Periprosthetic Shoulder Infection

What is periprosthetic shoulder infection?

A periprosthetic shoulder infection is an infection that develops in the tissues and bone surrounding an artificial shoulder joint. The word periprosthetic simply means “around the prosthesis,” and a prosthesis is the metal and plastic implant placed during shoulder replacement surgery (also called shoulder arthroplasty). When bacteria settle on or around the implant, the body often struggles to clear them, because the implant has no blood supply of its own and bacteria can form a protective layer called a biofilm on its surface.

Periprosthetic shoulder infection is considered an uncommon but serious complication of shoulder replacement. It can affect anyone who has had an anatomic shoulder replacement, a reverse shoulder replacement, or a partial replacement (hemiarthroplasty). It may appear within weeks of surgery, or it may develop slowly over months or even years. Because the shoulder is often infected by slow-growing, low-grade bacteria, this condition can be harder to recognize than infections in other replaced joints such as the hip or knee.

Care for this condition is usually shared between orthopedic surgeons who specialize in shoulder surgery and infectious disease doctors. In hospital groups such as Acibadem, this care is typically coordinated through the Orthopedics & Joint Center.

Periprosthetic shoulder infection symptoms

Periprosthetic shoulder infection symptoms vary a great deal depending on how soon after surgery the infection begins and which type of bacteria is involved. Some people have obvious signs of infection, while others notice only ongoing pain or stiffness that does not improve as expected after surgery.

• Persistent or worsening shoulder pain, especially pain that does not settle in the months after surgery
• Stiffness or loss of motion that is greater than expected during recovery
• Redness, warmth, or swelling around the surgical scar
• Fluid, pus, or cloudy drainage leaking from the wound
• A wound that opens, heals slowly, or breaks down after appearing healed
• Fever, chills, or night sweats
• A general feeling of being unwell or unusually tired
• A sense that the implant is loose or unstable

Early (acute) infection is usually described as beginning within the first several weeks after surgery. It tends to be caused by more aggressive bacteria and often produces the classic signs most people associate with infection: redness, heat, swelling, wound drainage, and sometimes fever.

Late or chronic infection develops more slowly, often months or years after the operation. In the shoulder, this type is frequently caused by a bacterium called Cutibacterium acnes (formerly known as Propionibacterium acnes), which normally lives harmlessly in the oil glands of the skin around the shoulder. These slow-growing infections often cause only vague, ongoing pain and stiffness, with no fever, no redness, and a normal-looking scar. Many people with chronic infection are first thought to have a mechanical problem, such as loosening of the implant, rather than an infection.

Less commonly, a shoulder replacement may become infected long after surgery when bacteria travel through the bloodstream from another part of the body, such as a dental abscess, a urinary infection, or an infected skin wound. In these cases, symptoms may begin fairly suddenly in a shoulder that previously felt well.

Causes and risk factors

Periprosthetic shoulder infection causes come down to bacteria reaching the implant and surviving there. This can happen in a few main ways:

• Contamination during surgery. Even with careful sterile technique, small numbers of skin bacteria can enter the wound during the operation. The skin of the shoulder, especially in men, carries relatively high numbers of Cutibacterium acnes deep in the hair follicles and oil glands, where surgical skin preparation cannot fully reach.
• Wound problems after surgery. If the wound drains for a long time, opens, or develops a blood collection (hematoma), bacteria from the surface can travel down to the implant.
• Spread through the bloodstream. An infection elsewhere in the body can seed the joint at any point after surgery.

Once bacteria attach to the implant, they can build a biofilm, a slimy protective coating that shields them from the immune system and from antibiotics. This is one of the main reasons periprosthetic infections are difficult to cure with antibiotics alone.

Several factors are known to raise the risk of infection after shoulder replacement. Having one or more of these does not mean an infection will occur, but doctors take them into account when planning surgery and follow-up.

• Male sex, largely because of higher skin levels of Cutibacterium acnes on the shoulder
• Younger age at the time of replacement
• Previous surgery on the same shoulder, including earlier replacements or fracture repair
• Revision (redo) shoulder surgery
• Diabetes, particularly when blood sugar is poorly controlled
• Obesity
• Rheumatoid arthritis and other inflammatory conditions, and the medicines used to treat them that suppress the immune system
• Smoking
• Long-term steroid use or other causes of a weakened immune system
• Prolonged wound drainage or a hematoma after surgery
• Malnutrition or anemia
• Infection at another site in the body, including dental infections and skin conditions

Periprosthetic shoulder infection diagnosis

Confirming a periprosthetic shoulder infection can be difficult, especially in chronic cases. There is no single test that is reliable on its own, so doctors combine your history, physical examination, blood tests, imaging, and laboratory analysis of fluid or tissue taken from the joint. Many surgeons use published sets of diagnostic criteria, which assign weight to different findings, to decide whether an infection is likely, possible, or unlikely.

