A Study to Assess the Functional Outcome of Decompression and Posterior Lumbar Interbody Fusion of Low Grade Spondylolisthesis of Lumbar Vertebra.

Introduction: Spondylolisthesis is defined as the forward displacement of one vertebra over the vertebra below. It is often accompanied by spinal canal stenosis and compression, which is the cause of all the symptoms.

Aim: To assess and study the functional outcome after decompression and Posterior Lumbar Interbody Fusion (PLIF) of isthmic spondylolisthesis of lower lumbar vertebra and to study the complications occurring with this technique.

Materials And Methods: A prospective study was conducted in the Department of Orthopaedics in Justice KS Hegde Charitable Hospital, Mangalore, Karnataka, India from March 2015 to August 2016. A total of 15 diagnosed patients with Grade I and II spondylolisthesis of L4-L5 and L5-S1 vertebrae with no neurological deficits, between the age group of 25-50 were included in the study. An initial two months of conservative treatment of back physiotherapy and flexion exercises was tried. Patients who did not improve with the conservative therapy were taken up for surgery with consent. Decompression and PLIF with bone grafting with interbody cage placement and pedicle screw instrumentation was performed. The patients were discharged on postoperative day 10 after suture removal. They were reviewed at postoperative day 10, week six and week 24. The scoring of the functional outcome of the back was done as per the Modified Oswestry low back pain Disability Questionnaire. The statistical analyses were done using the repeated measures ANOVA, SPSS version 20.

Results: The mean Modified Oswestry low back pain Disability score preoperatively was noted to be 42.87+/- 3.46 points. The mean Modified Oswestry low back pain Disability score at postoperative day 10 was noted to be 36.93±3.75 points. The mean Modified Oswestry low back pain Disability score at postoperative week six was noted to be 28.47±3.70 points. The mean Modified Oswestry low back pain Disability score at postoperative week 24 was noted to be 24.27±3.01 points. Improvement in the Modified Oswestry low back pain Disability scores was noted during the follow ups. Foot drop was noted in two cases postoperatively which improved during the final follow up with physiotherapy.

Conclusion: Decompression and PLIF is noted to produce good to satisfactory functional results in cases of isthmic spondylolisthesis of lower lumbar vertebra.