Intraoperative CT in spine surgery.

Background: In spinal instrumentation the misplacement of screws, cages and rods may cause neurovascular complications. Therefore a large variety of methods have been used in recent years to reduce such complications especially by navigation techniques and intraoperative three-dimensional fluoroscopy. The aim of this study is to answer the question: will intraoperative CT improve the efficiency of the treatment as well as the safety for the patient at the spinal instrumentation? Specific questions were: are the implants placed correctly and has decompression been performed sufficiently?

Methods: This is a prospective study in 100 patients mostly with degenerative diseases, tumours and trauma. 80 patients were treated by spinal instrumentation. A helical CT (Somatom Emotion 2003) was used, which is firmly bound to the OR table by a track system.

Results: 569 implants were used: 159 vertebra body screws and plates, 88 cages, 154 pedicle screws, 73 facet joint screws and 95 rods. There was malpositioning in seven patients (8.75%). 18 of 154 pedicle screws were misplaced, 2 of 88 cages, and 4 of 73 facet joint screws, for a total of 24 (7.6%).

Conclusions: Intraoperative CT is a useful tool to check the correct position of the implants used, the extent of decompression and the realignment as early as possible. It therefore reduces second operations. A postoperative CT is no longer necessary.