Severe complications after primary hip or knee replacement can necessitate revision surgery in some cases. The decision to undergo revision surgery should not be taken lightly. Modern implants have a long lifespan and can enable many patients to live pain-free and active lives for decades. Nevertheless, there are situations where replacement of the prosthesis is necessary. This blog highlights the main reasons for revision surgery, describes the typical symptoms that indicate the need for revision, and outlines modern approaches to treatment.

Common reasons for prosthesis replacement in hip and knee

Loosening of the prosthesis

One of the most common causes of prosthesis revision is loosening of the implant. This can occur over time due to mechanical stress or, less commonly, as a result of infection. A loosened prosthesis often leads to pain and reduced stability.

Symptoms:

• Pain in the affected hip or knee
• Instability while walking or standing
• Changes in the leg axis

Treatment:
Depending on the type of loosening, a partial or complete replacement of the prosthesis is necessary. Modern surgical techniques often enable minimally invasive interventions that promote rapid rehabilitation.

Periprosthetic infections

Prosthetic infections are rare, but they represent a serious complication. Infections can occur in the immediate post-operative period (acute) or years later (chronic).

Periprosthetic infection: A challenge in endoprosthetics

Periprosthetic infection is one of the most serious and common reasons for prosthesis replacement. This involves an infection in the area of the implant and surrounding tissue structures. The cause is often the penetration of bacteria during or after surgery, but also a later hematogenous spread of pathogens from other body regions can trigger an infection.

Symptoms and diagnosis

Typical symptoms of a periprosthetic infection include:

• Pain in the area of the implant, which can also occur at rest.
• Swelling and redness.
• Overheating of the affected region.
• Fever or general feeling of illness in acute cases.
• Wound healing disorders such as discharge of pus.

The diagnosis is made by a combination of clinical findings, laboratory values (CRP, leukocytes) and imaging procedures. A joint puncture with microbiological analysis is usually the decisive step in identifying the pathogens.

Treatment strategies: One-stage vs. two-stage prosthesis replacement

The choice between a single-stage and a two-stage prosthesis replacement depends on the severity of the infection, the patient's health status, and the identifiability of the pathogen.

One-stage revision

In a single-stage revision, the infected implant is removed in a single operation, the infection is treated, and a new implant is immediately inserted.

Advantages of single-stage revision:

• Shorter treatment duration and faster regain of mobility.
• Less burden on the patient due to only one operation.
• More cost-effective compared to two-stage revision.

Requirements for a one-stage revision:

• Identification of the causative pathogen and its sensitivity to antibiotics.
• Only minor destruction of the surrounding tissue.
• Generally good health status of the patient.

After the new prosthesis is implanted, local antibiotic therapy is often carried out via a special antibiotic carrier in the joint environment.

Two-stage revision

The two-stage revision is considered the 'gold standard' for severe periprosthetic infections or when the exact cause cannot be reliably determined.

Procedure for the two-stage revision:

1. Removal of the infected prosthesis: First, the implant is removed, and the infected area is thoroughly flushed and cleaned.
2. Insertion of a spacer: A spacer coated with antibiotics is used to partially maintain the functionality of the joint and to treat the infection specifically.
3. Antibiotic therapy: A longer phase (usually several weeks) follows with targeted intravenous or oral antibiotic treatment.
4. Re-implantation: After complete infection control, the new implant is implanted in a second operation.

Advantages of the two-stage revision:

• Higher success rates for complex or difficult-to-treat infections.
• Possibility of intensive treatment of extensive tissue damage.

Disadvantages:

• Higher burden for the patient due to two operations.
• Longer treatment duration and limited mobility in the meantime.

Challenges and prospects for success of prosthesis replacement

Both one-stage and two-stage revisions show good results when performed correctly and with early intervention. In the long term, two-stage revision is often more sustainable in cases of severe infection, as it allows more time for complete eradication of the infection. Nevertheless, the decision must always be made individually and takes into account factors such as the patient's medical history and the availability of microbiological diagnoses.

The treatment of periprosthetic infection requires specialized expertise, precise diagnostics, and a well-coordinated interdisciplinary team. Patients benefit from early intervention and consistently implemented therapy, regardless of whether a one-stage or two-stage revision is performed.

Material wear

Over time, wear and tear can occur, especially in prosthetic components made of polyethylene. These wear particles can irritate the surrounding tissue and cause bone damage.

Symptoms:

• Pain under load
• Loosening of the prosthesis
• Reduced mobility

Treatment:
In most cases, replacing the worn prosthetic component is sufficient. Modern materials such as ceramic or highly cross-linked polyethylene minimize the likelihood of wear.

When is a revision with prosthesis replacement urgently necessary?

Acute pain

Sudden, severe pain can indicate loosening, material failure, or infection. In such cases, an orthopedic specialist should be consulted immediately.

Reduced functionality

If everyday movements become increasingly restricted or feelings of instability occur, a more detailed examination is required. Often, it is a gradual process that develops over months.

Revision techniques: Modern and patient-friendly

Advanced methods are now available for prosthesis replacement. Minimally invasive approaches and the use of patient-specific implants improve the success rate and reduce rehabilitation time.

Examples of modern procedures:

• One-stage revision: In cases of sterile loosening or minimal infection, the old prosthesis is removed and directly replaced with a new one.
• Two-stage revision: Especially in cases of severe infections, to ensure careful wound healing.

Conclusion

A revision with prosthetic replacement at the hip or knee is a demanding but sometimes necessary operation to regain quality of life. Thanks to modern technologies and innovative treatment methods, the prospects for a long-term solution are better than ever. Trust in the expertise of an experienced specialist and take advantage of the possibilities of modern orthopaedics early on. Your path back to more joy in life begins with a well-founded consultation!