Background Short-term outcomes of the Wallis system in the treatment of lumbar degenerative disease (LDD) have been shown to be effective,whereas there is a paucity of studies on the mid-long-term effects of the treatment of the Wallis system.This study was to evaluate the mid-long-term effects of the Wallis dynamic stabilization system in the treatment of LDD.Methods A total of 26 patients who received the treatment of the Wallis system between February 2008 and January 2009 were included in the study,with 14 patients (Group 1) with L4/5 disc hiation and 12 patients (Group 2) with L5/S1 disc hiation and L4/5 intervertebral disc degeneration (IDD).Visual analog scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical outcomes and lumbar x-rays and MRI were obtained to observe imaging changes before and after operation.Results The mean follow-up period was (63.50±2.12) months.The mean ODI and VAS scores decreased obviously three months and five years after operation (P ＜0.05).In Groups 1 and 2,L4/5 Cobb angle and range of motion (ROM) decreased and L4/5 posterior disc height increased at the last follow-up (P ＜0.05).There were no statistically significant changes in L4/5 anterior disc height and L3/4 University of Califia at Los Angeles grading before and after operation.There was no statistically significant change in Pfirrmann grading system of L4/5 IDD in Group 2 before and after operation.Adjacent segment degeneration at the last follow-up was found in two patients (2/26,7.69％) and Modic changes in L4/5 endplates were detected in one patient (1/26,3.85％).Conclusions The mid-long-term effects of the Wallis system in the treatment of LDD were satisfied.The Wallis system,as a dynamic stabilization system,which can preserve some ROM of the fixed segment,sustain the lumbar stabilization,and prevent adjacent segment disease and fixed segment degeneration,is an effective instrument to treat LDD.