An antibiotic knee spacer is a temporary device used to manage infection following knee replacement surgery. This article explains its purpose and guidelines for walking and weight-bearing during this treatment phase.
Understanding the Antibiotic Knee Spacer
An antibiotic knee spacer is a medical device primarily used to treat infections that can occur after a total knee replacement. This treatment is often part of a two-stage revision process, which is considered a standard approach for managing periprosthetic joint infections. The first stage involves removing the infected knee implant and thoroughly cleaning the area.
The spacer itself is typically made from bone cement, specifically polymethyl methacrylate (PMMA), which is mixed with high doses of antibiotics. This composition allows the spacer to continuously release antibiotics directly into the knee joint, targeting the infection locally. Spacers are temporary and are designed to maintain the joint space and soft tissue tension until the infection is resolved.
There are two main types of antibiotic knee spacers: static and articulating (or mobile). Static spacers generally keep the knee in a fixed position, while articulating spacers are designed to allow some range of motion. The choice of spacer can influence a patient’s mobility during the treatment period.
Mobility and Weight-Bearing Guidelines
Walking and weight-bearing with an antibiotic knee spacer depend heavily on the type of spacer implanted and the specific instructions from the surgeon. While some articulating spacers may allow for limited mobility and partial weight-bearing, static spacers typically restrict movement and may require a non-weight-bearing approach. The primary goal during this phase is to eradicate the infection and prepare the knee for a permanent implant.
Weight-bearing is often restricted to protect the healing tissues, prevent dislocation of the temporary spacer, and ensure that the antibiotics effectively clear the infection. Excessive stress on the spacer could lead to its breakage, loosening, or dislocation, which would complicate the treatment. Patients are usually advised to use mobility aids such as crutches, walkers, or canes to reduce stress on the knee.
Some articulating spacers are designed to facilitate early rehabilitation and preserve a range of motion, potentially leading to improved mobilization. However, even with articulating spacers, patients are often cautioned against full weight-bearing, with recommendations for partial weight-bearing based on individual bone quality and clinical conditions. It is crucial to follow the surgeon’s instructions precisely, as these guidelines are tailored to the individual’s condition and the specific characteristics of the spacer used.
Living with the Spacer and Daily Care
Daily life with an antibiotic knee spacer involves careful management and adherence to medical advice. Movement limitations extend beyond weight-bearing; activities that involve deep bending or twisting of the knee may be restricted to prevent complications. Pain management is an important aspect of living with a spacer, and patients may receive medication to control discomfort.
Wound care is also essential to prevent new infections. Patients will receive instructions on how to care for their incision, including showering guidelines, which may initially involve sponge baths or covering the wound. Monitoring for signs of complications is important. Patients should be aware of symptoms such as a fever above 100°F (37.8°C), increasing pain that is not relieved by medication, excessive redness, swelling, or drainage from the incision. Any such signs require immediate medical attention.
What Happens After the Spacer is Removed
The antibiotic knee spacer is a temporary solution, and its removal marks the next phase of treatment. Once the infection is successfully eradicated, typically confirmed by blood tests showing normalized infection markers, a second surgical procedure is performed. This second surgery involves removing the temporary spacer and implanting a new, permanent knee prosthesis.
The interval between the two surgical stages can vary, often ranging from several weeks to a few months, allowing sufficient time for the infection to clear. After the permanent implant is in place, recovery and rehabilitation will begin, similar to an initial knee replacement surgery. This final stage focuses on restoring knee function, strength, and mobility, allowing patients to gradually return to their normal activities.