Fracture-related infection is a serious complication that can occur when bacteria enter the body after a bone breaks or during surgical repair. While most broken bones heal without problems, when infections do develop, the journey to recovery becomes significantly more complex and prolonged.
Epidemiology
Fracture-related infection, often called FRI, does not happen in every case of a broken bone. In fact, the majority of fractures heal without any infectious complications. However, when infections do occur, they represent a significant medical challenge that affects patients across all ages and backgrounds.[1]
The frequency of these infections varies depending on several factors, particularly the type of fracture and how it is treated. For surgically managed fractures in healthy individuals, the risk of infection is relatively low, typically ranging from less than 1% to about 2 to 3%.[1][3] This percentage can change based on the specific injury and the type of operation performed. Recent data suggests that FRI occurs in approximately 1 to 2.5% of surgically managed fractures overall, with rates heavily influenced by the severity of the trauma and the treatment setting.[13]
The situation becomes more concerning with open fractures, which are breaks where the bone pierces through the skin or where a wound exposes the bone. These injuries carry a much higher risk of infection because bacteria from the environment can directly contact the broken bone. Open fractures develop infections in more than one-quarter of cases, making them particularly dangerous.[14] In approximately 3% of fracture-related infection cases, the outcome is severe enough to require amputation of the affected limb.[14]
Research has identified certain demographic patterns in fracture-related infections. Factors such as age, male sex, and socioeconomic status have been associated with increased susceptibility to these infections, though the condition can affect anyone regardless of background.[13]
In a major trauma center study reviewing cases from January 2015 to January 2021, researchers identified 102 patients with fracture-related infection, including 35 open fractures and 67 closed fractures. Of these patients, treatment failed in 24 cases (23.5%), meaning the infection returned or amputation became necessary.[2] This substantial failure rate highlights the serious nature of these infections and the difficulties healthcare providers face in treating them completely.
Causes
Fracture-related infections develop when bacteria find a way into the body and reach the broken bone. Understanding how this happens is crucial to grasping why some fractures become infected while others heal normally.
The most common pathway for infection occurs during the initial traumatic event that breaks the bone. When severe force causes a fracture, bacteria from the environment can enter the body at the moment of injury.[1] This is especially true for open fractures, where the protective barrier of skin is breached. Normally, your skin serves as a natural shield against outside contaminants, including countless bacteria present in the environment. When a bone breaks through the skin, or when a wound penetrates down to the bone level, bacteria can easily travel directly to the broken bone.[6][10]
Surgery to repair a fracture creates another potential entry point for bacteria, though this is less common. During an operation to fix a broken bone, surgeons must cut through the skin and soft tissues to reach the fracture site. Even with strict sterile techniques, there remains a small risk that bacteria could enter through these surgical incisions.[1] Medical teams work hard to prevent this by administering preventive antibiotics before surgery and maintaining high standards of care in operating rooms.[3]
In rare instances, an infection can develop long after the initial injury has healed. This delayed infection can occur when bacteria enter the body during a completely unrelated medical or dental procedure, such as a tooth extraction or root canal. These bacteria can travel through the bloodstream and settle on the metal plates, screws, or other implants that were used to stabilize the fractured bone.[1][9]
The extent of damage to surrounding tissues plays a significant role in infection development. When a fracture occurs, it’s not just the bone that suffers trauma. The skin, muscles, arteries, and veins near the fracture site can also be damaged. Generally, the greater this surrounding damage, the higher the risk for infection.[3][12] Severely damaged tissue may have reduced blood flow, making it harder for the body’s immune system to fight off any bacteria that enter the area.
Risk Factors
Not everyone who breaks a bone faces the same risk of developing an infection. Certain health conditions, lifestyle choices, and characteristics of the injury itself can significantly increase the likelihood that bacteria will take hold and cause problems.
