Biomechanical analysis using FEA and experiments of a standard plate method versus three cable methods for fixing acetabular fractures with simultaneous THA

- Plate versus cable fixation was investigated for acetabular fractures.
- Finite element computational models were developed.
- Non-destructive and destructive mechanical tests were carried out.
- The standard plate method showed greater mechanical stability.
- The optimal cable method is a reasonable alternative to plating.

Acetabular fractures potentially account for up to half of all pelvic fractures, while pelvic fractures potentially account for over one-tenth of all human bone fractures. This is the first biomechanical study to assess acetabular fracture fixation using plates versus cables in the presence of a total hip arthroplasty, as done for the elderly. In Phase 1, finite element (FE) models compared a standard plate method versus 3 cable methods for repairing an acetabular fracture (type: anterior column plus posterior hemi-transverse) subjected to a physiological-type compressive load of 2207 N representing 3 x body weight for a 75 kg person during walking. FE stress maps were compared to choose the most mechanically stable cable method, i.e. lowest peak bone stress. In Phase 2, mechanical tests were then done in artificial hemipelvises to compare the standard plate method versus the optimal cable method selected from Phase 1. FE analysis results showed peak bone stresses of 255 MPa (Plate method), 205 MPa (Mears cable method), 250 MPa (Kang cable method), and 181 MPa (Mouhsine cable method). Mechanical tests then showed that the Plate method versus the Mouhsine cable method selected from Phase 1 had higher stiffness (662 versus 385 N/mm, p = 0.001), strength (3210 versus 2060 N, p = 0.009), and failure energy (8.8 versus 6.2 J, p = 0.002), whilst they were statistically equivalent for interfragmentary sliding (p ≥ 0.179) and interfragmentary gapping (p ≥ 0.08). The Plate method had superior mechanical properties, but the Mouhsine cable method may be a reasonable alternative if osteoporosis prevents good screw thread interdigitation during plating.