1 Research data
1.1 General Information
The medical records of 94 patients with acetabular fractures caused by trauma who were admitted to our department during the 10-year period from December 2006 to December 2016 and met the indications for traditional surgery were retrospectively analyzed and included in the traditional surgery group, and they were divided into simple fracture group (n = 43) and complex fracture group (n = 51) according to the Judet-Letournel classification of acetabular fractures. Among them, there were 24 male patients and 19 female patients in the simple fracture group, aged 32 to 67 years, with an average age of (49.23 ± 11.05) years. The time from fracture to admission for surgery ranged from 1 day to 3 weeks, with an average of (1.02 ± 0.28) weeks. Among them, 23 patients were injured due to traffic accidents, 14 caused by high-altitude fall, and 6 patients were injured due to violence; there were 30 male patients and 21 female patients in the complex fracture group, aged 31 to 65 years, with an average age of (48.61 ± 10.96) years. The time from fracture to admission for surgery ranged from 3 days to 3 weeks, with an average of (1.12 ± 0.41) weeks. Among them, 27 patients were injured due to traffic accidents, 16 caused by high-altitude fall, and 8 patients were injured due to violence.
A total of 46 patients with acetabular fracture who met the surgical indications since 2017 were enrolled. All patients were treated with 3D printing technique-assisted surgery. They were included in the 3D printing technique-assisted surgery group and divided into simple fracture group (n = 25) and complex fracture group (n = 21) according to Judet-Letournel classification of acetabular fracture. Among them, there were 13 male patients and 12 female patients in the simple fracture group, aged 33 to 66 years, with an average age of (49.12 ± 10.03) years. The time from fracture to admission for surgery ranged from 5 days to 3 weeks, with an average of (1.08 ± 0.38) weeks. The causes of injury were traffic accidents in 16 patients, caused by high-altitude fall in 6 patients, and violent impact injury in 3 patients. In the complex fracture group, there were 12 male patients and 9 female patients, aged 31 to 68 years, with an average age of (48.69 ± 10.79) years. The time from fracture to admission for surgery ranged from 2 days to 2.5 weeks, with an average of (1.12 ± 0.35) weeks. The causes of injury were traffic accidents in 13 patients, caused by high-altitude fall in 5 patients, and violent impact injury in 3 patients
In the simple fracture group, there was no significant difference in gender, age, cause of injury, course of disease and other baseline data between the traditional surgery group and 3D printing technique-assisted surgery group (P > 0.05), demonstrating that the two groups of patients could be compared and analyzed; and in the complex fracture group, there was no significant difference in the above general data between the traditional surgery group and 3D printing technique-assisted surgery group (P > 0.05). A comparative study could be performed between the two groups.
1.2 Inclusion criteria
The patients were over 18 years old; all patients were classified according to Letournel-Judet classification criteria; The time from fracture to admission for surgery was less than 3 weeks; the patients volunteered to participate in this study, their families gave informed consent, and signed a surgery-related agreement; the study was approved by the medical ethics committee of the hospital.
1.3 Exclusion criteria
Patients who do not meet the inclusion criteria; Patients with severe bone defects; Patients with severe osteoporosis; Patients with severe mental illness and paraplegia; Patients with incomplete case data; Patients with loss of follow-up; Patients who voluntarily withdraw from the study or transfer halfway.
Preoperative treatment of patients in the two groups: patients with posterior dislocation of the hip underwent manual reduction immediately after admission. After admission, all patients underwent 6 to 8 kg traction of the supracondylar bone, and all patients underwent routine preoperative X-ray examination and thin-section scanning using 64-slice spiral CT (produced by Philips, the Netherlands) to observe the pelvis and upper femur, with a pitch set at 0.5 mm, a current set at 100mAs, and a voltage set at 100 kV during scanning. Prepare 400 ~ 800ml of allogeneic blood in advance, and prepare the autologous blood transfusion set. Give antibiotic injection 0.5 ~ 2.0 hours before operation to prevent infection. Perform general anesthesia through endotracheal intubation before operation, and the operation is completed by the same group of surgeons
3D print-assisted surgery group: the 64-slice spiral CT scan results were imported into the 3D image editing processing software Mimics 14.0 in DICOM format, three-dimensional reconstruction was performed at the fracture site, Figure 1, the relative space of the fracture was accurately observed, and virtual surgical reduction was performed, the appropriate surgical approach was selected using the fracture reduction model, and the position of the preset plate and the exact site of the screw hole were determined by drawing a line on the model. Create a cylindrical virtual screw path simulation with the diameter of 2.5 mm, adjust the direction and length of each virtual screw according to the actual situation in the surgical operation, and measure the screw length. Arrange a red curve on the model through the Create Spline function to mark the optimal position of implanted plate, then perform three-dimensional cutting for the fracture model at the preset plate position. The size is according to the actual reconstructed plate size. Import the format into the 3D printing software as STL format, and then print the physical module with the 3D printing model. Figure 2. Select the reconstruction plate in combination with the 3D printed model, and select the appropriate number of holes. Bend the plate in a large arc at one time as far as possible to avoid repeated bending. The procedure was reduced according to a preset protocol and compared with a pre-bent reconstruction plate to ensure perfect fit between the reconstruction plate and the bone surface.
