Arthrogram (anesthetic)

An arthrogram injection is a procedure in which a solution is administered into a joint under imaging guidance. These procedures are more accurately named direct arthrogram injections, although they are routinely known as arthrograms. Fluoroscopy, ultrasound, and CT can be used for image guidance and corticosteroid and longer-acting local anesthetics are the more frequently used injectates.  

Indications

• pain: arthropathy, e.g. osteoarthritis
• stiffness: soft tissue stiffness, e.g. in the frozen phase of adhesive capsulitis
• diagnostic injection

Contraindications

Absolute

• anaphylaxis to contrast/injectates
• new avascular necrosis of a joint
• active local/systemic infection 

Relative

• bleeding diathesis
• recent injection with steroid in same/other body parts
• unable to remain still for the procedure
• young age

Procedure

The general principle of any direct arthrogram is to:

• cannulate the joint
• confirm an intra-articular position with imaging
• administer intra-articular injectate, usually a corticosteroid and a longer-acting local anesthetic, i.e. ropivacaine. 

Unless performing a shoulder hydrodilatation, unlike an arthrogram injection before MRI/ CT, the joint does not need to be distended therefore lower volumes are injected. 

Pre-procedural evaluation

Relevant imaging should be reviewed and details of the patient confirmed.  The patient should have an opportunity to discuss the risks and benefits and consent obtained. 

Risks include 

• infection
• bleeding
• allergy 
• steroid flare

Driving is not advised after any injection, particularly if local anesthetic is used.  The reasons include an inability to perform an emergency procedure and be in safe control of a vehicle.

Technique

Patient positioning and technique will vary depending on the joint, method of access and individual performing the injection ¹.

Steps of anesthetic arthrogram injection

• check for allergies, if on blood thinners, if unwell and/or if any recent steroid injections
• consent
• optimize patient positioning
• optimize imaging and mark skin
• clean skin and draw up appropriate medications
• local anesthesia along the needle track
• obtain joint access with image guidance
• confirm an intra-articular position
• administer injectate
• apply dressing/ band-aid

In fluoroscopy, either an ‘eye of the needle’ approach can be used - parallel to the x-ray beam making the needle look like a dot, or an ‘oblique’ approach, which are out-of-plane with the x-ray beam, and the needle will look like a line.  In ultrasound-guided procedures, the needle should be visualized entering the joint ². 

Extension tubing should be used in fluoroscopic procedures, so contrast can be injected under direct observation and thus avoiding exposing the practitioner's hands. 

Imaging modalities

Different institutions will perform different techniques based on multiple factors, which usually revolve around availability and practitioner preference. Ultrasound is an excellent technique to use in those with iodinated contrast allergies.  

Equipment

• skin marker and a metal rod for marking (fluoroscopy)
• skin marker and a marking grid (CT)
• ultrasound machine and sterile probe cover (ultrasound)
• skin cleaning product
• sterile drape
• sterile field and tray for sharps
• syringe selection
• larger bore drawing up needle/ quill
• needle to administer local anesthetic i.e. 25 gauge needle
• needle to cannulate the joint i.e. 22 gauge Quincke needle
• short extension tubing
• injectants i.e local anesthetic, iodinated contrast, corticosteroid
• sterile gauze
• adhesive dressing

Syringe selection

Syringe selection will help identify the different solutions for injecting. Anesthetic arthrograms are different from other arthrogram injections, as the commonly used corticosteroids are white in color, so identifying the steroid-containing syringe obvious. Keeping the local anesthetic syringe, and contrast syringe for fluoroscopy, the same for both diagnostic and anesthetic arthrograms is good practice to limit confusion when switching between the different indications on the same list.

Common corticosteroid medications

• triamcinolone acetonide (e.g. Kenalog ^TM, Volon A)
• methylprednisolone acetate (e.g. Medrol)

The named steroids are 1 mL in volume, i.e. 40 mg triamcinolone acetonide (40 mg/1 mL).  There are documented cases of adverse events after anesthetic arthrogram injections with corticosteroids which include accelerated osteoarthritis progression, subchondral insufficiency fracture, and loss of bone density ³. Further research is required in this area, but the frequency and dose of these injections should be considered when protocolling and performing in all intra-articular steroid injections. 

A suggested syringe and injectate selection for a fluoroscopic anesthetic arthrogram injection -

• 5 mL syringe: 5 mL of local anesthetic i.e. 1% lidocaine
• 10 mL syringe: 5 mL non-ionic iodinated contrast i.e. iohexol
• 5 mL syringe: 40 mg triamcinolone acetonide (40 mg/1 mL) and 3 mL 0.5% ropivacaine

A suggested syringe and injectate selection for an ultrasound-guided anesthetic arthrogram injection -

• 5 mL syringe: 5 mL of local anesthetic i.e. 1% lidocaine
• 5 mL syringe: 40mg triamcinolone acetonide (40 mg/1 mL) and 3 mL 0.5% ropivacaine

Anesthetic arthrogram injectate

Syringe selection for the anesthetic arthrogram injectate will be based upon the size of the joint and total injectate to be administered.  Luer lock syringes are recommended in smaller joints as they can be under pressure. Suggested volumes of local anesthetic for different joints are suggested below:

• shoulder/ hip/ knee: 3-5 mL
• elbow/ ankle: 2-3 mL
• ACJ/ subtalar: 1 mL
• 1st CMCJ/ TMTJs/ 1st MTPJ: 0.5 mL

There are reported chondrotoxic effects of local anesthetics, and intra-articular lidocaine should be avoided. Other lower strength local anesthetics are reported as having less of a chondrotoxic effect. i.e. ropivacaine ⁴. 

Needle selection

Needle selection will depend on the depth and size of the joint.  Smaller gauge needles can be less painful, but when used to reach deeper joints are less stiff and can bend.  Suggested needles for different joints are below - 

• shoulder/ hip/ knee:  22-gauge Quincke needle (spinal) 
• elbow/ ankle: 25-gauge needles
• ACJ/ subtalar: 25 or 27-gauge needles
• 1st CMCJ/ TMTJs/ 1st MTPJ: 25, 27 or 30-gauge needles