Minimum 5-year follow-up study on the effects of the Wallis dynamic stabilization system in the treatment of lumbar degenerative disease

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 herniation and 12 patients (Group 2) with L5/S1 disc herniation 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 California 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.