The design and application of an individualized 3D printing assisted guide plates in assisting sacroiliac screws insertion.

OBJECTIVE: Currently, the sacroiliac screws insertion still faces several challenges in the fixation of pelvic and acetabular injuries. This study was aimed to design a personalized three-dimensional (3D) printing assisted guide plates to assist sacroiliac screws insertion, so as to provide a reference for further clinical applications. METHODS: Eight pelvic specimens (5 males and 3 females) of normal adults were used to simulate actual operation. After thin-layer CT scanning, the 3D models of pelvis were established based on the images data. Furthermore, in Mimics 17.0 software, the screw entry points and screw channels of sacroiliac screws were further simulated and designed, and the appropriate range of the posterior superior iliac spine was selected to establish and print the virtual guide plates. Then, the simulated screws insertion was performed in vitro, the pelvic specimens after screws insertion were scanned again by CT, and the effect of screws insertion was further evaluated. RESULTS: A total of 16 sacroiliac screw guide plates were designed and printed, and 48 screws were inserted on both sides. Therein, 45 screws were completely located in the sacral vertebra, which was determined as grade 0, with an accuracy rate of 93.2%. The other 3 screws penetrated the anterior cortex or sacral canal of sacral vertebra, including 2 screws in Grade 1 (4.1%) and 1 screw in Grade 2 (2.1%). Compared with the simulated screw channels, the anterior and posterior offset angles of the cross section were (0.912 ± 0.625) ° and (0.802 ± 0.681) ° respectively, with no significant difference (p > 0.05). The upper and lower offset angles of coronal plane were (1.158 ± 0.823) ° and (1.034 ± 0.908) ° respectively, and there was no significant difference (p > 0.05). CONCLUSIONS: 3 D printing guide plates assisted sacroiliac screws insertion can enhance the stability of pelvic posterior ring fixation and assist surgeons to reduce the difficulty of operation.

The Novel Application of Three-Dimensional Printing Assisted Patient-Specific Instrument Osteotomy Guide in the Precise Osteotomy of Adult Talipes Equinovarus.

OBJECTIVE: This current research is aimed at assessing clinical efficacy and prognosis of three-dimensional (3D) printing assisted patient-specific instrument (PSI) osteotomy guide in precise osteotomy of adult talipes equinovarus (ATE). METHODS: We included a total of 27 patients of ATE malformation (including 12 males and 15 females) from June 2014 to June 2018 in the current research. The patients were divided into the routine group (n = 12) and 3D printing group (n = 15) based on different operative methods. The parameters, including the operative time, intraoperative blood loss, complications, time to obtain bony fusion, functional outcomes based on American Orthopedic Foot and Ankle Society (AOFAS), and International Congenital Clubfoot Study group (ICFSG) scoring systems between the two groups were observed and recorded regularly. RESULTS: The 3D printing group exhibits superiorities in shorter operative time, less intraoperative blood loss, higher rate of excellent, and good outcomes presented by ICFSG score at last follow-up (P < 0.001, P < 0.001, P = 0.019) than the routine group. However, there was no significant difference exhibited in the AOFAS score at the last follow-up and total rate of complications between the two groups (P = 0.136, P = 0.291). CONCLUSION: Operation assisted by 3D printing PSI osteotomy guide for correcting the ATE malformation is novel and feasible, which might be an effective method to polish up the precise osteotomy of ATE malformation and enhance the clinical efficacy.

Stress analysis of the thoracolumbar junction in the process of backward fall: An experimental study and finite element analysis.

The aim of the present study was to evaluate the biomechanical mechanism of injuries of the thoracolumbar junction by the methods of a backward fall simulation experiment and finite element (FE) analysis (FEA). In the backward fall simulation experiment, one volunteer was selected to obtain the contact force data of the sacrococcygeal region during a fall. Utilizing the fall data, the FEA simulation of the backward fall process was given to the trunk FE model to obtain the stress status of local bone structures of the thoracolumbar junction during the fall process. In the fall simulation test, the sacrococcygeal region of the volunteer landed first; the total impact time was 1.14±0.58 sec, and the impact force was up to 4,056±263 N. The stress of thoracic (T)11 was as high as 42 MPa, that of the posterior margin and the junction of T11 was as high as 70.67 MPa, and that of the inferior articular process and the superior articular process was as high as 128 MPa. The average stress of T12 and the anterior margin of lumbar 1 was 25 MPa, and that of the endplate was as high as 21.7 MPa, which was mostly distributed in the back of the endplate and the surrounding cortex. According to the data obtained from the fall experiment as the loading condition of the FE model, the backward fall process can be simulated to improve the accuracy of FEA results. In the process of backward fall, the front edge of the vertebral body and the root of vertebral arch in the thoracolumbar junction are stress concentration areas, which have a greater risk of injury.

Clinical application of multiple 3D-printed guide plates for precise reduction and fixation of comminuted patellar fractures.

Because of the lack of anatomical landmarks during reduction of multiple articular surfaces and fragments in comminuted patellar fractures, loss of bone fragments or aggravation of soft tissue and ligament injuries readily occurs. In the present case, we used multiple three-dimensional (3D)-printed guide plates to reduce and fix a comminuted patellar fracture. A 22-year-old man was hospitalized for 2 days because of left knee joint pain and limited movement caused by a traffic accident. Preoperative imaging revealed a comminuted fracture of the left patella (type 34-C3 according to the AO/OTA classification). Throughout a 2-year follow-up, the patient remained in generally good condition with no significant limitation of his left knee joint activity. Application of multiple 3D-printed guide plates is a safe and effective auxiliary technique for the treatment of comminuted patellar fractures. This novel technique can shorten the operation time, reduce the number of fluoroscopic procedures, and ensure fracture healing and recovery of knee joint function through reliable reduction of the articular surface.

Three-Dimensional Printing-Assisted Cervical Anterior Bilateral Pedicle Screw Fixation of Artificial Vertebral Body for Cervical Tuberculosis.

BACKGROUND: Cervical tuberculosis accounts for only 4.2%-12% of the total incidence of spinal tuberculosis cases. Although antituberculosis drugs have been the mainstay treatment of cervical tuberculosis, they have been ineffective against the symptoms of existing spinal deformities and spinal cord compression, which often require surgical intervention. The conventional surgical methods have been anterior debridement and titanium mesh, cage bone graft fusion and internal fixation. However, all have certain deficiencies regarding the stability of fixation. CASE DESCRIPTION: We have presented the case of a 41-year-old Chinese man who had been experiencing neck pain and stiffness for 1 month. The symptoms had been accompanied by low-grade fever and repeated night sweats. The purified protein derivative test result was positive and the antituberculosis test result was negative. Imaging examination showed destruction of the C5 and C6 vertebral bodies and C5 andC6 intervertebral discs, with an intensive abscess at the C5-C6 vertebral level. After 3-dimensional printing-assisted anterior debridement and artificial vertebral body replacement, his preoperative symptoms of neck pain and stiffness had been alleviated. Also, his symptoms of numbness in both upper limbs had disappeared completely. At the last follow-up examination, he had recovered well and the tuberculosis focus had been completely cured. CONCLUSION: To the best of our knowledge, we have reported the first clinical application of 3-dimensional printing-assisted cervical anterior bilateral pedicle screw fixation of an artificial vertebral body. We accomplished ultrashort segment fixation, with excellent clinical outcomes obtained, which were maintained at the recent 2-year follow-up examination.