The PJI medical abbreviation stands for periprosthetic joint infection, meaning an infection in the tissue and space around an artificial joint such as a hip or knee replacement. Some notes expand it as prosthetic joint infection; both names describe the same problem.
PJI is not common, but it is one of the more serious complications after joint replacement surgery, so orthopedic surgeons, infectious disease teams and wound care nurses write it often. You may see it next to TKA for total knee replacement or THA for total hip replacement. Here you will find the meaning, the tests and surgeries named alongside it, and a worked chart example.
At a glance
Stands for
Periprosthetic joint infection (also prosthetic joint infection)Specialty
Orthopedics, infectious diseaseWhere you see it
Post surgery notes, consult notes, operative reports, discharge summariesWord roots
Peri means around; prosthetic means artificial partCommon joints
Knee and hip, also shoulder and elbowDo not confuse with
Septic arthritis of a natural joint, or a superficial wound infection
Breaking down periprosthetic joint infection
Each word carries part of the meaning. Peri is a prefix for around, prosthetic refers to the artificial implant, and joint infection says where the germs are. Put together, PJI means bacteria, or less often fungi, have settled on or around the metal and plastic parts of a replaced joint.
Germs can stick to an implant surface and form a thin, protective layer called a biofilm. Biofilm shields bacteria from antibiotics and the immune system, which is the main reason PJI often needs surgery and not antibiotics alone. Staphylococcus species are among the germs most often found.
Early, delayed and late PJI
Surgeons often describe PJI by when it starts after the operation, because timing hints at how the infection began and which treatment may work.
| Label | Rough timing | What it often suggests |
|---|---|---|
| Early | Within the first few months | Germs entered around the time of surgery |
| Delayed | Several months to about a year or two | A slower, low grade infection, also from the time of surgery |
| Late | Long after surgery | Germs that traveled through the blood from another site, such as skin or teeth |
The exact cutoffs vary between hospitals and published systems, so a chart may use slightly different numbers.
Tests you may see ordered for suspected PJI
No single test proves PJI, so teams combine clues. Blood tests such as CRP and ESR look for inflammation. A joint aspiration, where fluid is drawn from the joint with a needle, is a key step: the lab counts white blood cells in the fluid and grows a culture to find the germ. Imaging may be added, and tissue samples taken during surgery are cultured as well.
A sinus tract, which is a small channel draining from the joint to the skin, is treated as strong evidence of PJI on its own.
Reading the PJI medical abbreviation in a note
Orthopedic follow up: "POD 21 s/p L THA, wound erythema and drainage, CRP up, r/o PJI." This reads as postoperative day 21 after a left hip replacement, with redness and drainage at the incision and a rising inflammation marker. The team wants to rule out an infection around the implant.
| Shorthand | Meaning |
|---|---|
| Chronic PJI R TKA | A long standing infection around the right knee replacement |
| staged revision | The implant will be removed and replaced in two operations |
| abx spacer | A temporary block loaded with antibiotics placed between operations |
Lines like these are examples of format, not a plan for any one person.
Treatment words that travel with PJI
Treatment usually pairs surgery with a long course of antibiotics, often abbreviated ABX. Three surgical approaches appear most often in notes:
- DAIR: debridement, antibiotics and implant retention. The joint is washed out and cleaned, and the implant stays in place. It is mostly used for early infections.
- One stage revision: the infected implant is removed and a new one placed in the same operation.
- Two stage revision: the implant comes out, an antibiotic spacer goes in, and a new implant is placed weeks or months later.
An infectious disease specialist often guides the antibiotic plan. A washout may also be charted as I&D. More infection and condition shorthand sits in our conditions and diagnoses section.
Questions for your surgical team
If PJI shows up in your own records or a family member's, these questions can help a visit go further.
- Was the infection confirmed, or is it still being ruled out?
- Which germ grew, and which antibiotic is planned?
- Is the implant staying in, or is a revision being discussed?
- What warning signs at home should prompt a call?
Only the surgical and infection teams caring for a joint can say whether an infection is present and what the plan should be. Use this page to follow the wording in your records, then take questions to them.
Frequently asked questions
What does PJI mean after knee surgery?
After a knee replacement, PJI means periprosthetic joint infection, an infection around the artificial knee parts. Notes may write it as PJI R TKA or PJI L TKA to show which side.
Is PJI the same as a wound infection?
Not exactly. A superficial wound infection affects the skin and tissue near the incision, while PJI reaches the joint space and the implant itself. A doctor may run tests to tell the two apart.
Can PJI happen years after joint replacement?
Yes. Late PJI can develop long after surgery, often when germs travel through the blood from an infection elsewhere in the body. This is one reason surgeons ask about new infections in people with joint replacements.
What is DAIR in a PJI note?
DAIR stands for debridement, antibiotics and implant retention. It means the surgeon cleans out the joint and keeps the implant in place, then antibiotics continue afterward.
What does r/o PJI mean?
It means rule out periprosthetic joint infection. The team suspects an infection might be present and is running tests to confirm or exclude it.