OBJECTIVETo compare the radiographic outcome of three different fusion methods in maintenance of intervertebral height after cervical anterior corpectomy.

METHODSFrom May 2005 to November 2009, a total of 77 patients with cervical spondylotic myelopathy who underwent anterior cervical corpectomy and fusion were reviewed in the study. Fusion methods included autogenous iliac bone grafting in 22 patients (group 1), titanium mesh cages without end caps in 21 patients (group 2) and titanium mesh cages with modular end caps in 34 patients (group 3). No significant differences were found in age, gender or level of corpectomy among the three groups (P > 0.05). The height of anterior border (HAB) and the height of posterior border (HPB) of the fused segment were measured on lateral radiographs pre-operatively, post-operatively and at final follow-up to evaluate the outcome. The incidence of subsidence of titanium mesh cage and iliac bone was also reviewed retrospectively. The statistical analysis included One-way variation analysis and chi-square test.

RESULTSAll cases obtained the follow-up with an average of (30 ± 5) months (range 24 to 46 months). At final follow-up, the loss of the height of anterior border (HAB) of the fused segment in group 3 ((0.4 ± 0.4) mm) was less than that in the other two groups ((0.9 ± 0.6) mm in group 1 and (1.1 ± 0.8) mm in group 2) (mean difference = -0.45 mm and -0.70 mm, P < 0.05), but the difference was not statistically significant between group 1 and group 2 (P > 0.05); the loss of HPB of the fused segment in group 3((0.6 ± 0.5) mm) was less than that in the other two groups ((1.1 ± 0.7) mm in group 1 and (1.6 ± 0.8) mm in group 2) (mean difference = -0.52 mm and -0.98 mm, P < 0.05), but the difference was not statistically significant between group 1 and group 2 (P > 0.05). Iliac bone subsidence occurred in 10 cases (45.5%) in group 1, including mild subsidence (1 - 3 mm) in 9 cases (40.9%) and severe subsidence (> 3 mm) in 1 case (4.5%), and titanium mesh cage subsidence occurred in 11 cases (52.4%) in group 2, including mild subsidence in 9 cases (42.9%) and severe subsidence in 2 cases (9.5%), and 2 cases (5.9%) in group 3 showed mild subsidence of titanium mesh cages. The incidence of titanium mesh cage subsidence in group 3 was less than that in the other two groups (χ(2) = 12.423 and 15.551, P < 0.05), but the difference was not statistically significant between group 1 and 2 (P > 0.05).

CONCLUSIONSTitanium mesh cage with modular end cap is superior to both titanium mesh cage without end cap and auto iliac bone graft in maintenance of the cervical intervertebral height postoperatively. The usage of modular end cap can efficiently reduce postoperative subsidence rate of titanium mesh cage.