Chronic diseases that weaken or suppress the immune system place patients at considerably higher risk for infection after a fracture. Diabetes mellitus, a condition affecting how the body processes blood sugar, makes it harder for the body to fight infections and for wounds to heal properly.[1][10] People with immune deficiencies, such as HIV, have compromised defense systems that struggle to combat invading bacteria.[1] Rheumatoid arthritis, an autoimmune disease, also increases infection risk, as does treatment with medications that suppress immune function.[1][9] Patients undergoing hemodialysis, a treatment for kidney failure, face elevated infection risks as well.[10]
Beyond smoking, other lifestyle factors contribute to infection risk. Morbid obesity makes surgical procedures more difficult and can impair the body’s healing processes.[1][10] Poor nutrition deprives the body of essential building blocks needed for tissue repair and immune function.[1][9] Poor hygiene can introduce additional bacteria to wound sites, increasing contamination risk.[1][9] Drug use also elevates the risk of developing fracture-related infections.[10]
Research from a major trauma center identified specific factors that predict treatment failure when fracture-related infections do occur. Their statistical analysis revealed that obesity more than doubles the risk of treatment failure.[2] The severity of open fractures, particularly the most severe type classified as Gustilo Anderson type 3c, increases the odds of treatment failure nearly five-fold.[2] When surgical implants are retained during infection treatment rather than removed, this decision almost triples the risk that treatment will not succeed.[2]
The characteristics of the fracture itself matter enormously. Open fractures, where the bone protrudes through the skin, present a particularly high infection risk because of direct exposure to environmental bacteria during the injury.[13] The type of fracture, whether it’s a simple break or a comminuted fracture where the bone shatters into multiple pieces, influences infection likelihood. The extent of soft tissue damage and whether the injury is an isolated fracture or part of multiple injuries (polytrauma) all affect the final infection risk.[13]
Symptoms
Recognizing the signs of a fracture-related infection early can make a substantial difference in treatment success. While some pain and swelling are normal after any fracture, certain symptoms signal that bacteria may have invaded the injury site and require immediate medical attention.
Pain is expected after breaking a bone, but infection causes a different quality of discomfort. An infected fracture produces increased pain that goes beyond what would be considered normal for the healing process.[1][6] This pain is persistent and doesn’t improve when you rest and elevate the injured limb as it would with routine healing.[1][9] The affected area becomes noticeably warm to the touch, as the body’s immune response generates heat while fighting the infection.[1][10]
Visual changes around the fracture site provide clear warning signs. The skin becomes increasingly red, and swelling develops that exceeds normal post-fracture inflammation.[1][6] These changes indicate active infection and inflammation as white blood cells rush to the area to combat invading bacteria. The combination of warmth, redness, increased pain, and excessive swelling together strongly suggests infection rather than normal healing.[3][12]
Drainage from the wound is one of the most recognizable infection symptoms. A pocket of pus may form at or near the fracture site. If this pocket ruptures, pus will drain from the injury, appearing as a thick, often discolored fluid.[1][9] When a fracture has been surgically repaired with hardware like plates and screws, drainage is particularly common and often the most obvious symptom that patients notice.[10] Any persistent, increasing, or new drainage around a healing fracture should prompt immediate contact with your doctor.[10]
Infections don’t always stay localized. Your whole body may react to the bacterial invasion. Fever indicates your body is mounting a systemic immune response to fight the infection.[1][6] Chills and night sweats often accompany the fever, as your body’s temperature regulation struggles with the infection.[1][10] These whole-body symptoms signal that the infection may be spreading beyond the immediate fracture site.
When the infection occurs near a joint, such as the knee or shoulder, additional problems arise. The joint may become difficult or painful to move, as inflammation and infection affect the surrounding structures.[1][3] This loss of mobility can significantly impact daily function and is a clear sign that medical evaluation is urgently needed.
Prevention
While not all fracture-related infections can be prevented, especially those resulting from severe trauma, several important measures can significantly reduce your risk of developing this serious complication.
For open fractures, immediate medical care is absolutely critical. An open fracture represents a surgical emergency that requires rapid intervention.[3][12] Antibiotics should be started as quickly as possible, ideally in the emergency room, to fight any bacteria that entered during the injury.[3][18] The next crucial step involves surgically cleaning the wound through a procedure called debridement and irrigation, where surgeons remove contamination from the skin, soft tissues, and bone.[3][12] This procedure typically takes place in an operating room under sterile conditions. Depending on the severity of the injury, multiple cleaning procedures may be necessary to adequately remove all contaminated material.[3][12]
For surgical repair of fractures, preventive antibiotics play a vital role. These medications are administered before the operation begins to reduce the risk of bacteria establishing an infection during surgery.[1][9] Operating rooms maintain high standards of sterile technique and environmental control to minimize infection risk.[3] Despite these precautions, patients should understand that a small risk always remains with any surgery.
