-
Indications for arthrocentesis
- Diagnostic: Septic arthritis, Hemarthrosis/Traumatic effusion, Crystal-induced arthropathy (Gout, Pseudogout), Unexplained joint effusion or mono-arthritis
- Therapeutic: provide pain/discomfort relief due to a tense effusion
- Therapeutic: administer a pharmacologic agent, Steroid injections, Viscosupplementation
-
Contraindications to intra-articular injection
- Cellulitis overlying the proposed site for the injection
- Adjacent osteomyelitis
- Known or relative bacteremia (although if septic arthritis is suspected, this should not prohibit aspiration for diagnosis)
- Prosthetic joint – if effusion is in a replaced joint, consult the orthopaedic surgeon –or—impending joint replacement surgery (planned procedure w/in days)
- Osteochondral fracture
- Poorly controlled diabetes
- *** Do not inject any therapeutic agent into a joint found to have a hemarthrosis (aspiration is appropriate)
- Relative contraindication: known coagulopathy or anti-coagulated state
-
Normal Synovial Fluid Findings
- Appearance: clear yellow, amber
- Viscosity: high
- Special Findings: none
-
Traumatic Synovial Fluid Findings
- Appearance: straw to red
- Viscosity: high
- Special Findings: blood may be ++
-
OA Synovial Fluid Findings
- Appearance: clear yellow
- Viscosity: high
- Special Findings: cartilage fragments
-
Gout Synovial Fluid Findings
- Appearance: cloudy
- Viscosity: decreased
- Special Findings: monosodium urate crystals (needle-like shape)
-
RA Synovial Fluid Findings
- Appearance: greenish, cloudy
- Viscosity: low
- Special Findings: latex RA, hemaglutination titer, or sheep-cell agglutination test
-
Septic Arthritis Synovial Fluid Findings
- Appearance: turbid to purulent
- Viscosity: low
- Special Findings: positive culture
-
TB Arthritis Synovial Fluid Findings
- Appearance: cloudy
- Viscosity: low
- Special Findings: positive culture for acid-fast bacillus
-
Arthrocentesis Procedure
- 1.Examine the knee joint. You may observe a supra-patellar bulge, the hollows of the knee around the medial & lateral patellar border disappear. Palpate for temperature
- 2.If you determine that aspiration and/or injection is an appropriate intervention. Place the patient in a comfortable position on the exam table with their knee in full extension or slightly flexed to no greater than 15◦(results in a relaxed quadriceps & patellar tendon). Obtain informed consent for the procedure!
- 3.Palpate the bony margin of the patella medially & laterally (you may choose to either side based on your comfort & preference based on the clinical exam)
- 4.Optimal location to enter the joint space is ~1cm medially or laterally from the superior 1/3 of the patellar border (you may mark the site if you prefer)
- 5.Prepare the site. Cleanse the site with antiseptic solution and you may choose to use a sterile drape to isolate the field
- 6.Anesthetize the superficial skin with 1% lidocaine and then proceed to administer ~5-10cc of 1% lidocaine deeper along the trajectory of the arthrocentesis needle
- 7.Identify your bony landmarks again (the medial or lateral patellar border)
- 8.Insert an 18 gauge syringe posterior to the patella (the needle should not come in contact with the bone)
- 9.Constantly pull back on the plunger as you advance the needle until you begin to collect synovial fluid in the syringe
- 10.You may need to remove the 1st syringe from your needle (while leaving the needle in place) & attach a 2nd syringe if the volume of the effusion is large. Use your non-dominant hand to compress the opposite side of the joint if needed
- 11.Once you observe decreased flow of synovial fluid into your syringe and are able to see the hollows of the knee around the medial & lateral patella – gently remove the syringe & arthrocentesis needle. Cleanse the area & place a bandage over the injection site
- 12.Place the used needles in the biohazard receptacles’ for sharps
- 13.You should note the appearance of the fluid in your office visit notes & on any lab request form
- 14.Depending on the suspected diagnosis – you will fill an: EDTA tube (purple top) – for cell count & differential, Sodium/heparin tube (green top) – for crystal examination, Leaving at least 5cc for culture & gram stain (usually placed in a red top tube)
-
Injection
- If you are planning to inject a therapeutic agent following the arthrocentesis – follow the same steps #1-9 above & then
- 10. While the needle remains in place (you can use a hemostat on the hub of the needle to stabilize it but DO NOT touch the needle tip against joint surfaces when you remove the syringe) attach a syringe filled with corticosteroid and gently empty into the joint space
- - Proceed with steps #11-14 from above
-
Therapeutic choices:
- Corticosteroids: Celestone, 6mg/mL – use 1 mL mixed with 3-5mL of 1% lidocaine. Depo-medrol 40mg/mL – use 1 mL mixed with 3-5mL of 1% lidocaine.
- Viscosupplementation: Hyalgan, Orthovisc, and Synvisc
- Generally not a primary care procedure – performed in orthopeadic & rheumatology practices
-
Potential Complications:
- Iatrogenic infection
- Local trauma
- Pain
- Reaccumulation of effusion
|
|
