A broken bone, or fracture, represents significant trauma, and the subsequent healing process can trigger a rise in body temperature. This reaction is usually a temporary, low-grade elevation, which is a normal physiological response to the injury. A fever is defined as a body temperature of 100.4°F (38°C) or higher. Understanding the difference between this expected increase and a higher, persistent fever is important, as the latter may signal a serious complication requiring immediate medical attention.
The Body’s Low-Grade Temperature Reaction to Injury
The initial, mild temperature rise following a fracture is a direct consequence of the body initiating its repair mechanism. When a bone breaks, blood vessels tear, leading to internal bleeding that forms a fracture hematoma. The destruction of bone and surrounding soft tissue triggers an immediate, localized inflammatory response.
This process involves the mobilization of immune cells that release signaling proteins into the bloodstream, specifically pyrogenic cytokines like Interleukin-1 (IL-1) and Interleukin-6 (IL-6). These messengers travel to the hypothalamus, which acts as the body’s thermostat, and reset the temperature set point higher. This temporary elevation is a systemic manifestation of the body’s attempt to clear damaged tissue and begin the healing cascade.
The absorption of the fracture hematoma is a recognized cause of this non-infectious temperature elevation, sometimes called “absorption fever.” This mild fever typically begins within the first 24 to 48 hours after the injury. It is usually short-lived, remaining below 101°F (38.3°C), and often resolves within a few days as the initial inflammatory phase subsides. A temperature in this range is not cause for alarm unless it persists or is accompanied by other concerning symptoms.
High or Persistent Temperature: Identifying Serious Complications
A high-grade fever or one that develops several days to weeks after the initial trauma suggests a condition beyond the normal inflammatory response. These fevers may indicate a serious complication requiring prompt diagnosis and treatment. Recognizing the timing and accompanying symptoms is important for post-fracture care.
Fracture-Related Infection
A persistent, high fever appearing after the first 48 hours often raises concern for infection, such as an infected wound or osteomyelitis (bone infection). This risk is elevated with open fractures, where the skin is broken, but can also occur after surgery. Accompanying symptoms include increased pain, localized warmth, redness, and swelling that extends beyond the expected injury area. Drainage of pus is a clear indicator of a bacterial infection.
Deep Vein Thrombosis and Pulmonary Embolism
Immobility following a fracture, especially of the lower limbs, increases the risk of Deep Vein Thrombosis (DVT). DVT can cause a low-grade fever, but its primary symptoms are unilateral swelling, pain, and tenderness in the affected leg or calf. If a portion of this clot travels to the lungs, it causes a life-threatening Pulmonary Embolism (PE). PE is characterized by sudden shortness of breath, chest pain, and a rapid heart rate.
Fat Embolism Syndrome
Fat Embolism Syndrome (FES) is a rare but severe complication associated with fractures of long bones like the femur or pelvis. FES develops within 12 to 72 hours post-injury and involves a triad of distinct symptoms. These include respiratory distress (rapid breathing and shortness of breath), neurological changes (confusion or lethargy), and a unique petechial rash of pinpoint spots, typically on the chest, neck, or armpits. The fever associated with FES is a non-specific sign, but its occurrence alongside respiratory and neurological symptoms is a significant indicator.
Guidelines for Monitoring and When to Contact a Doctor
Monitoring temperature is an important component of fracture recovery, particularly during the first week. An isolated, mild fever below 101°F (38.3°C) in the first 48 hours is expected and can be managed by following healthcare provider guidance. This mild elevation is typically self-limiting and does not require urgent intervention.
Contact a medical professional immediately if the temperature rises above 101.5°F (38.6°C) or if a fever persists beyond three days. Urgent medical care is necessary if the fever is accompanied by warning signs such as increasing pain, excessive redness, warmth, or pus draining from the injury site. Serious symptoms also include sudden shortness of breath, chest pain, confusion, or marked swelling and tenderness in a limb not affected by the fracture.