Osteoid Osteoma Excision

Overview

An osteoid osteoma is a small, benign, active, painful osteoblastic bone lesion. To effect a cure, the entire nidus must be removed because residual nidus is associated with recurrance of the osteoid osteoma. The pain brought on by an osteoid osteoma can be debilatating. The technical objective of this work was to perform a minimially invasice excision of osteoid osteoma by means of computer-assisted guidance technology. The principal technical hurdle to be overcome was the difficulty of registering the surface of a long bone with minimal surgical exposure.

Traditional Technique

Traditionally, osteoid osteomas are removed by shaving the bone overgrowth, removing the tumour, and implanting a plate for added strength. Alternatively, a wire can implanted and visually tracked using repeated CT scans. Both procedures are lengthy and have a long recovery period.

Computer Assisted Intraoperative Guidance

Intraoperatively, a dynamic reference body (DRB) was attached to the affected bone using conventional external-fixation screws. A hyperdermic needle was attached to a tracked probe and calibrated. The surgeon then percutaneously contacted the bone in key regions with the needle and an initial registration was computed. Additional surface points were collected to refine the registration. The computer then tracked the drill and superimposed image of the drill on the visualization model and on axial, sagittal, and coronal reformats of the CT scan.

Once the nidus was localized with image-guidance, a small hole (10mm) was drilled through the cortex. Unroofing of the nidus by gradual removal of the overlying reactive bone and undertaken prior to excision with curettes. The computer-related hardware was removed and the wounds were closed using SteriStrips. Patients were discharged within 24 hours of the procedure. For each patient, the specimens were sent out for pathology analysis.

Outcomes

Patients showed immediate relief of their discomfort following the surgery and were permitted to bear weight as tolerated. There were no surgical complications.

Our technique allows an accurate localization of small lesions and is particularly useful for those that are deep within reactive bone. Accurate localization allows a small incision and a minimally invasive excision technique that does not destroy the integrity of the reminaing bone. There is elimination of, or a lesser need for, postoperative immobilization, bone grafting, internal of external fixation and a shortened period of limited activity postoperatively. All of these factors make this technique particularly appealing to the young, active patient.

References

Further information on our work can be found using the links below:

1. R. E. Ellis, D. Kerr, J. F. Rudan, and L. Davidson. Minimally invasive excision of deep bone tumors. In Medical Image Computing and Computer-Assisted Intervention - MICCAI 2001, pages 1154-1156. Springer Lecture Notes in Computer Science, 2001.