| BackgroundAcetabular T-shaped and anterior column posterior hemi-transverse(ACPHT)fractures are two complex types in Letournel-Judet acetabular fracture classification,and belong to B2 and B3 respectively in AO classification.Both are based on transverse acetabular fractures(B1 in AO classification),and the common feature is that they have a transverse fracture line.B3 is actually a variation of B2.It has similar injury characteristics to B2 and is difficult to deal with.For acetabular T-shaped and ACPHT fractures with significant displacements,open reduction and internal fixation(ORIF)is still the gold standard in clinical treatment.Their fracture lines both involve the quadrilateral area,which is thin in bone,deep in the anatomical location,and adjacent to important blood vessels and nerves,making it extremely difficult to reduce bone fragments around the area.Poor reduction and fixation of the quadrilateral area may increase the incidence of postoperative traumatic arthritis and the central subluxation of femoral head for patients.Therefore,the anatomical reduction of the quadrilateral area is particularly important for the patient’s long-term prognosis and functional recovery.Clinically,the traditional internal fixation methods include an anterior titanium plate combined with a posterior column lag screw and double-column titanium plates,but there exist disadvantages in them such as screws misplacement into the joint cavity and large surgical trauma.In 2005,Cai XianHua etal innovatively proposed and used a novel method called "dynamic anterior plate-screw system for quadrilateral area,DAPSQ",namely the first-generation DAPSQ to treat such complex acetabular fractures involving the quadrilateral area.The surgical approach was adopted as the classic ilioingual approach,and there was no risk of screws entering the joint cavity,which has achieved satisfactory clinical efficacy.And Wu Yongde etal have verified its biomechanical stability by pelvis biomechanical experiment and finite element analysis.However,the first-generation DAPSQ needed to be temporarily shaped during surgery,which was difficult for beginners to grasp its ingenuity and might extend operation time and increase intraoperative blood loss.Meanwhile,the learning curve was long,making it difficult to be prompted clinically.Therefore,in 2016,our research group optimized on the basis of the first-generation DAPSQ and then designed the standardized secondgeneration DAPSQ for clinical use.But at present,there is still a lack of corresponding biomechanical basis for it.So this research will compare the clinical efficacy between the two generations of DAPSQ in the treatment of B2 and B3 acetabular fractures by retrospective analysis to determine whether there is a difference.And this research will evaluate the biomechanical stability of the second-generation DAPSQ in the treatment of B2 and B3 acetabular fractures by the method of finite element analysis to provide more guidance and biomechanical basis for its clinical application and promotion.Chapter OneComparison of the curative effect of the first and second generation DAPSQ in the treatment of B2 and B3 acetabular fracturesObjectiveTo explore and compare the curative effect of our first-generation DAPSQ and second-generation DAPSQ in the treatment of B2 and B3 acetabular fractures through the ilioinguinal approach.MethodsA retrospective analysis was conducted of 64 cases with acetabular fractures(including 28 B2 and 36 B3)who had been treated at Department of Orthopaedics of our hospital from January 2008 to December 2019.They were divided into 4 groups according to fixation methods and fracture types.Group F1[15 B2,11 males and 4 females,an age of(43.5±9.1)years)]and Group F2[19 B3,11 males and 8 females,an age of(43.7±8.1)years)]were treated with the first-generation DAPSQ while Group S1[13 B2,8 males and 5 females,an age of(42.5±7.0)years)]and Group S2[17 B3,12 males and 5 females,an age of(41.3±5.6)years)]with the second-generation DAPSQ.The operation time,intraoperative bleeding,fracture reduction quality,function of the affected hip and postoperative complications were recorded and compared among the groups.Results1.The 64 patients were followed up for 12 to 60 months(average,34.64 months).The operation time[(193.9±3 3.3)min、(196.2±26.8)min]and intraoperative bleeding[(830.8± 177.4)ml、(838.2±159.9)mL]in Group S1 and Group S2 were significantly less than those in Group F1 and Group F2[(231.3±40.0)min、(229.5 ±32.2)min]and[(1043.3± 190.7)ml、(1040.0±208.9)mL].And the differences were all statistically significant(P<0.05).2.According to the Acetabular Matta scoring,the fracture reduction in Group F1 was rated as excellent in 8 cases,as good in 5 and as poor in 2;while 8,4 and 1 respectively in Group S1;Group F2 was rated as excellent in 10 cases,as good in 6 and as poor in 3;while 11,5 and 1 respectively in Group S2.According to the modified Merled’Aubigne&Postel scoring at the final follow-up,the function of the affected hip in Group F1 was categorized as excellent in 9 cases,as good in 3,as fair in 2 and as poor in 1;while 9,2,2 and 0 respectively in Group S1;Group F2 was categorized as excellent in 11 cases,as good in 4,as fair in 3 and as poor in 1;while 12,2,3 and 0 