Introduction
A break or a discontinuity in the bone is called a fracture. It may be a simple or a compound fracture, a displaced or a nondisplaced fracture. A fracture in which the skin is exposed due to the piercing of the bony fragments is called an open fracture. If the fragments are out of alignment, it is called a displaced fracture. Fractures can be caused due to various reasons, such as high-energy trauma like accidents, sports injuries, falls from heights, or fractures occurring due to pathological conditions like osteoporosis, tumors, or cancers. Simple and undisplaced fractures are treated by aligning the bones to their normal position (closed reduction) by traction and counter traction. In contrast, compound or open fractures are managed by open reduction and internal or external fixation or surgery.
How Does a Fracture Heal?
There are mainly two modalities of bone healing; primary and secondary. Primary bone healing requires direct reduction of the fractured ends followed by stability and low strain environment. Secondary bone healing requires reduction indirectly with relative stability and high strain environment around the fracture site. Secondary bone healing is characterized by bone formation (ossification), which is either endochondral or intramembranous, along with healing tissues at the fractured ends, which are mineralized and replaced by the bone. Various fixation methods provide stability to the bones and help promote bone healing. Compression plates and lag screws provide absolute stability, and relative stability is provided by intramedullary rods, bridge plating, or cast application. In most cases, both types are involved in achieving stability.
What Is Compression Plating?
Open reduction is the treatment of choice for most displaced and compound fractures. It is also usually employed in cases of delayed union, avulsion fractures, and pathological fractures. Open reduction is followed by internal fixation, during which the aligned bones are stabilized with the help of metal screws, metal plates, pins, rods, etc., to promote bone healing and restore normal function. Plating of fractures was first started in the year 1895, and the metal plate for internal fixation was introduced by Lane. In 1949, Danis recognized the need for compression between the fractured fragments. The early understanding of metal fixation was that they were designed to provide stiffness, or a stable fixation was necessary to hold the fractured fragments tightly in place by applying a compression force. This was achieved by using plates with screws that anchor and press the plates tightly against the bone, creating a stable connection between the implant and the bone.
What Is the Material Used in Compression Plates?
Metals like stainless steel and pure titanium or its alloys are utilized for manufacturing compression plates. Stainless steel plates are cheaper and corrosion-resistant and are commonly used in orthopedic implants. Titanium alloys have enhanced mechanical strength and reduced chances of corrosion. Stainless steel implants that are nickel-free and biodegradable polymer implants are being introduced to avoid allergic reactions and better assess the bone healing process.
What Are the Types of Compression Plates?
Different types of compression plates include:
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Dynamic Compression Plates (DCP): These are also called eccentric compression plates, and are applied following the anatomical reduction of fracture fragments, to achieve rigid internal fixation. During this procedure, ovoid holes are made on the plates, which are used to apply direct compression towards the site of fracture. The first screw is placed adjacent to the fracture line, and as the screw is tightened, the plate gets pulled toward the fracture site. The remaining screws are placed in holes in a neutral position and do not create additional compression. The compression force generated by DCP at the fracture ends neutralizes any external force providing absolute stability. The stability also depends on the quality of the bone, as well as in the case of comminuted fractures, where the bone may be broken in more than two areas.
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Locked Bridging Plates: In this method, the screws are firmly fixed to the plate at an angle that acts as bars similar to external fixators. This facilitates fracture healing by the secondary healing process, as there is no need for rigid fixation on the bone surface at the fracture site. The micro-movements which occur between the fracture fragments generate sufficient gap stains to improve the quality of the healed bone. There is less injury to the surrounding tissues and blood vessels due to the non-requirement of anatomical reduction, reducing further complications.
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Locked Compression Plates (LCP): This implant was designed as a hybrid as it could be used as conventional plates along with plates with screw heads locked at predetermined angles on the internal or external fixators. It provides greater flexibility for the specialist in choosing the plating method depending on the characteristics of fracture and bone quality. The locked plates effectively convert parallel forces (shear forces) experienced at the implant site into vertical force (compressive force) at the interface of bone and screws. This conversion of force is vital in fracture fixation because the cortical bone remains tougher against the compressive forces in comparison to the shear forces. The fixed angle of the locked screws helps in the even distribution of the load on the screws compared to the uneven loading seen in the conventional plates. The stability of LCP mainly depends on the mechanical properties of the plate, and the load applied. In non-comminuted fractures, three screws are inserted into the main fragment with three cortices, whereas in cases of comminuted fractures, a minimum of two screws and four cortices are inserted. Two to three holes are left over at the fracture site to avoid any stress adjacent to the interface of the screw and bone and promote effective healing.
How Is Compression Plating Done?
The procedure of compression plating mainly depends on the location and severity of the fracture, the type of compression plate, and the surgical approach. An incision is made at the fracture site, and the area is exposed depending on the approach. Debridement and irrigation of the surgical area are done, followed by minimal mobilization of the periosteum around the fractured edges to control the reduction. The use of reduction forceps reduces the damage to the periosteum and the soft tissues. The fracture is then reduced and rotated to the anatomical position. Drilling is done centrically through the plate hole, close to the fracture line, and the first screw is inserted. When the plate is secured in position, a second drill is done, and eccentric screws are inserted and tightened. All the other additional screws are inserted between the proximal and distal fragments, and compression is confirmed. The surgical site is then closed with sutures, followed by antibiotic and analgesic therapy to prevent infections and control pain. The bone healing process is periodically monitored by radiographs.
What Are the Advantages and Disadvantages of Compression Plating?
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The advantages of dynamic compression plates include; stable internal fixation, decreased rate of improper union (malunion), and no requirement for external fixation, which allows immediate movement of the neighboring joints. There is no requirement for anatomical reductions in locked bridging plates, so relatively less injury is caused to the surrounding tissues.
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The disadvantages of DCP include; a lack of secondary bone healing, cortical bone loss that may be seen under the compression plates, and injury to the surrounding soft tissues due to surgical handling at the fracture site, which may lead to delayed union or non-union of fractures and infections.
What Are the Complications of Compression Plating?
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Breakage or loosening of implants over time.
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The progressive degeneration of the bone (osteolysis) may occur, resulting in weaker bones.
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Inflammation may occur at the surgical site.
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Hypersensitivity or allergic reactions may occur due to the implants.
Conclusion
Compression plates are metal plates applied to fix the reduced fracture fragments to achieve stability and promote bone healing. Dynamic compression plates and locked compression plates are the mainly used implants. LCP is preferred due to secondary healing, which is more beneficial. Newer materials, such as biodegradable,polymer-based, or nickel-free implants, etc are being introduced to eliminate the complications of conventional compression plates.
