Abstract:

BACKGROUND: Cage displacement is a serious complication after posterior lumber interbody fusion， which often requires reoperation. However, revision surgery is difficult and its effect is uncertain.
OBJECTIVE: To analyze and summarize the correlation factors affecting the displacement of Cage.
METHODS: A retrospective analysis was conducted in 16 cases of Cage displacement in the Third Xiangya Hospital of Central South University and 4 cases from other hospitals between January 2004 and January 2010. We observed and measured the following indexes: the number and depth of implanted Cage, the fitness of Cage and vertebral endplate, the fastness of the pedicle screw system and the hight of intervertebral space.
RESULTS AND CONCLUSION: Single cage was used in lumbar interbody fusion in 9 patients, and other 11 cases were implanted double cages. Insufficient depth of implanted cage was found in 12 patients and unfitness of cage and vertebral endplate was found in 10 patients. Eight cases had the problem of insufficient recovery of the lesion intervertebral height. Pedicle screw fixation was wrong in location in 2 patients, and loosed in 6 patients. Some aspects relating to internal implants, such as design and choice of cage, and the depth of implantation of cage, as well as the fastness of the pedicle screw system, may have effects on the stability of cage.