It has now become easy to treat the serious bone problems with the beginning of technological developments and this became possible with modern orthopedic implants.
Though some time back, diseases and bone fractures were not so common and were often seen in adults today the situation has changed. These issues are now troubling young players and dancers too. But thanks to modern day advancements, nowadays some very sophisticated orthopedic equipment like bone plates and orthopedic bone screws are available with the orthopedic implants and instruments manufacturers that can treat people from a multiplicity of bone fractures.
Doctors are conducting fruitful surgeries and placing orthopedic implants in the body of their patients, therefore, relieving them from various bone disorders. In the case of severe fractures, these implants have proved very useful as they have the capability of holding back the fractured bones in their position.
But if you are undergoing this surgery for a bone plate and bone screw implantation then do read the following instructions so that they help from them fully.
Precautions before opting for surgical implants: –
- Consult your doctor before the operation and ask for pre-surgery testing so that you don’t develop metal sensitivity in your bones after surgery. This test will decide whether screws and orthopedic plates are appropriate for your skin and body or not. As some cases of serious skin reactions and wound infections have been reported by patients.
- Next, make sure that you opt for good quality & non-toxic orthopedic implants so that you safeguard yourself from any type of inflammation after implantation.
- Discuss with your surgeon so that after surgery you do not face difficulty in carrying out normal body movements or else you will face up much trouble than before!
- If available, one can opt for biodegradable implants that possess almost similar properties and qualities as that of the original bone, so that you can avoid the trauma of undergoing a second surgery for the removal of bone screws.
- As the plates and bone screws are made from metals like titanium and its alloys, corrosion risk can’t be totally overruled. So, the best way to handle these kinds of issues is to use the same metal screws and plates in a single bone.
- Don’t strain yourself after surgery and take proper rest because broken bones or ankles take enough time, sometimes many months to heal and rehabilitate that joint.
- You might experience serious pain from the bone screws and bone plates while these ortho surgical implants take you through the process of healing. In that case, directly consult your doctor and ask for pain medication rather than getting rid of these ortho implants.
The risks and precautions detailed above are not to dissuade one from enjoying the advantage of this miraculous equipment. It is just a piece of advice which can help you really minimize your pain and suffering arising out of bone related problems. Recovery of your infected part, joints, and ankles can be quick when these orthopedic implants are fitted by adopting essential safety measures and you gain maximum out of them.
Screw and plates fixation of fractures has undergone continual design modifications and improvements during recent years. Friedrich Pauwels for the first time defined and applied the tension band principle in nonunions and the fixation of fractures. This principle of engineering applies to the conversion of tensile forces to compression forces on the convex side of an eccentrically loaded bone. This is done by placing a tension band (bone plate) across the fracture on the tension (or convex) side of the bone. Tensile forces are counteracted by the tension band at this place and converted into compressive forces. If the plate is applied to the compression (or concave) side of the bone, it is possible to bend, fatigue, and fail. Thus, a basic principle of tension band plating is that it must be applied to the tension side of the bone so that the bone itself will receive the compressive forces.
Plates offer the advantages of anatomic reduction of the fracture with open techniques and stability for the early function of muscle-tendon units and joints, but they must be secured from premature weight bearing. Disadvantages of the plate fixation include stress protection and osteoporosis beneath a plate, the risk of bone refracture after their removal, plate irritation, and in rare cases an immunologic reaction. Plates neutralize deforming forces that can’t be counteracted by only screws. Plates need countering to maintain the optimum stability of the fracture reduction. The application of the screws is also critical because incorrect sequence or placement will result in displacement or shear and loss of reduction.
A researcher named Danis was the first person to design and use a rigid longitudinal compression system that results in the healing of fractures without the formation of a visible callus. This kind of conventional rigid plating promotes primary healing through the direct compression of the plate to bone with or without a removable compressor and is now known as the AO/ASIF method (ASIF: Association for the study of internal fixation). These techniques depend on the axial force generated by the insertion torque of spherical screw heads to compress the plate to the bone. It should be noted that not all plating devices depend on this method of compression. For example, in the case of comminuted fractures, lag screws provide the required compression through the purchase of the distal bone fragment.
Although inherently stable, DCPs also have some major disadvantages. These are: the damage caused to vascular tissue adjacent to the bone, the bending needed prior to surgical insertion, and most important is stress shielding in the underlying bone. some researchers advise that necrosis associated with vascular insufficiency, due to the application of bone plates, is the main cause of increased bone porosity. Thus, to decrease the damage of soft tissue, researchers sought the use of plating devices which limit the area of contact between the plate and bone. A variation of the DCP, known as the LC-DCP or locked-compression DCP systems gives stability through locked tapered screw heads while limiting the contact area of plate-bone. Another method commonly used to reduce stress shielding is to limit the difference between plate and bone rigidities using more flexible plating materials.
