Abstract
Introduction
In a prospective randomized trial we aimed to validate PMMA spacer in TLIF. Compared with standard, preformed PEEK spacer we didn't find significant difference regarding the clinical outcome, completed bony fusion, subsidence or loosening. When performing TLIF there are different arguments to position the intervertebral spacer in different position (anterior or posterior) In this prospective, randomized study we would like to compare the segmental anatomical changes following the position of a custom made PMMA spacer in monosegmental TLIF.
Material and Methods
In our study we planned to collect 60 consecutive patients to whom we perform one level TLIF in the lumbar spine. The patients are randomized in two groups by the GraphPad QuickCalcs software. Group A is standard TLIF with PMMA spacer placed in the anterior part of the intervertebral space. Group B is standard TLIF with PMMA spacer positioned in the posterior part of the intervertebral space. Patients between 18–65 years/o were inclouded. Patients with a high grade spondylolisthesis, metabolic bone desease, spinal infection, cancer, severe scoliosis (Cobb over 30°) were excluded. We evaluate changes in segmental, and overall lordosis and in the height of the neuroforamen according to the position of the spacer.
Results
58 patients, 31 in group A and 27 in group B, has a minimum of one year follow up. In both groups the segmental lordosis increased. The mean change was 6° in group A and 4° in group B, the difference was not significant. The foraminal height also increased in both groups, the mean change was 18% in group A and 27% in group B but this difference was not significant eather.
Conclusion
Anterior position of the intervertebral spacer seems to provide more possibility to correct lumbar lordosis, but the advantage on posterior position hasn't been shown significant in this study. Better foraminal height restoration was found in the posterior position of the spacer, but there was no correlation of this parameter to the clinical outcome. We can conclude that both positions provide good radiological and clinical result.