Subsidence of stand-alone cervical carbon fiber cages

OBJECTIVE: To investigate the number of subsidences of inserted cervical carbon fiber cages and to define predictive factors for subsidence. METHODS: All patients treated for a cervical herniated disc and fusion with a cervical carbon fiber cage between January 2002 and December 2003 were retrospectively identified. The radiological examinations were reviewed, and, especially, the presence of subsidence was noted. Possible predictive factors for subsidence were determined before the investigation. RESULTS: In 69 patients, there were 96 cages inserted, of which 29.2% subsided. Of all factors investigated, only smoking seemed to be predictive for subsidence, whereas insertion at C6 to C7 clearly had a higher risk at subsidence. Subsidence was not related to outcome or fusion. CONCLUSION: Although the high number of subsidence of cages has never been described before, clinical outcome and fusion rate is comparable with the literature.