respectively in Group S2.There were no statistically significant difference among the groups in reduction quality or in the function of the affected hip(P>0.05).Follow-up observed hip traumatic arthritis in(2、1、1、1)cases respectively in Group F1、S1、F2、S2.ConclusionsIn the treatment of B2 and B3 acetabular fractures,both of the two generations of DAPSQ achieved comparable curative effect.Compared with the first-generation DAPSQ,the second-generation DAPSQ could shorten operation time and decrease intraoperative bleeding significantly for patients.Chapter TwoFinite element analysis of the mechanical properties of the second-generation DAPSQ in the treatment of B2 acetabular fracturesObjectiveTo study the biomechanical stability of the second-generation DAPSQ in the treatment of B2 acetabular fractures by using the method of finite element.Methods1.Establishment of the normal pelvis finite element model and verification of its effectiveness:A 33-year-old healthy male adult volunteer was selected and scanned by CT from the fifth lumbar spine to upper 1/3 of femur.And then the CT scanning image acquired was imported to softwares such as Mimics 12.0、Geomagic studio 2013、Hyperworks 19.1 to establish the normal pelvis finite element model and verify its effectiveness from aspects of anatomy and mechanical conduction.2.Comparison of the mechanical properties of the second-generation DAPSQ and the two traditional internal fixation methods in the treatment of B2 acetabular fractures:Based on the finite element model of the normal pelvis,the right subapical B2 acetabular fracture model and three sets of internal fixation models were established:the second-generation DAPSQ(Group A1),double-column titanium plates(Group B1)and an anterior column titanium plate combined with a posterior column lag screw(Group C1).The stress distribution、the stress shielding rate and the average displacement of nodes on fracture line paths in each group were compared under 600 N of physiological load imitating standing position.Results1.The maximum stress of internal fixations in the three groups were ranked in a sequence of Group A1(45.07MPa)>Group B1(44.24MPa)>Group C1(40.75MPa).2.The average displacement of nodes on fracture line paths in the three groups were ranked in a sequence of Group Al[(2.04±0.17)μm]<Group B1[(2.05±0.17)μm]<Group C1[(2.25±0.18)μm].3.The stress shielding rates for the three groups were ranked in an order of Group B1[(62.80±2.30)%].>Group Al[(61.50±1.84)%]>GroupC1[(59.30±2.47)%].4.In terms of the average displacement and the stress shielding rate,the statistically significant difference between Group A1 and Group B1 was neither established(P>0.05),while the differences between Group C1 and Group A1 or Group C1 and Group B1 were both statistically significant(P<0.05).ConclusionsIn the treatment of B2 acetabular fractures,the second-generation DAPSQ could maintain the stability of the fracture more effectively than an anterior column titanium plate combined with a posterior column lag screw.It had quite comparable biomechanical stability to double-column titanium plates and they were both superior to an anterior column titanium plate combined with a posterior column lag screw.Chapter ThreeFinite element analysis of the mechanical properties of the second-generation DAPSQ in the treatment of B3 acetabular fracturesObjectiveTo study the biomechanical stability of the second-generation DAPSQ in the treatment of B3 acetabular fractures by using the method of finite element.MethodsBased on the finite element model of the normal pelvis,the right B3 acetabular fracture model(high anterior column type)and three sets of internal fixation models were established:the second-generation DAPSQ(Group A2),double-column titanium plates(Group B2)and an anterior column titanium plate combined with a posterior column lag screw(Group C2).The stress distribution、the stress shielding rate and the average displacement of nodes on fracture line paths in each group were compared under 600 N of physiological load imitating standing position.Results1.The maximum stress of internal fixations in the three groups were ranked in a sequence of Group A2(52.50MPa)>Group B2(42.76MPa)>Group C2(37.69MPa).2.The average displacement of nodes on fracture line paths in the three groups were ranked in a sequence of Group A2[(2.09±0.24)μm]<Group B2[(2.11±0.23)μm]<Group C2[(2.32±0.23)μm].3.The stress shielding rate for the three groups were ranked in an order of Group B2[(62.49±2.06)%]>Group A2[(60.96±1.74)%]>Group C2[(58.34±3.82)%].4.In terms of the average displacement and the stress shielding rate,the statistically significant difference between Group A2 and Group B2 was neither established(P>0.05),while the differences between Group C2 and Group A2 or Group C2 and Group B2 were both statistically significant(P<0.05).ConclusionsIn the treatment of B3 acetabular fractures,the second-generation DAPSQ could maintain the stability of the fracture more effectively than an anterior column titanium plate combined with a posterior column lag screw.It had quite comparable biomechanical stability to double-column titanium plates and they were both superior to an anterior column titanium plate combined with a posterior column lag screw. |
PDF Full Text Request