Lag screw is a type of fastener with a large hex head used to attach materials that require high torque. These screws can be found in woodworking, automotive, construction, and general industrial applications. While many of these fasteners come with hex heads, there are also those with square, slotted, and Philips drives. These types of screw are designed to withstand heavy loads and can be driven into materials such as wood or metal with tools like a nut driver or ratchet.

Lag screws are usually used in the construction of wood structures because they have a higher shear capacity than other fasteners such as bolts. These screws are used to bind together pieces of wood and provide stability to the structure. They are especially useful when working in environments with high moisture content because they are designed to resist corrosion.

Despite the advantages of lag screws, this type of fastener has some disadvantages. For example, the use of lag screws in wood requires predrilling to ensure that the threads are properly engaged. This is necessary to prevent screw withdrawal and lateral load resistance failure.

Using lag screws can cause complications such as metacarpophalangeal joint stiffness, extensor tendon adhesion, and iatrogenic injury of the dorsal cutaneous branch of the ulnar or radial nerve. This can significantly reduce the range of motion and speed of recovery after a fracture in the metacarpal shaft and can lead to pain, weakness, and numbness in the hand. Lag screw fixation has been shown to be more effective than bone plate fixation in the treatment of these injuries, but additional research is needed to determine whether the blade or non-spiral-blade lag screws are superior for this purpose. Lag screw