Biomechanics of fixation methods for epiphysis and massive allograft

Aim: To study the theoretical basis of the methods for fixing epiphysis and massive allograft. Methods: The experiment was conducted in the Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University of Chinese PLA from March to August 2004. Fifteen fresh pig femurs were randomly divided into three different groups: vertical fixation group, cruciate fixation group and wire loops fixation group. All the groups were made into femur-epoxy resin compound pieces. So, such biomechanical experiments as compression rigidity, tension rigidity, torsion rigidity, bending rigidity were carried out, and the steadiness of different fixation methods was observed. Results: In the test of tension rigidity, the situation of the cruciate fixation group was the best, and that of the wire loops fixation group was the worst. In the test of torsion rigidity, the situation of the vertical fixation group was the best, and that of the wire loops fixation group was the worst. In the tests of anterior and posterior bending rigidity, the situation of the cruciate fixation group and the vertical fixation group was better than that of the wire loops fixation group. Conclusion: The project that epiphysis and massive allograft are fixed with the cruciate fixation or the vertical fixation can provide more reliable early steadiness in the limb salvage surgery for reserving epiphysis.