Experiencing chills after knee replacement surgery is a common occurrence for many individuals. While it can be an unsettling sensation, it often stems from the body’s normal responses to the surgical process and the initial stages of healing.
Immediate Surgical Aftermath
The immediate period following knee replacement surgery frequently involves a drop in body temperature, leading to chills. Anesthesia significantly impairs the body’s natural ability to regulate its temperature, causing heat to redistribute from the warmer core to the cooler extremities. This can result in a condition known as perioperative hypothermia.
The surgical environment itself also contributes to this temperature decrease. Operating rooms are typically kept cool, and a patient’s skin is often exposed for extended periods during the procedure, leading to heat loss. Furthermore, the administration of intravenous fluids at room temperature can further lower the patient’s core body temperature.
As the effects of anesthesia begin to wear off, the body’s thermoregulatory system attempts to restore normal temperature, often by initiating shivering. This post-anesthetic shivering is a common and sometimes distressing side effect, representing the body’s involuntary effort to generate heat through muscle activity.
Body’s Natural Reaction to Trauma
Beyond the immediate effects of surgery and anesthesia, the body’s natural response to the trauma of the procedure can also contribute to chills during the recovery phase. Knee replacement involves significant manipulation of bone and tissue, which triggers an inflammatory response. This inflammation is a normal and necessary part of the healing process, as the body works to repair damaged tissues and integrate the new joint.
During this inflammatory period, the immune system becomes activated and releases various pro-inflammatory mediators, such as cytokines. These substances can influence the body’s temperature regulation, sometimes causing a fever-like reaction or chills as part of the immune system’s activation. While a mild fever is common in the days following surgery, persistent or high fever should always be evaluated.
The healing process also involves the formation of scar tissue around the surgical site, which is a natural part of repair, though excessive formation can impact mobility. It is also normal to experience mild swelling, redness, and warmth around the incision for several weeks, and sometimes even up to six months to a year, as the healing progresses.
Identifying Concerning Symptoms
While chills are often a normal part of post-operative recovery, they can sometimes signal a more serious underlying issue. Infection is a primary concern following knee replacement surgery, although it is a relatively rare complication, occurring in about 1 out of every 100 people.
Signs of infection extend beyond just chills and include persistent or increasing redness, warmth, tenderness, and swelling around the knee. A fever higher than 100°F (37.8°C) that persists or appears several days after surgery, along with chills, can indicate an infection. Any drainage from the incision, especially if it is grayish, has a bad odor, or continues for more than a few days, should also prompt immediate medical attention. Infections can be superficial, affecting the skin around the incision, or deep, involving the artificial joint itself, with deep infections being more serious and potentially occurring weeks or even years after surgery.
Blood clots, specifically deep vein thrombosis (DVT), are another serious concern following knee replacement. Symptoms of a DVT in the leg can include pain, cramping, or tenderness unrelated to the incision, often feeling like a pulled muscle. Swelling, particularly in the calf or thigh, that is more pronounced or does not improve with elevation, along with warmth and redness in the affected area, are also warning signs.
If a blood clot travels to the lungs, it becomes a pulmonary embolism (PE), which is a medical emergency. Symptoms of a PE include sudden shortness of breath, chest pain that worsens with deep breathing, or coughing up blood. Any of these symptoms warrant immediate contact with your healthcare provider.