Cortical Screws Specification, Uses & Sizes

Cortical Screws Introduction

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

Cortical Screws Specification

Cortical Screws available lengths are 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm, 34mm, 36mm, 38mm, 40mm, 42mm, 44mm, 46mm, 48mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm ,115mm, and 120mm.
Cortical Screws are made from pure Titanium and SS 316L.
Any additional length sizes of this screw will be made on demand.
This is Self Tapping Screw. Self Tapping Screws cuts its own thread while being driven into the bone. It makes a small hole while entering the bone which creates a tight friction fit between the threads. This helps fight vibration loosening and allows the parts to be taken apart if needed..
Instruments are available for this screw such as Bone Taps, Combined Drill & Tap Sleeve, Counter Sink, Depth Gauge, Drill Bits, Drill Guide, Drill Sleeve, Hollow Mill Screw Removal, Reverse Measuring Device, Screw Drivers and Screw Holding Forceps etc.

Cortical Screws uses

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

2 mm screws used for 2 mm plates
2.4 mm screws used for 2.4 mm plates
3.5 mm screws used for 3.5 mm plates
4.5 mm screws used for 4.5 mm plates

Cortical Screws Contraindications

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:

Any active or suspected latent infection or marked local inflammation in or about the affected area.
Compromised vascularity that would inhibit adequate blood supply to the fracture or the operative site.
Bone stock compromised by disease, infection or prior implantation that can not provide adequate support and/or fixation of the devices.
Material sensitivity, documented or suspected.
Obesity. An overweight or obese patient can produce loads on the implant that can lead to failure of the fixation of the device or to
failure of the device itself.
Patients having inadequate tissue coverage over the operative site.
Implant utilization that would interfere with anatomical structures or physiological performance.
Any mental or neuromuscular disorder which would create an unacceptable risk of fixation failure or complications in postoperative care.
Other medical or surgical conditions which would preclude the potential benefit of surgery.
All associated diseases which could endanger the function and success of the Cortical Screws.

Warnings and Precautionary for Cortical Screws

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.

Factors which could impair the success of the operation:

Allergies to implanted materials.
Localized bone tumours.
Osteoporosis or osteomalacia.
System disease and metabolic disturbances.
Alcohol and drug abuse.
Physical activities involving excessive shocks, whereby the implant is exposed to blows and/or excessive loading.
Patients who are mentally unable to understand and comply with the doctor’s instructions.
Poor general health.

Possible Adverse Effects

The following adverse effects are the most common resulting from implantation:

Loosening of the screw, which may result from cyclic loading of the fixation site and/or tissue reaction of the implant.
Early and late infection.
Further bone fracture resulting from unusual stress or weakened bone substance.
Temporary or chronic neural damage resulting from pressure or hematomata.
Wound hematomas and delayed wound healing.
Vascular disease including venal thrombosis, pulmonary embolism and cardiac arrest.
Heterotopic ossification.
Pain and discomfort due to presence of the Cortical Screws.
Mechanical failure of the implant, including bending, loosening or breakage.
Migration of implant resulting in injury.

Preoperative Planning for Cortical Screws

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.

Cortical Screws Precautions

Confirm functionality of instruments and check for wear during reprocessing. Replace worn or damaged instruments prior to use.
It is recommended to use the instruments identified for screws.
Handle devices with care and dispose worn bone cutting instruments in a sharps container.
Always irrigate and apply suction for removal of debris potentially generated during implantation or removal.

Cortical Screws Warnings

Cortical Screws can break during use (when subjected to excessive forces). While the surgeon must make the final decision on removal of the broken part based on associated risk in doing so, we recommend that whenever possible and practical for the individual patient, the broken part should be removed. Be aware that implants are not as strong as native bone. Implants subjected to substantial loads may fail.
Instruments, screws and cut plates may have sharp edges or moving joints that may pinch or tear user’s glove or skin.
Take care to remove all fragments that are not fixated during the surgery.
While the surgeon must make the final decision on implant removal, we recommend that whenever possible and practical for the individual patient, fixation devices should be removed once their service as an aid to healing is accomplished. Implant removal should be followed by adequate post-operative management to avoid refracture.

Cortical Screws General Adverse Events

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.

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