Accuracy and limitations of computer-guided curettage of benign bone tumors.

Adequate curettage of benign bone tumors located close to articular joints or neurovascular tissue is difficult without damaging those tissues. The purpose of this study was to evaluate the adequacy of tumor removal in computer-assisted curettage of benign bone tumors. The study is a prospective case series involving eight patients with benign bone tumors located near an articular joint or major neurovascular tissue. Image-to-patient registration with the navigation system was performed using paired-points methods in conjunction with CT images. A cortical window was created to visualize the tumor cavity. After removal of the gross tumor with sharp curettes, a specially designed burr attached to a navigation probe was used to monitor the location of the burr tip in real time. The high-speed burr extended the bony margin a few millimeters over the cavity wall. The empty cavity was then filled with bone cement. We assessed the accuracy of curettage and articular involvement by comparing pre- and post-operative CT images. In all cases, deeply seated or multi-cystic tumors were sufficiently removed according to the pre- and post-operative fusion CT images. The subchondral bone was punctured when the initial thickness of the subchondral bone was less than 2.5 mm. However, use of the computer-guided burr was safe if the thickness of the subchondral bone was greater than 3 mm. Computer-assisted curettage is a safe and useful method for localizing deeply seated benign bone tumors. However, use of the burr should be avoided when the bone thickness is less than 3 mm to avoid major tissue damage.