Lumbar pedicle morphology in the immature spine: a three-dimensional study using spiral computed tomography.

Study Design: A cross-sectional study was conducted.

Objective: To investigate the pediatric pedicle morphology with the help of modern computed tomography technology.

Summary Of Background Data: The use of pedicular screws recently has gained popularity because of their ability to provide three-dimensional correction of spinal deformity. Extensive work has been published on the pedicle morphology of the adult and adolescent thoracolumbar spine. Less is known about the pedicle morphology of children.

Methods: A total of 21 patients ages 5 to 10 years underwent standard spiral computed tomography of the abdomen. The patients were grouped according to age: Group 1 (5 to 8 years of age) and Group 2 (9 to 10 years of age). Images were reformatted, and multiplanar reconstructions were used to attain images of lumbar pedicles on sagittal, coronal, and transverse planes. The measurements included the inner and outer pedicle diameters on the transverse plane, the pedicle angle on both the transverse and sagittal planes, and pedicle length.

Results: The smallest pedicle lengths were 24 mm for Group 1 and 25 mm for Group 2. When the average values were considered, the smallest lengths were at L5 and the longest at L3. The smallest diameter was at L1 (2.3 mm for Group 1 and 3 mm for Group 2), whereas L5 had the largest diameter (6.17 mm for Group 1 and 8.72 mm for Group 2). In the transverse plane, the pedicle angle increased from L1 to L5 in both groups. In the sagittal plane, the angulations followed an opposite trend.

Conclusions: The inner transverse diameter of the lumbar pedicle, particularly in young children, is smaller than previously reported. Insertion of screws currently available commercially screws seems to be safe in the L4-L5 pedicles of children ages 5 to 8 years, and in the L3-L5 pedicles of older children. Custom-made screws might be considered for upper levels for safe application.