Is second distal locking screw necessary in interlocking nailing of femur fractures?

Aim. Distal locking screw deformation is frequent in interlocking nailing of femur fractures. For today's clinical application applying two distal locking screws together is mostly used method. The aim of this study was to research whether second distal locking screw is necessary in interlocking nailing of femur fractures or not

THE BIOMECHANICAL PROPERTIES OF MENISCUS

In this study, the biomechanical properties of meniscus under pull-out and compression forces are investigated

The Mechanical Effect of Rod Contouring on Rod-Screw System Strength in Spine Fixation

OBJECTIVE: Rod-screw fixation systems are widely used for spinal instrumentation. Although many biomechanical studies on rod-screw systems have been carried out, but the effects of rod contouring on the construct strength is still not very well defined in the literature. This work examines the mechanical impact of straight, 20° kyphotic, and 20° lordotic rod contouring on rod-screw fixation systems, by forming a corpectomy model. METHODS: The corpectomy groups were prepared using ultra-high molecular weight polyethylene samples. Non-destructive loads were applied during flexion/extension and torsion testing. Spine-loading conditions were simulated by load subjections of 100 N with a velocity of 5 mm min(-1), to ensure 8.4-Nm moment. For torsional loading, the corpectomy models were subjected to rotational displacement of 0.5° s(-1) to an end point of 5.0°, in a torsion testing machine. RESULTS: Under both flexion and extension loading conditions the stiffness values for the lordotic rod-screw system were the highest. Under torsional loading conditions, the lordotic rod-screw system exhibited the highest torsional rigidity. CONCLUSION: We concluded that the lordotic rod-screw system was the most rigid among the systems tested and the risk of rod and screw failure is much higher in the kyphotic rod-screw systems. Further biomechanical studies should be attempted to compare between different rod kyphotic angles to minimize the kyphotic rod failure rate and to offer a more stable and rigid rod-screw construct models for surgical application in the kyphotic vertebrae