Early implants mainly consisted of stainless-steel. Interesting to note that there is still much debate between the use of completely rigid systems and systems with increased material flexibility. Some researchers believe that a small volume of micro-motion at the fracture site promotes more rapid fracture healing because a combination of primary and secondary healing can be done in this case. As it is a well-accepted concept, flexural rigidity is dependent both on the material properties and cross-sectional area of the plating device. In terms of materials, less rigid titanium alloy devices with increased resistance to corrosion have proven to be beneficial and are slowly beginning to replace devices of stainless-steel that previously dominated the market. The experimental evidence discloses an increasing trend towards the general acceptance of more flexible systems, as the level of stress shielding is reduced.
Specific plate designs include tubular plates, spoon plates, T and L plates, dynamic compression plates (DCP), large fragment locking plates, reconstruction plates, distal tibia plate, locking compression plates (LCP), limited contact DCP (LC-LCP). The many different designs and types of plates can be grouped functionally into four categories:
Compression plates, buttress plates, neutralization plates, and bridge plates.
Neutralization plates are not a specific type of plates, but neutralization refers to how a plate functions in fixation of the fracture. A neutralization plate reduces the loading forces on a fracture by spanning the fracture and transferring the loading forces through the plate rather than through the site of the fracture. Neutralization plates are used in conjunction with inter-fragmentary fixation of the screw and neutralize torsional, shear forces, and bending. These are commonly used in a fracture with wedge-type or butterfly fragment after interfragmentary screw fixation of the fracture’s wedge portion. Plate’s stability is significantly improved by the interfragmentary screw. Common fractures fixed with neutralization plates are wedge fractures of the radius, ulna, humerus, and fibula.
Compression plates are indicated to apply compression to fractures. The standard compression plate is generally referred to as a dynamic compression plate (DCP), which is a misnomer since these plates provide static compression to a fracture. The holes in the plate have sloped edges on the side of the hole distal from the fracture. A screw can be inserted in the hole at the end that is close to the fracture. This will lock the plate to the bone without moving the bone in relation to the plate. This is how the screw on the right of the plate was inserted. The screws on the left side of the plate are inserted at the far end of the hole with the screw’s shank touching the far end of the hole. As the screw is inserted, the head will be forced to the right by the slope in the hole, moving the bone and its attached screw towards the fracture compressing.
Buttress plates are employed to rigidly hold in place fractures at the end of long bones, especially at the ankle and knee, where the fracture site experiences large compressive and other type of forces. In order to provide suitable fixation, these plates are broadened and carefully contoured at joint end of the plate. That is why, the buttress plates are referred to as peri-articular plates. The periarticular surfaces of long bone are complex with several surfaces at each joint. Buttress plates are contoured to a surface (lateral, medial, anterior, etc.), and so many plate designs may be needed for an individual peri-articular region. There are many buttress plates, and some of the more common configurations are L-shaped, T-shaped and bulbous end shaped plates. The contoured, periarticular portion of the plate provides a three-dimensional configuration to these plates. Compression plates negate bending, torsional, shear forces and create compression across the site of fracture either through especially designed self-compression holes in the design of dynamic compression plate (DCP). These holes exert compression through plate’s translation as the screw engages it.
The helical thread screw is an important invention in Mechanical Engineering which converts angular motion to linear motion to transmit power or to develop large forces. Screws are complex tools with a four-part construction: head, thread, shaft, and tip. The head works as an attachment for the screw driver, which may be hexagonal, slotted, cruciate or in design. The head also serves as the counterforce against which compression generated by the orthopedic screw acts on the bone.
The shank or shaft is the smooth portion of the screw between the thread and the threaded region. The thread is defined by its thread (or outside) diameter, its root (or core) diameter, its pitch (or distance between adjacent threads), and its lead (or distance it advances into the bone with every complete turn). The root area determines the screw’s resistance to pull-out forces and relates to the area of the bone at the thread interface and the root area of the tapped thread. The cross-sectional design is usually a V-thread (usually used in machine screws) or a buttress. The tip is either self-tapping (fluted or trocar) or round (requires pre-tapping).
