A fracture fixation device is a surgical implant used to hold the broken pieces of a bone together in the correct position. The primary purpose of these devices is to provide stability and alignment, which allows the body to properly heal the bone. These devices act as an internal or external scaffold, maintaining the proper anatomical arrangement of the fracture fragments while new bone tissue forms. This process ensures the bone heals in its original shape and strength, which is important for restoring function.
Internal Fixation Devices
Internal fixation devices are surgically placed inside the body to stabilize a fractured bone. This procedure, known as open reduction and internal fixation (ORIF), involves an incision to directly access and realign the bone fragments. Surgeons then use various implants to hold the pieces together, providing a strong internal framework that allows for earlier mobilization.
One of the most common types of internal fixation involves plates and screws. Plates act as internal splints, conforming to the bone’s surface and spanning the fracture. Screws are then inserted through holes in the plate and into the bone, securing the plate and holding the fracture fragments in a stable position. This method is frequently used for fractures near joints, such as in the wrist or ankle, and along the shaft of long bones.
For fractures in the long bones of the body, such as the femur or tibia, surgeons often use intramedullary rods, also called nails. These rods are inserted into the hollow, marrow-containing center of the bone, known as the medullary cavity. The rod passes across the fracture line, functioning like an internal splint to keep the bone aligned. Screws are placed at both ends of the rod to lock it in place and prevent the bone from rotating or shortening while it heals.
In cases involving small bones, like those in the hands and feet, or when securing small bone fragments, surgeons may use pins and wires. These smaller implants hold pieces of bone that are too small to be fixed with larger screws. Pins and wires are often used with other fixation devices but can also be used alone to treat certain fractures, particularly in children.
External Fixation Devices
External fixation devices provide stability to a fracture from outside the body. A surgeon places pins or screws through the skin and into the bone on either side of the fracture. These pins are then connected to an external frame, which holds the bones in the correct position while they heal.
This method is used for severe open fractures, where the bone has broken through the skin, causing significant soft tissue damage and increasing the risk of infection. The external frame stabilizes the bone without requiring a large incision or placing internal hardware in a contaminated area. This allows the soft tissue wounds to be more easily cleaned and cared for.
External fixators are also valuable for managing complex pelvic fractures and as a temporary measure to stabilize a patient with multiple injuries. The device can be applied relatively quickly to provide initial stability until the patient is stable enough for a definitive surgical repair. Because the pins pass through the skin, diligent pin-site care is required to prevent infections.
Materials Used in Fixation Devices
The implants used for fracture fixation are made from materials that are both strong and compatible with the human body. Medical-grade metals are the most common choice, with stainless steel and titanium alloys being the primary options. Stainless steel is a traditional, cost-effective material known for its high mechanical strength.
Titanium alloys have become increasingly popular. Titanium is strong, lightweight, and demonstrates excellent biocompatibility, meaning it is less likely to cause an adverse reaction. An added benefit of titanium is that it causes less interference with magnetic resonance imaging (MRI) scans compared to stainless steel. The choice between materials often depends on the specific fracture and surgeon preference.
A different class of materials used for some fixation devices is bioabsorbable polymers. These implants are designed to gradually dissolve and be absorbed by the body as the fracture heals, which eliminates the need for a second surgery to remove the hardware. These devices are used in situations where a permanent implant is not ideal, such as in certain fractures in children.
Potential Complications
While fracture fixation is generally successful, potential complications can arise. The primary concerns include:
- Infection: This can occur at the surgical site or around the implant itself. The risk is higher in open fractures and with external fixators due to the pins passing through the skin.
- Hardware failure: Though uncommon with modern implants, this can involve screws loosening or the breaking of a plate or rod. Such failures can compromise the fracture’s stability and may require further surgical intervention.
- Bone healing issues: A “nonunion” describes a situation where the fracture fails to heal completely, while a “malunion” occurs when the fracture heals in an incorrect position. Biological factors can sometimes impede the healing process.
- Hardware irritation: Prominent hardware, particularly in areas with little soft tissue coverage like the elbow or ankle, can irritate adjacent tendons or skin. This can lead to discomfort with movement.
Hardware Removal
The decision to remove fracture fixation hardware is not automatic and is made on a case-by-case basis. Many implants are designed to be left in place for life. If the hardware is not causing any pain or functional problems, the risks associated with a second surgery are often considered greater than the benefit of removal.
There are specific reasons why a planned removal surgery might be recommended:
- Persistent pain or discomfort if the implant is prominent under the skin or irritates nearby soft tissues.
- Patient preference, particularly in young and active individuals who may not want a permanent implant.
- The hardware crosses a joint and restricts the range of motion after the fracture has healed.
- An allergic reaction to the metal, though rare, may necessitate removal.
The procedure to remove hardware is more straightforward than the initial fixation surgery, but it still carries surgical risks that must be weighed against the potential benefits.