Sternal wires, technically known as cerclage wires, are a common form of internal fixation used after a major chest operation called a median sternotomy. This procedure involves cutting the breastbone (sternum) down the middle to access the heart and lungs, often for procedures like coronary artery bypass grafting. Following the operation, these wires reapproximate the two halves of the bone. The immediate answer to whether these wires are permanent is yes; they are typically designed to remain in the body indefinitely.
The Mechanical Role of Sternal Wires
A median sternotomy creates structural instability that must be managed for patient safety and recovery. The sternum experiences significant mechanical stress from breathing, coughing, and arm movements. Without adequate stabilization, these forces could cause the cut edges of the bone to separate, leading to sternal dehiscence. Sternal wires are threaded around the bone halves and twisted tight to provide rigid fixation.
The primary function of this fixation is to hold the bone fragments together until the natural process of bone fusion (osseous union) is complete. This healing process requires the bone to be held securely to bridge the gap with new tissue. Complete sternal fusion generally takes between six to twelve weeks, depending on the patient’s health. During this period, the wires bear the mechanical load, protecting the developing bone bridge from disruptive forces.
Beyond bone healing, the wires serve to protect the organs situated beneath the sternum, particularly the heart. A stable sternum minimizes movement and friction at the surgical site, which helps reduce the risk of injury to the underlying mediastinal structures. The presence of the wires is a temporary mechanical requirement that facilitates a permanent biological repair.
The Permanence Question: Why Wires Typically Stay
Sternal wires are typically left in place because of the materials used in their construction. They are almost universally made from surgical-grade stainless steel (like 316L) or occasionally titanium. These materials are classified as inert, meaning they are chemically stable and do not react with the body’s biological environment. This biocompatibility ensures that the wires will not corrode, degrade, or trigger an immune response over time.
Once the sternum has fully fused, the wires are no longer necessary for stability, but their removal often carries greater risk than benefit. Over the months and years following the operation, the body often incorporates the wires into the surrounding tissues. This process, called fibrous encapsulation, sees the wires become surrounded by scar tissue and sometimes new bone growth. Attempting to extract these integrated wires can cause damage to the surrounding healthy tissue and potentially destabilize the healed bone.
Unlike temporary orthopedic implants designed for later removal, sternal wires are considered permanent fixtures. They do not require ongoing monitoring or maintenance once the initial recovery period is complete. For most patients, the wires remain silent and unnoticed for the rest of their lives.
The decision to leave the wires in place is based on a risk-benefit analysis where the risks of a second surgery, including anesthesia and potential infection, outweigh the benefits of removing a non-symptomatic implant. The absence of symptoms confirms the material’s inertness and successful integration into the chest wall. Therefore, removal is reserved only for situations where the wires become the source of a medical problem.
Specific Reasons for Sternal Wire Removal
The most serious indication for wire removal is the presence of an infection, particularly a deep sternal wound infection or mediastinitis. Bacteria can colonize the foreign material of the wire, creating a biofilm that makes antibiotic treatment ineffective without physical removal of the contaminated material. In these cases, the infected wires must be extracted to clear the infection and allow the wound to heal. This procedure is usually undertaken in conjunction with wound debridement and specialized antibiotic therapy.
Wires may also require removal if they suffer mechanical failure, such as migration or breakage. If a wire loosens, shifts position, or fractures, the sharp end can become palpable or cause localized irritation to the surrounding soft tissues. This irritation can lead to chronic, localized pain or discomfort that impacts a patient’s quality of life.
Chronic pain localized over the wire site, even without evidence of infection or breakage, can necessitate removal. While exceedingly rare, a patient may also develop a hypersensitivity or allergic reaction to the metal alloy itself, which would mandate the extraction of the foreign material. In some lean patients, the wires may be positioned close to the skin surface, making them easily palpable and uncomfortable when rubbed against clothing or during movement. Removal in these elective cases is performed only after ruling out other causes of chest wall pain.