OBJECTIVETo study the accuracy the pedicle screw placement in the thoracic spine using funnel technique and free hand technique.

METHODSEight cadavers including 5 males and 3 females were analysed. The age ranged from 57 to 82 years (mean 68 years). Cadawers were randomly assigned to one of two instrumentation groups. In four cadavers, "funnel technique" was used for screw placement. In the remaining four cadavers,free hand technique then was used. Success of pedicle screw placement was judged by CT scan. The rate of success of two ways was compared using statistic analysis.

RESULTSNinety-six screws were inserted by "funnel technique" and free hand technique respectively, 84 of "funnel technique" were successful, and 73 of free hand technique were successful. Significant differences were found between two ways (P < 0.05). Chanciness tresis occurred in "funnel technique" on 2 screws and free hand technique on 9 screws. There were significant differences in rates of chanciness tresis (P < 0.05).

CONCLUSIONFunnel technique is simple, safe and cost-effective alternative to any other thchnique for pedicle screw placement in thoracic spine,funnel technique is able to reduce the chance of critical injury of nerve root and dura.