ObjectiveTo compare the biomechanical stability of acetabular transverse fracture fixed with single column locking reconstruction plate, locking reconstruction plate combined with lag screw, and double columns lag screws. MethodsAcetabular transverse fractures were established in 20 adult fresh semi-pelvis specimens, and divided into 5 groups randomly (n=4). The anterior columns were fixed with locking reconstruction plates in group A; the posterior columns were fixed with locking reconstruction plates in group B; the anterior columns were fixed with locking reconstruction plates and the posterior columns with lag screws in group C; the anterior columns were fixed with lag screws and the posterior columns with locking reconstruction plates in group D; the double columns were fixed with lag screws in group E. When loading three times weight, the longitudinal displacement of fracture fragment was measured, and the shear rigidity was calculated to compare the stability among groups. ResultsThe longitudinal displacement of groups A and B were significantly greater than that of groups C, D, and E (P<0.05), and the shear rigidity of groups A and B were significantly lower than that of groups C, D, and E (P<0.05). The longitudinal displacement of group B was significantly greater than that of group A (P<0.05), but no significant difference was found in the shear rigidity between groups A and B (P>0.05). There was no significant difference in the longitudinal displacement and shear rigidity among groups C, D, and E (P>0.05). ConclusionLocking reconstruction plate combined with lag screw and double columns lag screws have similar stability, they have stronger stability than the single column locking reconstruction plate. The stability of anterior column locking reconstruction plate is better than that of the posterior column locking reconstruction plate.
ObjectiveTo compare the biomechanical difference of 4 kinds of internal fixations for acetabular fracture in quadrilateral area. MethodsThe transverse fracture models were created in 16 hemipelves specimens from 8 adult males, and were randomly divided into 4 groups according to different internal fixation methods (n=4): infrapectineal buttress reconstruction plate (group A), infrapectineal buttress locking reconstruction plate (group B), reconstruction plate combined with trans-plate quadrilateral screws (group C), and anterior reconstruction plate-lag screw (group D). Then the horizontal displacement, longitudinal displacement of fractures, and axial stiffness were measured and counted to compare the stability after continuous vertical loading. ResultsUnder the same loading, the horizontal and longitudinal displacements of groups A, B, C, and D were decreased gradually; when the loading reached 1 800 N, the longitudinal displacement of group A was more than 3.00 mm, indicating the failure criterion, while the axial stiffness increased gradually. Under 200 N loading, there was no significant difference (P>0.05) in horizontal displacement, longitudinal displacement, and axial stiffness among 4 groups. When the loading reached 600-1 800 N, significant differences were found in horizontal displacement, longitudinal displacement, and axial stiffness among 4 groups (P<0.05) except the horizontal displacement between groups C and D (P>0.05). ConclusionFor acetabular fracture in the quadrilateral area, anterior reconstruction plate-lag screw for internal fixation has highest stability, followed by reconstruction plate combined with trans-plate quadrilateral screws, and they are better than infrapectineal buttress reconstruction plate and infrapectineal buttress locking reconstruction plate.
ObjectiveTo discuss the biomechanical stability of locked reconstruction plate for internal fixation of transverse and posterior wall acetabular fracture so as to provide a reliable basis for clinical application. MethodsThe models of transverse and posterior wall acetabular fracture were established in 16 anti-corrosion acetabular specimens from 8 adult cadavers, which were randomly divided into experimental group and control group (n=8). Fracture was fixed with 10-hole posterior column locked reconstruction plate in the experimental group, and with 10-hole posterior column reconstruction plate combined with anterior column lag screw and posterior wall screws in the control group. Biomechanical testing machine was used for loading of 5/6 donor body mass the specimen in a speed of 15 N/s; the loading time was calculated and vertical loading.The longitudinal and quadrilateral body displacements of fracture were recorded to compare the biomechanical stability was performed. ResultsThe quadrilateral body displacement of the experimental group[(1.99±0.32) mm] was greater than that of the control group[(1.75±0.22) mm], but there was no significant difference (t=-1.735, P=0.105). The longitudinal displacement[(1.56±049) mm] and the displacement of the posterior wall fracture block[(0.86±0.33) mm] in the experimental group were lower than those of the control group[(1.64±0.51) and (1.01±0.35) mm], showing no significant difference between 2 groups (t=0.293, P=0.772; t=1.516, P=0.154). ConclusionFor transverse and posterior wall acetabular fracture, application of locked reconstruction plate can provide sufficient biomechanical stability, reduce the risk of screw placement to acetabular joints.