What is a Hip Spacer and Why is it Used?
A hip spacer is a specialized medical device primarily used in hip replacement surgery for periprosthetic joint infection (PJI). This temporary implant delivers antibiotics directly to the affected area and maintains joint space, preventing tissue collapse and facilitating subsequent surgery.
These devices are typically fashioned from bone cement, specifically polymethylmethacrylate (PMMA), mixed with antibiotics. The antibiotics slowly release from the cement, creating a high concentration at the infection site. This localized delivery is often more effective than systemic antibiotics alone in combating stubborn bacterial biofilms.
Spacers come in two main forms: static and articulating. A static spacer is a solid, non-moving block that fills the joint space, while an articulating spacer allows for some limited movement, mimicking the function of a natural joint. Both types suppress infection and preserve joint anatomy until a permanent solution can be implemented.
The Standard Treatment Pathway with a Hip Spacer
A hip spacer is typically a temporary solution within a two-stage revision surgery for periprosthetic joint infection. The initial stage involves removing infected hip components and thoroughly cleaning surrounding tissues.
A hip spacer is then implanted. This first stage allows for targeted antibiotic treatment, often lasting several weeks to a few months, with local and sometimes intravenous antibiotics. The goal is to eradicate the infection completely before proceeding to the next step.
Once infection control is confirmed, typically through blood tests and sometimes fluid analysis from the joint, the second stage involves removing the temporary hip spacer and implanting a new, sterile permanent hip prosthesis. This sequential approach is considered the most effective for hip PJI, highlighting the spacer’s transient role.
Circumstances Where a Spacer May Remain
While the standard approach involves eventual removal, there are specific, uncommon situations where a hip spacer might remain indefinitely. One primary reason for long-term spacer retention is when patients have significant health issues or frailty that make undergoing a second major surgery too risky. Conditions such as severe heart disease, lung problems, or advanced age can increase the potential complications associated with another operation.
Another circumstance involves cases of extremely aggressive or recurrent infections where repeated attempts to implant a permanent prosthesis have failed or are deemed unlikely to succeed. In such scenarios, leaving the spacer in place might be considered a palliative measure to manage pain and infection, prioritizing the patient’s overall well-being over full joint reconstruction.
Patients, after careful discussion with their medical team, may also choose not to proceed with the second stage of surgery. This decision often stems from a comprehensive understanding of the risks and benefits, weighing the potential for improved function with a permanent implant against the challenges and recovery associated with another surgical procedure. These situations represent exceptions to the typical treatment protocol for hip PJI.
Considerations for Long-Term Spacer Retention
When a hip spacer remains permanently, patients often experience notable functional limitations compared to those with a successfully implanted prosthesis. Mobility can be significantly reduced, leading to an altered gait and difficulty with everyday activities like walking long distances or climbing stairs. The inherent design of a spacer, even an articulating one, does not provide the same stability or range of motion as a definitive hip replacement.
There is also a persistent, albeit lower, risk of the infection recurring or flaring up, as the spacer itself can sometimes harbor residual bacteria. Mechanical complications, such as the spacer fracturing or dislocating from its position, can also occur over time, potentially causing pain and requiring further intervention. Such events can be particularly challenging to manage in patients who were already deemed too frail for a second surgery.
Patients living with a permanent hip spacer require ongoing medical monitoring and follow-up care to manage potential issues and ensure the best possible quality of life. This includes regular check-ups to assess joint stability, monitor for signs of infection, and address any pain or functional decline. The decision to retain a spacer long-term involves a careful balance of infection control, functional capacity, and patient safety.