Cannulated Screws are used in bone and joint surgery to repair the fracture and to secure artificial implants which can be used to replace part or whole of a joint. The main advantage of cannulated screws is that they can be inserted over a guide pin or guidewire. The diameter of the guide pin is much smaller than the cannulated screw and can be more correctly placed using fluoroscopy in the operating room. In addition, given its small diameter, the guide pin can be reinserted many times if necessary, for correct placement without excessive damage to the bone.
Specifications of Cannulated Screws:
- Thread on the full cannulated screws extends into the head profile. Greater gripping ability, especially with osteoporotic bone, allow for easy removal.
- A low-profile head lessens the possibility of soft tissue irritation.
- Hemispherical head ensures optimal annular contact with plates or washers when screws are angled.
- Cancellous threads profile uses deep cutting threads with a large pitch to increase resistance to pullout. A large pitch also accelerates the insertion of the screw and its removal.
- Self-tapping screw tip facilitates insertion of the screw. Reduces the need for tapping and pre-drilling.
- Reverse cutting flutes for removal with ease.
Uses of Cannulated Screws:
Cannulated screws are designed for the fixation of fractures, fusions, and osteotomies of large and small bones appropriate for the size of the device.
Cannulated screw consists of a hollow central shaft that can be obtained from Orthopedic Manufacturers. Both cancellous and cortical screws can be cannulated. Cannulated cancellous screws are used for metaphyseal fractures while non-cannulated and cannulated cortical screws are used as lag screws for the fixation of diaphyseal fractures.
Partially threaded screws can be used to lag one bone fragment to another, where the bone fragment is captured by the threads of the screw and pulled towards the near cortex fragment on the screw’s head side. Fully threaded screws are used to stabilize fractures with little to no compression across the fracture.
Cannulated screw system provides percutaneous screw fixation, emergency closed reduction, and excellent stability.
Cannulated bone screws in comparison with traditional screws allow more precise screw placement, decrease surgical time, and reduce the possibility of errors.