Dear Dr Shahi,

You can find a new marker in the paper with the link below:

http://www.sciencedirect.com/science/article/pii/S0009898114005348

The diagnosis of PJI is complex. One should take in consideration complaints, clinical and imaging signs, lab test, puncture with aspiration, etc. I believe blood analysis with CRP and ESR has not loss its importance.  

CRP and Gram stain of the joint aspirate

Alpha Defensis Test gives you a reliable prediction when no metallosis i observed.

beyond doubt it is CRP in blood test

and result on aseptic joint aspirate

ALpha Defensin: Test called Synnovasure, easy to use, but not available everywhere!Good papers out from Parvizi and his group as well as Deirmengian!

We have had good results in detecting the causative organisms by subculturing a portion of the sample to a blood culture bottle containing antibiotic neutralizing resins and incubating for 10 days.  We have isolated MRSA and Candida sp. by this method that never grew on solid media.

Defensin in the joint aspirate is very accurate. But I do not know wheather it is comercially available already (should be)

100% sensitive and specific marker (but very late) is reflection sign.

Alpha defensin.

http://synovasure.zimmer.com/

if you don't have anything more specific, I think procacitonin (PCT) may be more acurate for infection diagnosis than CRP, which is mainly an inespecific inflammation biomarker

Perhaps Luis but PCT is not possible everywhere;

if CRP is over 100 we must have a intraarticular puncture

CRP in combination with a joint puncture only if there are clinical or x-ray symptoms.

Joint fluid - Gram stain, NPL count has to be the most accurate for diagnosis of PJI, no?  whether you do other things with the joint fluid is another question.

Joint fluid must be undergo an antibiogram (resistancy tests). Patient must not take antibiotics otherwise there is not growth of bacteria. NPL-count is is mostly false-negative.

In joint fluid we can perform Lactate, LDH, CRP and Gram stain

Fernando: If you can perform all those laboratory parameters as well, than with a bacterial culture as well you have killed two birds with one stone. So thats a good idea, in case the patient had already administered antibiotics.

I think this question is overdiscussed. In my opinion the best "biomarker" is the experienced surgeon who in the given case comes to the suspicion of periprosthetic infection.

Early PJI have sign and symptoms like other site infections. But i agree with Dr Tanchev that in late onset infections and microorganisms with low pathogenesis clinical suspicion in patient with sustained pain is better

Diagnosis has always been a challenge in the PJI. Until now, there has been no golden standard for the diagnosis of PJI, but based on the PJI definition (for example, the definitions of European Bone and Joint Infection Society, Musculoskeletal Infection Society, Infectious Diseases Society of America), combined with preoperative and intraoperative diagnostic methods, infection can be confirmed or ruled-out in most cases.

CRP undoubtedly

C-reactive protein may misdiagnose prosthetic joint infections, especially in chronic and low-grade infection cases.