Fractures articulaires complètes de l’extrémité distale du radius chez le sujet jeune actif

Application of ultra-low-dose CT in 3D printing of distal radial fractures

PURPOSE

To explore the effect of ultra-low-dose computed tomography (CT) on three-dimensional (3D) printing models and the diagnosis of wrist fractures.

METHOD

This study enrolled 76 patients with distal radial fractures (DRFs). All patients underwent 320-row detector CT and were divided randomly into two groups. In Group A, 38 patients were scanned with the standard-dose protocol using a tube voltage of 120 kV and current of 100 mA. In Group B, 38 patients were scanned with the ultra-low-dose protocol using a tube voltage of 80 kV and current of 10 mA. For objective image quality assessment, the noise, CT number, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured. Subjectively, two experienced orthopaedic surgeons blinded to the scan parameters evaluated the clarity of the 3D printing model and fracture line using a 3-point scale (the diagnosis was considered acceptable with scores ≥2). The mean radiation dose was calculated. The diagnostic performances for the fractures between the two groups were compared.

RESULTS

The effective radiation dose was significantly reduced by 97.1 % in Group B, compared to Group A (0.28 ± 0.05vs. 9.75 ± 2.23 μSv, respectively). Quantitative objective image quality parameters (e.g., CNR, SNR, and CT numbers) were higher in the standard-dose group (p < 0.001). However, there was no difference in subjective scoring of the 3D printing model. Although the fracture line score was higher in Group A (2.92±0.27 vs. 2.16 ± 0.37; p < 0.001), the diagnostic performance of the two groups was consistent (all scores ≥2). There were no statistically significant differences in the sensitivity, specificity or accuracy between standard-dose group and ultra-low-dose group.

CONCLUSIONS

The ultra-low-dose protocol effectively reduced the radiation dose by 97.1 %, while maintaining the image quality for diagnosis of DRFs. Therefore, this protocol can meet the needs of 3D printing models for preoperative assessments.

Anatomical reduction and precise internal fixation of intra-articular fractures of the distal radius with virtual X-ray and 3D printing

To evaluate and precisely internal fix intra-articular distal radial fracture (IDRF) using the virtual X-ray and three-dimensional (3D) printing technologies. Twenty-one patients with IDRF were recruited, and the data from digital design group (DDG) and real surgery group (RSG) were collected and analyzed. In DDG, the data from thin-slice computed tomography scan, virtual X-ray measurement parameters, including volar tilt, palmar tilt, radius length (D1), ulnar variation (D2), locking plate position parameter (D3) and distance between key nail and joint surface (D4) were collected. The bone was virtually fixed with the locking plate, and the final model of radius with the screw was obtained by 3D printing. In RSG, the locking plate was precisely pre-bended and used in surgery. During the surgery, the key K-wire was accurately placed and the locking plate was adjusted with the aid of the U-shaped navigation arm. The C-arm was used to observe the positions of key K-wires and the locking plate, and the same above-mentioned parameters were measured intra- and post-operatively. The data from RSG and DDG were compared statistically by t test. This approach proved to be successful in all 21 patients, and none of the screws pierced through the wrist joint surface. All the measured parameters, including the volar tilt, palmar tilt, D1-4, in RSG were not significantly different from preoperative DDG data. Virtual X-ray measurement of anatomical reduction parameters and 3D printing can help the anatomical reduction and precise internal fixation by providing quantitative references, preoperatively, intraoperatively and postoperatively.