ACCURACY OF PEDICLE SCREWS IN DORSAL LUMBAR SPINAL-FUSION

We evaluated the placement of pedicle screws (N = 131) in 30 patients after lumbar dorsal spinal fusion. Postoperatively all patients were examined by CT. 39.9% of all screws penetrated the cortex of the vertebra. Of special interest were those implants which led to medial penetration of the pedicle, which is of potential hazard to the neural structure within the nerve root canal. 28.5% of all screws showed a medial deviation. In our study, a penetration of more than 6 mm coincided with a high risk for nerve root damage. In 2 patients there was a proven damage to a nerve root due to screw placement. In another 3 patients a coherency was likely to exist. The technique of transpedicular screw fixation for spinal fusion is highly demanding and should be performed only by experienced surgeons after a clear indication and after a trial of intense conservative therapy.