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4.5mm Malleolar Screw Specification, Uses, Sizes and Surgical Techniques.

4.5mm Malleolar Screws

4.5mm Malleolar Screw Specification

4.5mm Malleolar Screw has a smooth shaft and is partially threaded. Malleolar Screws with cortex thread, shaft and trocar tip have limited use in the metaphyseal area, distal humerus, trochanteric area and sometimes in the ankle, where the bone is rather dense.

  • 4.5mm Malleolar Screw available lengths are 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm and 100mm.
  • Screw has a smooth shaft and is partially threaded.
  • Screws available in both Titanium and Stainless steel.

4.5mm Malleolar Screw uses

4.5mm Malleolar Screw is designed to be used for fracture fixation of small fragments in cancellous bone. It is primarily used in interfragmental compression bone plates and used in hard cortical where buttress thread form provide enhanced pull-out resistance. Hemispherical head diameter ensures optimal annular contact with washers and plates when screw is angled. Partially threaded offers best fit of threads into far bone fragment, for better interfragmentary compression.

Safe zone for the placement of medial 4.5mm Malleolar Screws

Background

Hardware placement for fracture fixation can put soft-tissue structures at risk for injury or abutment. The prominence of the hardware is a frequent cause of pain after the fixation of ankle fractures. This study was designed to assess the risk of injury or abutment of the posterior tibial tendon with the placement of medial 4.5mm Malleolar Screw.

Methods

Ten unmatched cadaveric limbs that had been disarticulated at the knee were used, and the medial malleolus was exposed by dissection of the skin. With use of fluoroscopy and direct visualization of the deep fascia, three Kirschner wires were placed through the tip of the medial malleolus and directed parallel to the medial articular surface. The first wire was placed in the center of the anterior colliculus. Two additional wires were placed parallel and posterior to the initial wire at 5-mm intervals. The wires were overdrilled, and 4.0-mm screws were inserted over the Kirschner wires. The specimens were dissected to inspect for trauma and the proximity of the screws to the posterior tibial tendon. The medial malleolus was divided into three zones on the basis of anatomic landmarks. Zone 1 is the anterior colliculus; Zone 2, the intercollicular groove; and Zone 3, the posterior colliculus.

Results

4.5mm Malleolar Screw placed in Zone 1 (the anterior colliculus) did not contact the posterior tibial tendon in any specimens. Screws placed in Zone 2 (the intercollicular groove) were, on the average, 2 mm from the posterior tibial tendon. Screws placed in Zone 3 (the posterior colliculus) resulted in tendon abutment in all ten specimens and in tendon injury in five of the ten specimens.

Conclusions

4.5mm Malleolar Screws inserted posterior to the anterior colliculus place the posterior tibial tendon at significant risk for injury or abutment.

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Different Types of Screws including 4.5mm Malleolar Screw

Locking Cortical Screws

Cortical Screws

Locking Cancellous Screws

Cancellous Screws

Locking Cannulated Screws

Cannulated Screws

Headless Screws Full Thread

Headless Screws Partially Thread

  • 2.5 mm Headless Compression Screws Partially Thread
  • 3 mm Headless Compression Screws Partially Thread
  • 3.5 mm Headless Compression Screws Partially Thread
  • 4 mm Headless Compression Screws Partially Thread
  • 4.5 mm Headless Compression Screws Partially Thread
  • 5.5 mm Headless Compression Screws Partially Thread
  • 6.5 mm Headless Compression Screws Partially Thread
  • 7.5 mm Headless Compression Screw Partially Thread

Interlocking Nail Screws

Interference Screws

  • 5 mm Interference Screw
  • 6 mm Interference Screw
  • 7 mm Interference Screw
  • 8 mm Interference Screw
  • 9 mm Interference Screw
  • 10 mm Interference Screw

Herbert Screws

Craniomaxillofacial Screws

Malleolar Screws

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 “4.5mm Malleolar Screw” 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.

4.5mm Malleolar Screw 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 4.5mm Malleolar Screw.

Warnings and Precautionary for 4.5mm Malleolar Screw

Before using 4.5mm Malleolar Screw, 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 4.5mm Malleolar Screw.
  • Mechanical failure of the implant, including bending, loosening or breakage.
  • Migration of implant resulting in injury.

Preoperative Planning for 4.5mm Malleolar Screw

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 4.5mm Malleolar Screw 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.

4.5mm Malleolar Screw 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 this screw.
  • 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.

4.5mm Malleolar Screw Warnings

  • 4.5mm Malleolar Screw 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.

4.5mm Malleolar Screw 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.

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