History and examination. Your doctor will ask when the pain began, how the wound healed, whether you have had fevers, and whether you have had recent infections or dental work. The shoulder is examined for warmth, swelling, redness, tenderness, drainage, and range of motion. A sinus tract, which is an open channel from the skin down to the joint, is considered strong evidence of infection when present.

Blood tests. Common tests include the white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). ESR and CRP are markers of inflammation in the body. They are often raised in early, aggressive infections, but they are frequently normal in chronic low-grade infections of the shoulder, so a normal result does not rule infection out.

Imaging. Plain X-rays are usually the first step. They cannot show infection directly, but they may reveal loosening of the implant, bone loss around the components, or other changes that raise suspicion. Ultrasound may be used to look for fluid collections and to guide a needle. CT scans give more detail about bone, and MRI may be used with special techniques to reduce distortion from the metal implant. Nuclear medicine scans are sometimes used but are not considered definitive.

Joint aspiration. In this procedure, a needle is used to draw fluid from the joint, often under ultrasound or X-ray guidance. The fluid is analyzed for its white blood cell count and sent for culture, which means it is placed in conditions that let bacteria grow so they can be identified. In the shoulder, aspiration is sometimes unsuccessful because there is little fluid to remove, and cultures may be negative even when infection is present.

Tissue samples and prolonged cultures. Because Cutibacterium acnes grows very slowly, laboratories are often asked to keep shoulder cultures for around two weeks rather than the usual few days. During surgery, surgeons typically take several separate tissue samples from different areas around the implant. Finding the same organism in multiple samples supports the diagnosis, while a single positive sample may represent contamination and is interpreted with caution.

Additional laboratory tests. Some centers use newer tests on joint fluid or on the removed implant itself, such as sonication (using sound waves to shake bacteria loose from the implant surface) or molecular tests that detect bacterial genetic material. Availability varies, and results are always interpreted alongside the clinical picture.

Periprosthetic shoulder infection treatment options

Periprosthetic shoulder infection treatment aims to clear the infection, relieve pain, and preserve as much shoulder function as possible. The right approach depends on how long the infection has been present, which bacteria are involved, whether the implant is loose or well fixed, the condition of the bone and soft tissues, and your general health. Treatment is usually planned jointly by an orthopedic surgeon and an infectious disease specialist.

Antibiotics. Antibiotics are part of nearly every treatment plan, but they are rarely enough on their own because of biofilm. They are usually chosen based on culture results and may be given through a vein at first, then by mouth, often for several weeks or months. In some people who cannot safely have surgery, long-term suppressive antibiotics may be used to control symptoms rather than cure the infection.

Debridement with implant retention. For early infections in which the implant is well fixed and the bacteria are considered treatable, surgeons may perform a thorough surgical cleaning of the joint, remove infected tissue, and exchange the removable plastic or modular parts while leaving the main implant in place. This is followed by a course of antibiotics. It is less invasive than full revision but is generally reserved for infections caught early.

One-stage revision. In a one-stage (single-stage) revision, the infected implant is removed, the joint is cleaned, and a new prosthesis is placed during the same operation. This may be considered when the bacteria are known before surgery, the soft tissues are healthy, and the person is otherwise well.

Two-stage revision. This is often regarded as the standard approach for chronic infection. In the first operation, the implant is removed, the joint is cleaned, and a temporary antibiotic spacer, a block of bone cement mixed with antibiotics, is placed in the joint. Antibiotics are then given for several weeks. Once blood tests and examination suggest the infection has cleared, a second operation is performed to place a new permanent implant. The time between stages can be many weeks, and some people have limited use of the arm during this period.

Resection arthroplasty. In some cases, particularly when bone loss is severe, infections keep returning, or health problems make further surgery risky, the implant is removed and not replaced. Pain is often reduced, but the shoulder is usually weak and has limited motion afterward.

Rehabilitation. Physical therapy is an important part of recovery after any of these treatments. The program is adjusted to protect healing tissues and the new implant, and progress is often slower than after a first-time shoulder replacement. A realistic goal for many people is a comfortable shoulder that allows daily activities, rather than full strength or overhead motion.

