Joint Injection

Author: A/Prof Howard Galloway*

What is a joint injection?

This is procedure where a needle of appropriate length and calibre is placed in a specific joint under imaging guidance. This often uses ultrasound, but X-ray fluoroscopy or CT can also be used depending on the radiologist doing the procedure and the joint required.

A mixture of steroid and long-acting anaesthetic is injected once the radiologist is satisfied that the needle tip is correctly located in the joint cavity. A small amount of contrast medium may be used in X-ray or CT guidance to confirm needle tip placement.

Particulate injectable steroid medication (e.g. Kenacort or Celestone) is commonly used, except in joints around the spine where dexamethasone is recommended. Particulate steroids leaking into soft tissues around the spine have been associated with microvascular coagulation and spinal complications.

The injection is used for pain relief in both therapy and in the diagnostic assessment of a potential painful joint.

What are the generally accepted indications for a joint injection?

The following are generally accepted indications for therapeutic joint injections:

• Where there is known inflammation in the joint not improving with other medication (e.g. NSAIDs) or physical therapy.
• If pain is present in the region of a joint and diagnostic local anaesthetic block is required to assess whether the joint is the cause of the symptoms.
• If special medications or treatments need to be injected directly into the joint and not into the surrounding soft tissues (e.g. stem cell therapy or radioactive synovectomy).
• When it forms part of a more detailed imaging examination of your joint (see InsideRadiology: Arthrogram).
• Where attempted intra-articular injection without image guidance has failed.

What are the prerequisites for having a joint injection done?

Generally, the patient will require at least a plain X-ray of the joint and often an ultrasound, CT scan or MRI. These imaging studies should be brought to the appointment.

What are the absolute contraindications for a joint injection?

Infection in or overlying the joint at the site of potential needle placement.

What are the relative contraindications for a joint injection?

• Reflex sympathetic dystrophy
  Any procedure or minor injury may reactivate or aggravate the symptoms. The Reflex Sympathetic Dystrophy Syndrome Association guideline recommends the avoidance of all types of even minor procedures on the affected limb.
• Avascular necrosis of bones adjacent to the affected joint
  Anecdotal reports suggest that intra-articular injection aggravates the pain of avascular necrosis.
• Anticoagulation
  There is no evidence to suggest that injection is contraindicated for patients on anticoagulants within the normal therapeutic range.
• Failure to respond to previous injection

What are the adverse effects of a joint injection?

This is a very safe procedure with few risks.

There is a risk of infection, which is very small and probably lies between 1 in 20,000 and 1 in 75,000 injections carried out. The procedure should not be carried out if there is broken skin or infection overlying the joint at the site of needle placement or if the joint may already be infected.

There are possible complications of the steroid injection, which include aggravation of the pain due to a transient increase in synovitis from irritation of the joint lining by crystals in the steroid solution.

If the steroid is not injected solely into the joint, there is a risk of damage to the soft tissues at the injection site, including atrophy of the skin or subcutaneous fat and rupture or weakness of the tendons around the joint.

A localised area of skin depigmentation at the injection site can also occur.

Although the exact risk is not known, most doctors would advise against injection more than three or four times a year to avoid damage to the joint.

Occasionally, people are allergic to the injected medication. The exact risk of this is not known, but it seems to be very uncommon. The radiologist should be advised on the referral if there is a known iodine allergy and/or a prior contrast reaction. An ultrasound-guided injection does not use X-ray contrast, but this may be used if the injection is carried out using fluoroscopy or CT.

Steroid therapy can elevate blood sugars for a few days in patients with diabetes, but generally the dosage of steroid injected into a joint is relatively small and it has a minimal effect.

Is there any specific post procedural care required following a joint injection?

In patients with diabetes, more frequent monitoring of blood glucose for 48 hours is advised, particularly in patients using insulin or whose diabetes is unstable.

If joint pain and swelling increases over more than 48 hours (i.e. more than that expected from transient synovitis), then infection needs to be considered. Please contact the specialist who did the injection, the radiology clinic or, if clinically indicated, refer directly to the local emergency department for further assessment.

Are there alternative imaging tests, interventions or surgical procedures to a joint injection?

• Conservative management with NSAIDs and physical therapy.
• In some cases surgical washout and debridement may be considered if the joint is infected.
• Surgical, radioactive or chemical synovectomy in patients with refractory symptomatic chronic synovitis

*The author has no conflict of interest with this topic.

Page last modified on 31/8/2018.