BACKGROUND: Humeral intercondylar fractures with osteoporosis are often fixed by ordinary plate and bolt which are likely to get loose. Locking plate has a good pullout strength and the function of angle stability.
OBJECTIVE: To compare the biomechanical changes of locking plate and ordinary plate fixation for treatment of complex humeral intercondylar fractures of elderly patients.
METHODS: The humerus specimens from five elderly formalined cadavers were divided into two groups for bone density measurement of the metaphysis. The humerus was cut by electric pendulum saw from inside and outside the condyle to the olecranon fossa at right angles in order to prepare the C3 type complex intercondylar fracture model of the humerus. The fractures were fixed with locking plate and ordinary plate respectively after reduction. The specimens of the two groups underwent axial pressure test under 600, 800, and 1 000 N load, as well as torsion test under 2 N•m using universal biomechanical ergograph.
RESULTS AND CONCLUSION: The average bone mineral densities of the metaphysis in the two groups had not significant difference (P > 0.05). The vertical compressive displacements under 600, 800 and 1 000 N loads in the locking plate group were obviously reduced compared with the ordinary plate group (P > 0.05). The average load of the locking plate group was obviously bigger than the ordinary plate group (P > 0.05), and the rotation angle was obviously smaller (P < 0.05) according to the failure standard of 3 mm for vertical displacement system. It is indicated that the locking plate has stronger biomechanical properties of anti-bend and anti-torsion than the ordinary plate for treatment of complex humeral intercondylar fractures of elderly patients.