lag screw orthopedics are used for compression between refractures through sliding holes, which is suitable for sphenoid bone block, medial malleolus fracture, etc.
Lag screw technique is a common technique in orthopedic that uses sliding holes to create pressure between bone blocks.
Advantages
1.Without micro-movement,it can create direct healing between fractures.
2.A way to achieve absolute stability.
3.It is often used for oblique or spiral fractures (cortical or cancellous).
4.The fracture end must be anatomically reduced and the screw position must be accurate to obtain maximum compression.
Operation attentions
1. The reduction clamp should be in the same direction as the orthopedic Bone Screw,which can effectively prevent displacement.
2. When drilling the sliding hole in the proximal cortical, drill the hole vertically firstly(drilling a groove), and then drill the hole at an Angle, which can effectively prevent sliding (when drilling to the bone surface at an Angle,the drill bit will easily slide along the bone).
3. When sounding,it should be noted that the direction of the hook of the sounding ruler should be obtuse Angle side to avoid the deviation of screw measurement.
4. Long oblique and spiral fractures should be fixed with multiple lag screws,because one lag screw is weak in resisting rotation, torsion and shear forces.
5. It is not possible to drill two screw holes at the same time and then screw the lag screws at the same time,because concentric circles cannot be guaranteed.
6. The Orthopedic Screw should not be screwed into too deep or too tight to prevent micro-fracture and tensile failure.
7. The lag orthopedic implant screw should be perpendicular to the fracture line.
8. Transverse and short oblique fractures are not suitable for lag screws. When the length of the fracture line is ≧2 times the diaphysial diameter, lag screws are more suitable.
9. Countersunk head can spread the load of the screw head on the underlying cortex. The absence of a countersunk head may result in a high pressure on the screw head over the bone, causing a micro-fracture and resulting in loosening of the screw.
