Anterior cervical fusion: a comparison of cage, dowel and dowel-plate constructs.

Abstract

Threaded lumbar cages have been used as a safe and effective surgical fusion method for a decade. Smaller versions have now been developed for the cervical spine to obviate the need for allograft use or iliac autograft harvest and to provide initial stability before fusion. To compare anterior cervical interbody fusion with the BAK/C Cervical Interbody Fusion System, cage (Centerpulse Spine-Tech Inc., Minneapolis, MN), conventional anterior cervical discectomy and fusion (ACDF) and plate constructs (anterior cervical locking plates). Radiological and clinical outcomes of patients who underwent cervical fusion with the BAK/C (filled with local autograft reamings) are compared with ACDF and plate fusion constructs (anterior cervical locking plates). One surgeon performed 88 fusions: BAK/C (n=30), ACDF (n=32), plate (n=26). There were 43 one-level and 45 two-level fusions from C3-C4 to C7-T1. The patients represented a wide range of diagnoses as indications for cervical fusion. Patients (n=88) were 40 men (45%) and 48 women (55%) with a mean age of 51 years (range, 30 to 70 years). Thirty-five percent of patients were smokers, and 26% had known workers' or other compensation issues. Hospital records were examined for data from operative reports and discharge summaries. An independent spine radiologist performed a radiological review of cervical flexion and extension films, noting fusion status, graft position and cage subsidence. Short Form (SF)-36 inventories for physical/mental functioning and visual analog scales (VAS) for pain were administered. A retrospective clinical and radiological review was performed. Hospital and clinic chart data, flexion-extension X-rays and self-assessments (SF-36, VAS) were evaluated. Follow-up at X-ray was 2.4 years (range, 1.0 to 5.5 years). Iliac crest harvesting was least likely for BAK/C patients (2 of 30; 6.7%) compared with ACDF (30 of 32; 93.8%) and plate patients (13 of 26; 50.0%; p<.0001). Plate surgeries took longest (3.5 hours), followed by ACDF (2.3 hours) and BAK/C (2.2 hours; p<.0001). Blood loss was greatest for plate procedures (289 cc), followed by BAK/C (142 cc) and ACDF (121 cc; p<.01). No BAK/C patient stayed in the hospital more than 1 day; ACDF, 1 to 2 days; plate, 1 to 5 days (p<.02). BAK/C patients were most likely to have a successful fusion: BAK/C, 29 of 30, 97%; ACDF, 26 of 31, 84% (one X-ray fusion status indeterminate); plate, 22 of 26, 85% (p<.0585). No BAK/C patient experienced prolonged donor-site pain (0%) compared with ACDF (25.0%) and plate (23.0%) patients. SF-36 and VAS scores, influenced by compensation, were comparable for all groups. Revisions were as follows: ACDF, 4 of 32, 13%; plate, 2 of 26, 8%); BAK/C, 1 of 30, 3%). In this study, the BAK/C cage group had the lowest graft requirements/risks, generally required fewer hospital resources, achieved similar patient outcomes and fused at a higher rate than ACDF and plate groups.