3D printing guide plate for accurate hemicortical bone tumor resection in metaphysis of distal femoral: a technical note

BACKGROUND

Surgical resection and reconstruction for low-grade bone sarcoma in the metaphysis of the distal femur remain challenging. We hypothesized that 3D printing osteotomy guide plate could assist to accurately resect the tumor lesion and save the joint function.

METHODS

From January 2017 to August 2019, five patients diagnosed with low-grade bone sarcoma in the metaphysis of the distal femur were treated with hemicortical resection using 3D printing guide plate. Autologous bone graft was inactivated in a high-temperature water bath and re-implanted in situ fixed with plate and screw. Patients were followed up from 17 to 33 months. The Musculoskeletal Tumor Society Score was used to evaluate the joint function. X-ray was used to evaluate the bone union.

RESULTS

One patient was paracorticular osteosarcoma, and four cases had highly differentiated chondrosarcoma. All cases were involved in the metaphysis of the distal femur. Patients were followed up from 13 to 33 months, with an average of 23.6 months. There was neither post-operation infection, internal fixation loosening, nor fracture occurrence in any of the patients. The Musculoskeletal Tumor Society Score averaged at 28.1, while the International Society of Limb Salvage imaging score examination averaged 89.8%.

CONCLUSIONS

Here, we demonstrate that the 3D printing osteotomy guide plate-assisted hemicortical bone resection is a beneficial strategy to effectively resect the primary low-grade malignant bone tumors in the metaphysis of the distal femur and retained satisfied joint function.

[Comparative study between 3D guide plate assisted and free-hand insertion of anterior cervical transpedicular screw]

OBJECTIVE

To compare accuracy of anterior cervical pedicle screws between assist of rapid prototyping 3D guide plate and free-hand insertion, and evaluate the safety of two methods.

METHODS

Eight adult cervical cadaver specimens after formaldehyde immersion, including 4 males and 4 females, aged 32 to 65(40.3±5.6) years old. After X-ray examination to exclude bone damage and deformity, 4 of them (3D guide plate group) randomly selected were for CT scan to obtain DICOM format data, and the data was imported into Mimics software for model, designed the ideal entry point and nail path for anterior cervicaltranspedicular screw (ATPS). After obtaining the personalized guide plate of the nail channel, it was exported as STL data, and the individual guide plate was printed by rapid prototyping and 3D printing technology. In turn, with the assistance of 3D guide plates, one-to-one personalized ATPS screws were placed on the four lower cervical cadaver specimens. Another 4 (free-hand group) lower cervical cadaver specimens were implanted with ATPS screws using free-hand technique. All specimens were performed CT thin-layer scanning and three-dimensional reconstruction after operation. The Tomasino method was used to evaluate the safety of the screws on the CT cross-sectional and sagittal images, to determine whether there was a cortical puncture of the lower and inner edges of the pedicle. According to the CT rating results, gradeⅠandⅡwere safe, and grade Ⅲ- Ⅴ were dangerous.And the accuracy of screws was recorded and analyzed between two groups.

RESULTS

Two screws were inserted in each segment from C₃ to C₇ in 8 adult cadavers. A total of 80 screws were inserted, 40 in the 3D guide plate group, and 40 in the free-hand group. The Tomasino screw rating method was used to evaluate the safety of screw, 21 screws were gradeⅠ, 14 screws were gradeⅡ, 3 screws were grade Ⅲ, 1 screw was grade Ⅳ, 2 screws were grade Ⅴ in 3D guide plate group, while 14 screws were gradeⅠ, 8 screws were gradeⅡ, 8 screws were grade Ⅲ, 6 screws were grade Ⅳ, 2 screws were grade Ⅴ in free-hand group. The safety rate of 3D guide plate group was 87.5%, and 55.0% of the free hand group (χ²=8.7, P=0.003).

CONCLUSION

The 3D printing rapid prototyping guide plate assisted insertion of the anterior cervical pedicle screw can significantly improve the accuracy and safety, and provide a theoretical basis for further clinical application.