gms | German Medical Science

Objective: In dorsal spine instrumentation trajectories of screw placement and visual approach often diverge depending on the systems manufacturer. Drilling and screw insertion for narrow and sloped lateral mass as well as lateral directed C7 pedicle often demand extreme trajectories making broad exposure necessary. We report our first experience with percutaneous tube based drilling and screw insertion as a prototype enhancement of a dorsal cervical spine instrumentation system to minimize surgical approach.

Method: In 12 patients with need for dorsal cervical spine instrumentation the entry points were exposed by a microsurgical approach. In 7 patients with lateral mass fixation a single extra skin incision about 5-7cm below the approach served to place a dilator and consecutively a tube into the surgical site. Via the tube the drilling, screw and rod placement was performed, whereas the screw fixation was performed through the microsurgical approach. In 5 patients instrumentation of C7 pedicle screws was performed respectively using a far lateral incision on each side.

Results: 42 screws (32 lateral mass screws and ten C7 pedicle screws) have been placed via percutaneous tubing. Ideal screw placement could be achieved in 30 (94%) and 8 (80%), respectively, following a learning curve. No revisions had to be done. In C7 pedicle screws an angle of more than 45° from sagittal plane could be achieved. The minimum length of skin incision for single level lateral mass was 1.5 and 2 cm, for C7 pedicle screws 4 and 1.4 cm on each side. No wound infection occurred.

Conclusions: Percutaneous screw placement enables extreme screw trajectories while sparing length of skin incision and soft tissue trauma. A prospective trial will evaluate the clinical benefit of minimized approach.