Thumb CMC joint Injection
As a treatment where significant symptoms not responding to conservative measures and for symptom
control prior to surgery.
When to avoid injection
- Short duration of symptom control or minimal benefit from previous injection
- If significant dermal or adipose atrophy from previous injections
- When surgery is planned in near future (next two months)
- Local or systemic infection
Risks and complications
Infection – very rare probably 1 in 15000
Skin depigmentation, dermal atrophy, adipose atrophy, particularly if injection too superficial
Tendon rupture – very rare in non-rheumatoid patients
Flare of symptoms
Increased blood sugars in diabetic patients, this may last for 3-7 days with significant elevation of blood sugars
Facial flushing particularly in ladies
Equipment
We recommend two syringes, one for the local anaesthetic placement and a separate syringe for the steroid. We feel this allows a more comfortable experience for the patient and allows more accurate injection placement, potentially reducing complications.
5ml of 1 or 2 % lidocaine, 5 ml syringe, drawing up needle.
Long orange needle 25mm, 25 guage
10 – 20mg of triamcinolone or Kenalog in a separate 1ml syringe
Positioning
How patients are positioned during the procedure
The patient is seated, and the affected hand in mid pro-supination with the thumb facing the ceiling on a table or other flat surface.
The injector should identify the thumb CMC joint and mark with a pen if necessary. Viewing a radiograph is often very useful to visualise the pathway for the needle especially in advanced arthritis or where there is joint subluxation.
Where to inject
After antiseptic application and under strict aseptic technique.
With the local anaesthetic first and the orange needle , at 90 degrees to the skin, entry point over the midpoint of the dorsal/radial surface of CMC joint . Slowly advance the needle injecting small amounts of local anaesthetic so as to avoid obscuring the anatomy. Once you hit bone with the needle by moving the thumb metacarpal you can identify if you are too distal or not. By getting an assistant to apply gentle traction to the thumb and counter traction to the forearm easier joint entry is facilitated. The needle should slide easily into the joint without any significant resistance.
Once the joint is entered the patient will often experience a very tight feeling as the joint capsule is distended. The thumb may also move/ abduct slightly as the joint is filled. At this point remove the syringe being careful to leave the needle in the joint. If you have filled the joint with local anaesthetic you will see fluid bubbling back through the top of the orange hypodermic needle. If you are not in the joint this will not occur. If intra-articular placement of the needle is confirmed then inject 10-20 mg of steroid . (Robati S, Ardolino A, Walsh SP. Accurate injection of small joints – a useful technique.Ann R Coll Surg Engl 2009; 91: 623–624.)
The needle is withdrawn and firm pressure applied for 5 minutes to prevent extravasation of the steroid. Then a light dressing is applied. Advise the patient to be cautious with use of the hand over the next day. Expect some discomfort for a day or two.
Pearls
Remind the patient that steroids take some time to have effect. Patients often wait 3-7 days to experience a difference in clinical symptoms.
Gentle traction on the joint by an assistant can be very helpful in opening up the joint.
A relaxed patient will allow easier injection placement
The radial artery runs a few millimetres proximal to the thumb CMC joint and intra-arterial injection must be avoided. To avoid potential complications of vascular or nerve ischemia, tissue necrosis, and serious damage to nerve, lidocaine with adrenaline should not be used.