The benefit of wire cerclage stabilisation of the medial hinge in intramedullary nailing for the treatment of subtrochanteric femoral fractures: a biomechanical study.

PURPOSE: Reduction and intramedullary fixation of subtrochanteric fractures is often challenging. Osteosynthesis frequently fails and a higher rate of non-unions is found. The aim of this study was to evaluate the benefit of an additional cerclage to anatomically reduce and support the medial hinge. The application is based on the experience of the surgeon; as yet no biomechanical data are available.

METHODS: Ten pairs of human cadaveric femora were used to determine the biomechanical and clinical advantage of an additional cerclage. All femora were tested in a materials testing system after osteotomy, osteosynthesis with the Gamma III nail and randomisation into two groups with or without additional cerclage.

RESULTS: After cyclic loading the compressive load to reach plastic deformation of 5 mm was 2,160 N on average in the group without cerclage vs 2,330 N on average in the group with cerclage. This biomechanical advantage showed no statistical significance (p = 0.2). Radiological examination when the abort criterion was reached revealed that use of the additional wire cerclage could significantly decrease the failure of osteosynthesis (100 vs 10%) after intramedullary nailing of subtrochanteric fractures (p < 0.05).

CONCLUSION: In view of the more invasive operative approach with additional soft tissue injuries, application of an additional cerclage should still be considered carefully. Nevertheless, a mini-open approach to difficult fractures could be helpful in reducing the fracture with a clamp and is sometimes essential. The damage to the soft tissue must be weighed against the benefits of the procedure. An additional cerclage in oblique subtrochanteric fractures is a good option to ensure the reposition and cortical medial support if appropriate and to decrease osteosynthesis failure and rates of non-unions.