Retained broken knife blades within the disc space.

Study Design: Four cases in which, during standard laminectomies, knife blades broke deep into the disc space are reported.
Summary of Background Data: These broken knife blades could not be removed at the time of initial operations.
Results: Follow-up studies indicated further anterior migration of retained fragments in two cases after ambulation.
Conclusions: Because of the potential hazards of late intraabdominal visceral or vascular injuries, removal of sharp retained fragments at another session is recommended.