lateral and anterior perforation were measured using Pacs Client software（PACS）.The distance between aorta and screw tip was measured if the left pedicle screw penetrated lateral wall or anterior vertebral cortex.The misplacement was defined as pedicle screws breaking medial，lateral，anterior vetebral cortex more than 2mm or perforating endplate and neural foramen.Result:A total of 242 pedicle screws were inserted，128 in thoracic spine and 114 in lumbar area，with an average of 5.8 screws for each patient.208　screws（86.0%） were sited completely in pedicle.18 screw malposition was noted（breaking more than 2mm），5 of which penetrated lateral pedicle cortex，8 penetrated medial pedicle cortex，and 5 penetrated vertebral anterior cortex.The vertebra with malformation or at the concave side had higher perforation rate（24.1% and 17.9% respectively）．The mean distance between the screw tip and the anterior wall was 2.3mm for eight screws breaking the anterior wall.Screw loosening occurred in one patient.Conclusions:For children less than 10 years old，free-hand screw placement is of high accuracy and safety；however the vertebra with malformation or at the concave side should be paid attention.