Morphometric analysis of thoracic and lumbar vertebrae in idiopathic scoliosis.

STUDY DESIGN Prospective study on the morphometry of 337 pedicles in 29 patients with idiopathic scoliosis. OBJECTIVES To analyze by means of computed tomographic scans the vertebral morphometry in idiopathic scoliosis treated by pedicle screw instrumentation. SUMMARY OF BACKGROUND DATA Although several studies exist on the vertebrae's morphometry in normal spines, little is known concerning the morphometry of scoliotic vertebrae. METHODS The pedicles' morphometry between T5 and L4 was analyzed by computed tomographic scans in 29 surgically treated patients with idiopathic right thoracic scoliosis. Measurements included chord length, endosteal transverse pedicle width, transverse pedicle angle, and pedicle length. RESULTS The endosteal transverse pedicle width was significantly smaller (P < 0.05) on the concavity in the apical region of the thoracic spine and measured between 2.5 and 4.2 mm in the middle thoracic spine (T5-T9) and between 4.2 and 5.9 mm in the lower thoracic spine (T10-T12). In the lumbar spine, the width varied between 4.8 and 9.5 mm without significant differences between the concave and convex sides (P > 0.05). The chord length was shortest at T5, measuring 37 mm and increased gradually to 50 mm at L3 with significantly larger dimensions in male patients and on the concavity of the apical region in the thoracic spine (P < 0.05). The pedicle length varied minimally, with a range of between 20 and 22 mm, and was relatively consistent throughout the thoracic and lumbar spine. The transverse pedicle angle varied between 6 degrees in the lower thoracic spine and 12 degrees in the upper thoracic and lower lumbar spine. CONCLUSION The morphometry in scoliotic vertebrae is substantially different from that of vertebrae in normal spines, with an asymmetrical intravertebral deformity shown in scoliotic vertebrae. Pedicle screw instrumentation on the concavity in the apical region of thoracic curves appears critical because of the small endosteal pedicle width.

[1]  L. Lenke,et al.  The Use of Pedicle Screw Fixation to Improve Correction in the Lumbar Spine of Patients With Idiopathic Scoliosis: Is It Warranted? , 1996, Spine.

[2]  C. K. Lee,et al.  Segmental Pedicle Screw Fixation in the Treatment of Thoracic Idiopathic Scoliosis , 1995, Spine.

[3]  L. Wiltse,et al.  Anatomic Analysis of Pedicle Cortical and Cancellous Diameter as Related to Screw Size , 1989, Spine.

[4]  A. Vaccaro,et al.  Potential Large Vessel Injury During Thoracolumbar Pedicle Screw Removal: A Case Report , 1997, Spine.

[5]  R. Yeasting,et al.  Anatomic Relations Between the Lumbar Pedicle and the Adjacent Neural Structures , 1997, Spine.

[6]  M M Panjabi,et al.  Internal Architecture of the Thoracic Pedicle: An Anatomic Study , 1996, Spine.

[7]  H. Halm,et al.  Pedicle Screw Instrumentation of the Thoracic Spine in Idiopathic Scoliosis , 1997, Spine.

[8]  A G Patwardhan,et al.  Analysis of the Morphometric Characteristics of the Thoracic and Lumbar Pedicles , 1987, Spine.

[9]  The Removal of a Transdural Pedicle Screw Placed for Thoracolumbar Spine Fracture , 1996, Spine.

[10]  R. Hedlund,et al.  Structural vertebral changes in the horizontal plane in idiopathic scoliosis and the long-term corrective effect of spine instrumentation , 2004, European Spine Journal.

[11]  R. Dickson,et al.  The Transverse Plane Deformity of Structural Scoliosis , 1991, Spine.

[12]  R. Winter,et al.  The selection of fusion levels in thoracic idiopathic scoliosis. , 1983, The Journal of bone and joint surgery. American volume.

[13]  A. King,et al.  Measurement of effective pedicle diameter in the human spine. , 1989, Orthopedics.

[14]  R. Yeasting,et al.  Anatomic Relations of the Thoracic Pedicle to the Adjacent Neural Structures , 1997, Spine.

[15]  M H Krag,et al.  Morphometry of the Thoracic and Lumbar Spine Related to Transpedicular Screw Placement for Surgical Spinal Fixation , 1988, Spine.

[16]  R. Perdriolle,et al.  Thoracic Idiopathic Scoliosis Curve Evolution and Prognosis , 1985, Spine.

[17]  H. An,et al.  Placement of pedicle screws in the thoracic spine. Part I: Morphometric analysis of the thoracic vertebrae. , 1995, The Journal of bone and joint surgery. American volume.

[18]  J. Moran,et al.  A Morphometric Study of Human Lumbar and Selected Thoracic Vertebrae , 1987, Spine.

[19]  S R Garfin,et al.  Placement of pedicle screws in the thoracic spine. Part II: An anatomical and radiographic assessment. , 1995, The Journal of bone and joint surgery. American volume.

[20]  J. Emans,et al.  Lumbar Pedicle Screws Versus Hooks: Results in Double Major Curves in Adolescent Idiopathic Scoliosis , 1997, Spine.

[21]  M H Krag,et al.  Hole Preparation Techniques for Transpedicle Screws Effect on Pull‐Out Strength from Human Cadaveric Vertebrae , 1991, Spine.

[22]  L. Lenke,et al.  Complications of Pediatric Thoracolumbar and Lumbar Pedicle Screws , 1998, Spine.

[23]  B Latimer,et al.  Vertebral Body and Posterior Element Morphology: The Normal Spine in Middle Life , 1988, Spine.

[24]  B. T. Field,et al.  A biomechanical study of intrapeduncular screw fixation in the lumbosacral spine. , 1986, Clinical orthopaedics and related research.