Cannulated screws are a common method of fixation used by orthopedic surgeons for multiple fracture patterns. These screws may be cannulated or "hollow" to allow them to be placed over a guidewire facilitating better alignment prior to drilling or screw insertion. The guidewire is then removed and the screw is left in place.

Screws consist of multiple parts:

• head

• shaft

• thread

• tip

Using these elements, the screws are then further defined by their length, core diameter, outside diameter (the diameter of the thread), or tip (round/non-tapping or fluted/self-tapping).

The length of the thread (fully or partially threaded) and the head allows the surgeon to compress fractures. Screw thread may be cortical (smaller thread) or cancellous (larger thread).

By using cannulated screws, the orthopedic surgeon is able to avoid drilling multiple holes in the bone which may result in poor fracture fixation. When using cannulated screws it is important to use the principles for interfragmentary screw fixation.

Cannulated screws are often used in the fixation of undisplaced or valgus impacted hip fractures. However, due to the potential for avascular necrosis of the femoral head and subsequent femoral head collapse, some surgeons opt for alternative techniques such as a sliding hip screw or arthroplasty.

Screw selection