https://www.selleckchem.com/products/heparan-sulfate.html IV; retrospective study. IV; retrospective study. Instrumented posterior lumbar fusion with top-loading pedicle screw systems (PSS) requires fully tightened set screws to achieve a secure fixation and symmetric load condition. This assumes a complete reduction of the rod by 90°, which is not always attainable in situ, especially under constraint. The objective of this work is to compare the mechanical performance of different innovative set screw technologies, which should improve the tightening process. The hypotheses of the study are that modifications to the screw and screwdriver unit can (1) improve the quality of set screw tightening and (2) increase the axial gripping capacity of the construct. The four set screw technologies under investigation include a standard set screw with a flat surface (F-S; control group), a set screw with a convex surface (C-S) and a shaft tip method screwdriver used in combination with both flat (F-STM) and convex set screws (C-STM). The quality of set screw tightening is categorized as follows failed=the rod is not coction or fixation during PSS assembly as well as friction-reduced final alignment and tightening with the aim to reduce implant loosening, hardware failure and reoperations, while respecting anatomical and biomechanical balance. Several biomechanical and clinical case studies have identified possible effects of misaligned rod-screw interfaces such as screw pull-out during rod reduction, screw loosening, screw or rod breakage, misalignment, adjacent segment degeneration and worsening of the clinical outcome. C-STM-technology thus supports controlled fixation in the sense of applying appropriate forces for correction or fixation during PSS assembly as well as friction-reduced final alignment and tightening with the aim to reduce implant loosening, hardware failure and reoperations, while respecting anatomical and biomechanical balance. Arthroscopic surgery has ear