Sixty-eight cases of degenerative spondylolisthesis were subjected to micro bone saw laminectomy, complete nerve decompression and laminoplasty with PLLA pins. Twenty-two cases were male, and 46 female. Pre and post operative JOA score was 18.1±4.4, 27.9±1.9. This improvement ratio was 90.7% and very satisfactory. Pre and post operative slip ratio was 20.1±6.7%, 22.3±7.3%. The slip ratio was slightly progressive. The next another two groups were comprared. One group of 10 cases were operated on with PLIF. The other 10 cases were operated on with laminoplasty using PLLA pins. The slip angle of these 20 cases was more than 23%. Pre and post operative slip ratio and the spinal stability at the operative slip level of these two groups did not differ significantly. 75.8% of the facet joints fixed with PLLA pins obtained stability and immobility in 62 cases. Spinal stability was achieved with this new operation method.
