What's the Diagnosis #8


A 3 year old child is carried into the emergency department because of pain in her left hip. Her mother stated that she woke up with the pain and has refused to walk all day because of the pain. The patient has been running a low grade fever and “just wasn’t acting right.”

The mother brought the child to the pediatrician earlier in the day. The pediatrician diagnosed the patient with “double ear infections” and prescribed the child that powerful pink healing elixir otherwise known as amoxicillin. When the mother asked the pediatrician why the child’s hip was hurting, the pediatrician stated that the child “probably slept on it wrong.” The mother stated that the pediatrician never even examined the child’s leg.

The child didn’t seem like she was getting better, so the mother brought her to the emergency department for another exam.

When I examined the leg, the child held her hip in flexion and cried with any movement of the hip joint. Distal sensory, motor, and circulatory exams were intact to the extent that the patient would allow an exam to be done. There was no appreciable swelling over the joints. She wouldn’t even try to walk. Oh, and her otoscopic exam was within normal limits.

I decided to do a few labs. Her WBC was 13,000 with 91% segs. The sedimentation rate was 120.

What’s the diagnosis, how is the diagnosis made, and what’s the treatment?






Final Diagnosis: Septic arthritis of the hip.
Culture showed staph aureus, which is the responsible organism in about half of all cases.
Nice summary of septic hip in pediatric patients is at Wheeless’ Online Orthopaedics
Kocher criteria include non-weight bearing on the affected side, sedimentation rate > 40, fever, and WBC count > 12,000. When all four criteria are present, septic arthritis has a 99% likelihood. When three criteria are present, the likelihood of septic arthritis is still 93%.
Diagnosis requires joint aspiration under either ultrasound or fluoroscopy.
Treatment requires surgical drainage and antibiotics. Preliminary treatment is usually a third generation cephalosporin – pending culture results.  Keep in mind that MRSA is a growing problem (no pun intended) and that IV vancomycin may be necessary. Also keep in mind that sickle cell patients are prone to salmonella infections in bone and joints.
Unfortunately, septic arthritis may lead to many long-term hip problems such as dysplasia, deformities in hip development, and postinfectious arthritis – even with appropriate care.

As an aside, I was completely blown away by the number of thoughtful responses and differential diagnoses for this case. I intended it to be just a relatively straightforward case to jog the memories of the attendings and to teach the young grasshoppers. You guys came up with several things that even I hadn’t considered.
I’ll have to post these cases more often.
Thanks for the education!


  1. Lord save me from the double ear infection! And the “my baby has had three ear infections this month”! And, of course, a three year old can benefit from “delayed antibiotics”!

    Image results of the hip? And my that, I mean a plain film and ultrasound. Could be the classic transient synovitis or septic joint. But, I’ve seen more than one fracture (often from NAT) present the same way.

    • Totally agree. Ultrasound it and get ortho involved. I’m surprised the pediatrician dismissed it. Joint pain in these younger kids should always be taken pretty seriously, as should back pain. It could still be a post viral toxic synovitis, but you have to prove that. The irritating part is that being on amox might interfere with the culture results. She will need to be admitted for IV antibiotics.

  2. Madrocketscientist on

    Staph infection? (I recall similar symptoms in the child of a friend years back and the boy had a staph infection in his hip)

  3. Septic – hip aspiration – Abx and OR for washout.

    I had a tough one last shift – still waiting on the final dx. 3 YO c early morning limp X 2months – resolves after 30 minutes or so – not much pain. Referred in by PCP because a week ago the WBC was 22k – so rule out septic hip. On exam child totally normal. WBC 16k, CRP < 0.4, ESR 70, nl US/xrays. Differential? I'm thinking possibly JRA or another sponyloarthropathy

  4. I’m a medstudent so I don’t really know jack shit but could it be appendicitis? The way you describe the hip joint movement sounds like a positive obturator sign to me

  5. Good thought, Shah – would definitely want to throw in an abdo exam. Having said that, if things had progressed far enough to get a positive obturator sign, I would think the primary complaint would be abdo pain consistent with signs of peritonitis as opposed to hip pain with the inability to bear weight.

    Definitely imaging and a tap – with a white count and a fever I wouldn’t hesitate starting some empiric therapy considering the risk of sepsis.


