Inclusion and exclusion
Criteria From September 2020 to January 2023, a total of 22 patients who underwent 3D-printed personalized steel plate implantation at the Department of Orthopedics, affiliated with Shenyang Medical College Center Hospital, were included in the study. Simultaneously, 22 patients who received traditional steel plate treatment with matching baseline characteristics were included, totaling 44 patients in the study. Inclusion Criteria: 1.Age between 25 and 60 years old, with unilateral tibial plateau fracture combined with joint surface depression.2. Closed fracture, with normal limb function before injury.3. Time from fracture to surgery less than 2 weeks. Exclusion criteria:1. Open fractures.2. Severe concomitant injuries on the same limb.3. Patients with severe hepatic or renal dysfunction, cardiovascular or cerebrovascular diseases, and those lost to follow-up. Control group (traditional steel plate internal fixation treatment) consisting of 22 cases and experimental group (3D printed model combined with individualized customized steel plate internal fixation treatment) consisting of 22 cases. The control group adopted the conventional steel plate internal fixation method, while the experimental group underwent preoperative 3D printing of solid models and customization of individualized steel plates. The surgical procedures, radiographic evaluations, and physical examinations were performed by the same orthopedic surgical team. All patients provided informed consent for treatment and signed written informed consent forms. This trial was approved by the Ethics Committee of the Affiliated Central Hospital of Shenyang Medical College (Ethics No.2020018).
Preoperative preparation
After admission, all patients underwent comprehensive physical examinations and routine preoperative assessments. Preoperative X-rays (Netherlands, Philips digital radiography DR system) and three-dimensional CT scans (Netherlands, Philips 256-slice spiral CT machine, with a scanning layer thickness of 0.6 mm) were performed to assess the injuries. The injured lower limbs of the patients were temporarily immobilized in the extended position at 0° using plaster splints, with limb elevation and ice packs applied to reduce swelling. Routine preoperative pain relief and anticoagulant medications were administered. For the individualized steel plate group, fracture data were virtually simulated, 3D models were printed, and individualized steel plates were customized. All patients received one dose of antibiotic prophylaxis 30 min before surgery.
3D model and individualized steel plate production
The CT data of the patient’s fracture site (Fig. 1) was imported into Mimics 20.0 software (Materialise, Belgium) workstation in DICOM format. Three-dimensional modeling of the tibial plateau fracture data was performed (Fig. 2A). The fracture fragments were separated and color-coded (Fig. 2B), followed by anatomical virtual reduction of the fracture fragments (Fig. 2C). Subsequently, the three-dimensional modeling and virtually reduced fracture data were exported as STL format and imported into FashPrint 5 software (FlashForge, China) to print out the three-dimensional physical models of the fracture after modeling and virtual reduction (Figs. 4 and 5). Through a collaboration between medical professionals and engineers, a customized individualized steel plate solution was designed (Fig. 3).
Engineers use Unigraphics NX software (Siemens PLM Software, USA) for detailed design of steel plates in the subsequent project. They utilize FashPrint 5 software to print a physical model of the steel plate (Fig. 5). The physical model of the steel plate is then imported into Mimics software through reverse scanning to confirm the placement, length, direction, and diameter of the screws (Fig. 3). Transparency processing is applied to the fracture model to ensure that the implanted screws do not enter the ankle joint cavity. Additionally, the recommended length of the screws is marked beside each screw hole on the steel plate (Fig. 3). Individualized custom steel plates are fabricated using pure titanium TA3 as the raw material at the manufacturing facility. Furthermore, detailed inspection and sterilization are required for the steel plates.
