A Total Knee Replacement (TKR) is a common surgical procedure that alleviates pain and restores function by resurfacing the joint with metal and plastic components. Chemotherapy is a systemic medical treatment designed to destroy rapidly dividing cancer cells throughout the body. Because chemotherapy affects healthy, quickly multiplying cells as well, it interferes with normal cellular processes. This interference can significantly affect the outcomes of an elective surgery like a TKR, primarily by compromising the body’s ability to heal and fight infection.
How Chemotherapy Increases Infection Risk
Chemotherapy directly impacts the immune system, causing systemic immunosuppression. Chemotherapy agents often suppress the bone marrow, the source of all blood cells, including infection-fighting white blood cells. This suppression results in neutropenia, characterized by an abnormally low count of neutrophils, which are the body’s primary defense against bacteria.
Patients face the highest risk of infection when their Absolute Neutrophil Count (ANC) is severely depressed. This immunosuppressed state makes them vulnerable to a Periprosthetic Joint Infection (PJI), the most catastrophic complication of a TKR. Studies show that patients receiving chemotherapy within a year after joint replacement surgery have significantly higher rates of PJI. Since the body cannot mount an adequate immune response, bacteria can colonize the knee implant, leading to a severe infection that often requires multiple surgeries to resolve.
Impact on Post-Surgical Healing and Recovery
The effects of chemotherapy compromise the fundamental processes required for surgical recovery beyond the immune system. Wound healing relies heavily on the rapid proliferation and migration of cells. Chemotherapy drugs interfere with cell division and inhibit cellular metabolism, directly delaying the repair of the surgical incision and surrounding soft tissues. This delayed wound closure increases the risk of wound complications and provides a potential entry point for bacteria.
The long-term success of a knee replacement also depends on osseointegration, the process where surrounding bone grows onto or into the implant components. Chemotherapy has an adverse effect on bone regeneration at the bone-prosthetic interface. Studies show that bone formation is both delayed and diminished in patients who receive chemotherapy post-surgery. The compromised ability of the bone to regenerate and secure the implant affects the long-term stability and function of the knee replacement.
Timing the Surgery Around Chemotherapy
The timing of an elective TKR requires careful coordination between the orthopedic surgeon and the oncologist. Surgeons generally will not perform an elective procedure during active chemotherapy or radiation treatment. The body is in a state of maximum stress and immunosuppression, making the risks of infection and poor healing too high. Cancer treatment is the primary concern, and the knee replacement is deferred until treatment is complete or paused.
The recommended waiting period, often called a “chemo holiday,” allows the bone marrow and immune system to recover. Since a precise, universal timetable does not exist, a period of several weeks to months is often required, depending on the cancer treatment and patient response. The decision to proceed is based on laboratory values demonstrating sufficient recovery of physiological systems.
The Absolute Neutrophil Count (ANC) is a metric used to determine safety thresholds. A count of less than 1,500 cells/µL signals an increased risk of infection and warrants a delay in surgery. Preoperative blood tests must also confirm that other organ systems, such as the liver and kidneys, are functioning adequately to withstand the stress of surgery and anesthesia. Close consultation with the oncology team is essential to ensure the timing of the knee replacement does not negatively impact the patient’s cancer treatment schedule.