Accurate Placement of Cannulated Screws in Femoral Neck Fractures: Screw and Guide Wire Combined Technique.

Cannulated screw fixation is widely used in the treatment of femoral neck fractures. During surgery, we often face the situation that a guide wire needs to be adjusted because of poor positioning in the femoral neck. It is difficult to adjust the direction of the guide wire in the neck of the femur due to its elasticity. This study developed a practical technique to adjust the guide wire to the correct position. When the direction of insertion of the guide wire has deviated, first, measure the length of the guide wire. Second, select the appropriate cannulated screw based on the measurement, and screw the cannulated screw in along the direction of the guide wire to Ward's triangle. Then return the guide wire to the front of the cannulated screw. At this time, the cannulated screw can be used as a built-in guide, and a screwdriver can be used to fine-tune the position of the screw to the optimal direction under the X-ray guidance. Finally, the cannulated screw is screwed in in this direction until it passes through the Ward triangle area, and the guide wire is inserted. This technique can help doctors insert a guide wire more quickly and accurately, reducing intraoperative injury and the operation time.

Preoperative 3D and 4D-CT imaging using 640-Multislice CT (640-MSCT) in diagnosis of female urethral diverticulum.

OBJECTIVE: To determine the sensitivity and specificity of 640-Multislice CT (640-MSCT) in diagnosing the female UD. MATERIALS AND METHODS: We investigated 16 patients with symptomatic UDs preoperatively in our hospital from August 2010 to March 2016. The patients' average age was 38.8 years. All patients were performed 640-MSCT of pelvis; then, 3D and 4D images were reconstructed preoperatively. RESULTS: In 3D and 4D-CT images, out of 16 patients, thirteen patients had one ostium, two had 2 ostia and one had 3 ostia. Out of those thirteen patients, eight patients' ostia were located at 5 o'clock and five patients' at 7 o'clock. Patients with 2 ostia location were at 5 and 6 o'clock and 5 and 7 o'clock, respectively. Patients with 3 ostia location were at 5, 6 and 7 o'clock. The mean distance from the bladder neck to the ostia was 22.5 mm. The shape of UD was out-pouching in 11 patients (68.8%), U-shaped in four patients (25.0%) and circumferential in 1 patient (6.2%). The CT findings were confirmed by surgical findings. CONCLUSIONS: 640-MSCT is a useful tool in identifying UD's shape and ostium (including number, location) before operation. Preoperative 640-MSCT should be an adaptable modality for clinically suspected UD patients. ADVANCES IN KNOWLEDGE: Several imaging methods have been used to diagnose female UD. 640-MSCT may be more suitable to diagnose it for its higher sensitivity and specificity in diagnosis of female UD, especially in identifying UD's shape and number and location of ostium.

Comparison of biomechanical properties of single- and two-segment fusion for Denis type B spinal fractures.

OBJECTIVE: To compare the biomechanical properties of single- and two-segment fusion for Denis type B spinal fracture. METHODS: Two female patients with Denis type B L1 vertebral fractures were studied. Both patients had achieved intervertebral fusion by 1 year postoperatively, at which time CT data were collected, including data of one patient before and after removal of pedicle screws and of another whose pedicle screws were not removed. The data were imported into Mimics software and T11 -L2 three dimensional models established. After construction of the models, they were imported into ANSYS software. An axial load (260 N) and 10 Nm torque were loaded to simulate the flexion, extension, lateral bending and rotation of the spine, respectively. RESULTS: There was no significant difference in the average displacement of the spine motion between the two-segment and single-segment fusion patients without removal of pedicle screws. However, for all motion forms, the average displacement of the single-segment fusion patient' spine after removal of pedicle screws was significantly greater than that before removal of pedicle screws and that of the two-segment fusion patient. The average Von Mises stress of T11-12 intervertebral disc of two-segment fusion patient was significantly greater than that of the one-segment fusion patient. Moreover, the average Von Mises stress of T11-12 intervertebral disc of single-segment fusion patient was greater before than after removal of pedicle screws. CONCLUSION: Provided there is satisfactory interbody fusion, removal of pedicle screws after one-segment fusion can increase spinal motion, reduce the stress on adjacent intervertebral discs and delay disc degeneration.