Preoperative CT coronal, sagittal, and axial data of the patient
(A) 3D modeling of the fracture data using Mimics software. (B) Separation of the fracture fragments using the threshold selection function and labeling them with different colors. (C) Virtual anatomical reduction of the fracture fragments using the move and rotate functions
Based on the virtually reduced fracture model, a personalized plate scheme was customized, confirming the optimal placement of the plate and screws. The fracture model was made transparent to ensure that the implanted screws did not enter the joint cavity. The length of the fixation screws was measured, and the recommended length was marked next to the screw holes
3D printing of the physical model of the fracture after encoding the fracture fragments
3D printed model of the fracture after virtual reduction and the customized personalized plate
Surgical procedure
Experimental Group: General anesthesia or lumbar epidural anesthesia is administered. After the anesthesia takes effect, the patient lies supine on the operating table, with a tourniquet placed at the root of the thigh of the affected limb. The surgical area is routinely disinfected, and sterile drapes are applied. Different surgical incisions are selected according to the type of fracture, and subcutaneous tissues and fascia are dissected layer by layer to expose the fracture ends. The fracture fragments are realigned according to the pre-printed 3D model, and bone grafting is performed at the bone defect site to fill in the gap. The collapsed fracture fragments are supported to restore the smoothness of the joint surface. Kirschner wires are temporarily used to fix the fracture fragments to maintain alignment. After the joint surface is restored to smoothness under C-arm fluoroscopy, individually customized steel plates are selected and placed in appropriate positions. Screws are then sequentially inserted. C-arm fluoroscopy is performed again to ensure the smoothness of the joint surface, good alignment of fracture lines, appropriate screw lengths, ensuring they do not penetrate the joint surface. The knee joint is flexed and extended, confirming firm fixation at the fracture site before suturing.
Control Group: Patients in this group undergo the same surgical procedure as the experimental group. However, the placement of steel plates and screws is based on the surgeon’s experience rather than predetermined by the 3D model.
Postoperative care
After surgery, the patient’s plaster fixation is removed. Within 24 h, a single dose of antibiotics is administered to prevent postoperative wound infection. Cold compresses are applied to the patient’s knee joint, and routine treatments for reducing swelling, relieving pain, and preventing lower limb deep vein thrombosis are performed. On the first day postoperatively, after reviewing the knee joint’s anteroposterior and lateral X-rays, exercises such as quadriceps isometric contractions, straight leg raises, and ankle pump exercises are initiated. The surgical incision dressing is changed every 2–3 days to observe the wound healing progress. Sutures are removed at 2 weeks postoperatively. At 4 weeks postoperatively, patients are allowed to bear light weight with the aid of crutches for protection and gradually perform knee flexion exercises. At 8 weeks postoperatively, patients begin full range of motion and partial weight-bearing exercises on the knee joint until full flexion is achieved. At 12 weeks postoperatively, based on the results of follow-up X-rays, gradual full weight-bearing training is initiated. For older patients or those with severe comminuted fractures or significant osteoporosis, the use of crutches may be extended as necessary.
Observation indicators
Comparison of the following parameters between the two groups of patients: preoperative preparation time, surgical time, intraoperative blood loss, number of intraoperative fluoroscopy sessions, fracture healing time, length of hospital stay, incidence of complications, knee joint range of motion (ROM), Rasmussen anatomical and functional scores, and Knee joint function HSS score. Postoperatively, knee joint anteroposterior and lateral X-rays are taken at day 1, 1 month, and 2 months postoperatively every two weeks to assess bone healing until fracture union. At 1 month, 2 months, 6 months, and 12 months postoperatively, knee joint function is evaluated according to the HSS scoring criteria.
Statistical methods
Analysis is conducted using SPSS 27.0 statistical software. Count data is represented by the number of cases, and analysis is performed using the chi-square test. Continuous data is presented as mean ± standard deviation. Continuous data is first assessed for normality using the Shapiro-Wilk test. For continuous variables that follow a normal distribution, independent samples t-test is utilized for analysis. For continuous variables that do not adhere to a normal distribution, Mann-Whitney U test is employed for analysis. In these analyses, a p-value less than 0.05 is considered statistically significant.
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