Living with periprosthetic shoulder infection and outlook

Being told that a shoulder replacement is infected can be discouraging, especially after going through surgery to relieve pain in the first place. Treatment usually involves more than one operation, weeks of antibiotics, and a lengthy period of restricted activity. Many people find it helpful to understand the plan in stages and to ask their care team what they can expect at each step.

The outlook varies. In many cases, infection can be controlled and a functioning shoulder can be restored, particularly when the infection is recognized and treated promptly. However, the shoulder after revision for infection often does not move or feel as well as an uncomplicated replacement, and some stiffness or weakness may remain. A small proportion of infections return, and some people need further surgery. Slow-growing infections caused by Cutibacterium acnes tend to be less destructive than more aggressive bacteria, but they can be persistent.

During treatment, good general health supports recovery. This may include managing blood sugar carefully if you have diabetes, stopping smoking, eating well, and taking antibiotics exactly as prescribed. Long-term, your doctors may recommend prompt attention to any infections elsewhere in the body and may discuss whether preventive antibiotics are appropriate before certain dental or medical procedures. Regular follow-up visits allow your team to check the wound, the implant, and blood markers over time.

Frequently asked questions

What are the first signs of periprosthetic shoulder infection?

The first signs depend on the type of infection. Early infections often cause redness, warmth, swelling, wound drainage, and sometimes fever within weeks of surgery. Chronic infections are more subtle and may show up only as shoulder pain and stiffness that fail to improve, or that return after an initially good recovery. Any of these changes should be assessed by a doctor.

How is periprosthetic shoulder infection diagnosed if blood tests are normal?

Normal ESR and CRP do not rule out infection in the shoulder, because slow-growing bacteria often cause little inflammation in the blood. Doctors rely on the overall picture, including symptoms, X-ray findings such as loosening, joint aspiration when possible, and multiple tissue cultures held for an extended period. Sometimes the diagnosis is only confirmed by cultures taken during revision surgery.

Can periprosthetic shoulder infection be treated with antibiotics alone?

Antibiotics alone rarely cure an established periprosthetic shoulder infection, because bacteria protected by biofilm on the implant are difficult to reach. Surgery to clean the joint and often to remove or exchange the implant is usually needed. Long-term antibiotics without surgery may be used in selected people to control symptoms when surgery is not a safe option.

What causes periprosthetic shoulder infection years after surgery?

Late infections are often caused by bacteria that entered at the time of surgery but grew very slowly, such as Cutibacterium acnes from the skin. They can also result from bacteria traveling through the bloodstream from another infection, such as a dental abscess or urinary infection, and settling on the implant. Your doctors may try to identify the source as part of your care.

Will I need my shoulder replacement removed?

Not always. If the infection is caught early and the implant is stable, surgeons may clean the joint and keep the main components. In chronic infections or when the implant is loose, removal is usually recommended, either with immediate replacement or in two stages using a temporary antibiotic spacer. The decision is individualized and depends on your bone quality, the bacteria involved, and your overall health.

How long does periprosthetic shoulder infection treatment take?

Treatment commonly takes months rather than weeks. A two-stage revision, for example, involves an operation to remove the implant, a period of antibiotics that often lasts several weeks, a waiting period to confirm the infection has settled, a second operation, and then rehabilitation. Your care team can give you a more specific timeline based on your situation.

Can periprosthetic shoulder infection come back after treatment?

Yes, recurrence is possible even after appropriate treatment, and this is one reason follow-up continues for a long time. Signs of recurrence are similar to the original infection, particularly new or worsening pain, stiffness, swelling, or drainage. Reporting these promptly gives the best chance of managing a returning infection early.

When to see a doctor

Anyone with a shoulder replacement should be aware of the warning signs of infection and report new or unusual symptoms to their surgical team, even long after the operation. Early evaluation gives the best chance of a simpler treatment. Seek medical attention promptly if you notice any of the following:

• Fever, chills, or night sweats, especially combined with shoulder symptoms
• Redness, warmth, or swelling spreading around the scar
• Pus, cloudy fluid, or any drainage from the wound, or a wound that reopens
• Shoulder pain that is worsening, that wakes you at night, or that has not improved as expected after surgery
• Sudden loss of motion or a feeling that the implant has shifted or loosened
• Shoulder pain that develops during or shortly after another infection, such as a dental, urinary, or skin infection
• Feeling generally unwell, confused, very weak, or having a rapid heartbeat or breathing, which may indicate that infection is spreading and requires urgent care

If you have a shoulder replacement and are unsure whether a symptom is important, it is generally safer to have it checked than to wait.