Published papers

We report a case of a 31-year-old male with coccygodynia caused by calcification of the coccygeal intervertebral disc. He developed coccygodynia without any history of trauma. A plain radiograph of the coccyx showed no obvious abnormality. Plain CT scans clearly demonstrated calcification in the coccygeal intervertebral disc right at the tenderness spot in the coccyx. Conservative treatment with nonsteroidal anti-inflammatory drugs was effective, and his symptom diminished in 3 weeks. To the authors' knowledge, this is the first report regarding symptomatic calcification of the coccygeal intervertebral disc.

The new era of spinal implants, such as pedicle screws, has enhanced mechanical stability of the spine but also has resulted in increased risks. Misplaced pedicle screws cause complications, including neurovascular injuries and instrumentation failure. With the advent of accurate tracking devices, computer-assisted frameless image guidance has been used to improve the safety and efficacy of pedicle screw placement. Early in vitro and in vivo studies have shown that stereotaxic guidance increases the accuracy and safety of implant placement. Improvement of registration technique using intraoperative ultrasonography may extend the use of the registration technique to less invasive percutaneous indications in the future.