Trapezoidal titanium cage in anterior cervical interbody fusion: a clinical experience.

BACKGROUND Use of autogenous bone grafting taken from anterior iliac crest for anterior cervical interbody fusion has been the "gold-standard" for decades. Substitutes for autogenous bone graft continue to be sought to avoid potential donor site morbidity. A titanium-alloy square-shaped hollow cage was applied to facilitate the process of fusion as a bone graft substitute, then assessed in this retrospective clinical study. METHODS From July 2000 to July 2001, sixty-three discs from fifty-four patients were selected to receive this cage for one or two segments of the cervical spine for anterior cervical interbody fusion. The Japanese Orthopedic Association (JOA) score and Odom's criteria were used to measure the clinical outcome. Postoperative radiographs were analyzed for graft dislodgement, loss of anterior and posterior disc heights, maintenance of lordosis correction, and status of fusion between the cage and endplates to assess their suitability as a grafting substitute. RESULTS Eighty-seven percent of patients exhibited satisfactory clinical outcome. Successful fusion was obtained in ninety point five percent of operated discs. Partial cage dislodgement was observed in four point eight percent of discs and caused no adverse symptoms. The mean collapse of the anterior and posterior disc heights were 1.73 mm and 0.91 mm, respectively. Moreover, the mean loss of lordosis correction was 2.75 degrees. CONCLUSIONS Based on this primary clinical experience, the trapezoid-design, titanium-alloy cage provided adequate mechanical support and stability in the disc space and an excellent fusion result without significant subsidence of disc height or any other complications.