Orthopedic bone screws are commonly used devices for fixation of the bone fracture. They are used as both standalone fixators and in combination with other orthopaedic hardware devices, mainly plates. Screws are primarily responsible for retaining the stability of most screw-plate fixation devices and are commonly associated with failure because of pull-out associated with poor screw purchase or bone loss. Thus, specific attention should be placed on the type of screws in use and their placement in bone. Primarily responsible for supplying necessary interfragmentary compression and maintaining the stability of plated-bone constructs is very crucial.
It is well known that geometric parameters influence the pullout strength of orthopedic screws, though their effect on the long-term bone screw interaction is largely unknown. Pullout tests performed in vivo and in synthetic samples have suggested a link between a geometry of screw, material properties, and its pullout strength. As expected, the resistance to bone shearing proves to be predominantly reliant upon the host material’s density; however, the length of engagement and the screw’s outer diameter critically affect the holding strength of screws in bone. Other characteristics, such as inner diameter, the pitch of the screw, and thread profile shape contribute to the holding power as well, but to a lesser degree. Although enough pullout strength is necessary to prevent initial screw avulsion, it is not a good indicator of potential stress shielding effects. Clinically, if pull-out of the screw is a concern due to soft bone, a larger thread diameter may be preferred, whereas if the bone is strong and fatigue is more of a concern, a bone screw with a wider root diameter will have a higher resistance to fatigue failure.
The screw’s use to convert torque forces to compression forced across a fracture is a valuable technique. Its success needs an application of the screw in a manner that allows gliding of the screw’s proximal portion in the near bone and threads purchase in the opposite cortex so that the screw’s head will exert load and force the fracture together.
Careful selection of the screw angle respective to the fracture is essential to prevent sliding of the fracture fragments as they are compressed. The basis of bone-plate fixation depends on the compression of the plate to the bone by the inducted tensile stresses in the screw. An approximately linear relationship exists between the insertion torque applied to the screw and the resulting tension. The screw should be inserted at the highest possible torque (without shearing the bone), to induce a desired higher screw tension. A higher screw tension is desirable due to a higher frictional force must be overcome for an occurrence of loosening, and it will also likely result in an increased transfer of mechanical stimuli to a bone, which will lessen the stress shielding.
Since the screw remains attached to the bony tissue after it is healed, it may reduce the bone’s strength and stiffness. The metallic screw (elastic modulus of 100 to 200 GPA) that is significantly stiffer (carries most of the shared load, causing the adjacent bone (elastic modulus of 1 to 20 GPA for cortical and cancellous bones, respectively) to be atrophied in response to the reduced load it is carrying, in accordance with Wolff’s law of functional adaptation. According to Wolff’s law “Every change in the function and form of a bone is followed by certain definite changes in their internal architecture and equally definite secondary alterations in their external conformation, in relation with mathematical laws”. Stress shielding is the effect of metallic screws on the bony tissue in their vicinity. The biochemical compatibility of a screw with bone can, thus, be characterized by the stress (or strain, or any other mechanical stimulus) distribution developing in the bone around the screw because of screw’s tightening during implantation. Screw loosening is a common problem faced in fixation of bone fracture. Stress shielding around screw threads is partly responsible for excessive bone resorption. Research related to bone loss around screw threads is a topic which is under-studied, and a great deal of consideration must go into the implant’s design to reduce this pitfall. This is mainly true in the case of brittle fractures associated with low density osteoporotic bone. In these cases, it is possible that the rate of bone resorption in the vicinity of implants will be higher than that of a similar fracture in a healthy bone, because of its already weakened state.
Histological evidence has revealed that active compression of the bone screw interface resulted in little activity at the site of compression, however neutral regions wherein a gap exists between the bone and screw, exhibited areas of high activity, such as resorption of necrotic bone followed by formation of a new bone.
Celebrate Pollution free Diwali
Diwali is a festival of lights and sweets, not the pollution. Diwali can be a real blessing without air and noise pollution. Here are the few tips to celebrate pollution-free Diwali this year.
- Crackers are banned in Delhi this year by the government. So, avoid firecrackers totally and celebrate pollution free Diwali.
- Use eco-friendly paints to paint your beautiful homes.
- Use natural colors to make Rangoli which are not harmful. You can also use things like rice (white), pulses (yellow), cloves (brown) for different colors.
- Use fresh flowers such as roses, jasmine, etc. which suit the festive atmosphere.
- Make people aware about the pollution-free Diwali. Let them know the value of a clean environment.