  6. Did the orthopedist want to make the diagnosis of toxic synovitis over the phone or did he/she come in and help rule out septic joint?

  7. These kind of stories always interest me. It would be nice to know the pediatrician’s story. It’s possible that the pediatrician just completely ignored the mother’s chief complaint of hip pain in her child, but there is also a very high chance that hip pain wasn’t the chief complaint or even a secondary complaint but was actually just an ‘oh by the way’ on the way out of the door complaint. We all know that those are sometimes the actual reasons fot the visit but it can be very hard to turn around and essentially begin the visit after having just finished it. Of course another possibility is that the hip wasn’t mentioned at all because I’ve had that happen as well.
    Anyway, as everyone else has already said, you have to r/o septic hip though decent chance it is transient synovitis.

  8. Septic joint. Diagnose (and drain) with tap, best under ultrasound. First step in treatment is drainage, serially if necessary, along with IV abx. (written before reading current comments)

  9. The comments seem on the money. I agree that septic arthritis is a worry, so is osteomyelitis. Fracture + ear infection is a possibility, too. The patient is a bit young for Perthes disease, but if there is an infection elsewhere to account for fever and malaise then one must consider other diagnoses. More of an exam and imaging may help sort it out. You will need to check the spine, hip, entire lower extremity (and abdomen as noted above). It’s not alway really safe to accept a patient’s (or parents) version of another doctor’s opinion or evaluation, and increasing numbers of patients seem to arrive subacutely with significant problems that one would think would have presented more acutely.

    Steve Zeitzew, Orthopaedic Surgery

  10. William the Coroner on

    I’ll go for the total Zebra–Lemierre’s Syndrome. Supperative jugular pharyngitis that can also cause joint pain–from a fusobacterium. As there are only…136 cases reported, it probably ain’t it.

  11. Rule-out septic hip would be my number one – particulary with that impressive ESR.

    @William the Coroner. I looked after a guy with Lemierre’s Syndrome when I was an intensive care resident in 2004. Sickest guy I have ever seen.

    • William the Coroner on

      Mine wasn’t any more sick than any of my other patients. Though that’s not saying much, she was a 14 year old.

  12. I would certainly think about a tap and fluid aspirate for analysis, but might want to think about Reiter’s Syndrome (reactive arthritis). Any recent GI symptoms?

    Also, not sure where you are, but with ticks coming out here in new england, I’d think about Lyme too.

  13. Assuming you hid a big pertinent positive – Henoch-Schonlein purpura. I’ve seen unilateral joint pain, mild purpura and the disorder can occur post strep. Of course, that would assume you hid something from us (and I doubt you did), so I’ll agree with the above – likely toxic synovitis but you have to rule out the toxic joint.

  14. Kind of another possibility, rheumatic fever? I know she only has pain in one joint, but the elevated sed rate, CRP, WBC, and joint pain could point to that. Guess would have to see if they have a rash or a prolonged PR on ECG, but it could be. By the way, not a doctor, but an ER tech about to start PA school.

  15. Just to throw out another option, (I’m with Steve)…what about Legg-Calve-Perthes Disease? Sed rate can be elevated if the infection is present. It should at least be in the DDX.

  16. Hmm, a haunting silence from Matt and other

    Guess they are better at using the retroscpectoscope (sp?) when the final results are known…

  17. Vamsi Balakrishnan on

    @Sarah G: “Silly question from an antibiotic n00b: what effect should the amoxicillin have had on the infection? If it isn’t the right drug, what would be?”

    The amoxicillin would possibly treat the ear infection (first line treatment; if the bacteria are resistant, then use amoxicillin-clavulonate). The problem is, as I viewed it, I think the infection is secondary to the possible osteomyelitis (infection of the bone). http://goo.gl/iL0L (link to an explanation I buzzed).

    You’d probably want to do a tap + culture to see what bacteria…and what resistances are there. I’m not positive, but…that’s what my limited knowledge would tell me to do. :-/

  18. Yeap, a septic hip. My nephew just had this. He got taken to emerg after complaining of hip pain for a few days that led to immobility. He went to the OR for washing, and antibx of course. Luckily all better now. 🙂

  19. Septic arthritis immediately jumped to my mind — it’s unfortunate that the pediatrician disregarded the mother and neglected a thorough physical exam!

    Septic arthritis
    Toxic synovitis
    RA (JRA)


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