Can’t Miss Diagnoses
- Septic Arthritis
- Also, assess overlying soft tissues for infections which can also be very life-threatening (e.g. Necrotizing Fasciitis).
- Open Joint
- Prosthetic Joint Infection
- Rheumatoid arthritis
DDx for Monoarticular Arthritis
O – Osteoarthritis
S – Septic arthritis
T – Tumor in nearby bone / Trauma
R – Rheumatic & autoimmune disease
I – Intra-articular pathology
C – Crystal arthropathy (Gout, pseudogout)
H – Hemarthrosis
More details here!
DDx for Prosthetic Joint Pain:
- DDX for Prosthetic Joint Pain:
- Septic Loosening
- Aseptic Loosening
- Dislocated/damaged polyethylene liner (especially in Unicompartmental Knee Replacements)
Points to focus upon
To note and document; Tetanus status, anticoagulation, surgical manipulation if any
If Joint Pain & Fever, must suspect septic joint, especially if a patient has no history of similar pain OR has any of the following risk factors:
– recent intravenous drug use
– Diabetes Mellitus
Check for White count, CRP, Joint aspiration
Polyarticular arthritis is usually suggestive of a more systemic problem. Consider a sexual history in these patients or in any young patients with joint pain. Before you go hog-wild on tests, chat with your rheumatology colleague and/or consult this resource.
Prosthetic Joints- all joints should be aspirated with sterile technique. However, this is especially applicable to prosthetic joints. If there is an orthopaedic doctor on call, it is worth discussing with them prior to doing an aspiration. If an aspiration of a prosthetic joint is going to be done, a full drape, sterile setup, and sterile technique must be followed. When calling the orthopaedic surgeon, ideally know the date of original surgery, surgeon, and onset of symptoms. This most applicable for knees. Hips should be done under image guidance.
Clinical Decision Tools
- Ottawa Ankle (and foot) Rule – can be used in adults (100% sensitive) and in children over 12 (98.5% sensitive)
- Ottawa Knee Rule
- Acute Gout Diagnosis Rule
- CBC, BUN, Cr, Lytes, Glucose, VBG,
- C-reactive protein (CRP), ESR (if available at your lab)
- Consider joint aspiration
- Consider weight-bearing X-rays for lower extremity.
- REMEMBER: All x-rays need 2 at least 2 views, for knee joint pain include a sunrise or patellar view.
Septic arthritis will require surgical wash-out. Involve your consultants early if this is a suspicion. Also, don’t be a hero if you are not confident with your aspiration technique. Remember, during COVID-19 many hospitals have shut down their operating rooms and your orthopedics colleagues may be available to help – especially if you are redeployed to the ED. NEVER ASPIRATE THROUGH A CELLULITIS, FIND CLEAN TISSUE AND AVOID MAJOR VESSELS/NERVES.
Joint aspiration – Medscape Article
First 10:EM – Joint Aspiration Video
Recommended reading, videos, and podcasts
- CanadiEM knee exam post
- Orthobullets -Septic Arthritis – Adult
- Orthobullets – Gout
- Orthobullets – OsteoArthritis
- Prosthetic Joint Infections
- Review of Dermatomes
- Lower Limb Sensory & Motor Examination
Would you like to read more MSK topics? Read about common fractures, or extremity soft tissue pathologies.
This is part of the CanadiEM Frontline Primer. An introduction to the primer can be found here. To return to the Primer content overview click here.
This post was copyedited and uploaded by Evan Formosa.