While the biomechanical properties of trans-pedicular screws have proven to be superior in the lumbar spine, little is known concerning pullout strength of trans-pedicle screws in comparison to different distal terminal constructs like sublaminar hooks alone, trans pedicular screws with sublaminar hooks and clow hooks alone in the thoracolumbar spine surgery. In vitro biomechanical pullout testing was performed to evaluate the axial pullout strength of four different distal terminal constructs in thoracolumbar spine surgery. 32 fresh-frozen lamb spines were used. The lamb spines were divided into four groups, each group is composed of eight lamb spine cadavers with a different distal fixation pattern was used to terminate the construct at L1. (Group 1) trans-pedicular screws alone, (Group 2) sublaminar hooks alone, (Group 3) trans-pedicular screws augmented with a sublaminar hooks via a domino connector and (Group 4) clow hooks alone.Background
Methods
Intramedullary nailing is a widely accepted treatment method for femoral fractures. Failure of locking screws is often a threatening complication, particularly on comminuted fractures. For comminuted fractures, the locking nails are load-bearing devices. The load transfer between fractured fragments is made through especially the locking screws for these load bearing situations. Nonunion, malunion, delayed union, shortening, and nail migration are the expected results if early failure of locking screws is present with comminuted fractures. In this study our aim was to compare the bending resistance of titanium and stainless steel locking screws. We tested 60 locking screws in six groups (titanium, stainless steel, unthreaded, low threaded and high threaded) in a steel tube that has 30 mm inner diameter, which imitates the lesser trochanter level. We determined the yield points at three-point bending tests that permanent deformation started in the locking screws using an axial compression testing machine.Background
Methods
Femur fracture fixation systems depend on the stability of the supporting cortical screws, inside the host bone. Only a few works have studied the stability of cortical screws in femur shafts and compared their results with previous studies. In present study, five different cortical screw types are assessed using artificial femurs, under equated testing conditions. The maximum force needed to cause screw-bone inter face failure was measured, for each screw type by pullout tests. The obtained results were normalised according to traditional methods and cross-compared. The best performer was searched for and the effect of screw dimensions on the screw performance was investigated. To make the pullout tests solely dependent on screw dimensions, the effect of the bicortical bone thickness was eliminated by equating the conditions of screw insertion.Background
Methods
