Bone Plates
Bone Screws
© Vast Ortho: Orthopedic Implants Manufacturers
First Floor, Khasra No. 104/14 | B-Block, Sant Nagar, Burari | Delhi-110084, INDIA
Cortical Screws are designed to anchor and stabilize bone fragments or implants in the cortical, or outer, layer of bone tissue.
The cancellous or trabecular bone is the more porous inner part of a bone, while the cortex is the bone’s hard, dense outer covering. The thread arrangement and shape of Cortical Screws are specifically created for insertion and fixation in the dense cortical bone. When compared to screws used for cancellous bone, they often have a more prominent threading.
Cortical screw threads are designed to contact with cortical bone and provide stability by resisting withdrawal pressures. The screw’s shank, which connects the head to the threads, is often smooth to allow for easier insertion through sensitive tissues and to reduce irritation.
Cortical screws are frequently used in operations like fracture fixation, where solid fixation of bone fragments is critical for optimal healing. Cortical screws are favoured in locations with high bone density, such as the femur, whereas cancellous screws are better suited in areas with low bone density, such as the vertebrae.
The decision between cortical and cancellous screws is determined by the surgical process, the kind of bone being worked on, and the level of stability sought. When selecting the proper type of screw for a given circumstance, surgeons examine aspects such as bone density, the patient’s age, the type of fracture or condition being treated, and the biomechanical requirements of the fixation.
Cortical Screws are used in fixation of different size of surgical plates such as
Contraindications may be qualified or total, and need to be taken into consideration when evaluating the prognosis in each case. The physician’s education, training and professional judgement must be relied upon to choose the most appropriate device and treatment. Conditions presenting an increased risk of failure include:
Before using Cortical Screws, the surgeon and ancillary staff should study the safety information in these instructions, as well as any product-specific information in the product description, surgical procedures and/or brochures.
Screws are made from medical grade materials and are designed, constructed and produced with utmost care. These quality screw assure best working results provided they are used in the proper manner. Therefore, the following instructions for use and safety recommendations must be observed.
Improper use of screw can lead to damage to the tissue, premature wear, destruction of the instruments and injury to the operator, patients or other persons.
It is vital for the operating surgeon to take an active role in the medical management of their patients. The surgeon should thoroughly understand all aspects of the surgical procedure and instruments including their limitations. Care in appropriate selection and proper use of surgical instruments is the responsibility of the surgeon and the surgical team. Adequate surgical training should be completed before use of implants.
The following adverse effects are the most common resulting from implantation:
The operating planning is carried out following a thorough clinical evaluation of the patient, Also, x-rays must be taken to allow a clear indication of the bony anatomy and associated deformities. At the time of the operation, the corresponding implantation instruments in addition to a complete size of Cortical Screws must be available.
The clinician should discuss with the patient the possible risks and complications associated with the use of implants. It is important to determine pre-operatively whether the patient is allergic to any of the implant materials. Also, the patient needs to be informed that the performance of the device cannot be guaranteed as complications can affect the life expectancy of the device.
As with all major surgical procedures, risks, side effects and adverse events can occur. While many possible reactions may occur, some of the most common include: Problems resulting from anesthesia and patient positioning (e.g. nausea, vomiting, dental injuries, neurological impairments, etc.), thrombosis, embolism, infection, nerve and/or tooth root damage or injury of other critical structures including blood vessels, excessive bleeding, damage to soft tissues incl. swelling, abnormal scar formation, functional impairment of the musculoskeletal system, pain, discomfort or abnormal sensation due to the presence of the device, allergy or hypersensitivity reactions, side effects associated with hardware prominence, loosening, bending, or breakage of the device, mal-union, non-union or delayed union which may lead to breakage of the implant, reoperation.
Bone screws are the most commonly used orthopedic implants. There are many different types and sizes of screws for different types of bones. Most bone screws are made out of stainless steel or titanium alloys. The outer diameter, root diameter, and thread pitch and angle are important in determining screw mechanics.
In orthopedics, screws are typically described by their outer diameter, for example, a “4.5 mm Cortical Screws” has an outside diameter of 4.5 mm. The pitch of a screw is the linear distance travelled by a screw for one full turn of the screw. The screw advances by a distance equal to the distance between the threads with each full turn. Cortical screws have a lower pitch and therefore more number of threads. Cancellous bone screws have a greater depth of the screw to increase the surface area and therefore improve the purchase, as the bone is weaker.
Screws function by converting the tightening torque into internal tension in the screw and elastic reactions in the surrounding bone. This creates compression between the fracture fragments that the screw is holding together. Screw is typically inserted into holes drilled equal to the root diameter and are either self-tapping or are inserted tapped (threaded) holes. The torque to insert cortical bone screws can be high, so the screws must be properly inserted into the correct size drilled hole and designed to withstand insertion torque levels expected in cortical bone. Cancellous bone screws have large, deep threads that grip the spongy bone well. Because of the relatively low strength of the cancellous bone, failure of the screw itself during insertion is rare, but pull out can be an issue.