9: Musculoskeletal

Methylene Blue Injection/Open Joint Evaluation

INDICATIONS

When there is clinical suspicion of communication between a traumatic wound and joint space

When intra-articular air within the joint space is seen on radiographs

CONTRAINDICATIONS

Evidence of overlying cellulitis on the site of arthrocentesis

Patients taking serotonergic psychiatric drugs (risk of serotonin syndrome) and those having glucose-6-phosphate dehydrogenase deficiency (risk of anemia and methemoglobinemia) (FIGURE 49.1)

RISKS/CONSENT ISSUES

Risk of iatrogenic septic arthritis

Risk of iatrogenic hemarthrosis

Allergic reaction to local anesthetic

Pain during and after procedure

LANDMARKS

In most cases approach is via the extensor surface of joints (avoids vessels and nerves)

Specific landmarks should be utilized depending on the joint

If available, ultrasound can be used to facilitate arthrocentesis

TECHNIQUE

Prepare the Methylene Blue Injection

Methylene blue usually comes in 1-mL ampoules. There are no exact dilutional guidelines; we recommend diluting 1 mL of methylene blue with 29 mL normal saline in a 30-mL syringe.

Attach an 18- or 20-gauge needle to the syringe

Prepare the Joint Before Injection

Prepare the skin using either a povidone–iodine solution or a chlorhexidine solution and a large sterile drape

Using a small-gauge needle, deposit a small wheal of either 1% or 2% lidocaine for local anesthesia

Inject the Joint

Enter the joint space using standard arthrocentesis technique

Inject the methylene blue solution into the affected joint space until the joint is fully distended or methylene blue exudes from the wound

The amount of solution necessary to fully distend the joint is mostly dependent on the joint in question

The shoulder can hold ∼30 mL and the knee can hold approximately 60 mL

Studies support injecting up to the maximum tolerated volume of the joint or until fluid begins to extravasate through the wound

A positive test is considered if any extravasation of fluid is seen from the wound

FIGURE 49.1 Arthrocentesis with injection of methylene blue dilution to assess traumatic arthrotomy in a patient with a deep laceration over the elbow. (Courtesy of Felipe Teran, MD.)

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