Effect of PLIF and TLIF on sagittal spinopelvic balance of patients with degenerative spondylolisthesis

Objective: The aim of this study was to evaluate the effects of PLIF and TLIF on sagittal spinopelvic balance and to compare radiological results of two surgical procedures with regard to spinopelvic parameters. Methods: Thirty-five patients (34 female and 1 male; mean age: 52.29 +/- 13.08 (range: 35-75)) with degenerative spondylolisthesis cases were included in the study. Patients were divided into two groups according to surgical technique: PLIF and TLIF. The level and the severity of listhesis according to Meyerding classification were assessed and spinopelvic parameters including sacral slope, pelvic tilt, pelvic incidence (PI), lumbar lordosis, and segmental lumbar lordosis were measured on digital X-rays. All preoperative and postoperative parameters and the results were compared between two groups. Results: The age distribution was similar in both groups (p = 0.825) and there was no difference between the mean PI of the groups (p = 0.616). In 15 patients, spondylolisthesis level were at the L5-S1 level (PLIF: 8, TLIF: 7), in 16 patients at the L4-L5 level (PLIF: 6, TLIF: 10) and in 4 patients at the L3-L4 level (PLIF: 2, TLIF: 2). According to Meyerding classification, before the operation, the sliding grades were 0 in 4 patients, 1 in 21 patients, 2 in 7 patients, and 3 in 3 patients. The grades changed into 0 in 28 patients, 1 in 5 patients, and 2 in 2 patients after surgery. There were no differences in the grade of listhesis between PLIF and TLIF groups preoperatively (p = 0.190) and postoperatively (p = 0.208). In both groups, the spondylolisthesis-related deformities of patients were significantly corrected after surgery (p < 0.001). Conclusion: PLIF and TLIF techniques have similar radiological results in restoring the sagittal spinopelvic balance in patients with degenerative spondylolisthesis. Both techniques are good options to achieve reduction and fusion in patients with degenerative spondylolisthesis, but have no advantage over each other for restoring spinopelvic balance. (C) 2018 Turkish Association of Orthopaedics and Traumatology. Publishing services by Elsevier B.V

Restoration of pull-out strength of the failed pedicle screw: biomechanical comparison of calcium sulfate vs polymethylmethacrylate augmentation

Objective: The aim of the present study was to compare calcium sulfate (CAS) and polymethylinethaaylate (PMMA) bone cements used for the augmentation of a failed pedicle screw with biomechanical pull-out strength (POS) testing. Methods: Thirty lumbar vertebrae were harvested from 6 calves and bone mineral densities (BMD) were measured. Primary polyaxial pedicle screws were randomly inserted and pulled out and the POSs of the specimen were recorded. For revision, specimens were randomly assigned to the CAS-augmented pedide screws group (Group 1) or PMMA-augmented pedicle screw group (Group 2). Pull-out tests were repeated to compare both groups. Results: Mean BMD of the specimens was 1.006 +/- 0.116 g/cm(2). There were no statistically significant differences between BMD results of the two groups (p=0.116). For Group 1, mean POS of primary screws was 2,441.3 +/- 936.4 N and was 2,499.5 +/- 1,425.1 N after CAS augmentation, demonstrating no statistically significant difference (p=0.865). In Group 2, mean POS of the primary screws was 2,876.6 +/- 926.6 N and significantly increased to 3,745.5 +/- 1,299.2 N after PMMA augmentation (p=0.047). There was also a significant difference in mean POS between the CAS and PMMA groups (p=0.026). Conclusion: Although CAS augmentation facilitates a revision screw POS as strong as that of primary screws, it is not as strong as PMMA augmentation