Titanium Mesh Cages Subsidence Following Anterior Cervical Corpectomy And Fusion

Objective:To investigate the factors of titanium mesh cage(TMC) subsidence following two-levels anterior cervical corpectomy and fusion(ACCF) with TMC in patients with cervical spondylotic myelopathy (CSM).Method:86 patients with CSM underwent two-levels ACCF from January 2011 to December 2012 were included in the retrospective study, the radiologic findings and clinical materials of them were collected. All patients were followed up for 6 months. According to the subsidence, patients were divided into two groups, one was subsidence group, the other was non-subsidence group. The subsidence associated factors, including age, sex, surgical level, clinical effect, space distraction and position of TMC were evaluated retrospectively.Result:22 of the 86 inserted titanium mesh cages (25.6%) were found to have cage subsidence at 6 months after surgery. ① The single factor analysis shows:the differences of age, sex and surgical level in C5-C7 between subsidence group and non-subsidence group had statistically significant(P<0.05), others had no significant differences(P>0.05).The postoperative JOA score in two groups was significantly better than preoperative, with statistical significance(P<0.05). The difference between two groups was statistically significant(P<0.01).The rate of fusion between two groups had no significant differences(P>0.05). There were 63 cages with intervertebral distract angle less than 30°, the subsidence group was noted in 12(19.0%), while of 23 cages more than 30°, the subsidence group was noted in 10(43.5%). The influence of intervertebral distract angle more or less than 30°on incidence of subsidence had significant differences(P<0.05). There were 66 cages with the distance between anterior edge of cage and anterior edge of vertebral body less than lmm, the subsidence group was noted in 13(19.7%), while of 20 cages with the distance between anterior edge of cage and anterior edge of vertebral body more than 1mm, the subsidence group was noted in 9(45.0%). The influence of the distance between anterior edge of cage and anterior edge of vertebral body more or less than lmm on incidence of subsidence had significant differences(P<0.05). ② The multi-factor analysis results showed:Intervertebral Distract Angle more than 30° (OR=6.236, P=0.005) may be the risk factor of TMC subsidence, the Distance between anterior edge of TMC and anterior edge of vertebral body more than 1mm (OR=4.583, P=0.024) may be another risk factor.Conclusion:Space distraction and placement were two risk factors for TMC subsidence in this study, which might led to subsidence-related complications, in addition, age, gender, operation section, BMI had different effect on the TMC subsidence.