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

Abstract

Background context: 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. Purpose: 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). Study design/setting: 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. Patient sample: 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. Outcome measures: 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. Methods: 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). Results: 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%). Conclusions: 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.