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[A comparative study on maintenance of disc height by different anterior cervical fusion methods].

OBJECTIVE
To compare the effect of autograft, cage and autograft plus internal fixation with plate on maintenance of disc height and recovery of spinal cord function.


METHODS
From March 1998 to June 2004, 117 cervical spondylotic patients who received anterior fusion surgery were reviewed. There were 65 males and 52 females with an average age of 57 years (range from 31 to 72 years). One level was involved in 91 patients, and two levels in 26. Fusion methods included autogenous tri-cortical iliac bone grafting alone in 31 patients, cage with autograft bone in 38 and autogenous tri-cortical iliac bone grafting combined with self-locking plate in 49. The measured fusion length was determined as the distance from the midpoint between the anterior and posterior aspects of the superior endplate of the top level of the fusion to the midpoint of the inferior endplate of the bottom level of the bottom level of the fusion. JOA rating criteria was used for cord function evaluation. One-way variation analysis was used to compare the disc height loss and cord function among the 3 groups.


RESULTS
All patients were followed-up for an average period of 23 months (range, 13 to 59 months). At final follow- up, disc height loss averaged 1.94 mm in autogenous tri-cortical iliac bone grafting group, greater than that in the other two groups (1.48 mm in cage group and 1.25 mm in instrumented group) with statistical significance. Recovery of spinal cord function was satisfactory in all groups at one year postoperatively with no statistical difference. Three implants failure occurred in self-locking plate group and was salvaged with uneventful recovery.


CONCLUSIONS
In anterior cervical fusion surgery, maintenance of disc height could be achieved by proper application of cage or internal fixation with plate.