A 75 year old female with a history of rheumatoid arthritis (on methylprednisolone and methotrexate) presents to the emergency department due to bilateral wrist swelling. She states that she has been having bilateral wrist swelling, right greater than left, with associated pain for the past 3 months but getting worse over the past week.
She has seen a rheumatologist and oral steroids, methotrexate, and received steroid injections in both wrists within the past 2 weeks without alleviation of her pain. She states that she is unable to flex and extend at the wrist due to pain. An MRI, completed 1 week prior, showed synovitis.
She denies fever, chills, forearm swelling, bug bites, recent travel, prior clots, rash, pruritus, lacerations, trauma, numbness, paresthesias, tingling.
Vitals: BP 169/93, T 36.6, HR 67, SPO2 99%
General: comfortable, alert, pleasant
Skin: No rashes, abrasions, lesions, or erythema. Well perfused.
CV: regular rate and rhythm, no murmur, normal peripheral perfusion, no lower extremity edema
Pulm: clear to auscultation bilaterally
GI: Soft abdomen, diffusely tender to palpation
MSK: bilateral wrist swelling with right more than left, decreased ability to flex and extend at right wrist due to pain
Neuro: alert and oriented x 3
Labs – Chem-8 and CBC WNL; ESR 63; CRP 4.1
Blood Cx – negative
ED wrist arthrocentesis – dry tap
Orthopedics and Rheumatology consulted in ED.
IR guided arthrocentesis – orange turbid synovial fluid; WBC 149800 (85% neutrophils); RBC 61000
Synovial Cx – No WBC growth, rare WBC
The patient underwent incision and drainage with whirpool therapy by orthopedics for fluid collection drainage and was started on vancomycin and ceftriaxone. All fluid analysis was negative for WBC or bacterial growth. Patient continued on ciprofloxacin and doxycycline for 3 weeks for possible septic arthritis.
Take Away #1:
How to Perform Wrist Arthrocentesis
Palpate Lister’s tubercle (dorsal head of distal radius)
Find the anatomic snuffbox and locate the extensor pollicis longus (EPL)
Sterile field, apply a wheal of lidocaine lateral to EPL and above Lister’s tubercle and direct a 22-gauge needle in this direction and pull back
EMRAP Wrist Arthrocentesis:
Take Away #2:
How to Analyze Synovial Fluid
Normal: clear, WBC <200, PMN <25%, negative gram stain, negative cx, negative crystals
Non-inflammatory: clear/straw, WBC <3000
Infectious: Pus/mixed, WBC >50000, PMN >75%, pos gram stain
Inflammatory: yellow, WBC >3000, PMN >50%, neg gram stain, +/- crystals
Remember, these are guidelines. Although WBC counts were found to be 90% sensitive for septic arthritis, gram staining is only 50% sensitive and may be negative. Gonococcal arthritis, for example, may present with a lower WBC count and negative gram stain.
Take Away #3:
Maintain a low threshold for antibiotic treatment for those with pre-existing joint disease. It isn’t uncommon for patients with RA or other joint pathologies to be on immunosuppressant agents (i.e. methotrexate) or have steroid injections for pain relief. These are all risk factors for developing an infection. Even if initial gram stain is negative, give antibiotic coverage for those clinically concerning for infection.
Shirtliff, Mark E. and Jon T. Mader. Acute Septic Arthritis. American Society for Microbiology, 2002. https://cmr.asm.org/content/15/4/527/article-info
Edited by Bassam Zahid