A table summarizing the different types of orthopedic plates and their indications for use in various fracture conditions:
Plate Type | Indications | Fracture Characteristics | Biomechanical Role |
Neutralization Plate | - Fractures where lag screws are used for interfragmentary compression (e.g., spiral or oblique fractures). | - Oblique or spiral fractures in long bones (e.g., tibia, humerus). | - Protects the lag screw fixation from torsional, shear, and bending forces. |
- Fractures that require stability but no additional compression. | - Fractures with minimal comminution that need neutralization of forces rather than compression. | - Provides stability by neutralizing disruptive forces without applying additional compression. | |
Compression Plate | - Simple transverse fractures (e.g., radial, ulna, humerus, tibia). | - Transverse or short oblique fractures that can benefit from compression to achieve primary bone healing. | - Provides axial compression to fracture site, promoting direct bone healing by bringing fragments together. |
- Diaphyseal fractures with simple fracture patterns. | - Non-comminuted fractures where tight anatomical reduction can be achieved. | - Dynamic compression plates use eccentric screw placement to compress the fracture. | |
Bridge Plate | - Comminuted diaphyseal fractures (e.g., femur, tibia). | - Multi-fragmented fractures where direct reduction is difficult or unnecessary. | - Acts as a splint, maintaining bone length and alignment without disturbing the fracture zone. |
- Fractures in which biological preservation of the periosteum is critical. | - Long bone fractures with large fracture gaps, comminution, and minimal intact cortex. | - Allows for secondary healing with callus formation by bridging the fracture site. | |
Tension Band Plate | - Fractures under tensile forces (e.g., patella, olecranon, greater tuberosity of the humerus). | - Avulsion fractures where tendons or muscles exert tensile forces across the fracture site. | - Converts tensile forces into compressive forces across the fracture to promote healing. |
- Fixation of bony prominences where tensile forces are significant. | - Small bones with fractures exposed to tensile forces from attached tendons or ligaments. | - Particularly useful in avulsion fractures or fractures around the knee, elbow, or shoulder. | |
Locking Compression Plate | - Osteoporotic bone or periarticular fractures (e.g., distal femur, proximal tibia, proximal humerus). | - Metaphyseal or periarticular fractures where traditional plate and screw fixation is insufficient due to poor bone quality. | - Provides angular stability and fixed-angle fixation, minimizing reliance on bone-screw interface strength. |
- Fractures requiring minimally invasive techniques or in cases where soft tissue preservation is key. | - Complex fractures with poor bone stock, e.g., osteoporotic fractures, intra-articular fractures. | - Offers a rigid fixation with locking screws, reducing the risk of secondary displacement in weak or soft bones. |
Orthopedic plates are one of the most commonly used internal fixation devices, designed to stabilize fractures and promote healing through various biomechanical principles. Each plate type has its distinct role, with indications based on fracture location, type, and stability. The goal is to restore the anatomical alignment, ensure proper load-sharing or load-bearing, and promote healing while minimizing soft tissue disruption.
1. Neutralization Plate
A neutralization plate is applied in conjunction with interfragmentary screws (such as lag screws), providing stability by protecting the fixation from torsional, bending, and shear forces. The plate itself does not provide compression across the fracture site but neutralizes the forces that would otherwise disrupt healing.
Indications: Used in fractures where lag screws are inserted to compress fracture fragments (e.g., oblique or spiral fractures). The neutralization plate prevents any disruptive forces during limb movement or weight-bearing, especially in areas subjected to torsion or bending.
Biomechanics: The neutralization plate acts as a "buttress," absorbing and redistributing mechanical forces that could compromise the fracture repair. It functions without compressing the bone but provides stability and protection to the already compressed fracture through the lag screw. For instance, in a spiral fracture of the tibia, interfragmentary screws create interfragmentary compression, while the neutralization plate prevents displacement under torsional forces.
Clinical Example: In a midshaft tibial spiral fracture, lag screws are placed first to compress the fracture line, and a neutralization plate is applied to prevent rotational or bending forces from affecting the alignment. The plate's role is purely protective, maintaining the integrity of the internal compression created by the screws.
2. Compression Plate
Compression plates are designed to apply axial compression across the fracture site. This promotes primary (direct) bone healing through contact healing, which occurs without significant callus formation. Compression plates work particularly well in simple fracture patterns where anatomical reduction is possible.
Dynamic Compression Plate (DCP): This type of plate allows for axial compression across the fracture using specially designed slotted holes that translate the screw's insertional force into axial compression. When the screw is tightened, it moves down a sloped surface, pulling the bone fragments together.
Limited Contact Dynamic Compression Plate (LC-DCP): The LC-DCP is an evolution of the DCP that minimizes contact between the plate and bone. By reducing plate-bone contact, periosteal blood supply is better preserved, reducing the risk of cortical necrosis and promoting faster healing. This is critical in preventing stress shielding, where the plate bears too much of the load, leading to bone weakening.
Biomechanics: The compression plate provides axial stability and ensures that the bone fragments remain tightly opposed. In simple fractures, such as a transverse fracture of the radius or ulna, compression plates ensure that the fracture surfaces are compressed tightly enough to allow primary bone healing via cutting cones across the fracture gap.
