Sternoclavicular Joint Disorders Info

What you're feeling

The sternoclavicular joint is the small joint at the front of your chest where the inner end of your collarbone (clavicle) meets your breastbone (sternum). You can feel it as the little bump just below the base of your neck, a couple of centimetres out from the midline. It is easy to overlook until something goes wrong with it.

Problems here tend to show up in one of a few ways. Some people notice a deep ache or tenderness right over that bump, often with a bit of swelling, that gets worse when they reach overhead, lift, push, or lie on that side. Others feel the joint click, slip or shift with certain movements, sometimes with a visible lump that comes and goes. And occasionally the trouble starts with a sudden injury (a fall onto the shoulder, a tackle, or a car accident), followed by pain, swelling and a change in the shape of the joint. How it feels depends a lot on which of these is going on, and we sort that out below.

What's actually happening

The sternoclavicular joint is the only true bony joint connecting your whole arm and shoulder to the rest of your skeleton. Everything your arm does is anchored back to your chest through this one small joint, which is why it is built tough, wrapped in strong ligaments. A few different things can affect it.

Arthritis (wear of the joint surfaces) is the most common problem. The smooth cartilage thins over time, the joint can swell, and it aches with use. This is seen most often in middle-aged women, frequently without any injury at all, and on its own it is a nuisance rather than a danger.

Atraumatic instability means the joint slips or partly pops out of place without a real injury, usually because the ligaments are naturally loose. It is most common in young, flexible (hypermobile) people, and the clavicle most often shifts forwards (an anterior slip), which you may see as a lump that appears when you move a certain way.

Traumatic dislocation happens when a strong force pushes the collarbone fully out of the joint. If it pops forwards (anterior), it is painful and looks abnormal but is rarely dangerous. The one that matters most is the posterior dislocation, where the collarbone is driven backwards, behind the breastbone, into the space holding the windpipe, the swallowing tube and the large blood vessels of the chest. This is rare, but it can be serious. More on that in the last section.

What we can do about it

The good news is that most sternoclavicular problems settle without surgery.

For arthritis and for anterior (forward) instability, the first-line plan is non-operative and usually works well: modifying the activities that aggravate it, simple pain relief and anti-inflammatory medication, and physiotherapy to settle the joint and build supporting muscle. If a painful arthritic joint is still troublesome after a fair trial of this, a steroid injection into the joint can calm it down and also help confirm the joint is the source of the pain.

Surgery is the exception, not the rule. It is reserved for selected people whose pain or instability does not settle despite proper non-operative treatment. Depending on the problem, that might mean stabilising the joint (rebuilding the ligaments to hold the collarbone in place) or, for stubborn arthritis, trimming away the worn end of the collarbone to take the painful surface out of the equation. These are considered carefully, because the joint sits right next to important structures in the chest.

A posterior dislocation is the situation that can't wait. It usually needs an urgent reduction (putting the joint back into place), and because of what lies behind the joint this is often done in an operating theatre with a chest or vascular surgeon on standby, just in case.

What to expect

For arthritis and for the common forward instability, the outlook is reassuring. With activity changes, physio and time, the great majority of people get comfortable enough to get on with normal life, and many never need anything more than that. Flexible joints often quieten down as the surrounding muscles get stronger and you learn which movements to avoid.

When surgery is needed, it can be very effective for the right person, but recovery takes patience: a period of protecting the joint followed by a staged return to activity over several months. Your surgeon will talk you through the specific plan for your situation.

A posterior dislocation treated promptly usually does well once the joint is safely back in place. The thing that matters is speed: get it assessed and reduced early.

When to see someone

See your doctor if you have:

• Ongoing pain, swelling or tenderness over the joint at the front of the chest that isn't settling, or a lump that keeps slipping in and out.
• A joint that feels unstable or repeatedly pops out with certain movements and is limiting what you can do.
• Pain after an injury to the front of the shoulder or chest, especially if the joint looks or feels out of shape.

Treat this as an emergency: call an ambulance or go straight to your nearest emergency department if, after a heavy blow or high-energy injury to the shoulder or chest, you have:

• Difficulty breathing, a feeling of pressure or choking, or a change in your voice.
• Trouble or pain on swallowing.
• Swelling, colour change, coldness or pins-and-needles in the arm, or a weak pulse on that side.

These can be signs of a posterior dislocation pressing on the windpipe, the swallowing tube or the major blood vessels behind the breastbone. It is uncommon, but it needs urgent hospital assessment. Do not wait to see if it settles.