11.5.14  Retained Bone Fragments

and New Bone Formation

11.5.14.1\ Discussion

Residual bone fragments after spine surgery can migrate and impinge upon neural structures. The bony fragments are readily depicted on CT (Fig. 11.113). Facet and pedicle fractures after laminectomy can produce similar findings. Alternatively, bone can regrow after surgery and cause stenosis.

a

b

Fig. 11.113  Retained bone fragment. Axial (a) and sagittal (b) CT images demonstrate sequela of prior lumbar laminectomy and a portion of retained lamina within the spinal canal (arrows). There is also an interbody fusion cage at L4–L5

11.5.15  Retained Surgical Tools

11.5.15.1\ Discussion

Various tools are used during spine surgery. In particular, drilling procedures are commonly performed during spine surgeries, which involve the use of drill bits. Rarely, the drill bits can break and become retained or even migrate. The small-­ diameter bits are more likely to break during surgery. Small retained drill bit fragments can initially go unnoticed, although patients may present with recurrent or new symptoms after surgery. CT is the modality of choice for evaluating possible retained drill bit fragments, which appear as linear metallic attenuation structures on CT (Fig. 11.114).

a

b

Fig. 11.114  Broken drill bit fragment. Axial (a) and sagittal (b) CT images show a cylindrical metallic object (arrows) posterior to the L5–S1 disc