When a bone breaks, stability is crucial for proper healing. Without adequate support, fractured bone fragments may shift, hindering recovery and potentially leading to improper alignment. Orthopedic surgeons stabilize these bones using internal fixation, a process where devices are placed inside the body to hold fragments in their correct positions during recovery.
Internal Fixation with Pins
Pins, also known as wires, are thin, smooth or threaded metallic rods used to stabilize bone fragments. Kirschner wires (K-wires) are fine, smooth pins typically used for temporary fixation or in complex fracture patterns. These wires are often employed for hand, foot, wrist, or elbow fractures, and for initial stabilization of long bone fractures. K-wires can be drilled through the skin to hold bone fragments in place, with one end often left protruding outside the skin for later removal.
Steinmann pins are larger and sturdier than K-wires, designed for use in bigger bones like the femur or tibia. They can be inserted into the bone marrow cavity or used externally for skeletal traction, providing stability and alignment. Pins generally offer less rigid fixation compared to screws and are often suitable for temporary stabilization or in smaller bones or pediatric fractures. Smooth pins rely on friction for stability, while threaded pins are more frequently used due to their improved stability and reduced complications.
Internal Fixation with Screws
Orthopedic screws are metallic devices designed to provide compression and rigid fixation for fractured bones. They are primarily used for internal fixation, remaining completely within the body to press bone fragments together and promote healing. Screws create compression between fracture fragments to promote healing.
Different types of screws are used depending on the bone and fracture characteristics. Cortical screws are designed for dense, hard bone, such as the shaft of long bones, featuring fine, closely spaced threads for strong anchorage. Cancellous screws, in contrast, are used for softer, spongy bone found at the ends of long bones, characterized by coarser, widely spaced threads for better grip. Locking screws are specialized types that engage with threaded holes in plates, creating a fixed-angle construct that offers enhanced stability, especially in cases of poor bone quality or complex fractures.
Choosing the Right Fixation Method
Choosing between pins and screws for fracture fixation is influenced by several factors. Fracture characteristics, including the type, location, and complexity of the break, play a significant role. Bone quality, patient age, and activity level also influence the choice, as does the specific need for stability or compression at the fracture site.
Pins might be preferred for smaller bone fragments, pediatric fractures, or when temporary stabilization is needed. They are less invasive, requiring smaller incisions, which can lead to reduced recovery times and lower complication risks like infection. Screws, however, are typically chosen for long bone fractures, fractures involving joints, or when strong compression across the fracture site is necessary to promote healing. Their ability to provide rigid fixation makes them suitable for load-bearing bones and more complex fracture patterns.
Life with Internal Fixation
Living with internal fixation involves a period of recovery and adaptation. Post-operative care typically focuses on managing pain, which is common around the surgical site, and participating in physical therapy to restore strength and mobility. Activity restrictions are usually in place to protect the healing bone and the implanted hardware.
While internal fixation devices are generally well-tolerated, potential complications can include infection at the implant site, irritation to surrounding tissues, or the hardware becoming loose or breaking. The decision to remove the hardware is made on an individualized basis, often considered if it causes pain, interferes with movement, or if an infection develops. However, removal is not always necessary once the bone has fully healed.