Bony fusion through an empty cervical disc interspace implant.

Objective: Today most cervical intervertebral implants (cages) have at least one cranio-caudal hole which can be filled to facilitate bony fusion. Whether this should be done or not remains a matter of debate. The assessment of bony fusion remains difficult, especially in titanium implants. Evaluation is therefore reserved for problem cases and revisions.

Patients and methods: We report one case with recurrent problems years after anterior cervical discectomy followed by the implantation of a titanium cage without an additional bone grafting procedure. The patient was revised and the contents of the cage examined histologically.

Results: The case was considered fused on plain radiograph investigation. Histological examination showed solid bone formation through the hollow interspace.

Conclusion: Solid bone formation through an empty implant is possible. In the discussion about bone substitutes or bone graft alternatives this fact should be taken into account.