Patients
After obtaining approval from our institution’s ethical committee(ethical review number: 2018024-1), we led a retrospective case-matched cohort study at a level I trauma center of military general hospital between May 2016 to May 2018. Inclusion criteria included all types of acetabular fractures involving quadrilateral plate, treated with anatomical titanium plate of DAPSQ, in patients above 18 years of age and fresh fractures. Exclusion criteria included open or pathologic acetabular fractures, patients with pre-existing osteoarthritis of the affected hip. Written informed consents had been obtained from all patients.
Twenty-two consecutive acetabular fracture patients treated with anatomical titanium plate of DAPSQ(ATP group), with a minimum of 1-year of follow-up, were formed group 1. Then, the fractures in group 1 were selected and matched according to age, gender, fracture pattern and surgical approach, to similar cases from our dedicated acetabular plate fracture database 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 ratio, 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 stable of vital signs[14]. Subsequently, all patients received routine physical and neurological examination. Radiological assessment included an anterior-posterior(AP) view and Judet views(iliac and obturator oblique views), along with two-dimensional computed tomography(CT) and three-dimensional(3D) CT reconstruction. Fracture pattern were classified according to Judet and Letournel classification[2]. Skeletal traction was applied via the femoral condyles or tibial tubercle in all patients. Low molecular weight heparin was routinely used to prevent thrombosis, and the color Doppler ultrasonography of Lower Limb Vessels was performed to exclude deep venous thrombosis. One day before the operation, autologous blood transfusion machine and heterogeneous blood(>1000mL ) should be prepared.
Operation procedures
The corresponding author and another senior orthopedic surgeon performed all surgeries. All the surgeries was performed on a radiolucent table using a standard ilioinguinal approach described by Letournel[15] or combination with Kocher-Langenbeck approach. Through the “middle window” of the ilioinguinal approach, the acetabular anterior column, pelvic boundary and the upper part of quadrilateral plate could be directly exposed or touched. First, the medial dislocation of femoral head was repositioned under manual traction on the leg or the assistant of mechanical lateral traction via a Schanz pin in the proximal femur. Then restore the continuity of the pelvic ring followed a principle of proximal to distal and the fracture fragments of ilium wing and anterior column were fixed with screws or plates. Subsequently, push the fracture fragments of acetabular posterior column or quadrilateral plate into its bed with the help of L-shaped spike pusher until a smooth quadrilateral medial surface with no external stepoff was obtained and use a 2 or 3-claw reduction forceps to maintain the reduction.
ATP group
After the reduction was accomplished in the ATP group, choose a appropriate mode of the anatomical titanium plate of DAPSQ. The anatomical titanium plate was placed on the superior arcuate line, and the ends extended toward the iliac wing and the superior pubic ramus. And according to the placement position, it was divided into three parts: the iliac region, the quadrilateral region and the pubic region(Fig.1). We have preliminary divided the anatomical titanium plate into three models according to the anatomical length of the DAPSQ trajectory and the different length proportion of the three regions measured in the Chinese (Fig.2). After placement, the both ends of the titanium plate were up-warped, and were not firmly against the bone surface. But through special nailing methods, the titanium plate could be fully adhered to the bone surface, and detailed nailing methods have shown in Figure 3. The key surgical procedures were as follows: Fistly, two or more fixition screws on the iliac and pubic region should be first 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 into the bone of quadrilateral plate to avoid entering the hip. And during the process of nailing, the torsion and elastic recoil of the plate could provide a strong holding force for the quadrilateral screws to block the inward displacement of quadrilateral plate. In addition, make sure that the distal of the quadrilateral screws have exceeded the fracture line by at least 10 mm.
RP group
Patients in the RP group were used a reconstruction plate. The shaping steps were as follows: Firstly, select a 12 to 16 hole arc-shaped reconstruction plate according to the actual anatomical length. Then the 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 that the both ends of plate were upturned after placed, and the plate in the quadrilateral region slightly incline to the intrapelvic about 15°(Fig.4). In order to achieve the best effect of screws placement, repeatedly adjustment of the torsion angle and proportion of the three regions was necessary. After well shaped, the nailing methods was similar to the ATP group.
Finally, if the reduction was unsatisfactory through a single ilioinguinal approach or patients complicated with the fracture of acetabular posterior wall, adding the Kocher-Langenbeck approach was a suitable choice. After the nailing process was completed in all patients, repeated fluoroscopy was necessary to confirm the good reduction and no screw entering the hip. After acquiring satisfied fluoroscopy, the operation area should be flushed completely and a drainage tube was placed before wound closed.
Postoperative Management
All patients regularly received an intravenous injection of prophylactic antibiotics for 5-7days after surgery. 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 was 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 analyzed included 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.
Quality of reduction was evaluated by 2 senior orthopedic surgeons using the Matta radiological criteria[16] according to immediate postoperative pelvic X-ray(anteroposterior, inlet, outlet, and Judet views) and 3D CT reconstruction. The scores were classified as anatomic(0-1mm), imperfect (2-3mm), or poor (>3 mm) 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 assessed using the modified Merle d’Aubigné score[17] at the last follow-up and graded 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.