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Acromioclavicular Joint Disorders

Pain right on the bony point at the top of your shoulder, worse reaching across your body or lying on that side? The AC joint is small, easy to overlook, and usually straightforward to treat once it’s been correctly identified.

Overview

What Is the AC Joint?

The acromioclavicular joint is where the collarbone meets the acromion, the bony shelf at the top of the shoulder blade. You can feel it as the small bump on top of your shoulder. It takes load every time you reach across your body, press overhead or carry, and it can be injured suddenly by a fall onto the point of the shoulder, or wear gradually over years of loading.

Shoulder blade Upper arm bone Collarbone Acromion

Tap a structure, or use the buttons, to see how each presents.

Traumatic

AC Joint Sprain (Shoulder Separation)

Usually the result of falling directly onto the point of the shoulder — common in cycling, rugby and horse riding. The ligaments holding the collarbone down are stretched or torn. Lower grades settle well without surgery; higher grades produce a visible step deformity and sometimes warrant a surgical opinion.

Symptoms

How It Tends to Feel

AC joint pain is one of the more localised shoulder presentations, which makes it relatively easy to identify:

Pinpoint Tenderness

You can usually put one finger on it — directly on the bony bump at the top of the shoulder.

Cross-Body Pain

Reaching across your chest towards the opposite shoulder is the classic aggravating movement.

Pain at End of Range

Discomfort in the last part of lifting the arm fully overhead, rather than in a mid-range arc.

Lying on That Side

Direct pressure through the joint at night is a frequent complaint.

A Visible Step

After a significant sprain, the end of the collarbone may sit noticeably higher than the acromion.

Pressing and Dipping

Bench press, dips, push-ups and overhead press are commonly the first things to become uncomfortable in the gym.

Causes & Risk Factors

What Drives It

AC joint problems fall into two fairly distinct groups — sudden and gradual.

01

Falling on the Point of the Shoulder

The classic mechanism for a sprain or separation. Cycling accidents, rugby tackles and falls from horses account for most of them.

02

Repetitive Overhead Loading

Years of overhead work, throwing or pressing gradually load the joint surfaces and contribute to wear.

03

Weight Training

Heavy bench pressing and dipping load the AC joint substantially, and are a common contributor in gym-going populations.

04

Age-Related Change

Joint surface changes at the AC joint are near-universal from middle age. They’re only relevant when they match your symptoms.

05

Previous Injury

A past separation increases the likelihood of the joint becoming symptomatic later, even if it settled well at the time.

How We Can Help You

Treatment & Management

Most AC joint problems settle well without surgery. The plan is to calm the joint, restore the strength around it, and rebuild tolerance to the positions that currently hurt.

Thorough Assessment: Confirming the AC joint as the source with specific tests, and grading a sprain where there’s been trauma.
Early Protection: For an acute sprain, short-term sling use and clear guidance on what to avoid while the ligaments settle.
Load Modification: Temporarily adjusting the specific movements that load the joint most — particularly cross-body reaching and heavy pressing.
Progressive Strengthening: Rebuilding strength and control through the shoulder blade and cuff so the joint is better supported through range.
Return to Sport or Gym: Structured reintroduction of pressing, dipping and overhead work, staged so you don’t simply reproduce the original problem.
Onward Referral: For high-grade separations, or persistent osteoarthritic pain that hasn’t responded, your physio will help you access imaging, injection or a surgical opinion.

What the evidence says

For low and moderate grade AC joint separations, randomised comparisons of surgical and non-surgical management have not shown a consistent advantage for surgery, and non-surgical management avoids the complication risk. Higher grades remain a genuine discussion point rather than a foregone conclusion.

For AC joint osteoarthritis, degenerative change is present on imaging in a large majority of people over 40 regardless of symptoms — so the diagnosis rests on clinical findings, not the scan report.

When to Seek Help

Red Flags — Don’t Ignore These

AC joint problems are rarely serious, but a few features warrant medical assessment:

⚠ Seek prompt medical assessment if you notice:

  • A hot, red, swollen joint with fever or feeling generally unwell (possible joint infection — seek emergency care)
  • Significant trauma followed by inability to take weight or use the limb, or an obvious deformity (possible fracture or dislocation)
  • Rapidly spreading redness, or a wound that is discharging
  • New, unexplained lump or swelling, or visible muscle wasting
  • Constant, unrelenting night pain unrelated to position or movement, particularly alongside unexplained weight loss or a history of cancer

These symptoms can point to a cause that needs medical rather than physiotherapy assessment. Please don’t wait for a physiotherapy appointment — contact your GP, call 111, or attend A&E as appropriate.

Common Questions

Frequently Asked Questions

I have a visible lump on my shoulder after a fall — is that permanent?

Often the cosmetic step remains to some degree even after the shoulder recovers fully, because the ligaments heal at a slightly longer length. That’s usually a cosmetic issue rather than a functional one — many people with a visible step have full strength and no pain. Higher grades are worth a specialist opinion.

Can I still lift weights?

Usually yes, with modifications. Reducing bench press range so the elbows don’t drop far below the torso, temporarily swapping dips for other pressing, and using a neutral grip often make a substantial difference. The aim is to keep training while giving the joint a lower dose.

Would an injection help?

A corticosteroid injection into the AC joint can be helpful for stubborn osteoarthritic pain, particularly to create a window for rehabilitation. It works best combined with a strengthening programme rather than as a standalone fix. your physio can help you access one if it looks appropriate.

How long does a sprain take to settle?

A low-grade sprain typically settles substantially within 2–6 weeks. Moderate grades take longer, often 6–12 weeks to comfortable function and a little longer for full contact sport. Your recovery is guided by your response, not by a fixed calendar.

Get the Top of Your Shoulder Sorted

A clear diagnosis, a plan for the movements that currently hurt, and a staged route back to pressing, lifting and sport.

Book Your Initial Assessment

This page is for general information only and isn’t a substitute for individual medical advice. If you’re experiencing any of the warning signs above, contact your GP or seek emergency medical care as appropriate.