[The direct repair of the defect and grafting with single segment reduction fixation system in the treatment of lumbar spondylolysis and spondylolisthesis].

We designed lumbar spondylolysis and spondylolisthesis single segment reduction fixation system according to neural arch measured in the 46 dried specimen. The biomechanical tests showed that its strength is 1.6 times that of Hefti's technique, 2.7 times that of Salib's technique. It used contacted point lamina by lamina hook as fulcrum, through lever and pedicle screw to pull back olisthetic vertebrae. 18 patients were treated with this method. The displacemen rate was 26.67% before operation and 3.38% after operation. The height of disc was 14.94 mm before operation and 17.08 mm after operation. 15 patients were followed up for 12 months. By Henderson standard, excellent result was moted in 13 patients, good in 1 and fair in 1. We conclude that LSRF has good reduction and rigid fixation and it is a new technique for lumbar spondylolysis and spondylolisthesis.