Separated Shoulder: What an AC Joint Sprain Means

You went over the handlebars, or you got tackled, or you slipped on ice and landed on the point of your shoulder. The pain sits on top, right where the collarbone ends. Reaching across your body to grab a seatbelt hurts in a specific way. And in the mirror, one side has a bump that the other side does not.

That bump is the reason most people book an appointment. It also worries patients far more than it worries the clinicians looking at it.

What you are describing is an acromioclavicular joint sprain, the injury most people call a separated shoulder. It is a common result of a direct fall onto the shoulder, and for most grades the treatment plan involves no surgery.

A separated shoulder and a dislocated shoulder are two different injuries

These two get mixed up constantly, including by people who have had one of them. They involve different joints.

The acromioclavicular joint, or AC joint, sits on top of the shoulder. It is the small joint where the outer end of the collarbone meets the acromion, a bony shelf that extends forward from the shoulder blade. It is a low-motion joint held together by ligaments. A separated shoulder is an injury to those ligaments. The joint surfaces come apart, and the collarbone end rides upward relative to the shoulder blade.

The glenohumeral joint sits deeper and lower. That is the ball-and-socket joint where the head of the upper arm bone sits in a shallow socket on the shoulder blade, and it produces most of the shoulder's movement. A dislocated shoulder means the ball has come out of that socket, usually forward. It typically needs to be put back in by a physician in an emergency department.

The practical difference shows up on arrival. An AC joint sprain usually presents with the arm still working, held close to the body, painful at the top of the shoulder. A glenohumeral dislocation presents with the arm locked in one position and an obvious deformity at the front, and it goes to hospital first.

The mechanisms differ too. AC joint sprains come from landing on the point of the shoulder with the arm at the side. Glenohumeral dislocations more often come from a forced rotation with the arm away from the body.

What the Rockwood grades actually describe

When a physician or physiotherapist tells you it is a "grade 2" or a "type 3", they are using the Rockwood classification. It is the standard system, and it sorts AC joint injuries into six types based on how badly the ligaments are damaged and which direction the collarbone has moved.

Two sets of ligaments hold this joint together. The acromioclavicular ligaments sit at the joint and control side-to-side stability. The coracoclavicular ligaments run from the collarbone down to the coracoid, a hook of bone on the front of the shoulder blade, and control how far the collarbone can ride upward. The grading follows the order in which those fail.

• Type I. The AC ligaments are stretched or partly torn. Nothing has moved on an X-ray. Pain on top of the shoulder, no visible step.
• Type II. The AC ligaments are torn, the coracoclavicular ligaments are intact or stretched. The collarbone end rides up a little. Sometimes a small step you can feel more than see.
• Type III. Both sets of ligaments are torn. The collarbone sits clearly higher. This is the classic visible step deformity.
• Types IV, V and VI. Both ligament sets are torn and the collarbone has displaced much further, or in an unusual direction: backward through the trapezius muscle in type IV, far upward in type V, downward under the coracoid in type VI. These are uncommon and are usually surgical.

The grading is less precise than the numbers suggest. A 2023 study in Orthopaedic Journal of Sports Medicine by Velasquez Garcia and colleagues tested how consistently clinicians assign the same Rockwood grade to the same X-ray. Agreement between observers was moderate, with a kappa of 0.52, so two competent clinicians can look at one image and land on different grades. The same paper notes type IV is rare, at 0.7% of cases.

Take the number as a guide to how much ligament damage happened, rather than as a measurement of your future.

What the step deformity does and does not predict

Patients ask about the bump first, so it deserves a direct answer.

The step is a real anatomical finding. It tells your clinician that the coracoclavicular ligaments have failed and the collarbone is sitting higher than it used to.

How well your shoulder works in a year is a separate question, measured separately, and the two track each other poorly. The evidence on that is unusually clear for an orthopaedic question.

A 2026 systematic review and meta-analysis in Orthopaedic Journal of Sports Medicine by Lameire and colleagues pooled 5 randomised controlled trials covering 367 patients with type III to V dislocations, 193 treated with surgery and 174 without. At 2 years or more, Constant scores were 92.4 in the operative group and 90.1 in the non-operative group, with no significant difference. Return to sport within a year ran at 73 to 85% after surgery and 85% without it. Major complications showed no significant difference between groups, and minor complications were higher in the operative group.

One finding in that review is worth sitting with. In one included trial, 76% of the non-operative group had returned to work at 3 months, against 43% of the operative group.

Surgery reliably improves the appearance on X-ray. Function came out the same in the pooled data. Satisfaction with how the shoulder looked ran at 60 to 67% after surgery and 67 to 78% without it, so even the cosmetic verdict from patients favoured neither approach.

The bump, in most cases, stays. Shoulders work well around it.

Why grades 1 to 3 are usually managed without surgery

Types I and II are treated without surgery as a matter of routine. The ligaments that matter most for vertical stability are intact, so the joint holds.

Type III is where the genuine debate sits, and it has been argued over for decades. The current evidence points toward starting without surgery in most cases. A 2024 meta-analysis in BMC Musculoskeletal Disorders by Xie and colleagues pooled 4 randomised controlled trials covering 244 patients with type III injuries, 131 surgical and 113 conservative. Constant scores showed no significant difference between the two approaches. Conservative treatment produced less pain at 6 weeks and 3 months. Surgery restored the distance between the collarbone and the coracoid better on X-ray, though one study in the pool found even that difference had gone by 24 months.

