Intern Report 6.3

 

Case Presentation by Dr. Heather Bowman

CC: “My legs and knees are swelling”

HPI: CG is a 93-year-old female with history of arthritis who comes to the to the emergency department stating that she is having leg and knee swelling.  She’s been unable to walk since last night.  She is unable to describe the quality or severity of the pain but she says “they’re killing her really bad”.  She says she’s had this before and they had put a needle in her knee last time.  Nothing makes the pain and swelling better or worse.  No trauma, fever or nausea or vomiting.

ROS: Negative except as per HPI

PMH:Patient is a poor historian and is only able to say she has had Shingles, review of EMR shows patient has arthritis and A. fib., CAD status post stent, hypertension, CHF, stroke, diverticulitis and breast cancer

PSH:Patient denies, per EMR had coronary catheter and stent placement 2007

MEDICATIONS: Patient is unsure.  Per EMS has pantoprazole, Klor-Con, acetaminophen, aspirin furosemide, & ranitidine

ALLERGIES:Penicillin

SOCIAL HISTORY: Patient lives in a senior citizen home.  Reports has lots of support from her neighbors and her granddaughter

Physical Exam:

Vitals: Blood pressure was 155/86, pulse 90, respirations 16, febrile 38.2, satting 100% on room air

General: No Acute Distress, lying comfortably on stretcher

HEENT: PERRL, EOMI, very hard of hearing, mucous membranes dry

Cardiovascular: +S1, S2, no murmers, Radial and DP pulses symmetric

Respiratory: Clear to auscultation bilaterally

Gastrointestinal:  NT/ND

Musculoskeletal: Strength 4/5 in upper extremities and right leg, strength 4/5 left leg limited due to pain, effusion over both knees left greater than right, right knee has good range of motion, not warm or indurated. Left knee is warm not indurated, left knee range of motion limited at 45° due to pain

Skin: Intact

Neurologic:  patient can’t ambulate due to pain.

Labs/Radiograph

Electrolytes: Na=140, K=3.8, Cl=103, HCO3=27, BUN=20, Createnine=0.9, Glucose=101, Ca=9.3, Mg=2.1

CBC: WBC=8.5, Hgb=10.4, Platelets=182

Others: CRP=75.30, ESR=53

UA: 2-5 squamous cells, Specific gravity=1.015, blood=2+, protein=1+, Nitraes: positive, Leukocyte esterase 2+, RBC=5-10, WBC=20-50, bacteria=4+, trichomonas=neg

Cell count and differential, gram stain and bacterial culture, and the answer to question#3: pending

Complete R knee:

1.  Generalized osteopenia without identification of an acutely displaced fracture.

2.  Development of a moderate joint effusion.

3.  Severe osteoarthritis of the right knee

Complete L knee:

1.  Generalized osteopenia without identification of an acutely displaced fracture.

2.  Moderate to large joint effusion and soft tissue swelling.

3.  Advanced osteoarthritis of the left knee with findings suggesting loose intraarticular bodies.

Questions:

1. Which of the following is an absolute contraindication to arthrocentesis?

A. Infection of soft tissues over joint

B. Prosthetic joints

C. Confirmed Bacteremia

D. Hereditary bleeding diatheses

E. Patient on oral anticoagulants

 

2. Which is the correct pairing of organism and at risk population for septic arthritis?

A. N. Gonorrhoeae is the most common cause of septic arthritis for teens and patients >65yo.

B. Staph, strep, H. Influenzae, and E. coli are the most common cause of septic arthritis for kids

C. Salmonella is the most common cause of septic arthritis in patients with sickle cell

D. Staph aureus, Strep epidermidis, enterobacteriaceae and pseudomonus are most common causes in patient with a prosthetic joint

E. Gonococcal septic arthritis is more common in young males

 

3.  Besides cell count with differential, gram stain and bacterial culture and sensitivity, which other test is high yield for working up most joint effusions?  

A. Uric acid

B. Synovial protein

C. Crystal analysis

D.Synovial glucose

E. Lactate dehydrogenase

F. Rheumatoid factor

 

Answers:

1)    A

2)    D

3)    C

Discussion

1. Which of the following is an absolute contraindication to arthrocentesis?

A. Infection of soft tissues over joint-YES, arthrocentesis is absolutely contraindicated if infection of soft tissues over the joint is present.  However, remember joint may be warm, swollen and tender with acute arthritis and it is appropriate to perform arthrocentesis once you have eliminated cellulitis as the cause of this finding.

 B. Prosthetic joints-NO, while prosthetic joints are high risk for infection and you should avoid arthrocentesis if possible, if you suspect an infected prosthesis, you should perform an arthrocentesis.

C. Confirmed Bacteremia-NO, confirmed bacteremia is considered a relative contraindication because infection can spread to the joint, but it is not an absolute contraindication.

D. Hereditary bleeding diatheses -NO, hereditary bleeding tendency is also a relative contraindication.  However it is acceptable to do arthrocentesis to relieve a tense hemarthrosis in bleeding disorder such as hemophilia after infuse appropriate clotting factors

E. Patient on oral anticoagulants-NO, There is little data regarding arthrocentesis of patients on oral anticoagulants, however studies have demonstrated risk iatrogenic hemarthrosis is quite low, even with INR as high as 4.5.  Therefore when necessary is appropriate to perform arthrocentesis in patient on oral anticoagulants.

  

2. Which is the correct pairing of organism and at risk population for septic arthritis?

A. N. Gonorrhoeae is the most common cause of septic arthritis for teens and patients >65yo.  NO, While N. Gonorrhoeae is the most common cause of septic arthritis for teens and young adults, staphylococcus is more likely once a patient is >40yo.

