Placement of pedicle screws in the thoracic spine. Part I: Morphometric analysis of the thoracic vertebrae.

We studied the morphology of the thoracic vertebrae in the spines of seventeen human cadavera in order to define parameters that could be used as guidelines for the placement of hooks and screws in the pedicles to obtain internal fixation. We also reviewed computerized tomographic scans of nineteen thoracic spines in living patients who had no evidence of any vertebral deformity. The transverse diameter of the pedicle, which helps to determine the size of the screw, ranged from a mean (and standard deviation) of 4.5 +/- 1.2 millimeters in the fourth thoracic vertebra to a mean of 7.8 +/- 2.0 millimeters in the twelfth thoracic vertebra. The pedicles were inclined anteromedially throughout the thoracic spine, and the angle ranged from 0.3 degree toward the midline in the twelfth thoracic vertebra to 13.9 degrees in the fourth thoracic vertebra. The morphometric data revealed wide variations in the dimensions of the pedicles, demonstrating the importance of accurate preoperative imaging with transaxial computerized tomographic scans to visualize the precise osseous margins and angles of insertion of the thoracic pedicles.

Placement of pedicle screws in the thoracic spine. Part II: An anatomical and radiographic assessment.

We used computerized tomographic scans and subsequent dissections to evaluate the position of ninety pedicle screws that had been inserted bilaterally into the fourth through twelfth thoracic vertebrae of five fresh-frozen cadavera. The screws had been inserted by five experienced spine surgeons without the use of radiographs or imaging studies. Of the ninety screws, thirty-seven were found to have penetrated the cortex of the pedicle. Twenty-one screws had penetrated the medial cortex and entered the spinal canal, and sixteen had penetrated the lateral cortex. The aorta and the esophagus were at greatest risk for injury after advancement of the screws beyond the anterior vertebral cortex. Computerized tomographic scans of the thoracic spine in nineteen living controls who did not have a spinal abnormality confirmed the proximity of the posterior mediastinal structures to the misplaced screws.

Cervical spine trauma.

STUDY DESIGN: The authors reviewed the results of a large number of studies of patients with acute cervical spine dislocations and subluxations. OBJECTIVES: The authors make recommendations regarding the evaluation and treatment of acute cervical spine dislocations based on a thorough review of the available literature. SUMMARY OF BACKGROUND DATA: Realization that a significant percentage of patients with acute cervical dislocations also have disc herniations has led to some controversy regarding the timing of MRI evaluation and attempted closed reduction. This article review studies of spine dislocations at one institution. METHODS: The review of the literature included 131 consecutive patients with acute cervical spine dislocations treated by the senior author followed both retrospectively and prospectively. These results were compared with those of many other authors. RESULTS: Emergent attempted closed reduction remains the treatment of choice for alert cooperative patients with acute cervical spine dislocations. Open or closed reduction under general anesthesia with an uncooperative or unconscious patient should be preceded by an MRI scan. In this situation, the presence of a herniated disc mandates decompression before reduction.

The effect of torque pressure on halo pin complication rates. A randomized prospective study.

At Thomas Jefferson University Hospital, 102 consecutive patients treated in a halo vest orthosis were randomized into one of two torque protocol groups based on their date of birth. The pins of patients who were born in even-numbered months were inserted with 8 inch-lbs of torque and those born in odd-numbered months were inserted with 6 inch-lbs. All patients were placed in an identical model halo using a standardized technique of application. The patients were followed prospectively, and all potential complications were evaluated by a member of the orthopedic attending staff, using protocols established at the onset of the study. Statistical analysis indicated no significant differences in halo pin loosening, infection, pain, or scarring between the torque protocols, but there was a trend toward a higher complication rate in the 8-inch-lbs group. There was no direct evidence of skull penetration in either group, and no patients developed a deep infection. Based on the results of this study, we conclude that insertion torque has no significant effect on halo pin complications within the ranges tested by this study. Our current protocol calls for routine insertion of halo pins with 6 inch-lbs of torque.

Metastatic cystosarcoma phyllodes associated with paraplegia: an uncommon complication of an uncommon tumor.

Cystosarcoma phyllodes is a rare form of breast cancer that rarely metastasizes. This case represents the first reported case of a pathological spine fracture and neurologic injury as a result of metastatic cystosarcoma phyllodes. Physicians should be aware of a recently identified histological subtype of cystosarcoma that exhibits an increased incidence of hematogenous metastasis.

Fractures of the shaft of the radius after treatment of Colles fractures with pins and plaster or external fixation.

Refracture of the radius through a pin site after the removal of pins and plaster or an external fixator for Colles fracture is rarely mentioned in the literature. We present the details of three such cases and review two others reported in the literature. Our aim is to alert orthopedists to the potential for this complication. Patients with superficial or deep pin tract infections appear to be at greater risk.

Intervertebral disc injury complicating cervical spine trauma.

The incidence of acute herniated nucleus pulposus was determined in 55 patients with cervical spine trauma. A standardized protocol and a 1.5-T magnetic resonance image scanner was used to document a 42% incidence of acute herniated nucleus pulposus in patients studied within 72 hours of injury. The incidence of herniated nucleus pulposus was correlated with the patients' presenting neurologic status and mechanism of injury. The incidence of herniated nucleus pulposus was highest in patients with bilateral facet dislocations (80%) and anterior cord syndromes (100%). There was no statistically significant correlation between the incidence of herniated nucleus pulposus and patients' age or sex.