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Study Design. Retrospective review of charts and fluoroscopic, radiographic, and computed tomography images for 252 screws (41 patients). Objectives. To describe a fluoroscopically assisted technique of thoracic pedicle screw insertion and to determine the technique’s safety, short-term complications, and accuracy. Summary of Background Data. Pedicle screw instrumentation is safe and effective for lumbar spine stabilization, but evidence of its accuracy and complications in the thoracic spine is lacking. Methods. Between 1997 and 2000, 41 consecutive patients with unstable cervicothoracic, thoracic, and thoracolumbar spine injuries were admitted to a regional, level 1 trauma center. These patients underwent posterior spine arthrodesis and pedicle screw instrumentation placed via intraoperative multiplanar fluoroscopic imaging. Pedicle screw placement accuracy was determined by review of postoperative computed tomography scans. Instrumentation failure prevalence was determined by review of fluoroscopic images, postoperative radiographs, and computed tomography scans. Neurologic, infectious, vascular, and gastrointestinal complications were determined by review of operative reports, hospital records, and clinic notes. Results. Of the 126 (50%) thoracic screws (22 patients) with postoperative computed tomography scans, 16 (12.7%) penetrated the pedicle cortex (4 [2.4%] medially and 13 [10.3%] laterally) and 7 (5.6%) penetrated the vertebral body. There were four surgical complications: one instrumentation failure (broken rod, no loss of correction), one deep infection, and two superficial infections. The infections resolved with irrigation, debridement, and intravenous antibiotics. During the 6- to 24-month follow-up period, there were no neurologic, vascular, or gastrointestinal complications. Conclusions. Cervicothoracic, thoracic, and thoracolumbar spine injuries can be managed safely and effectively with thoracic pedicle screws inserted under multiplanar fluoroscopic imaging.

Intraoperative proximal femur fractures are a significant concern during noncemented total hip arthroplasty. The current study was performed to investigate the hypothesis that broaching the femur and inserting the stem without using mallet applied impact loads will reduce the risk of intraoperative fracture. Rosette strain gauges were applied to the medial and anteromedial cortex of six human anatomic specimen femurs to compare the strain distribution for broaching and stem insertion. Eight additional femurs were used to compare the strain distribution for stem insertion using impact loading and constant rate stem insertion. For the impact loading stem insertions, the soft tissues surrounding the femur were modeled. Constant rate stem insertions were performed using a mechanical testing machine. The largest strains measured at the medial and anteromedial sites primarily were aligned with the femur hoop axis. The largest strain magnitude, orientation, and sign (tensile or compressive) varied widely among femurs. The stem insertion strains were significantly larger than the broaching strains (two-way analysis of variance with replication). The impact stem insertion strains were not significantly different from the constant rate stem insertion strains. The results indicate that the femur geometry and material properties have a greater influence on the strain distribution than does the implantation technique.