Posterolateral Lumbar Intertransverse Process Spine Arthrodesis With Recombinant Human Bone Morphogenetic Protein 2/Hydroxyapatite-Tricalcium Phosphate After Laminectomy in the Nonhuman Primate
Scott D. Boden, George J. Martin, Jr, Michael A. Morone, John L. Ugbo, and Peter A. Moskovitz

A nonhuman primate (rhesus) posterolateral intertransverse process fusion and laminectomy model was used to evaluate recombinant human bone morphogenetic protein 2 in a hydroxyapatite-tricalcium phosphate carrier. All of the animals that received growth factor achieved fusion, and no bony overgrowth into the spine through the laminectomy defect was observed.

Reconstruction After Multilevel Corpectomy in the Cervical Spine: A Sagittal Plane Biomechanical Study
John S. Kirkpatrick, Julie A. Levy, Jose Carillo, and S. Reza Moeini

The biomechanical behavior of the cervical spine was studied after a multilevel corpectomy and reconstruction with a strut graft and supplementation of the graft with anterior and posterior plates. Flexibility and failure testing were performed. Load to initial failure tended to be higher in posterior than in anterior plate specimens.

Internal Spinal Fixator Stiffness Has Only a Minor Influence on Stresses in the Adjacent Discs
Antonius Rohlmann, Jorge Calisse, Georg Bergmann, and Ulrich Weber

The influence of internal spinal fixator stiffness on spinal stresses was determined using three-dimensional, nonlinear finite-element models of the lumbar spine. Fixator stiffness had only a minor influence on stresses in the discs adjacent to the bridge region.

Atlas-Axis Facet Asymmetry: Implications in Manual Palpation
J. Kim Ross, David E. Bereznick, and Stuart M. McGill

Anatomic asymmetries were measured in a cadaveric study and linked to asymmetric force-displacement correlations. The clinician using palpation would be mislead to link perceived joint restriction with pathologic motion.

Magnetic Resonance Evaluation of the Intervertebral Disc, Spinal Ligaments, and Spinal Cord Before and After Closed Traction Reduction of Cervical Spine Dislocations
Alexander R. Vaccaro, Stephen P. Falatyn, Adam E. Flanders, Richard A. Balderston, Bruce E. Northrup, and Jerome M. Cotler

A study of the use of awake closed traction reduction with results evaluated by prereduction and postreduction magnetic resonance imaging and determination of neurologic status. The process was successful in 9 of 11 patients, and no patient had neurologic worsening. The implication of these findings to the neurologic safety of awake closed traction reduction remains unclear.

Persistent Osteopenia in Adolescent Idiopathic Scoliosis: A Longitudinal Follow-Up Study
Jack C. Y. Cheng, Xia Guo, and Andy H. L. Sher

A 3-year longitudinal follow-up study assessing the bone dynamics in 14 girls with osteopenia-associated adolescent idiopathic scoliosis showed that significantly lower bone mineral density persisted in all 14 patients.

Rotations of a Helix as a Model for Correction of the Scoliotic Spine
Stephen J. Tredwell, Bonita J. Sawatzky, and Barbara L. Hughes

Results of intraoperative analysis of 35 patients undergoing correction for idiopathic scoliosis demonstrated that posterior systems unwind or rotate the scoliotic helix, as indicated by changes in the unique axis of rotation of individual vertebrae. Posterior systems return the resultant sine wave toward the sagittal plane.

Left Thoracic Curve Patterns and Their Association With Disease
Caroline J. Goldberg, David P. Moore, Edmond E. Fogarty, and Frank E. Dowling

The lateralization of scoliosis was studied in 1384 children. Left thoracic patterns were more common in boys, but gender was more an indicator of underlying disease. In girls, left thoracic curves and juvenile onset showed a statistically significant increase in disease, but most scoliosis was in the right thoracic pattern.

The Association Between Static Pelvic Asymmetry and Low Back Pain
Pamela K. Levangie

A cross-sectional case-control approach was used to estimate the association between objectively assessed static pelvic asymmetry (innominate torsion) and low back pain. A direct association was not supported. A weak positive association between posterior superior iliac spine asymmetry in standing and low back pain may warrant further investigation.

The Surgical Treatment of Far Lateral L3-L4 and L4-L5 Disc Herniations: A Modified Technique and Outcomes Analysis of 25 Patients
Scott D. Hodges, S. Craig Humphreys, Jason C. Eck, and Laurie A. Covington

Twenty-five patients with far lateral disc herniation underwent surgery with a far lateral approach. The described technique allowed safe access to far lateral disc herniations with minimal disruption of spinal elements.

Spinal Biomodeling
Paul S. D'Urso, Geoffrey Askin, John S. Earwaker, Glen S. Merry, Robert G. Thompson, Timothy M. Barker, and David J. Effeney

Stereolithographic biomodeling transforms three-dimensional computed tomographic data into exact plastic replicas of anatomic structures. Results show that biomodels may be of use in the assessment of spinal morphology, surgical planning and rehearsal, intraoperative navigation, and patient education.

Iatrogenic Mycobacterium Infection After an Epidural Injection
David P. K. O'Brien and Daniel J. R. Rawluk

Case report of an iatrogenic Mycobacterium infection after an epidural injection for the treatment of low backache.

Sciatica Caused by Cervical and Thoracic Spinal Cord Compression
Takui Ito, Takao Homma, and Seiji Uchiyama

Two case reports of sciatica caused by cervical and thoracic cord compression. In both cases the sciatica disappeared immediately after decompression surgery. Cervical and thoracic cord compression should be considered in the differential diagnosis of sciatica.

Management of Degenerative Disc Disease Above an L5-S1 Segment Requiring Arthrodesis
Harry N. Herkowitz, David J. Abraham, and Todd J. Albert

Clear guidelines exist for treating spondylolisthetic deformity and instability. How the surgeon handles adjacent-level degenerative disease is not as well established. Because magnetic resonance imaging now provides us with far more information on the "health" of radiographically normal intervertebral discs, the treatment of dehydrated or degenerated discs adjacent to a fusion is becoming more problematic. In this discussion, two experts discuss their approach to symptomatic lumbosacral spondolisthesis accompanied by adjacent-level disc degeneration. Drs. Herkowitz and Abraham believe strongly that the adjacent segment should be left alone, whereas Dr. Albert recommends extending the fusion in many instances. [Key words: arthrodesis, dark disc, degenerative disk]