Finite element analysis of different internal fixation methods for acetabular T-shaped fractures / 中华创伤骨科杂志

ABSTRACT

Objective To investigate the biomechanical stability of 5 kinds of internal fixation for acetabular T-shaped fractures using finite element analysis.Methods After a three-dimensional model of normal pelvis was reconstructed using Mimics software,the model of acetabular T-shaped fracture was divided by Solidworks software.Models of acetabular T-shaped fracture fixated by 5 methods were reconstructed(A) a reconstruction plate for anterior column + lag screws for posterior column,(B) lag screws for anterior column + a reconstruction plate for posterior column,(C) a reconstruction plate for anterior column + a medial ilioischial plate for posterior column (combination plating),(D) retrograde lag screws for 2 columns,and (E) a reconstruction plate for anterior column + and a posterior ilioischial plate for posterior column.Valuation was conducted with software Ansys to simulate 600 N loading on the terminal plate of S1 vertebral body at standing and sitting positions.The biomechanical stabilities were compared between the 5 models of internal fixation.Results At standing and sitting positions,the displacements of anterior column in modelA (0.522±0.121 mmand0.762±0.181 mm),modelC (0.512±0.207mmand0.730±0.181mm) and model E (0.513 ± 0.184 mm and 0.733 ± 0.166 mm) were significantly smaller than those in model B (0.622±0.224 mmand 1.328±0.537 mm) and in modelD (0.655±0.174mm and 1.591± 0.270 mm) (P ＜ 0.05).However,there were no statistically significant differences in anterior column displacements between models A,C and E or between models B and D (P ＞ 0.05).At standing and sitting positions,the displacements of posterior column in model B (0.631 ± 0.151 mm and 0.572 ± 0.693 mm),in model C (0.621 ± 0.195 mm and 0.538 ± 0.075 mm) and in model E (0.625 ± 0.192 mm and 0.544 ± 0.063 mm) were significantly smaller than those in model A (0.742 ±0.140 mm and 0.715 ±0.072 mm)and in modelD (0.754±0.247 mm and 0.717 ± 0.071 mm) (P ＜0.05).However,there were no statistically significant differences in posterior column displacements between models B,C and E or between models A and D (P ＞ 0.05).Conclusions In the treatment of acetabular T-shaped fractures,reconstruction plating has better stability than screwing.Reconstructive plating shows the best stability for anterior and posterior columns,followed by combination plating which is the best choice for reducing surgical injury.