Cerclage cables are commonly used in the management of periprosthetic femoral fractures and for the fixation of trochanteric osteotomies. Fractures of the cable have been observed clinically and the frequency of these fractures may be reduced by increasing the fatigue life of the cable. It is theorized that changing the bundling pattern of standard 7x7 orthopaedic cables could improve the fatigue performance of the cable.

Methods

Experiments were conducted in fixtures that subjected pretensioned cables to bending fatigue loading. The fatigue life of the cable was measured at various tensile loads and bending distances. Cobalt chrome cables with 7x7 and 19x7 bundling patterns were tested. Both types of cables had an overall diameter of 2.0 mm.

Results

The tensile load and bending distance were both found to be significant factors in determining fatigue performance of cable. For all conditions tested, the fatigue life of the 19x7 cable was significantly higher than the fatigue life of the 7x7 cable.

Conclusions

Cable fractures contribute to poor bone fixation and delayed fracture healing. The bundling pattern enhancements studied could improve cable performance in-vivo, by increasing the fatigue life of the cable. This increase in fatigue life can partially be attributed to the greater flexibility of the 19x7 cable.