Figure 1.
Illustration of the simulated posterior wall fracture of the acetabulum.
The fracture began from 40 degree posterior to the acetabular vertex and extended another 50 degrees. The simulated fracture created a defect of the entire width of the articular surface of the posterior wall with this 50 degrees arc. The inferior portion of the articular surface of the posterior wall (the ischial facet) remained intact.
Figure 2.
Groups of different fixation constructs tested. SCREWS = two 4.0 mm cancellous screws.
CPS = two 4.0 mm cancellous screws and a standard 7-hole 3.5 mm conventional reconstruction plate with 4 cortical screws; LPS = two 4.0 mm cancellous screws and a standard 7-hole 3.5 mm locking reconstruction plate with 4 locking cortical screws; white arrow = superior fracture line; red arrow = inferior fracture line.
Figure 3.
The load cell and jig used to position the pelvis and femur.
Test set up: The pelvis is mounted in the up right position, simulating a double-limb stance, free movable in all three planes. The axial load is applied through the forth lumbar vertebra. The fracture dislocations, under axial loading were analysed. Insert at top right = Test set up in anterior-posterior view.
Figure 4.
Mean fracture translation in all three axes for each construct.
Dark bars = at superior fracture site (marked with a white arrow in Fig. 2); bright bars = at superior fracture site (marked with a red arrow in Fig. 2). n = 30 for Screws group, 15 for CPS and LPS group.
Figure 5.
Mean vectors of fracture dislocations for the different constructs.
Dark bars = at superior fracture site (marked with a white arrow in Fig. 2); bright bars = at superior fracture site (marked with a red arrow in Fig. 2). n = 30 for Screws group, 15 for CPS and LPS group.
Table 1.
the mean vector dislocation for three tested constructs.
Table 2.
Significances for the Relative Fixation stiffness of Different Constructs.