Clinical Example: In a transverse midshaft humerus fracture, a DCP or LC-DCP can be applied to provide compression across the fracture line, ensuring stability and promoting primary healing. When the screws are tightened in the plate's eccentric holes, they pull the bone fragments together, facilitating direct healing with minimal callus formation.
3. Bridge Plate
A bridge plate is used for comminuted fractures, where the anatomical reconstruction of all bone fragments is neither necessary nor possible. The plate functions as an internal splint, maintaining the length, alignment, and rotational stability of the bone while leaving the fracture zone largely undisturbed to promote biological healing through callus formation.
Indications: Indicated in highly comminuted diaphyseal fractures where direct reduction of individual fragments would compromise the blood supply or where stable fixation of individual fragments is not feasible. The goal is to maintain alignment without disturbing the fracture hematoma, which is vital for biological healing.
Biomechanics: The bridge plate acts as a load-sharing device, transferring loads through the plate rather than the fracture site, which is left to heal via secondary healing with callus formation. Unlike compression plates, which focus on bringing fragments into tight opposition, bridge plates allow for controlled motion at the fracture site, encouraging the development of a robust callus.
Clinical Example: In a comminuted midshaft femur fracture, where multiple small fragments are present, the bridge plate spans the fracture zone, maintaining length and alignment. Over time, callus forms as the bone heals, while the plate stabilizes the fracture mechanically, minimizing the disruption of soft tissues and preserving blood supply.
4. Tension Band Plate
The tension band plate employs the tension band principle, where tensile forces acting on the bone are converted into compressive forces across the fracture site, enhancing stability and healing. This is particularly useful in areas subject to high tensile stresses, such as around the patella, olecranon, or greater tuberosity of the humerus.
Indications: Commonly used for fractures where tensile forces predominate (e.g., patellar or olecranon fractures). Tension band wiring can be combined with a plate, especially in larger bones where additional stabilization is necessary.
Biomechanics: When a muscle pulls on a fractured bone (e.g., quadriceps on the patella), the tension band plate converts this pulling force into compressive force at the fracture site. This results in compression across the fracture when muscles contract, allowing primary bone healing. The tension band wire or plate effectively counters the tension forces that would otherwise pull the fracture apart.
Clinical Example: In a transverse olecranon fracture, the triceps tendon pulls the proximal fragment of the olecranon proximally, creating tension across the fracture. A tension band plate is applied along the posterior aspect of the olecranon to convert this tensile force into compressive force, aiding in fracture healing by applying dynamic compression during flexion and extension of the elbow.
5. Locking Compression Plate (LCP)
The locking plate is a fixed-angle device that allows for screw locking into the plate, creating a rigid, angular stable construct. This system is particularly useful in osteoporotic bone or periarticular fractures, where bone quality is poor, and traditional plating might not provide sufficient stability.
Indications: Used in metaphyseal or periarticular fractures where bone purchase is insufficient for conventional screw fixation, such as osteoporotic fractures, comminuted periarticular fractures (e.g., distal femur, proximal tibia), or fractures with poor bone quality. It is also useful in minimally invasive plating techniques, allowing for biological fixation with minimal soft tissue disruption.
Biomechanics: In contrast to traditional plates that rely on friction between the bone and plate, locking plates do not require bone-plate compression for stability. Instead, the screws lock into the plate, forming a rigid construct. This design distributes forces evenly across the bone-plate-screw interface and is particularly beneficial in osteoporotic bone where screw purchase is limited.
Advantages: Locking plates reduce the risk of secondary loss of reduction, particularly in osteoporotic bone. Additionally, because the screws lock into the plate, there is less dependence on the bone's cortical integrity for stability. The locking construct can also prevent collapse in metaphyseal areas, such as in proximal tibial plateau fractures.
Clinical Example: In a distal femur fracture in an elderly patient with osteoporotic bone, a locking plate is used to achieve stable fixation. The screws lock into the plate, providing angular stability and maintaining reduction even when the bone is too soft to provide adequate screw purchase with conventional plates. This ensures that the fracture remains stable during the healing process.
Key Biomechanical Principles for Plate Use
Load-Bearing vs. Load-Sharing: Plates can function as load-bearing or load-sharing devices depending on the fracture type and fixation strategy. For example, bridge plates function as load-bearing constructs, while compression plates distribute the load between the bone and the plate (load-sharing).
Biological vs. Mechanical Fixation: Plates such as locking plates and bridge plates focus on maintaining bone biology, preserving periosteal blood flow, and minimizing tissue disruption, promoting secondary healing. On the other hand, compression plates prioritize mechanical stability and direct healing, often at the expense of some biological compromise.
Stress Shielding and Periosteal Preservation: Excessive rigidity from plates can lead to stress shielding, where the bone beneath the plate experiences decreased mechanical stress, potentially weakening over time. Devices like the LC-DCP and bridge plates aim to minimize this effect by reducing contact between the plate and the bone, preserving periosteal blood supply.
Summary
The application of orthopedic plates is a nuanced decision-making process that involves understanding the fracture pattern, biomechanics, bone quality, and soft tissue condition. Each type of plate serves a specific purpose, whether it's to neutralize forces, apply compression, bridge comminuted fractures, convert tensile forces into compression, or provide angular stability in weak or osteoporotic bone.
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