Intra-Articular Methylene Blue Injection 

Open joint injuries are skin and soft tissue injuries that penetrate the joint space. Like open fractures, open joint injuries require timely diagnosis, exploration, and irrigation to minimize long-term morbidity and mortality. The procedure of intra-articular injection of methylene blue (see image below) is an easy and safe way to identify disruption of the joint capsule and may facilitate early intervention.

Intra-articular injection of methylene blue that demonstrates extravasation of dye from the wound site is highly suggestive for open joint injury. In the absence of dye extravasation, open joint injury may still be present; therefore, an orthopedic consultation is recommended for all patients with a suspected open joint injury.^[1]

For more information on aspiration techniques, see eMedicine Orthopedic Surgery article Aspiration Techniques and Indications for Surgery, Septic Arthritis.

Indications for methylene blue injection include soft tissue injury associated with at least one of the following:

• Periarticular fracture
• Visible joint capsule
• Proximity to a joint

No absolute contraindications exist for intra-articular joint injection, although the following situations highly suggest open joint injury and, therefore, require joint exploration and irrigation regardless of the results of intra-articular joint injection:

• Open fracture with obvious joint involvement on plain radiographs
• Intra-articular air or foreign bodies on plain radiographs

The FDA warns against the concurrent use of methylene blue with serotonergic psychiatric drugs, unless indicated for life-threatening or urgent conditions. Methylene blue may increase serotonin CNS levels as a result of MAO-A inhibition, increasing the risk of serotonin syndrome.^[2]

Inject a local anesthetic agent such as 1% lidocaine subcutaneously until a skin wheal appears before entering the joint space. For more information, see Local Anesthetic Agents, Infiltrative Administration. See Technique for precise details.

• Sterile preparation solution and surgical scrubs
• Sterile drapes
• Sterile gloves
• Sterile bowl
• Normal saline bottle (approximately 500 mL)
• Sterile methylene blue or fluorescein dye
• Syringes, 12-mL and 20- or 30-mL
• Needles, 18- and 21-gauge
• Local anesthetic solution
• Sterile 4 X 4 gauze pads

• Positioning varies based on the joint in question.

Obtain informed consent from the patient.

On a sterile drape, open the sterile bowl, syringes, and needles. Pour the sterile normal saline solution into the sterile bowl and add 1-2 mL of methylene blue to create a dark solution (see image below). Fill at least one 20- or 30-mL syringe with the dark solution.

After providing appropriate parenteral analgesia, cleanse a wide field by scrubbing the affected joint with a sterile preparation or a surgical scrub in circular motions starting from the within the wound and working outward (see image below). Repeat the scrubbing process at least 2 more times. Cover the joint with sterile drapes to create a sterile field.

Select a joint injection approach that is as far as possible from the skin wound (see image below). Make sure to avoid any neurovascular structures.

Elevate a skin wheal of local anesthetic using a 25-gauge needle (see image below).

Switch to a 21- or 18-gauge needle and continue to inject lidocaine in the subcutaneous and deeper soft tissues until the joint space is entered (see image below). Entry into the joint space can be confirmed by increased ease of injection and by aspiration of joint fluid (which is likely to be bloody rather than its normal straw-colored appearance).

Once the joint capsule is entered, secure the needle in the joint space with the nondominant hand while using the dominant hand to switch to the 20- to 30-mL syringe that contains the normal saline and dye solution (see image below).

Inject the solution into the joint until it is fully distended. (The required volume to fully distend a joint varies between different joints and patients.) Watch the wound site for contrast extravasation (see image below).

Aspirate back as much fluid as possible and withdraw the needle.

Clean the skin and wound with remaining preparation solution, and apply a sterile dressing over the wound and injection site. Extravasation of contrast from an open joint injury requires immediate administration of intravenous antibiotics and emergent orthopedic evaluation for exploration and irrigation of the joint.

• An alternative technique that can be used in patients who are allergic to methylene blue is injection of sterile fluorescein in normal saline solution into the joint space.^{[3, 4]} The authors recommend that the fluorescein solution and normal saline solution be tested for fluorescence with a Wood lamp before injection into the joint.
• Intra-articular injection of dye requires the ability to create enough dye pressure to distend the joint capsule and maximize the chances to visualize dye extravasation from the wound. An 18-gauge needle is the recommended gauge for injection or aspiration of most adult joints.
• Select a joint injection approach that is as far as possible from the skin wound. Make sure to avoid any neurovascular structures.
• This is a painful procedure that involves distention of the joint capsule (similar to arthroscopy); therefore, both parenteral analgesia and local anesthesia are indicated.^{[5, 6]}
• Intra-articular injection of methylene blue that demonstrates extravasation of dye from the wound site is highly suggestive of open joint injury. In the absence of dye extravasation, open joint injury may still be present; therefore, an orthopedic consultation is recommended for all patients with a suspected open joint injury.
• Extravasation of contrast from an open joint injury requires immediate administration of intravenous antibiotics^[7] and emergent (within 6 hours) orthopedic evaluation for exploration and irrigation of the joint.
• Aspirate back as much fluid as possible before withdrawing the needle.

• Infection: As with any other invasive procedure, infection may be introduced.^{[7, 8]} However, if infection occurs, introduction of infectious organisms is likely to have occurred by means of an open joint injury itself.
• Bleeding or nerve injury: Proper technique and awareness of normal anatomy should minimize the chances of injuring a neurovascular structure.
• False-negative result from injection: Small open defects to a joint capsule or failure to inject enough dye into the joint to allow dye extravasation might lead to a false-negative intra-articular dye injection result. Consultation with an orthopedic surgeon is recommended in all cases of suspected open joint injury.