Hip Prosthesis Loosening | Information & Find a Doctor

In 2019, approximately 240,000 patients in Germany received an artificial hip joint (also known as a hip endoprosthesis or total hip replacement, or TEP). With today’s techniques and materials, these artificial hip joints typically last 25 years or longer. However, this also means that the lifespan of hip prostheses is limited.

Increasing wear and tear between the components of the artificial hip joint can lead to loosening of the implant. 

In other words, the hip prosthesis is no longer firmly anchored in the bone. Doctors refer to this as hip prosthesis loosening. 

If the hip implant loosens within the first five to ten years, this is considered early loosening of the hip joint prosthesis.

An artificial hip joint does not last forever.

The reasons why an implanted hip joint loosens can vary. 

Doctors distinguish between two basic types of prosthesis loosening:

1. Septic hip prosthesis loosening: This involves a bacterial infection (septic) at the site of the prosthesis.
2. Aseptic hip prosthesis loosening: This term encompasses all forms of loosening in which there is no bacterial infection (aseptic). 

The causes in these cases lie with the patient, such as:

• severe physical strain or 
• severe obesity

However, the material and design of the prosthesis, as well as the fixation and surgical techniques, may also be responsible.

Pain is a typical symptom of hip prosthesis loosening. 

Depending on the extent of the loosening and which prosthetic component is loose, symptoms may occur in different areas:

Pain upon starting to walk or when bearing weight is indicative of early hip prosthesis loosening.

In cases of stem loosening, pain in the thigh often occurs while standing or walking. The pain may also radiate to the knee joint and the buttocks.

Pain in the groin may indicate acetabular loosening (loosening of the hip socket). This often causes little or no pain.

Other symptoms or signs of loosening of the artificial hip joint include:

• A gradual decrease in the maximum walking time or distance
• A feeling of unsteadiness when walking
• A tendency to fall
• A feeling of no longer being able to control the leg properly

If the leg has shortened, the loosening is likely already at an advanced stage. 

In this case, the hip socket has shifted from its original position, or bone fractures have occurred in the area of the femoral stem. This has led to a “compression” of the leg.

If the cause of hip prosthesis loosening is a bacterial infection, typical signs of inflammation or infection may occur:

• The skin above the implant is red, swollen, and warm. This can impair joint movement and cause pain.
• Fever, possibly accompanied by chills.
• In the case of recently implanted hip prostheses, the incision may split open and pus may ooze out.

A bacterial infection is only a possible cause of hip prosthesis loosening in the first few months to years following hip surgery. Later on, septic hip prosthesis loosening is rare. 

At later stages, the following factors are the primary causes of prosthesis loosening:

• Body weight
• Stress
• materials used, and
• Surgical technique

What are the causes of septic hip prosthesis loosening?

In about one to two percent of patients, bacteria are introduced during hip surgery. These bacteria colonize the area around the prosthesis, multiply, and form a biofilm. 

This, in turn, prevents the implant from properly integrating into the bone. The result is loosening of the hip prosthesis.

Any pre-existing conditions, treatments, or circumstances associated with a weakened immune system are considered risk factors for septic prosthesis loosening. 

These include, for example:

• Immune deficiencies
• Diabetes mellitus
• Rheumatoid arthritis
• Chronic inflammatory skin disease
• Cancer
• Coagulation disorders
• Use of corticosteroids or anticoagulants
• Advanced age
• Severe obesity
• Tobacco, alcohol, and drug abuse

If bacteria are introduced during hip surgery, it can lead to septic hip prosthesis loosening.

What are the causes of aseptic hip prosthesis loosening?

In an artificial hip joint, the joint components are not protected from wear by a layer of cartilage. In a healthy joint, however, this is the case.

The constant sliding of the artificial surfaces against one another causes abrasion of the surface material. 

The particles now present in the hip joint, in turn, lead directly or indirectly to bone loss via an inflammatory reaction. This bone loss then results in loosening of the hip prosthesis.

Other factors that negatively affect the durability of a hip prosthesis include:

• Material defects, such as cracks in the cement or fractures in the prosthesis
• The surgeon’s limited experience in implanting the artificial hip joint
• Surgical technique
• Bone already compromised by osteoporosis or osteonecrosis
• Pre-existing conditions (axial misalignments, diabetes, etc.)
• Advanced age
• Severe obesity
• Traumatic events, such as an accident or a fall

During the medical history interview, the focus is on the symptoms described by the patient and their medical history. 

These include, for example:

• Date of hip replacement surgery
• Pre-existing conditions or
• traumatic events

The nature and location of the pain provide an initial indication of possible prosthesis loosening.

During the clinical examination, the doctor attempts to provoke pain in the leg or hip.

This is done by:

• Shaking
• Compression, or
• Rotating

He also tests the range of motion in the hip joint and observes how you walk and whether your gait is normal.

If there is suspicion that the hip replacement has become loose, the doctor will take an X-ray of the hip. 

The entire prosthesis is visible on this X-ray. The doctor cannot always clearly identify signs of loosening on the X-ray. 

Therefore, it is helpful to compare it with an X-ray taken immediately after the hip replacement surgery. 

In unclear cases or when specific issues need to be addressed, the following diagnostic methods are often used:

• scintigraphy (examination using radioactively labeled substances),
• ultrasound (if necessary),
• MRI (magnetic resonance imaging) or
• CT (computed tomography)

If a septic cause is suspected, the doctor will have the inflammation markers measured in a blood sample. 

These include:

• Erythrocyte sedimentation rate
• White blood cells
• C-reactive protein

In addition, the doctor will aspirate the joint using a long hollow needle and then examine the joint fluid for bacteria.

Doctors first surgically remove loosened hip prostheses as part of a revision surgery. They replace the old artificial hip joint with a new one.

Orthopedic surgeons and trauma surgeons with extensive experience in hip replacement surgery are considered experts in hip revisions (revision surgeries).

The exact procedure for a revision surgery depends on whether the cause is bacterial or nonbacterial.

In cases of aseptic prosthesis loosening, doctors remove the hip prosthesis (explantation) in a single-stage revision surgery. They then implant the new prosthesis (revision prosthesis).

Most cases of septic prosthesis loosening, on the other hand, require a two-stage revision procedure. 

In this procedure, they implant the revision prosthesis in a second surgery after removing the infected tissue and administering antibiotic therapy. 

The bone healing process and antibiotic therapy can take several weeks. In some cases, the treatment may need to be repeated to completely eradicate the infection.

The implantation of a revision prosthesis following aseptic loosening is essentially the same as a standard hip replacement surgery. 

Therefore, the prognosis depends on the existing risk factors. The material properties of today’s artificial hip joints are significantly better. 

In general, hip replacements have a longer lifespan than they did 20 or 30 years ago.

In contrast, the prognosis following surgical treatment of septic prosthetic loosening depends crucially on the course of the infection. This is a protracted process that may require repeat surgeries and revision procedures.

The likelihood of hip prosthesis loosening also depends on the surgeon’s expertise. This was revealed by a study conducted by the AOK Scientific Institute.

Therefore, you should have your artificial hip joint implanted only by specialists with extensive experience in hip replacement surgery. This way, you can reduce the risk of future prosthesis loosening right from the start.

As mentioned earlier, being severely overweight is a potential risk factor for prosthesis loosening. Therefore, try to avoid excessive weight gain or, if you are severely overweight, work to reduce your body weight.

In addition, you should avoid, as much as possible, any activities or sports that place excessive strain on the hip joint.