Types of Orthopedic Bone Screws Used in Surgeries

December 23 , 2019
Bone screw

People who are in professions that require extensive physical activities, like sports players or professional fighters are often at the risk of fracturing body parts. This is also a common occurrence for regular people. Having a broken or damaged bone entails a lot of excruciating pain and suffering. Although bone fractures can often be healed by plasters, in some extreme cases, surgery may also be required. They are also required in transplants or implants of the hip, spine, or knee. Medical science has gone through an evolution in leaps and bounds and this has led to a lot of advancement in terms of surgical techniques. Amongst all the main materials that are needed for bone surgeries, the key material is a surgical screw. Although small, the orthopedic screws play a major role in making the surgery successful.

What is a surgical screw?

A surgical bone screw is much like regular screws, cylindrical-shaped, and consists of a head and body. Bone screws are used with the intent of creating pressure on the bones so that they can heal faster. When a bone is operated and the screws are implanted, following that all the pressure created from the bone movement is equalised over the injured bones thereby helping faster healing.
Bone Screw

Structure of a surgical screw:

An operational screw is specially designed to tend the bones. They come in different shapes and sizes to fit the need, however, the basic structure of orthopedic screws can be broken down as:

  • Head: This top flat part is common to all screws, mostly used to create the grip to insert the screw where it is supposed to be placed.
  • Length: This forms the body of the screw that penetrates into the section where it is supposed to hold the bones together.
  • Diameter: Bone Screw Manufacturers produce screws in different shapes and sizes and the diameter of the screw is very important to serve the purpose. When it comes to surgical screws, the diameter is classified as outside diameter, which is the total thickness of the screw and inner diameter which is the thickness of the screw to the thread.
  • Pitch: When the screw is inserted, it takes circular motions to penetrate. Each 360° turns that the screw takes and the distance it covers is called the pitch of the screw.
  • Tip: The rear end of the screw which ends exactly opposite to the head of the screw is called the tip.
  • Uses of Bone Screws:

    Surgical screws are often named after the areas that they are used in at the time of operation. There are classified mainly as:

  • Cancellous Bones: These are the soft bones which are also known as the spongy bones. The same types of screws cannot be used in both soft as well the firm parts of the bones. The cancellous bones are mostly found in parts like the skull, ribs, and pelvic bones. The cancellous screws are longer with a better pitch. The inner diameter is more than the outer diameter and they have a deeper thread, depending on the use they can have a full or half thread.
  • Cortical Bones: The tough outside bones which are responsible for the protection of the internal organs are known as cortical bones. These dense bones form about 80% mass of the human body. To mend these bones the screws used are known as cortex screws. They have a smaller pitch and the outer diameter is more than the inner diameter. These screws are always completely threaded.
  • Materials used for making surgical screws:

    Bone Screw Manufacturers use different materials to make the surgical screws. These are all body-friendly to avoid any internal reactions or side effects. The most commonly used bone screw manufacturing materials are:

  • Stainless Steel: This is a majorly used material for screw manufacturing. Stainless steel has got no side effects when placed inside the human body. Most of the implant parts are also made of stainless steel. They are available for both cortex and cancellous bones. The ones compatible with cortex bones measure about 1.5mm to 4.5mm, whereas the ones for the cancellous bones range between 3.5mm to 6.5mm. A matrix, we also use the F138 grade stainless steel which is a specialized surgical stainless steel. This type of stainless steel is designed for the highest amount of resistance against corrosion.
  • Titanium: Titanium is safer and more infection preventive than stainless steel and is mostly used for mandibular fractures. Titanium is also a major material in the production of bone implants. Titanium is used as it is known to fuse well with human bone.
  • Bioabsorbable: These are screws that have the capacity to get dissolved within the body and require no surgery to be removed. These are mostly made up of polylactic acid and polyglycolic acid. Although these don’t have to be removed but still there always runs a risk of encountering any reaction as the chemicals will get mixed with the bloodstream
  • Before any surgery is carried out, always ensure to check with the doctor as to what materials will be used and what or if any side effects are anticipated.

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