A screw is cylindrical mechanical equipment with spiral threads on its external surface. These screws were established in orthopedic treatments in ancient times. The profuse usage of these bone screws is to heal bones. The major rule of this bone is to generate required compression in bones to recover a bone injury.
The screw transfigures all the forces that dive out of the bone movement into compression and disperse this compression evenly around the surface of injured bones. This compression helps the bone to stay in one place and heal quickly. Avail of the bone screw from the best bone locking screw manufacturers that offer exceptional devices with a great solid structure and proper mechanisms.
Classification of orthopedic screws:
Orthopedic screws are categorized depending upon certain characteristics, including structure or design size material and characteristics or features.
- Structure or design: Conventional screws, headless screws, cannulated screws, single versus double lead threads, locking screws.
- Size: 3.5 mm 4 mm 4.5 mm and 6.5 mm
- Material: Bioabsorbable, Titanium, and stainless steel
- Characteristics or attributes: Self-drilling, self-tapping, self-tapping and self-drilling, and non-self tapping
Area of application:
- Cortex bone and screws:
This bone is meant to shield the internal cavity and is commonly known as the condensed outer layer of bones. Cortex screws comprise a smaller pitch when compared to cancellous screws. It means the cortex screw has a large number of threads. But the thread diameter to the core or outer diameter ratio is less. Generally, the screws are fabricated that significantly support the inside of the cortical bones, and this cortex screw is fully threaded.
- Cancellous bone and screws:
Compared to cortex bones, cancellous bones or b softer and sponge. And it is found in the areas like pelvic ribs and skulls. But the cancellous screw comprises the largest pitch, and the threads have a high ratio of inner diameter than the outer edge. The cancellous screw is fabricated to offer better support in the cancellous bone, but it can be fully or partially threaded
- Cannulated screws:
It is another type of screw commonly used in surgery. These kinds of screws are known for their hollow shaft.
It is to be noted that acquiring these orthopedic screws from the ideal bone locking screw manufacturers offers many more advantages than other forgery ones.
Bone screws working mechanism:
The working mechanism of bone screws are as follows:
- Neutralization screws:
These screws ensure to neutralize the forces on the plate during plate fixation
- Reduction screws:
These screws are to minimize replaced fracture by pulling or pushing.
- Locking screw:
This locking screw is deployed to fix locking plates. In these screws, the screw head is fully threaded, which fits into the threaded hole on the plate. Moreover, this screw is also deployed when simple traditional screws are utilized to lock the two edges in interconnecting nails
- Positions screws:
These position screws hold two pieces in position without compression. For instance, syndesmotic screw
- Lag screws:
For interfragmentary compression, these lag screws or majorly used.
- Poller screw:
These screws can be used similarly in locking screws in interconnecting nails where the medulla is broad to prevent extreme nail replacement and escort the nail path.
- Anchor screws:
These anchors screw acts as an anchor for stitches or wire. Deployed in screw reformation or in-tension band wiring.
Components of a screw:
The screw has the following parts that include:
Akola is the regent path from which the threads protrude outwards. And the core size defines the strength of the screw and the fatigue defiant. Moreover, the drill bit size deployed is equal to the core diameter
The head comprises two major functions.
It offers support to halt the entire screw descending into the bone. This brace or support can be extended by allocating a washer between the bone and the head to spread the load. It is majorly utilized in very soft bones.
The head bears a position where the screwdriver fits perfectly to rotate the screw. Moreover, the screw turns and moves forwards regarding a deforming force, so equal torque must be applied proficiently.
The screw’s head slot is accessible in multiple shapes.
Advanced orthopedic screws deploy a hexagonal slot. This shape is preferred because it offers potent integration, which is not likely to get damaged during the screwing process.
The bone locking screw manufacturers ensure fabricating an appropriate thread design that increases the initial contact, maximizes a surface area, and proliferates the pull-out strength. Some important aspects of the thread need to be given importance. It includes the shape of thread, thread pitch, and thread depth.
From the upper surface, these bone screws or flat when it comes in contact with the bone and are rounded beneath. It allows them to offer an extensive surface on the pulling side and minimal frictional resistance on the undersurface.
Depth of a thread:
The distance between the thread and the core is measured as the thread depth. It is estimated to be half the core diameter and the thread diameter.
Pitch of the thread:
The screw pitch is the distance lengthwise travele by a screw when the full 360-degree turn rotates the screw.
Tapping is the procedure of fragmenting of thread in bone. A screw that comprises a cutting tape allows it to fragment its female threa track when it is insert. This type of screw is entitle to be a self-tapping screw.
All cancellous screw falls under the self-tapping category. And to connect the screw into the bone, these cancellous bone screws comprise a corkscrew tip.
Before the screw insertion, the tapping needs to be done first in cortical bones. So in cortical bone, self-tapping screws for direct screw insertion or not typically use because it is rigid and extreme torque is require.
The cannulated screw falls under the shelf drilling category. In other words, it can drill a hole in the material without the requirement of a separate drill bit. The dip is shape of a trocar which offers an ideal cutting edge to act like a drill.
Above, we have discussed how bone screws play an important role in orthopedic surgery. Usually, these devices are deploye in clinical practices and surgical treatments. Generally, these bone screws are expensive import from exceptional international bone locking screw manufacturers.