Orthopaedic bone screw, non-biodegradable

Intended purpose

A small, threaded rod with various head drive configurations (single slot, cruciform, plus drive, star drive) typically used for internal orthopaedic fracture fixation by being screwed into bone (normally self tapping but can also be self drilling) to hold plates or nails to bone or to provide direct intrafragmentary stabilization of bone, or it may fasten soft tissue to bone. It is made of a material that cannot be chemically degraded or absorbed via natural body processes (includes implant grade metal such as surgical steel, titanium (alloy), or carbon fibre). There are a number of kinds available: cortical, cancellous, maleolar, scaphoid, partially-threaded/fully-threaded, cannulated, double threaded headless compression, locking to plate and locking to plate. A "lag screw" can be any of these used to obtain compression across bone fragments.