A 3D printed model after reset; B Preset plate, virtual implant screw on model
After the operation, the drainage tube was routinely placed for 48 hours to 72 hours, and the patient's lower limb sensation, movement and blood supply were examined after recovery from anesthesia. Postoperative routine X-ray and CT reexamination were performed to observe the fracture healing, and routine rehabilitation exercises were performed according to the patient's recovery to promote the recovery of hip joint function. Figures 3 to 10 for preoperative and postoperative imaging data of patients, 1:1 physical model of 3D printing, virtual surgical reduction, design of pre-bent plate, and design of screw position.
3. Observational indicators
The differences in the operation time, intraoperative blood loss, postoperative drainage volume, perioperative blood transfusion volume, intraoperative fluoroscopy times, incision infection rate, surgical reduction effect and postoperative hip joint function recovery effect between the traditional surgery group and 3D printing technique-assisted surgery group in the simple surgery group were compared and analyzed. Postoperative reduction was observed in the two groups; postoperative complications were statistically analyzed: wound healing, loss of reduction, traumatic arthritis and iatrogenic neurological symptoms and incision infection rate were mainly observed. The differences in the above indicators between the traditional surgical group and 3D printing technique-assisted surgery group in the complex fracture group were also observed. To further investigate which 3D printing technology has the greatest application value in the simple and complex types of acetabular fractures.
Imaging evaluation: Meta score was used to evaluate the reduction of acetabular fracture after operation. Criteria: excellent: the fracture was not displaced after operation; good: the postoperative fracture displacement distance was within 1 mm; fair: the postoperative fracture displacement distance was within 1 ~ 3 mm; poor: the postoperative fracture displacement distance was more than 3 mm. Overall response rate = (excellent cases + good cases + fair cases)/total cases × 100% .
Hip function evaluation: The postoperative hip function was evaluated by the patient's pain, walking and range of joint motion according to the modified MerleD 'Aubigne and Postel scoring criteria, In this criteria, the pain score ranges from 2 to 6, which are severe pain and limits walking; moderate to severe pain, which allows walking; pain after walking, which is relieved after rest; mild pain or intermittent pain; and no pain. Walking score from 12 to 6, respectively: unable to walk; very limited; limited use of walking aids; requires cane or crutch for long distance walking; slight limp, requires no cane; normal. The range of motion score is calculated as the percentage of postoperative range of motion to the normal range of motion, 1 point is < 50%, 2 points are 50% ~ 60%, 3 points are 60% ~ 70%, 4 points are 70% ~ 80%, 5 points are 80% ~ 95%, 6 points are 95% ~ 100%. The total score is obtained by summing the three parts. A total score of 18 points is considered excellent, a score of 15 ~ 17 points is considered good recovery, if a score of 13 ~ 14 points is fair, and a score of less than 13 points indicates that the patient's postoperative hip function recovery effect is poor. Excellent rate of hip joint function recovery = (excellent cases + good cases)/total cases × 100% 。
4 Statistical methods
Data were processed using SPSS 19.0 statistical software. Measurement data were first tested for normality, and those who met the normal distribution were subjected to two independent sample t-tests, which were expressed as (` x ± s), and paired t-tests were used for comparison before and after surgery in groups; Enumeration data were described by n (%), χ2 test was used, chi-square correction method was used for cells with minimum theoretical frequency < 5, and Fisher's exact test was used for cells with minimum theoretical frequency < 1, and P < 0.05 indicated that the difference was statistically significant.