INTRODUCTIONrnSlippage of lumbar vertebrae is a second common disease afterprotrusion of intervertebral discs. Although some patients werecured by conservstive therapy, surgical treatment is needed in somecases[1] . From March 1994 to March 2001, we used steal plateinternal fixation to treat 18 cases of slippage and the effect wasobvious. The following is the report.rn