ABSTRACT
Objective:To introduce the standard screw implantation methods and to analyze the biomechanical stability of the second-generation dynamic anterior plate-screw system for quadrilateral area (DAPSQ).Methods:Six adult formalin-preserved corpses were selected to make a complete pelvic specimen. Further, the left high double-column fracture models were made and randomly fixed with second-generation DAPSQ or anterior reconstruction titanium plate and 1/3 tube buttress-plate (ARTPB). The specimens of intact pelvis (IP) group, DAPSQ group and ARTPB group were fixed on a Zwick Z100 material machine and loaded vertically with 200 N, 300 N, 400 N, 500 N, 600 N, 700 N, and 800 N in a simulated sitting position, respectively. The axial displacement and strain changes in the anterior and posterior columns were tested in the three groups. The stiffness was calculated accordingly.Results:The axial compression displacement in the three groups showed an increase trend as well with the vertical load increased from 200 N to 800 N ( F=68.581, P<0.001; F=91.795, P<0.001; F=33.819, P=0.002). The axial displacement in ARTPB group was significantly larger than that in DAPSQ group and IP group ( P<0.05), while the difference between DAPSQ and IP groups was not significant ( P>0.05). Under the vertical load of 600 N, the pelvic axial stiffness of IP group, DAPSQ group, and ARTPB group were 220.72±70.33 N/mm, 185.68±48.49 N/mm and 135.83±60.58 N/mm, respectively. The axial stiffness of ARTPB group was significantly lower than that in DAPSQ group and IP group ( t=5.345, P=0.003; t=6.443, P=0.001), while the difference between DAPSQ and IP groups was not significant ( t=2.138, P=0.086). There were no significant differences of the strain values in anterior column among the three groups during the load increasing from 200 N to 800 N ( P>0.05). With the load increasing from 500 N to 800 N, the strain values of the posterior column in ARTPB group were significantly greater than those of IP and DAPSQ groups ( P<0.05). However, the differences between IP and DAPSQ groups were not statistically significant in strain values of the posterior column ( P>0.05). Conclusion:Compared with anterior reconstruction titanium plate and 1/3 tube buttress-plate, acetabular double-column fracture model fixed with the second-generation DAPSQ has less axial compression displacement but with greater axial stiffness. The stress change in the posterior columns of the acetabulum is like in IP. Therefore, the second-generation DAPSQ has reliable biomechanical stability.
ABSTRACT
Objective:To compare the clinical efficacy between our first generation and second generation dynamic anterior plate-screw system for quadrilateral area (DAPSQ) in the treatment of T-shaped acetabular fractures.Methods:A retrospective study was conducted of the 28 patients with T-shaped acetabular fractures who had been treated at Department of Orthopaedics, General Hospital of Central Theater Command from January 2008 to December 2019. They were divided into 2 groups according to fixation methods. Group A [15 patients, 11 males and 4 females, an age of (43.5±9.1) years] were treated with the first generation DAPSQ while Group B [13 patients, 8 males and 5 females, an age of (42.5±7.0) years] with the second generation DAPSQ. Operation time, intraoperative bleeding, fracture reduction, function of the affected hip and postoperative complications were recorded and compared between the 2 groups.Results:The 2 groups were comparable because there was no significant difference between them in the preoperative general data ( P>0.05). The 28 patients were followed up for 12 to 60 months (average, 35.0 months). The operation time [(193.9±33.3) min] and intraoperative bleeding [(830.8±177.4) mL] for Group B were significantly less than those for Group A [(231.3±40.0) min and (1,043.3±190.7) mL] ( P<0.05). In Group A, according to the Matta scoring, the fracture reduction was rated as excellent in 8 cases, good in 5 and poor in 2; in Group B, the fracture reduction was rated as excellent in 8 cases, good in 4 and poor in one. According to the modified Merle d'Aubigné & Postel scoring at the final follow-up, the function of the affected hip was rated as excellent in 9 cases, as good in 3, as fair in 2 and as poor in one in Group A while as excellent in 9 cases, as good in 2 and as fair in 2 in Group B. There were no statistically significant differences between the 2 groups in reduction quality or in the function of the affected hip ( P>0.05). Follow-up observed hip traumatic arthritis in 2 cases in Group A and in one in Group B. Conclusion:In the treatment of T-shaped acetabular fractures, compared with the first generation DAPSQ, the second generation DAPSQ can shorten operation time and decrease intraoperative bleeding significantly, though both achieve comparable functional outcomes.