Oblique Axis Body Fracture: An Unstable Subtype of Anderson Type III Odontoid Fractures-Apropos of Two Cases.

Purpose. Anderson type III odontoid fractures have traditionally been considered stable and treated conservatively. However, unstable cases with unfavorable results following conservative treatment have been reported. Methods. We present the cases of two patients who sustained minimally displaced Anderson type III fractures with a characteristic fracture pattern that we refer to as "oblique type axis body fracture." Results. The female patients aged 90 and 72 years, respectively, were both diagnosed with minimally displaced Anderson type III fractures. Both fractures had a characteristic "oblique type" fracture pattern. The first patient was treated conservatively with cervical spine immobilization in a semirigid collar. However, gross displacement was noted at the 6-week follow-up visit. The second patient was therefore treated operatively by C1-C3/4 posterior fusion and the course was uneventful. Conclusions. Oblique type axis body fractures resemble a highly unstable subtype of Anderson type III fractures with the potential of severe secondary deformity following conservative treatment, irrespective of initial grade of displacement. The authors therefore warrant a high index of suspicion for this injury and suggest early operative stabilization.

The Lumbar Spine as a Dynamic Structure Depicted in Upright MRI.

Spinal canal stenosis is a dynamic phenomenon that becomes apparent during spinal loading. Current diagnostic procedures have considerable short comings in diagnosing the disease to full extend, as they are performed in supine situation. Upright MRI imaging might overcome this diagnostic gap.This study investigated the lumbar neuroforamenal diameter, spinal canal diameter, vertebral body translation, and vertebral body angles in 3 different body positions using upright MRI imaging.Fifteen subjects were enrolled in this study. A dynamic MRI in 3 different body positions (at 0° supine, 80° upright, and 80° upright + hyperlordosis posture) was taken using a 0.25 T open-configuration scanner equipped with a rotatable examination bed allowing a true standing MRI.The mean diameter of the neuroforamen at L5/S1 in 0° position was 8.4 mm on the right and 8.8 mm on the left, in 80° position 7.3 mm on the right and 7.2 mm on the left, and in 80° position with hyperlordosis 6.6 mm (P < 0.05) on the right and 6.1 mm on the left (P < 0.001).The mean area of the neuroforamen at L5/S1 in 0° position was 103.5 mm on the right and 105.0 mm on the left, in 80° position 92.5 mm on the right and 94.8 mm on the left, and in 80° position with hyperlordosis 81.9 mm on the right and 90.2 mm on the left.The mean volume of the spinal canal at the L5/S1 level in 0° position was 9770 mm, in 80° position 10600 mm, and in 80° position with hyperlordosis 9414 mm.The mean intervertebral translation at level L5/S1 was 8.3 mm in 0° position, 9.9 mm in 80° position, and 10.1 mm in the 80° position with hyperlordosis.The lordosis angle at level L5/S1 was 49.4° in 0° position, 55.8° in 80° position, and 64.7 mm in the 80° position with hyperlordosis.Spinal canal stenosis is subject to a dynamic process, that can be displayed in upright MRI imaging. The range of anomalies is clinically relevant and dynamic positioning of the patient during MRI can provide essential diagnostic information which are not attainable with other methods.

Range of motion in reconstruction situations following corpectomy in the lumbar spine: a question of bone mineral density?

STUDY DESIGN: In vitro biomechanical study to evaluate the stability of different types of instrumentation in the lumbar spine following corpectomy in relation to bone mineral density (BMD). OBJECTIVES: To investigate the relation between the stability of a spinal instrumentation and BMD. To determine a threshold value of BMD allowing a single ventral instrumentation following corpectomy in the lumbar spine. SUMMARY OF BACKGROUND DATA: Some in vitro studies determined the biomechanical properties of different spinal instrumentations in various spinal injury models. To the authors' knowledge, there are no published data available concerning stabilization in relation to BMD. A guideline for the treatment of a corpectomy depending on BMD would be helpful in order to choose the appropriate surgical method. METHODS: Twenty-four fresh frozen human lumbar cadaveric spine specimens L1-L3 were used for testing of biomechanical properties. Plain radiographs were taken. BMD was determined using quantitative computed tomography (QCT). Testing in a 6 df loading device included native specimens and specimens after corpectomy of L2, restoration of the defect with a titanium cage, and two reconstruction situations: single ventral and additional dorsal instrumentation. Load-displacement curves and range of motion parameters were recorded and correlated with BMD. RESULTS: A significant (P < 0.05) influence of BMD on range of motion was found. Single ventral instrumentation was critical concerning axial rotation. Combined dorsoventral instrumentation offered sufficient stability. The threshold value for use of single ventral instrumentation is a BMD > or = 0.22 g/cm. CONCLUSIONS: Single ventral instrumentation can provide sufficient stability following corpectomy in the lumbar spine under the condition of a high BMD. Determination of BMD and the use of this guideline provides a valid tool for surgical planning.

Bone metastases: prognostic applications of cytometric DNA analysis.

OBJECTIVE: To examine DNA parameters as prognostic factors for developing metastases. STUDY DESIGN: Image cytometry was used to determine DNA content of 21 tumors and 28 metastases. DNA ploidy status, 2c deviation index (2cDI) and DNA malignancy grade (DNA-MG) (based on the variation of nuclear DNA content of tumor cells around the normal DNA [2c] peak) were examined for their prognostic value. RESULTS: Twenty of 21 tumors showed aneuploid content, and 1 tumor showed diploid DNA content. Twenty-one bone metastases showed aneuploid cells. In 6 cases both euploid and aneuploid cells were detected. In 1 metastasis only euploid cells were present. DNA-MG was increased in bone metastases (mean, 2.4) as compared to the corresponding primary tumor (mean, 2.2) in most of the cases. The mean value of the 2cDI was 30.07 in primary tumors and 42.5 in metastases. Twelve bone metastases had a higher 5cEE than did the primary tumor. CONCLUSION: Diploid and aneuploid cells were able to leave a tumor and establish metastases. DNA-MG and 2cDI were increased in metastases in comparison with the primary tumor, but even tumors with lower DNA-MG had metastatic potential.