Acromioclavicular Joint Arthritis: Why Your Shoulder Tip Hurts — and What to Do About It

That nagging ache at the top of your shoulder when you reach across your body, lift a bag, or lie on your side at night — it might not be coming from where you think. For many patients, the culprit is a small but important joint at the very tip of the shoulder called the acromioclavicular joint, or ACJ. The good news is that this is a well-understood condition, and the vast majority of people respond well to treatment.

What is the ACJ?

The acromioclavicular joint sits where your collarbone (clavicle) meets the bony tip of your shoulder blade (the acromion). It is a small joint, but it plays an important role in almost every movement your arm makes. Like any joint in the body, it is lined with cartilage that can wear down over time — and when it does, the result is ACJ arthritis.

Symptoms to look out for

The hallmark symptom is a localised ache or tenderness directly at the top of the shoulder. Patients often describe pain when reaching across the body — fastening a seatbelt, washing the opposite armpit, or hugging someone. Overhead activity and sleeping on the affected side can also aggravate symptoms. In some cases there is visible swelling or a slight bump over the joint.

Importantly, ACJ arthritis is different from rotator cuff problems, though the two can coexist. A careful clinical examination — and, where needed, targeted imaging — will identify which is driving your symptoms.

What causes it?

Wear and tear is the most common cause, and it is surprisingly prevalent; studies show changes consistent with ACJ arthritis in a significant proportion of adults over 50, many of whom have no symptoms at all. Previous injury — particularly an old shoulder separation — can accelerate the process. Repetitive overhead work or heavy weightlifting over many years is also a recognised risk factor.

Treatment options

Most patients with ACJ arthritis do not require surgery. A structured physiotherapy programme targeting the muscles around the shoulder and improving joint mechanics is the cornerstone of management and produces good results in the majority of cases.

Where symptoms are more persistent, a corticosteroid injection directly into the ACJ can provide effective, targeted relief — both confirming the diagnosis and settling inflammation. Evidence from recent systematic reviews supports this approach as a safe and effective short-term intervention (Woodward et al., Shoulder & Elbow, 2022; Borbas et al., Journal of Shoulder and Elbow Surgery, 2021).

For the small number of patients who do not respond to conservative measures, keyhole surgery to remove a small amount of bone from the end of the collarbone — known as a distal clavicle excision — reliably eliminates the source of pain. Recovery to full activity typically takes six to twelve weeks (Chalmers et al., Arthroscopy, 2023).

Taking the next step

If you recognise these symptoms, an expert assessment is the right starting point. Mr Jamie A'Court offers specialist orthopaedic consultations at Beaumont Hospital, where a clear diagnosis and personalised treatment plan can be established from the outset.

This article is intended for general information purposes only and does not constitute medical advice. It is not a substitute for a consultation with a qualified healthcare professional. If you are experiencing shoulder pain, please seek advice from your GP or a specialist.