An AC joint injection is used to treat problems such as AC joint arthritis. So when is an AC joint injection effective, how do we do it, and what do we use — and are there alternatives to cortisone for AC joint pain?
What is the acromioclavicular joint?
The acromioclavicular (AC) joint sits at the top of the shoulder. It joins the collarbone (clavicle) to the top of the shoulder blade (the acromion), held together by strong ligaments between the collarbone, acromion, and first rib.
AC joint arthritis usually develops with age, as the joint space narrows and the cartilage wears away. Trauma — a fall onto the shoulder or a hit in contact sport — can also damage the joint and lead to early AC joint arthritis.
AC joint arthritis is different from shoulder joint arthritis, which affects the ball-and-socket joint. The two differ not just anatomically, but in their symptoms and treatment.
Symptoms of AC joint arthritis
Acromioclavicular joint pain is common, and patients can often point directly to the AC joint as the source. Lying on the shoulder at night is typically painful, and moving the arm across the body recreates the pain. The joint may look swollen and feel tender to touch, while other tests — shoulder strength and neck mobility — are usually normal.
It’s important to exclude other causes of shoulder pain, particularly in weightlifters. Distal clavicular osteolysis (weightlifter’s shoulder), for example, is common in men who lift heavy weights and can mimic AC joint arthritis.
X-rays often show the typical changes of AC joint arthritis — a narrowed joint space and bony spurs. Where the diagnosis is uncertain, ultrasound and MRI can help confirm it.
Treatment of AC joint degeneration
Treatment depends on the severity of symptoms and any other shoulder problems, such as a rotator cuff tear.
In mild cases, anti-inflammatory tablets such as ibuprofen reduce pain, and physiotherapy strengthens the shoulder, with manual therapy and postural correction adding benefit. If you go to the gym, your technique may need modifying. An AC joint injection can also help settle the pain.
In severe cases that fail conservative measures, surgery may be needed — usually keyhole surgery to remove the end of the clavicle, opening up the joint so the bones no longer rub together.
More on the AC joint injection
A cortisone shot into the AC joint effectively relieves the pain of AC joint arthritis by reducing inflammation and swelling. Cortisone is a potent anti-inflammatory that can quickly ease pain and improve shoulder movement.
The injection can be done sitting or lying. The doctor directs a needle with a small syringe of cortisone and local anaesthetic into the joint. Entering the joint can be tricky when the space is narrowed, so ultrasound makes AC joint injections more straightforward. Image guidance also improves effectiveness and reduces side effects — such as accidentally injecting cortisone into the surrounding soft tissue, which can cause skin thinning and depigmentation.
Pain relief after an AC joint injection also confirms the joint as the source of the pain.
If the pain recurs after a cortisone injection, other options such as hyaluronic acid may help.
AC joint injection technique
We use a small needle to enter the joint from the front or back, with ultrasound to guide it accurately. A study found that landmark-guided injections (without imaging) were only 65% accurate at hitting the joint, whereas ultrasound-guided injections were 100% accurate. Ultrasound also makes the injection less painful and reduces side effects such as skin changes, because the cortisone goes directly into the joint rather than outside it.
AC joint injection side effects
A cortisone shot in the AC joint is generally well tolerated. Possible side effects include skin depigmentation, a post-injection flare, and (rarely) infection. We avoid repeating injections into the same joint within a short period (2–3 months).
How much does an AC joint injection cost?
Dr Masci performs the AC joint injection as a one-stop appointment — consultation, diagnostic ultrasound, and the injection in a single visit. At the Chelsea clinic (the most cost-effective location), a consultation with an AC joint injection is £400; other clinic locations cost more. See the full one-stop injection fees here and our clinic locations.
Frequently asked questions about AC joint injections
Does an AC joint injection heal the joint?
No. A cortisone injection reduces the inflammation and swelling, which relieves pain — but it doesn’t heal the joint or reverse the arthritis. Its value is easing pain so you can rehab, and confirming the AC joint as the source of the pain.
What size needle is used for an AC joint injection?
A small needle, typically 23 or 25 gauge. Ultrasound guidance improves the accuracy regardless of needle size.
How long does an AC joint injection last?
It depends on the cause, but for AC joint arthritis, a cortisone injection typically lasts 3–6 months, sometimes longer.
Is a PRP injection effective for AC joint arthritis?
While the evidence for PRP in knee arthritis is promising, there’s currently no good evidence that PRP works for AC joint arthritis, so we don’t routinely recommend it here.
Is an AC joint injection painful?
Most people tolerate it well. Local anaesthetic is included, and because ultrasound places the needle accurately, the injection tends to be quicker and more comfortable than a blind attempt into a narrowed joint.
How many AC joint injections can I have?
We avoid repeating cortisone into the same joint within about 2–3 months. If the pain keeps returning despite a good response, that’s a prompt to review the diagnosis and consider alternatives rather than repeated steroid injections.
Final word from Sport Doctor London about AC joint injection
An AC joint injection is used successfully for AC joint arthritis — a common but underappreciated cause of shoulder pain in active people. A careful examination usually confirms the diagnosis, and a cortisone injection into the AC joint both helps confirm the source of pain and settles it enough to rehab.
To discuss an AC joint injection with Dr Masci in London, contact the team here or call +44 (0) 203 488 0350.
Does an AC joint injection heal the joint or does it just numb it
Hi, It can reduce swelling and inflammation. But no – it does not heal the joint. No injeciton will reverse the damage.
https://sportdoctorlondon.com/can-osteoarthritis-be-reversed/