B. Staph, strep, H. Influenzae, and E. coli are the most common cause of septic arthritis for kids.  NO, Staph, strep and E. coli are true but the incidence of H. flu has decreased to almost zero since the vaccine was developed.

C. Salmonella is the most common cause of septic arthritis in patients with sickle cell-NO, while salmonella is more prevalent in patients with sickle cell compared to the general population, the more common causes still predominate.

D. Staph aureus, Strep epidermidis, enterobacteriaceae and pseudomonus are most common causes in patient with a prosthetic joint-YES, true

E. Gonococcal septic arthritis is more common in young males-NO, while gonorrhea is more common in males, disseminated gonococcal infection is actually more common in women (4:1 prevalence), especially during pregnancy or after menstruation when the alkaline vaginal environment makes the organisms more resistant to the host defenses in the bloodstream and therefore more likely to disseminated and because infected women more likely to be asymptomatic.

3. Besides cell count with differential, gram stain & bacterial culture and sensitivity, which other test is high yield for working up most joint effusions?  

A. Uric acid-NO, Uric acid is not helpful for diagnosing acute gouty arthritis because it actually can normalize during acute phase

B. Synovial protein-NO, Synovial protein is unreliable in distinguishing inflammatory and infectious from noninfectious and therefore is no longer recommended.  Synovial protein had a sensitivity of 0.52 in one study, and ordering it is discouraged because it is likely to provide misleading or redundant information.

C. Crystal analysis-YES, Of the answers listed, crystal analysis is the best.  Remember to use a green top (liquid sodium heparin) to prevent clotting.  Calcium oxalate and lithium heparin anticoagulatns can introduce artificial crystals into the fluid.  Under a polarizing microscope, calcium pyrophosphate (gout) is a positively birefringent crystal (long axis is blue when parallel to the Z-axis and yellow when perpendicular to it).  Calcium pyrophosphate crystals are smaller than 10 micrometers and can be rods, rhomboids, plates or needle like.  Monosodium urate (pseudogout) is a negatively birefringent crystal (long axis is yellow when parallel to Z-axis and blue when perpendicular).  Urate crystals are needle shaped, and between 2-10 micrometers.   You can also see cholesterol crystals which are large, very bright, square or rectangular with broken corners.  As always, use the entire clinical picture and your clinical judgment when ruling out septic arthritis.  Patients with underlying joint disease are more likely to develop a septic arthritis and finding crystals does not eliminate an infectious cause.

 pict 6.3 

D.Synovial glucose, -NO, Glucose is unreliable in distinguishing inflammatory and infectious from noninfectious and therefore is no longer recommended.  Glucose had a sensitivity of 0.2 in one study, and ordering it is discouraged because it is likely to provide misleading or redundant information.

E. Lactate dehydrogenase-NO, Lactate dehydrogenase is also unreliable in distinguishing inflammatory and infectious from noninfectious and therefore is no longer recommended

F. Rheumatoid factor-NO, Rheumatoid factor is less frequently obtained than crystal analysis and has little diagnostic value in the ED, though it can be useful to the clinician providing follow up care.

Clinical Course and analysis:

We elected to drain the left knee since it had a larger fluid collection, was warm, and was limiting her range of motion.  Approximately 40ccs of fluid were aspirated from GC’s left knee.  Her fluid gram stain showed numerous PMNs but no organisms.  Elevation of PMNs is consistent with an inflammatory or septic arthritis.  Culture was negative x 4 days.  Gram stain or culture of an organism would confirm septic arthritis but lack of an organism does not rule out septic arthritis as organism is not always cultured.  Cell count with differential and fluid crystals were ordered, but never done.  ID saw the patient and thought she had an inflammatory arthritis and recommended continuation of ceftriaxone for UTI with discontinuation of vanco.  The primary team continued ceftriaxone and vanco and their discharge diagnosis was septic arthritis.

WBC, ESR and CRP are sensitive but non-specific screening tests.  ESR is elevated in 90% of septic arthritis and along with CRP can be used to track response to infection, although the admitting team did not re-order these tests.  WBC greater than 10,000 can suggest a systemic illness but is only elevated in 50% of septic arthritis cases and sterile inflammatory processes create a similar leukocytosis.  Her WBC was not elevated throughout her hospital stay.  Cultures from infectious foci can often demonstrate the bacteria responsible for septic arthritis.  Her urine culture did show >100,000 CFU of E. coli and if she did have septic arthritis this is a likely source.

References:

Marx, J. A., R. S. Hockberger, et al. (2010). Rosen’s emergency medicine: concepts and clinical practice, Mosby/Elsevier.

Roberts, J. R. and J. R. Hedges (2009). Clinical Procedures in Emergency Medicine E-Book, Elsevier Health Sciences

3 Responses

  1. 1. A (still not an absolute contraindication, but more so than the other choices)

    – Vit

  2. 1. None of the above. All are relative contraindications. Best answer is probably A, but I think you could still do the tap if the pt is on IV ABX. For B, prosthetic joints should probably be tapped by ortho.

  3. Of interest regarding question 1, after submitting this case, I did a Rosh Review question with the one step further being that overlying cellulitis is a relative contraindication (instead of an absolute one), with a citation from Rosen’s. I was citing Roberts and Hedges, when saying that infection of soft tissues over the joint is an absolute contraindication, but it sounds like this may have not been the best question since two of our field’s great textbooks are saying two different things, so I apologize if anyone takes issue with question 1.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: