1.1 Inclusion and exclusion criteria for cases.
Inclusion criteria: ①cases of unilateral closed tibial plateau fracture treated by surgery in the department of orthopaedics of our hospital during 2017.01-2019.01. ② complex tibial plateau fractures with double-column or three-column injuries. ③The time from injury to operation was less than 14 days.
Exclusion criteria: ①patients with chronic lesions of knee joint and knee joint dysfunction before injury. ②complicated with vascular and nerve injury on the affected side. ③those with serious underlying diseases or unable to cooperate with treatment.
1.2 General information.
A total of 28 patients were included in this study, including 20 males and 8 females, with an average age of 49.5 ± 2.5 years old. According to the theoretical basis of three-column classification of tibial plateau, combined with 3D printing model classification, there were 9 cases of type Ⅳ fracture, 7 cases of type Ⅴ fracture, 4 cases of type Ⅵ fracture and 8 cases of type Ⅶ fracture. All cases were treated with internal fixation. The time from injury to operation was 12 days, with an average of 6.5 ± 1.3 days. This study has been approved by the Ethics Committee of our hospital. All patients have signed the informed consent form for the operation.
1.3 Using 3D printing model to refine the classification of plateau fractures from the geometric plane 3-column 3-zone typing method
3D model printing: all the 28 cases underwent 64-slice spiral CT thin-slice scanning (0.6mm) before operation, and the DICOM data were input into the computer. The Mimics software was used to process the data. And the 3D printing technique was used to print the three-dimensional model of the fracture (1:1).
Based on the classification of the geometric plane of the platform (Fig. 1), the overlooking view of the tibial plateau shows that the O point is the midpoint of the tibial spine line. The A' point is the tibial tubercle. The B' point is the medial crest of the tibial plateau. And the C 'point is the anterior edge of the fibular head. The tibial plateau is divided into three plane parts by OA', OB' and OC', which are defined as A zone, B zone and C zone respectively.(Table 1)
Table 1
Three-column and three-zone classification of tibial plateau fractures
Classification
|
Zone
|
Position
|
Approach
|
Ⅰ
|
A
|
Supine position
|
Anterolateral approach
|
Ⅱ
|
B
|
Supine position
|
Anteriormedial approach
|
Ⅲ
|
C
|
Prone position
|
Posterior approach
|
Ⅳ
|
A + B
|
Supine position
|
Combined medial and lateral approach
|
Ⅴ
|
A + C
|
Supine position
|
Anterolateral peroneal approach
|
Ⅵ
|
B + C
|
Supine position
|
Posteromedial approach
|
Ⅶ
|
A + B + C
|
Floating position
|
Anterolateral approach + posteromedial approach
|
Type IV-VII are included in this project |
1.4 Preoperative planning and surgical simulation steps.
① The CT data of patients with quasi-fracture were processed on a special computer platform. And then the tibial plateau fracture model was printed 1:1 (Fig. 2). The printing machine is the selective laser sintering equipment Farsoon401. The printing material is nylon powder material for laser sintering.
② The fractures were re-classified by three-column classification according to the fracture imaging data and 3D visual model so as to achieve accurate classification according to the principle.
③ Evaluate the displacement direction of the bone fracture block. And through the direction, distribution and movement of the fracture block, we can accurately evaluate the displacement direction of the bone fracture block.
④ Evaluate the collapse site of the articular surface. And through the detailed analysis and observation of the articular surface, we can determine the actual collapse site of the articular surface.
⑤ Establish the surgical approach. Through the analysis of the fracture mass and articular surface of the complex tibial plateau fracture, the intraoperative approach can be established to create conditions for reducing trauma injury.
⑥ Determine the position and the number of steel plate implantation. Predicting the position and number of steel plate implantation and the pre-bending data of steel plate before operation can effectively reduce the operation time, trauma injury and the use of anesthetic drugs.
⑦ Simulate the operation. The reduction of the fracture block and the placement of the steel plate can be performed on the 3D model according to the operation plan, so as to improve the proficiency of the operation.
1.5 Preoperative scheme design of complex tibial plateau fracture (type Ⅳ-VII).
Type IV: supine position, choice of surgical approach: combined medial and lateral approach. (Fig. 3).
Type Ⅴ: supine position, choice of surgical approach: anterolateral peroneal head approach to fix the lateral column, and whether to fix it according to the stability of the posterior column (Fig. 4).
Type VI: supine position, choice of surgical approach: modified posterior medial approach (Fig. 5).
Type Ⅶ: floating position, choice of surgical approach: the meniscus was repaired by the anterolateral approach, the lateral column was fixed by the anterolateral approach, and the medial column and the posterior column were fixed by the posteromedial approach. (Fig. 6)
1.6 Surgical methods and postoperative management.
All patients were treated with general anesthesia or combined block anesthesia. After successful anesthesia, the affected limb was bound with a tourniquet with a pressure of 50 KPA for 90 minutes. Antibiotics were routinely used before operation. Combined with preoperative classification, the operation was performed according to the surgical approach, fracture reduction mode, plate preshaping, screw direction and length designed before operation. During the operation, the mode and amount of bone graft were determined according to the collapse of the articular surface. Explore the articular surface to repair meniscus and ligament injuries that need one-stage surgical repair as far as possible [10]. Intraoperative C-arm fluoroscopy confirmed the degree of fracture reduction and articular surface elevation. After operation, the negative pressure drainage tube was routinely indwelled and removed within 48 hours. Prophylactic use of antibiotics was used within 48 hours after operation. The contraction exercise of quadriceps femoris was performed on the 3rd day after operation. The flexion and extension function of knee joint began to exercise 1 week later and partial weight-bearing began to be carried out 6 weeks after operation. And after the fracture healing was confirmed by X-ray 3 months after operation, patients began to bear weight completely gradually.
1.7 Observation indicators.
1.7.1 The coincidence rate between the preoperative planning and the final surgical plan.
Each case of complex platform fracture was designed according to the 3D printing model before operation. The specific surgical approach and implant scheme were designed. The specific operation plan was recorded. The consistency rate between the final operation plan and the preoperative plan was obtained.
1.7.2 Knee joint function score.
The patients were followed up for 1 year. During the follow-up, the anterior and lateral films of the knee joint were taken and the knee joint function was evaluated by HSS score [11]. HSS score>85 was excellent, 70–84 was good, 60–69 was fair, and score<59 was poor.
1.7.3 Fracture healing time and postoperative complications.
The fracture healing time of each case was recorded in the follow-up. And whether there were postoperative complications such as infection, screw fracture and other complications were recorded.
1.8 Statistical processing.
The above data were analyzed by SPSS18.0 statistical software. χ 2 test was used for the comparison of counting data. T test was used for the comparison of measurement data. The difference was statistically significant (P<0.05).