Anterior interbody fusion with the BAK-cage in cervical spondylosis.

BAK-C is a new autostabilizing interbody cage which is implanted during an anterior cervical procedure to provide stability to the motion segment and allow fusion to occur. Special instrumentation is provided with a bone collecting reamer. The system utilizes surgical site bone graft as the osteo-inductive material within the implant. Biomechanical testing indicates improved stability and animal studies show good fusion. The basic principle is distraction-compression using the tension forces of the annulus fibrosus. Operative material concerns a two years experience with 80 patients (101 levels), 72 with cervical radiculopathy, 8 with myelopathy. Clinical evaluation is assessed on a ten point analogue pain scale for neck and arm/shoulder pain, with neurological examination. Radiological evaluation includes dynamic X-rays, myelo-CT and MRI. Patients are re-evaluated at 1, 6, 12 months postoperatively. Results for neck and radicular pain is excellent, but neurological recovery for radiculopathy and myelopathy is quite different. Radiological results are also good with (except one case) no instability, no cage migration, no kyphosis, no pseudarthrosis. Bone fusion is assessed at 6 and 12 months. Complications are few with proper technique, mainly correct distraction, symmetrical endplate drilling and lateral X-ray control. Only one patient needed an early re-operation with additional miniplate fixation. Immediate stability with good clinical response and no graft morbidity are the advantages of this implant compared to conventional cervical interbody grafting techniques.