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Dynamic Hip Screw Specification, Uses, Sizes and Surgical Techniques.

Dynamic Hip Screw

Dynamic Hip Screw is designed to provide strong and stable internal fixation of a variety of intertrochanteric, subtrochanteric and basilar neck fractures, with minimal soft tissue irritation.

Our Dynamic Hip Screw are made from finest quality medical grade material (Titanium and SS 316L) to ensure highest quality. Different sizes of  Screws are:

50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm and 150mm.

Femoral Neck Fracture ORIF with Dynamic Hip Screw

PRINCIPLES

Displaced transcervical and subcapital fractures are unstable. Their prognosis is by and large the same and they will be discussed as one group for the purpose of manner of reduction and choice of fixation, should internal fixation be chosen as the method of treatment.

If added rotational stability is desired in addition to the Dynamic Hip Screw, a cannulated screw is inserted above and parallel in both planes to the Dynamic Hip Screw plate. It must be parallel in order not to block the sliding property of the  implant.

Positioning of the patient

The patient is positioned supine on the fracture table for closed reduction. The ipsilateral arm is elevated in a sling and the contralateral uninjured leg is placed on a leg holder.

If closed reduction is not successful the patient may be transferred to a conventional table for open reduction.

C-arm image intensifier control during surgery is a must.

Approaches for open reduction
For this procedure the following approaches may be used for open reduction:

  • Anterolateral approach
  • Iliofemoral approach

REDUCTION

Closed reduction
Reduction can usually be obtained with gentle traction and internal rotation of the fractured leg, carried out under image intensifier control. The reduction must be checked in both the AP and lateral view with an image intensifier.
Occasionally, anteroposterior pressure applied to the thigh may help to reduce retroversion.
If gentle closed reduction is unsuccessful, proceed to open reduction.
The reduction should restore anatomical alignment.

Open reduction
If closed reduction fails, an open reduction must be carried out. The reduction of the neck fracture is carried out under direct vision.
Once the capsule is opened up while applying traction the head is manipulated with hooks or K-wires, inserted to act as joy sticks until an anatomical reduction is achieved.

FIXATION WITH Dynamic Hip Screw Plate

Technique of insertion

The first step is to position a guide wire on the neck and hammer it into the head. With the C-arm positioned to show the neck axis, slide the guide wire along the neck, parallel to its axis, and gently tap it into the head.
With the C-arm in the AP, make sure that the wire subtends the CCD (collum-center-diaphysis) angle of the neck. This will help you with the insertion of the guide wire for the screw.

Insertion of the guide wire

Choose the correct aiming device according to the CCD angle of the neck. Check its position in the AP view with the image intensifier.
Insert the guide wire through the aiming device and advance it into the subchondral bone of the head, stopping 10 mm short of the joint.
In both the AP and lateral planes, the guide wire should be positioned along the axis of the neck and through the middle of the head, and advanced to within 5 mm of the subchondral bone.

Determination of the length of the Dynamic Hip Screw
Determine the length of the Dynamic Hip Screw with the help of the measuring device. Select a screw which is 10 mm shorter than the measured length.

Drilling
Adjust the cannulated triple reamer to the chosen length of the screw. Drill a hole for the screw and the plate sleeve.

Dynamic Hip Screw insertion
The correct Dynamic Hip Screw is mounted on the handle and inserted over the guide wire. By turning the handle it is advanced into the bone. Do not push forcefully or you may distract the fracture.
In young patients with hard bone it is best to use the tap to precut the thread for the screw. Otherwise the screw may not advance, and you may actually displace the fracture by twisting the proximal fragment as you attempt to insert the screw.
When the screw has reached its final position (checked with the image intensifier: 10 mm short of the subchondral bone in the AP and lateral), the T-handle of the insertion piece should be parallel to the long axis of the bone to ensure the correct position of the plate.

Fixation of the Dynamic Hip Screw Plate
Generally, a two-hole Dynamic Hip Screw plate with the preoperatively determined CCD angle will be chosen. Take the plate with the correct CCD angle, slide it over the guide wire, and mate it correctly with the screw. Then push it in over the screw and seat it home with the impactor.

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Importance of screw position in intertrochanteric femoral fractures treated by Dynamic Hip Screw

Background

Tip-apex distance greater than 25 mm is accepted as a strong predictor of screw cut-out in patients with intertrochanteric femoral fracture treated by dynamic hip screw. The aim of this retrospective study was to evaluate the position of the screw in the femoral head and its effect on cut-out failure especially in patients with inconvenient tip-apex distance.

Patients and methods

Sixty-five patients (42 males, 23 females; mean age of 57.6 years) operated by dynamic hip screw for intertrochanteric femoral fractures were divided in two groups taking into consideration the tip-apex distance less (Group A; 14 patients) or more (Group B; 51 patients) than 25 mm. Patient’s age and gender, follow-up period, fracture type, degree of osteoporosis, reduction quality of the fracture, position of the screw in the femoral head, number of patients with cut-out failure and Harris hip score were compared.

Results

The average follow-up time was 41.7 months. The mean tip-apex distance was 17.14 mm in Group A and 36.67 mm in Group B. One (7.1%) patient in Group A and three (5.8%) patients in Group B had screw cut-out. Except the screw position, no statistical differences were observed between two groups with regards to study data’s. The screw was placed in femoral head more inferiorly (p = 0.045) on frontal and more posteriorly (p = 0.013) on sagital planes in Group B, while central placement of the screw was present in Group A. The common characteristic of three patients with screw cut-out in Group B was the position of the screw which was located in femoral head more superiorly and anteriorly after an acceptable fracture reduction.

Conclusions

Peripheral placement of the screw in femoral head increases tip-apex distance. However, posterior and inferior locations may help to support posteromedial cortex and calcar femoral in unstable intertrochanteric fractures and reduce the risk of cut-out failure.

Different Types of Screws including Dynamic Hip 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 “12.5 mm Dynamic Hip Screw” has an outside diameter of 12.5 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.

Dynamic Hip 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 Dynamic Hip Screw.

Warnings and Precautionary for Dynamic Hip Screw

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

Preoperative Planning for Dynamic Hip 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 Dynamic Hip 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.

Dynamic Hip 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.

Dynamic Hip Screw Warnings

  • Dynamic Hip 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.

Dynamic Hip 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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