Lifestyle modifications can substantially impact your infection risk, particularly if surgery is planned. Stopping smoking and nicotine use is the single most important action you can take to improve your outcomes.[1][10] Even a short period of smoking cessation before surgery can improve blood flow and healing capacity. Addressing obesity through weight management, when possible before planned procedures, can reduce surgical complications. Improving nutritional status by eating a balanced diet rich in protein, vitamins, and minerals supports your immune system and healing processes.[1][9]
For people with chronic health conditions, optimizing disease management before and after a fracture is essential. If you have diabetes, working to control blood sugar levels as tightly as possible improves your body’s ability to heal and fight infection.[2][11] Those with immune-compromising conditions should work closely with their healthcare providers to balance necessary medications with infection risk. Good personal hygiene, including keeping wounds clean and dry, helps prevent bacterial contamination.[1][9]
After a fracture occurs, following your doctor’s instructions carefully can prevent complications. Keeping casts clean and dry is important, as moisture can promote bacterial growth and mold.[1] Never remove your cast on your own, as this can lead to further injury and potentially introduce infection. If you experience symptoms suggesting infection, such as increasing pain, redness, swelling, drainage, or fever, contact your doctor immediately rather than waiting for a scheduled follow-up appointment.
Pathophysiology
Understanding what happens in your body when a fracture becomes infected helps explain why these infections are so difficult to treat and why they can have such serious consequences for bone healing.
When bacteria enter the body and reach a broken bone, they don’t simply float around causing trouble. Instead, many types of bacteria can attach themselves to bone surfaces and surgical implants, where they form complex communities called biofilms. These biofilms act like protective shields, making the bacteria much harder for both your immune system and antibiotics to reach and eliminate. The bacteria within biofilms can survive in a dormant state, only to reactivate later, which explains why fracture-related infections can return even after seemingly successful treatment.
The presence of bacteria and the body’s immune response to fight them creates inflammation at the fracture site. While inflammation is a normal part of healing, excessive or prolonged inflammation interferes with the normal bone healing process. Blood vessels in the area may become damaged, reducing blood flow to the injured bone. Since blood carries oxygen, nutrients, and immune cells needed for healing, this reduced circulation impairs the bone’s ability to repair itself.[6]
Infection can lead to osteomyelitis, which means infection of the bone itself. When bacteria invade bone tissue, they can cause areas of bone to die, creating what doctors call sequestra – islands of dead bone tissue. These dead sections cannot heal and actually harbor bacteria, serving as ongoing sources of infection that are extremely difficult to eliminate without surgical removal. The body may try to wall off infected areas by forming new bone around them, but this reactive bone formation doesn’t solve the underlying problem.
Fracture-related infections can co-exist with nonunion, a condition where the broken bone fails to heal properly, and with bone defects where sections of bone are lost or must be removed.[6][10] The infection itself interferes with the bone healing process, while the instability of an unhealed fracture provides an environment where bacteria can thrive. This creates a vicious cycle where infection prevents healing, and poor healing perpetuates infection.
Surgical implants used to stabilize fractures, such as metal plates, screws, rods, or external fixators, can become colonized by bacteria. Once bacteria establish biofilms on these implants, they become extraordinarily difficult to eliminate with antibiotics alone. The implants themselves, while necessary for bone stabilization, can act as foreign bodies that provide surfaces for bacterial attachment and growth. This is why removing implants often becomes necessary when treating established infections, even though the bone may still need stabilization.[2]
The biochemical environment around an infected fracture changes significantly. Bacterial toxins and enzymes break down tissues. Immune cells release chemicals to fight the bacteria, but these same chemicals can damage healthy tissue. The local pH may change, and oxygen levels may drop in infected areas, creating conditions that favor certain types of bacteria while making antibiotic penetration more difficult.
Mechanically, infection weakens the bone structure. The combination of bacterial destruction, immune-mediated damage, and areas of dead bone makes the fracture site structurally unsound. This can lead to deformity if the bone heals in an incorrect position or to complete failure of healing. In cases where the infection spreads along the bone or into surrounding soft tissues, the damage can extend far beyond the original fracture site, potentially affecting joints, muscles, and other nearby structures.
