Patients
After getting approval from our institution’s ethical committee (ethical review number: 2018024-1), we led a retrospective case-matched cohort study at our Level 1 trauma center of military general hospital between May 2016 to May 2018. Inclusion criteria were as follows: (1) all types of acetabular fractures involving the quadrilateral plate, (2) treated with anatomical titanium plate of DAPSQ, (3) age > 18 years, (4) fresh fractures. Exclusions included open or pathologic acetabular fractures, patients with pre-existing osteoarthritis of the affected hip. Written informed consent was obtained from all the patients.
Twenty-two consecutive acetabular fracture patients were treated with anatomical titanium plate of DAPSQ (ATP group) formed group 1. Then, the fractures in group 1 were matched according to age, gender, fracture pattern and surgical approach, to similar cases from our databases which included more than 140 cases treated with the reconstruction plate of DAPSQ from January 2008 to January 2016. This pool of cases was then used to randomly choose individual cases to create a 1:1 proportion, and this matched cohort was group 2 (RP group).
Surgical technique
Preoperative Management
The initial management of acetabular trauma followed the principles of the Advanced Trauma Life Support (ATLS) and the most important was to keep the stability of vital signs[14]. All injuries were evaluated preoperatively with radiographs and CT scans. Acetabular fractures were categorized according to Judet and Letournel classification[2]. Skeletal traction was applied via the femoral condyles or tibial tubercle in all patients. One day before the operation, autologous blood transfusion machine and heterogeneous blood(>1000mL ) were prepared.
Operation procedures
All fractures were treated by 2 senior orthopedic surgeons on a radiolucent table using a standard ilioinguinal approach described by Letournel[15] or combination with the Kocher-Langenbeck approach. Through the “second window” of the ilioinguinal approach, the acetabular anterior column, pelvic boundary and the upper part of the quadrilateral plate could be directly exposed or touched. The first step was to reduce the medial dislocation of the femoral head, and the restoration of the continuity of the pelvic ring followed a principle of proximal to distal. Next, push quadrilateral plate fracture fragment into its bed until a smooth quadrilateral surface with no external step off was obtained.
ATP group
After the reduction was accomplished in the ATP group, an appropriate mode of the anatomical titanium plate of DAPSQ was selected and placed on the superior arcuate line, and the ends extended toward the iliac wing and the superior pubic ramus (Fig.1). The titanium plate was divided into three parts: the iliac region, the quadrilateral region and the pubic region according to the placement trajectory on the pelvis (Fig.1). We have preliminary designed three models based on the total anatomical length of the placement trajectory and the different proportion of the length in the three regions measured by Chinese population (Fig.2). Before screws insertion, both ends of the titanium plate were up-warped, and not firmly attached to the bone surface. But during the screws insertion, the titanium plate could gradually firmly attach to the bone surface and detailed screws placement methods showed in Fig 3. The key surgical steps were as follows: Two or more fixation screws on the iliac and pubic region should first be fixed to stabilize the acetabular anterior column. Then with the help of a 4.5mm screwdriver, quadrilateral screws were inserted along the pelvic brim and parallel to the surface of quadrilateral plate under direct vision, and only the 1/3 to 1/2 transverse diameter of the quadrilateral screw was screwed into the bone to avoid penetrating the hip. And during the process of screws insertion, the torsion and elastic recoil of the plate could provide a strong holding force for quadrilateral screws to block the inward displacement of quadrilateral plate. Also, make sure the distal end of the quadrilateral screws extended at least 10mm beyond the fracture line.
RP group
A reconstruction plate was used in patients of the RP group. The shaping steps were as follows: First, select a 12 to 16 hole arc-shaped reconstruction plate based on the total anatomical length of the placement trajectory. Then both ends of the plate were reverse twisted and upturned by using a bender and screwdriver. The torsion angle of the iliac and pubic regions was higher than the radian of the bone surface, so the both ends of plate were upturned after placed, and the plate in the quadrilateral region slightly incline into the pelvis about 15° (Fig.4). In order to achieve the best effect of quadrilateral buttress screws, the torsion angle and the proportion of the length in the three regions of the plate should be adjusted repeatedly. And the screws insertion methods were similar to the ATP group.
In addition, if the reduction through a single ilioinguinal approach was not satisfactory or patients complicated with fractures of acetabular posterior wall, adding the Kocher-Langenbeck approach was a appropriate choice. Throughout the application of DAPSQ, obturator neurovascular bundle were identified and protected. Fracture reduction and implant positioning was carefully checked using fluoroscopy prior to closure of the wound.
Postoperative Management
Intravenously administered antibiotics were continued for 24 hours. The drainage tube was removed within 3 days (24h drainage flow < 20 mL). Patients started early rehabilitation after awoke from anesthesia and were instructed to non-weight bearing exercises such as passive and active ipsilateral hip flexion or extension motion on the affected limb for 4-6 weeks. Then protected weight-bearing exercises were encouraged till 8-12 weeks, and gradually progress to full-weight bearing at 12 weeks.
Method of assessment and data collection
Gender, age, fracture pattern, mechanism of injury, fracture side, concomitant injuries, time between injury and surgery, surgical time, intraoperative bleeding, blood transfusion, hospital stay time were all collected. Complications including the deep venous thrombosis, sciatic nerve problem, lateral femoral cutaneous nerve injury, surgical site infections, posttraumatic arthritis, heterotopic ossification, screws penetrating into the hip joint cavity and implant failure were documented.
The immediate postoperative radiographs (anteroposterior of the pelvis and Judet views of the affected acetabulum) and 3D CT reconstruction were reviewed and the reduction was evaluated using the Matta radiological criteria by 2 senior orthopedic surgeons[16]. The Matta grading scores were classified as anatomic(0-1mm), imperfect (2-3mm), or poor (>3mm) based on the maximal displacement on all views.
Regular outpatient review and follow-up were performed 1, 2, 3, 6, 12 months after surgery and then yearly thereafter. Changes in clinical function, radiographic progress, fracture healing, and complications were recorded. Functional outcomes were evaluated by the modified Merle d’Aubigné score[17] assessed at the last follow-up and categorized as excellent (18 points), good (15-17 points), fair (13 or 14 points), or poor (<13 points).
Statistical analysis
Data was coded and analyzed with the statistical package SPSS version 19.0(IBM Corp, Armonk, NY). Continuous variables were expressed as mean ± standard deviations and categorical variables with absolute frequencies and percentages. Independent-samples t test was used to compare quantitative variables. Chi-square test or Fisher exact test was used to compare categorical variables. While the ranked data were analysed with Mann-Whitney U rank sum test. Cohen’s Kappa Index was measured to estimate the inter-observer agreement. A value of P <0.05 was considered statistically significant.