Efficacy Of PLIF With Pedicle Screw Systems For The Treatment Of Adult Isthmic Spondylolisthesis

Objective: To study the efficacy of PLIF with pedicle screw systems for the treatment of adult isthmic spondylolisthesis.Method: From January 2004 to January 2009, 38 cases (38 segments) of adult isthmic spondylolisthesis treated by pedicle screw systems and PLIF were followed up. 11 males and 27 females with average age of 58.6 years were included. All cases were treated by PLIF with posterolateral bone graft, and pedicle screw systems were supplemented. Single cage was inserted in 17 segments and double cages in 21 segments. The average preoperative and postoperative disc space height, foraminal height, lumbar lordosis, segmental lordosis, lumbar tilt, sacral tilt and the amount of sagittal rotation observed between the extremes of movement (on flexion–extension radiographs) were measured and compared. The JOA score and Oswestry Disability Questionnaire were used to evaluate the clinical outcome.Result: The follow-up period ranged from 16 to 60 months with an average of 36.5 months. The fusion rate is 97.37%. The clinical recovery rate (JOA) was 86.6% and the ODI decreased significantly. There were significant retrieve of disc space height and foraminal height, and the restoring of the amount of sagittal rotation observed between the extremes of movement was achieved. Mean lumbar lordosis and segmental lordosis of the fused segments showed significant changes postoperatively. Segmental lordosis increased from 8.8±3.2°to 13.5±3.5°at L4/5, and from 15.8±2.5°to 21.0±1.5°at L5/S1, lumbar lordosis increased from 32.8±7.6°to 41.5±9.4°. Analysis of changes in lumbar tilt did not show significant difference, and sacral tilt increased after surgery. The restoration of the interbody space height and achievement of optimal sagittal alignment of the lumbar spine are relevant factors influencing the clinical outcomes. Cases fused with one or two cages have no significant differences in radiological and clinical outcomes.Conclusion: (1) PLIF with pedicle screw systems is one effective method of treating adult isthmic spondylolisthesis. (2) With pedicle screw fixation, there is no significant radiological or clinical difference between groups using one or two cages. The use of one cage can reduce the risk and cost of surgery.