A break is the main injuryStrong evidence
In one hospital's 11-year series of 535 collarbone breaks, they made up 2.6% of all fractures, two-thirds were in men, and 81% were in the middle third of the bone; a review of trials puts them at 2.6% to 4% of all fractures. Most follow a direct blow or a fall onto the shoulder or an outstretched arm, the American Academy of Orthopaedic Surgeons (AAOS) says, and the signs include a shoulder that sags forward, a bump over the break, grinding when you lift the arm, and bruising and tenderness.
The NHS says you need an X-ray, and a broken collarbone needs treatment in hospital.
Sources 1, 2, 3, 4
The outer end: the AC jointStrong evidence
A shoulder separation is an injury to the AC joint, usually from a fall directly onto the shoulder, ranging from a mild sprain to a complete separation with a large bump, the AAOS says. The NHS links pain on top of the shoulder, where the collarbone and the shoulder joint meet, to problems in this joint (a page past its review date).
With no injury, wear at the end of the collarbone (osteolysis, or weightlifter's shoulder) is linked to weight training: in a review of 8 studies of 483 people, bench pressing was the commonest activity (49.1%), and in the original series, 45 of 46 men lifted weights. Our AC joint guide covers all of these.
Sources 5, 6, 7, 8
The inner end: the SC jointStrong evidence
The SC joint is the only joint linking the arm to the body. Its ligaments are some of the strongest in the body, so an injury usually takes a big force, such as a hard fall or collision in a contact sport like rugby, or a car crash. Most injuries are sprains that heal well without surgery; with no injury, arthritis, usually from about 50, causes pain, stiffness and sometimes a bony bump; and in people with loose joints the joint can pop out of place, the AAOS says.
A collarbone pushed backwards at this joint can press on the windpipe, the gullet and the main blood vessels, and needs urgent treatment. An infection here is rare, about 1% of joint infections in one review of 180 cases, and only 65% of those people had a fever.
Sources 9, 10, 11
Glands above the collarbone, and the thoracic outletStrong evidence
Lymph glands sit just above the collarbone. The NHS lists swollen glands just above or below the collarbone among the reasons to see a GP (a page past its review date), and from age 40, NICE asks GPs to consider an urgent chest X-ray for swollen glands above the collarbone.
The thoracic outlet is the space between the collarbone and the first rib. When its nerves and blood vessels are squashed, the arm can tingle, ache, tire, swell or turn cold, often worse with the arms raised.
Sources 12, 13, 14, 15
The heart and lungsStrong evidence
Heart pain can spread to the shoulder, neck, jaw and arms, so collarbone or shoulder pain with chest tightness, breathlessness, sweating or feeling sick is a 999 call. A collapsed lung causes a sudden, sharp, stabbing pain in the chest or shoulder with breathlessness, and lung cancer can cause chest or shoulder pain with a cough that won't go away.
Sources 16, 17, 18, 19
When a scan or test helpsStrong evidence
A possible break needs an X-ray in hospital; the AAOS adds X-rays of the whole shoulder to look for other injuries, and a computed tomography (CT) scan if other bones are broken. An AC separation is graded on X-ray, sometimes while you hold a weight to show the gap. The SC joint is X-rayed from several angles, and a CT scan tells a sprain from a dislocation or a break.
Osteolysis shows on a magnetic resonance imaging (MRI) scan, which should be read alongside the examination. A gland above the collarbone is checked by a GP, with NICE's chest X-ray step from age 40.
Sources 4, 3, 5, 9, 7, 13
How it usually goesEmerging evidence
The NHS says most people recover from a broken collarbone in 6 to 8 weeks, and children often in 3 to 4, with a sling for 2 to 3 weeks (a page past its review date); the AAOS says the bone can take several months to heal, and most people return to their regular activities within 3 months. In the trials, a bone that hadn't joined and caused symptoms affected 11.6% of people treated without surgery.
Most AC separations, even in professional athletes, return to normal function without surgery, though a bump may stay and some people have lasting pain. Most SC sprains heal well without surgery. With osteolysis, most people recover by changing their training, and 16% had surgery. No one can promise a date.
Sources 4, 3, 2, 5, 20, 9, 7, 8