Cannulated Screws are used in bone and joint surgery to repair the fracture and to secure artificial implants which can be used to replace part or whole of a joint. The main advantage of cannulated screws is that they can be inserted over a guide pin or guide wire. The diameter of the guide pin is much smaller than the cannulated screw and can be more correctly placed using fluoroscopy in the operating room. In addition, given its small diameter, the guide pin can be reinserted many times if necessary, for correct placement without excessive damage to the bone.
Specifications of Cannulated Screws:
- Thread on the full cannulated screws extends into the head profile. Greater gripping ability, especially with osteoporotic bone, allow for easy removal.
- Low-profile head lessens the possibility of soft tissue irritation.
- Hemispherical head ensures optimal annular contact with plates or washers when screws are angled.
- Cancellous threads profile uses deep cutting threads with a large pitch to increase resistance to pullout. Large pitch also accelerates insertion of the screw and its removal.
- Self-tapping screw tip facilitates insertion of the screw. Reduces the need for tapping and pre-drilling.
- Reverse cutting flutes for removal with ease.
Uses of Cannulated Screws:
Cannulated screws are designed for fixation of fractures, fusions, and osteotomies of large and small bones appropriate for the size of the device.
Cannulated screw consists of a hollow central shaft. Both cancellous and cortical screws can be cannulated. Cannulated cancellous screws are used for metaphyseal fractures while non-cannulated and cannulated cortical screws are used as lag screws for fixation of diaphyseal fractures.
Partially threaded screws can be used to lag one bone fragment to another, where the bone fragment is captured by the threads of the screw and pulled towards the near cortex fragment on the screw’s head side. Fully threaded screws are used to stabilize fractures with little to no compression across the fracture.
Cannulated screw system provides percutaneous screw fixation, emergency closed reduction, and excellent stability.
Cannulated bone screws in comparison with traditional screws allow more precise screw placement, decrease surgical time, and reduce the possibility of errors.
The human skeleton made of 206 individual bones that perform various important functions, protection, movement, including support, storage of minerals, and formation of blood cells. To ensure that the skeleton retains its ability to perform these functions, and to reduce disfigurement and pain, bones that become fractured should be repaired promptly and properly. Typically, a fractured bone is treated using a fixation device or an orthopedic implant, which reinforces the fractured bone and keeps it aligned during the healing process. Fixation devices and orthopedic implants may take a variety of forms, including casts and fixators for external fixation, and bone plates, and rods, and/or fasteners (screws, wires, pins, etc.) for internal fixation, among others.
Orthopedic rods may function as fracture fixation devices (e.g., intramedullary nails/rods) and/or in prosthetic devices (e.g., stem portions thereof), among others, received in the medullary canal of a broken and/or cut bone. For installation of the accessed from an end and/or side of the bone with an instrument such as an awl, saw or drill. The medullary canal also may be prepared to receive the orthopedic rod, for example, by reaming and/or broaching to enlarge and/or shape the canal. After placement of a rod into the canal, the rod may be secured in position using fasteners, for example, by attaching the rod to only one fragment or, in the case of fixation, to two or more bone fragments disposed on opposing sides of a break or cut in the bone. the rod, therefore, may include a plurality of apertures (holes) that receive threaded fasteners, such as bone screws, which may be anchored in bone adjacent each aperture via an external thread.
Each aperture within a rod may be locking (e.g., with a thread) or nonlocking (e.g., without a thread). A locking aperture may engage a suitable corresponding fastener such that fastener’s translational movement in both opposing directions along the aperture is restricted; in contrast, a nonlocking aperture usually permits this translational movement. Of these two types, nonlocking apertures may be relatively easy for an orthopedic surgeon to use because a nonlocking aperture usually can receive a threaded fastener that is aligned with the aperture, irrespective of the relative rotational disposition of the aperture and the fastener. However, nonlocking apertures may be less effective for fixing the threaded fasteners, rod, and/or bone in position.
Locking apertures of a rod may be more difficult for a surgeon to use. Because a locking aperture is spaced from the bone surface by bone, a threaded fastener that is advanced rotationally into the bone from the bone surface may arrive at the locking aperture at an unsuitable rotational (and therefore axial) disposition relative to an internal thread of the aperture. Therefore, the threaded may be hard to turn and/or may create an undesirable sound (such as squeaking), among others, during fastener advancement after the fastener is forced into registration with the locking aperture. Moreover, a bone may be damaged (e.g., a thread femoral formed in bone may be stripped) as the threaded fastener is forced into registration. This problem may be compounded by bone screws having a deep external thread (and therefore a relatively large pitch) for engagement with the cancellous bone.