Surgical techniques

Anterior column and posterior hemi-transverse acetabular fractures can be effectively treated through open reduction and internal fixation that use column plates and lag screws.13 The fixation device was composed of Nitinol (NiTi), a shape-memory alloy due to its inherent advantages, including: the shape-memory effect, remarkable resistance to wear and corrosion and good histocompatibility.14

In the anterior column plate combined with posterior column screws (P&PS) technique, the anterior column plate was implemented from the inner surface of the ilium to the superior surface of the superior pubic ramus. The screw was incorporated from the outer surface of the quadrilateral area superior to the arcuate line and into the ischial spine. The column plate was bent to meet the surgical requirement. The interface between the plates and the bone was modeled as face-to-face contact with a frictional coefficient of 0.1 to simulate the slide between the joint surfaces.15, 16 The embedded contact type was used to restrict the slide between the interfaces of the screws and the bones.17 The screws were simulated as rod-like structures, which had a diameter of 3.5 mm.

In the anterior column plate combined with quadrilateral area screws (P&QS) technique, the position at which the column plate attached was almost similar to that in the former system. The screws in the quadrilateral area were inserted into the outer surface along the arcuate line and into the ischial spine. Two quadrilateral area screws were fixed by the column plate and cortical bone.

In the double column plates (P*2) technique, if the fragment gap in both the anterior and posterior parts of the acetabulum is wide, the anterior and posterior plates should be combined.18 The anterior column plate was similar to that of former systems. Moreover, the posterior column plate was applied to the outer surface of the ilium. The acetabular rim was then incorporated into the ilium body above the acetabular dome. Attention was paid to prevent the screws from intersecting with one another during insertion.

To secure the clinical effectiveness of internal fixation in all fixation systems, a small plate was implanted at the end of the anterior superior spine.

The double limb stance was exerted on each model. The model was placed in a specific neutral position that was defined with the iliac wings level (coplanar in the horizontal plane).7 In the sagittal plane, the proximal femoral shaft was vertical. The degrees of freedom at the end of the femur were restrained to represent the double limb stance. A force of 600 N, representing the body weight, was loaded on the upper surface of the sacrum.17