An external fixator is a metal frame that stabilizes a broken or damaged bone from outside your body. Instead of plates or rods placed inside during surgery, an external fixator uses pins or wires drilled through your skin and into the bone, connected to a rigid frame that sits outside your limb. It holds the bone fragments in the correct position while they heal, and it’s removed once the bone is stable enough on its own.
How an External Fixator Works
The basic design is straightforward. Metal pins (called Schanz screws) are inserted through the skin and into the bone on either side of a fracture. Each set of pins connects to a rod or bar outside the body, forming a partial frame on each bone fragment. Those partial frames are then linked together by a connecting rod, locking the broken pieces in alignment. The whole structure acts like scaffolding, keeping everything still so the bone can knit back together.
The stiffness of the frame can be adjusted depending on the injury. Thicker pins, rods positioned closer to the bone, extra connecting rods, or additional pins all increase stability. Adding a second connecting rod between the partial frames is particularly effective for preventing rotation and improving bending strength. This modularity is one of the device’s biggest advantages: surgeons can customize the frame to match the complexity of the fracture.
Pin placement matters for long-term comfort and stability. Adjacent pins are positioned so that the bending forces they experience counteract each other. This opposing load pattern helps prevent the pins from gradually loosening in the bone, which is one of the most common problems with external fixation.
Types of External Fixators
External fixators come in two main designs, each suited to different situations.
Monolateral (unilateral) fixators have a single straight bar attached to one side of the limb, connected to the bone by screws. These screws are often coated with a mineral called hydroxyapatite, which encourages the bone to grip the screw more tightly and resist loosening. Monolateral fixators are simpler, lighter, and easier to live with day to day. They’re commonly used for straightforward long bone fractures and as temporary stabilization in trauma situations.
Circular fixators partially or completely encircle the limb with two or more metal rings connected by adjustable struts. The rings attach to the bone using thin wires or pins. The original circular fixator, the Ilizarov frame, was developed in Russia in the 1950s and has since evolved into more advanced versions like the Taylor Spatial Frame. Circular fixators excel at complex corrections because they allow precise, gradual adjustments in multiple directions. They’re the go-to choice for limb lengthening, correcting bone deformities, and treating difficult nonunions.
With both types, you or a family member may need to make small adjustments to the device several times a day, typically by turning knobs or using a small wrench. Your surgical team will show you exactly how and when to do this.
When External Fixators Are Used
External fixation isn’t the first choice for every fracture. It’s reserved for situations where internal hardware (plates, screws, or rods placed inside the body) isn’t safe or practical. The most common scenarios include:
- Severe open fractures: When bone breaks through the skin, the surrounding soft tissue is often too damaged or contaminated for immediate internal surgery. An external fixator stabilizes the bone while allowing access to treat the wound.
- Temporary stabilization in trauma: In patients with multiple serious injuries, surgeons often apply an external fixator as a quick “damage control” measure to hold a fracture in place until the patient is stable enough for a longer definitive surgery.
- Infected nonunions: About 40% of fractures that fail to heal involve infection. External fixation avoids placing metal hardware inside an infected area, which would make the infection harder to clear.
- Complex bone reconstruction: When bone segments need to be gradually moved, lengthened, or reshaped, external fixators provide the controlled, adjustable force required.
- Fractures near joints: When bone is broken into many small fragments near a joint, external fixation can hold everything in alignment without further disrupting fragile pieces.
Bone Lengthening and Regeneration
One of the most remarkable uses of external fixation is distraction osteogenesis, a process where new bone is grown to fill a gap. A surgeon cuts the bone at a specific location, then uses the external fixator to gradually pull the two ends apart, typically about one millimeter per day. The body responds by filling the widening gap with new bone tissue.
The success of this process depends on several factors: the stability of the fixator, where the bone is cut, how long the surgeon waits before beginning separation (the latency period), and the rate of distraction. Surgeons monitor bone regeneration with X-rays and adjust the pace accordingly. If new bone appears too thin, they may slow things down. If it’s forming too aggressively, they may speed up.
Circular fixators have a particular advantage here. The thin wires they use allow a small amount of beneficial flexibility at the bone site, which many biomechanical studies suggest actually promotes healing, while still preventing unwanted movement like angulation or rotation.
Living With an External Fixator
Caring for the pin sites is the single most important thing you’ll do while wearing an external fixator. Pin site infections are the most common complication, with reported rates ranging from 2% to 35% depending on the study and the type of fixator. Keeping the sites clean dramatically reduces your risk.
Pin site care involves regularly cleaning around each pin using sterile technique. Sterile water is commonly recommended as a cleansing solution, since there’s no strong evidence that saline or antiseptic solutions offer additional benefits. Antimicrobial foam dressings with a silver-based layer placed around each pin site help lower infection risk. Dressings are typically changed on a regular schedule, and your care team will teach you how to do this at home.
If a pin site becomes red or irritated without signs of deeper infection, the usual response is to increase dressing changes to every two to three days. If true infection develops (increasing redness, warmth, drainage, or pain), dressings on the affected site need to be changed daily or every other day, and antibiotics may be needed. Only the infected sites require more frequent care, not every pin.
Weight Bearing and Movement
How much weight you can put on the affected limb depends entirely on the injury and the purpose of the fixator. When an external fixator is applied as a temporary measure (common in trauma), it typically doesn’t provide enough stability for weight bearing. For more definitive fixation, progressive weight bearing usually begins as healing progresses. In general, you can expect to sit up the day after surgery and begin gentle passive and assisted exercises early on. Your surgeon will set specific weight-bearing guidelines based on your fracture pattern, the fixator’s stability, and how your bone is healing on follow-up imaging.
How Long It Stays On
The duration varies widely. When used as temporary “damage control” stabilization, the fixator may stay on for just days to a few weeks before conversion to internal fixation. Literature consistently supports converting to definitive surgery as early as the patient’s condition allows, ideally within about two to three weeks, because the risk of pin site infection rises beyond that window.
When an external fixator is the definitive treatment (for limb lengthening, deformity correction, or infected nonunions), it may need to stay on for several months. Limb lengthening patients, for instance, wear the device through both the active lengthening phase and the consolidation period while new bone matures and hardens. The total timeline depends on how much correction is needed and how quickly the bone regenerates.
How Removal Works
Removing an external fixator is generally less involved than putting one in, but it’s not always as simple as unscrewing pins in a clinic room. Pins coated with hydroxyapatite bond firmly to bone over time, which improves stability during treatment but means they require more force to extract. Many surgeons remove these fixators in the operating room under sedation rather than in the clinic.
Sedation for removal typically involves a combination of medications given through an IV, administered by an anesthesiologist. Full general anesthesia with intubation isn’t usually needed, though the anesthesia team makes that call based on the individual situation. During removal, the surgeon also cleans up the pin sites, breaking up any scar tissue that formed under the skin around the pins.
After removal, the pin holes are small but take a few weeks to close fully. Your team will give you instructions on keeping the sites clean and protected during that final stretch of healing. Some patients wear a cast or brace for a period after the fixator comes off, depending on how solid the bone feels.