I.For what purpose cannulated screw have a hole?
How does the cannulated screw systems work? Using thin Kirschner wires (K-wires) that have been drilled into the bone to direct screw trajectories accurately into small bone fragments.
Use of the K-wires avoids overdrilling the pilot holes and allows fixation of imminent bone fragments during screw insertion. Hollow tools and hollow screws are inserted into the bone over the K-wires. Cannulated screw fixation is useful in the cervical spine to stabilize odontoid fractures and to treat atlantoaxial instability.
Cannulated screws have several advantages compared to noncannulated screws: 1) the K-wires guide the screw position into the bone;
2)the K-wire trajectory makes reposition easily if the original trajectory was not ideal;
3)the K-wires allow continuous fixation of adjacent unstable bone fragments;
4)The K-wires prevent move of unstable bone fragments during screw insertion.
Complications associated with the K-wire (breakage, repositioning, and advancement) can be minimized using precise operative techniques. A special cannulated screw tool system was developed specifically for upper cervical fixation to allow percutaneous drilling using long tunneling devices, tissue sheaths, drill guides, and long K-wires. These tools allow delivery of cannulated screws at a low angle to the spine through long soft-tissue trajectories. Cannulated screws have significant advantages compared to noncannulated screws for fixation of the unstable cervical spine on system.
II.Which is better cannulated screws or intrameduallary nails?
Both intramedullary nails and cannulated nails are medical devices used for internal fixation of fractures. They each have their own advantages and are suitable for different types of fractures and treatment needs.
| Type | Advantage |
| Intramedullary Nail | The intramedullary nail fixation effect on stable fractures of long bones is good, with less injury and less bleeding. Intramedullary nail fixation belongs to central fixation. Compared with steel plates, intramedullary nails can also protect the integrity of the extraosseous membrane, prevent delayed fracture healing, and play a role in avoiding infection. |
| Cannulated Screw | It is mainly applied in areas such as femoral neck fractures, with special fixation and compression effects. Moreover, the damage is very small and no steel plates are needed. |
III.When to use cancellous vs cortical screws?
Cancellous screws and cortical screws are both types of orthopedic implants used in bone fixation, but they are designed for different types of bone and have distinct applications:
Cancellous Screws are Specifically designed for use in the spongy, less dense, and trabecular bone tissue, commonly found at the ends of long bones, such as the femur and the tibia.Typically used in areas where the bone is more porous and less dense, such as the metaphyseal regions of long bones. They are often used in procedures involving the spine, pelvis, and certain parts of the shoulder and hip.
Cortical Screws is designed for use in denser, cortical bone, which forms the outer layer of most bones and is much harder and stronger than cancellous bone. Generally used in situations where greater strength and stability are required, such as in the fixation of fractures in the diaphysis (shaft) of long bones. They are also used in certain internal fixation devices and plates.
In summary, the choice between cancellous and cortical screws depends on the type of bone being fixed and the specific requirements of the orthopedic procedure. Cancellous screws are suitable for softer, more porous bone, while cortical screws are ideal for denser, load-bearing bone.
Post time: May-09-2025
