Cervical arthroplasty complicated by delayed spontaneous fusion. Case report.

The authors describe the case of a 55-year-old woman who presented with a left C-6 radiculopathy and neck pain and in whom there was evidence of disc/osteophyte compression of the left C-6 nerve root. The patient underwent a C5-6 anterior cervical decompression and placement of a Bryan disc prosthesis. More than 7000 cervical discs have been inserted worldwide. Postoperatively, dynamic imaging demonstrated loss of motion at the instrumented level. The patient suffered persistent neck and arm pain that was slow to resolve. Seventeen months after the initial surgery osseous fusion was observed across the interspace and posterior surface of the prosthesis. This is the first documented case of fusion occurring at the level at which cervical arthroplasty had been performed. The precise reason for this phenomenon is unclear, but potential contributing factors include patient-related issues, poor motion due to neck pain, or possibly implant-related issues. To date, this is an exceedingly rare complication and warrants careful and prolonged follow up of all arthroplasty-treated cases.