When "Gout" Is Not Gout-Risks for Septic Arthritis

     As many people have heard me state, septic arthritis is an insidious diagnostic quandary. It can skirt many fairly reliable labs, yet have long term, devastating consequences.

Septic arthritis is the stealth bomber of joints. 

     Even worse, like most urgent care work, this feared enemy may only show itself every 3-5 years or so in your patient pool, so complacency can grow on your diagnostic lenses, like moss on a roof. Complacency is even more tempting by the preponderance of gout in our patients and its similar presentation of a hot, red, tender joint.
     The October 2012 released book of Urgent Care Emergencies- Avoiding the Pitfalls and Improving the Outcomes, by Goyal and Mattu, has a nice blurb on warnings that "gout may not be gout." I also attached some real world commentary.

RISK FACTORS ASSOCIATED WITH AN INCREASED LIKELIHOOD OF SEPTIC ARTHRITIS

(in no particular order)

1. PROSTHETIC JOINT
2. AGE >80 YEARS
3. RHEUMATOID ARTHRITIS
4. OVERLYING CELLULITIS
5. HISTORY OF TRAUMA TO AREA OVER THE JOINT
6. IV DRUG USE
7. IMMUNOSUPPRESSION

Real World Commentary Point by Point:
1. People almost always forget to mention surgeries from years ago. If you see an old scar, ask about it! You will be surprised how often you get, "Oh, that's my knee replacement from 8 years ago...."
2. Age brings wisdom but robs the body. Enough said.
3. Note the "perfect storm" of points 3 and 7-just think how many RA patients are on immunomodulators like Humira, Embrel, and the like now. Don't show your age by forgetting or "blowing off" the role of these medicines. Remember, "immunosuppression" is a heck of a lot more nowadays than COPDers on 20mg of daily prednisone! Note also the urgent care pitfall that most people view immunomodulators as pulmonary risks (ie- get the chest x-ray) due to all the publicity and litigation over activated fungal lung infections from these medicines.
4. We all see countless superficial CA-MRSA abscesses. If the entire joint though starts to look red and angry, push for the septic joint work up. Recall that the major pathogen in septic arthritis is Staphylococcus aureus, especially MRSA.
5. Ask and document about the IV drug use if you are even remotely considering septic arthritis. The patient may lie, but you need to show your diligence by asking. (Ask about HIV status also-remember the last provider meeting?)
6. The article mentions that all the tests- CRP, ESR, WBC, are riddled like swiss cheese with holes in sensitivity and specificity. A positive has little predictive value, and a negative has little predictive value. As such, stay aware of the above risk factors.

Lastly, recall that the diagnostic test of choice is joint arthrocentesis with joint fluid analysis. Hence, take advantage of your orthopedic comrades in the same office building, and also do not be afraid to avail yourself of the emergency room, with its needed IV antibiotics and consultations, especially for pediatric cases.