The complication picture pushed the same direction. The surgical group in that analysis had more hardware failure, more subacromial erosion, and a 17% rate of revision related to posttraumatic osteoarthritis.

That is why a common approach for a type III is to rehabilitate first and reassess at around 3 months. If the shoulder is working and the pain has settled, that is the answer. If it has not, surgery remains available, and delayed reconstruction is a normal pathway rather than a failure. Athletes in overhead or collision sports, and people doing heavy overhead manual work, sometimes get a different conversation, because the demands on that joint are higher.

Types IV, V and VI generally go to an orthopaedic surgeon, because the displacement is large enough that shoulder mechanics do not recover without it.

Do not assume a low grade means an easy recovery

There is a habit of calling grades I and II "minor", and the long-term data complicates that.

A 2016 review in Joints by North gathered three studies following conservatively managed grade I and II injuries over years rather than weeks. In one series of 35 patients, 40% still had pain at 6 months, falling to 14% at around 20 months. In a second series of 33 patients followed for 6.3 years, 27% eventually had surgery for persistent symptoms at an average of 26 months after injury, and 54% showed degenerative changes. A third series of 23 patients followed for 10.2 years found 54% reporting mild, occasional symptoms, with none needing further treatment.

Those numbers vary a lot between studies, which tells you something on its own. A low grade shifts the odds toward an uncomplicated recovery without promising one. If your "minor" AC sprain is still bothering you at 3 months, that is a recognised pattern that deserves reassessment.

The sling question, and when loading starts

A sling helps early, mostly for comfort. It takes the weight of the arm off the injured ligaments, which reduces the downward pull on the joint. Most people find it useful for somewhere between a few days and 2 to 3 weeks, depending on the grade and the pain.

What happens while you wear it matters more, along with how quickly you stop. Prolonged immobilisation costs range of motion and shoulder blade control, and both are harder to get back than to keep. So the general approach is gentle movement early: pendulum swings, elbow and wrist motion, scapular setting, and range within a comfortable arc, with limits set by your grade and by how the joint responds.

Early loading follows a predictable order in most plans:

• Isometrics first. Pushing into a wall or a hand with no joint movement, building tolerance without asking the ligaments to control a moving load.
• Scapular control. Rowing patterns, lower trapezius and serratus anterior work, because the shoulder blade is now the foundation the arm has to work from.
• Below shoulder height first. Rotator cuff and deltoid strengthening with the arm below 90 degrees, where the AC joint is under less compression.
• Then overhead, then load. Range above shoulder height comes before heavy weight above shoulder height, and the gap between those two steps is often longer than people expect.

Two movements deserve caution well into rehab because they compress the AC joint directly: reaching across the body to the opposite shoulder, and deep bench press or dip positions. Those come back late and gradually.

Timelines depend on the grade, on what you need to return to, and on how the joint responds to each step up in load. Your physiotherapist will set expectations after the assessment rather than from a chart.

Getting back to contact sport and overhead lifting

Returning to a sport where you might land on that shoulder again is a different decision from returning to a desk.

For contact and collision sport, the milestones are usually full pain-free range, strength matching the other side on your therapist's tests, the ability to absorb load through the arm, and tolerance of the positions your sport demands. A rugby player needs to tolerate contact through the shoulder. A cyclist needs to hold a sustained position on the bars, which is its own kind of load, covered in our post on cycling injuries and physiotherapy.

For overhead lifting, the progression is usually slower than athletes want, because pressing overhead loads the AC joint at the top of the movement. Most plans run landmine and incline pressing before strict overhead pressing, and lighter overhead work before anything near a previous maximum. Bench press and dips often come last, because the bottom position compresses the joint hardest.

A useful rule through all of it: pain during a movement that settles within 24 hours is usually acceptable progress. Pain that builds over the following day means the step was too big, and the answer is to drop back a stage rather than push through.

Shoulder pain that persists after an AC injury sometimes involves the rotator cuff as well, particularly after a heavy fall. If the pain has shifted from the top of the shoulder to the outer arm, see our comparison of shoulder impingement and rotator cuff problems, and our post on when a rotator cuff tear needs surgery.

The long-term picture, including AC joint arthritis

The AC joint carries load every time you use your arm, and it develops osteoarthritis readily even in people who never injured it. After a sprain, the odds go up.

The studies above give a sense of scale. In the grade I and II series North reviewed, 54% showed degenerative changes at 6.3 years. In the type III surgical groups Xie and colleagues pooled, posttraumatic osteoarthritis drove a 17% revision rate. Both come from small samples, so treat them as a direction rather than a precise probability for you.

In practice it is manageable. AC joint osteoarthritis usually shows as localised pain on top of the shoulder, discomfort reaching across the body, and aching after a night lying on that side. It responds to what helps most joint arthritis: keeping the surrounding muscle strong, managing load, and adjusting the movements that irritate it. Some people get relief from a corticosteroid injection, which is a physician decision. A small number eventually have a distal clavicle excision, an operation removing the last centimetre of collarbone to stop the two bones rubbing.

A visible step deformity by itself does not commit you to any of that. Plenty of people carry one for decades with a shoulder that does everything they ask.

What a first visit looks like

A first physiotherapy assessment for an AC injury starts with the fall. Your therapist will ask how you landed, where the pain sits, what you cannot do yet, and whether anything has changed since the injury.

The examination includes looking at and feeling the joint, comparing both sides, and testing how far the collarbone moves under gentle pressure. Expect tests that load the AC joint, including the cross-body adduction test, which reproduces AC joint pain by bringing the arm across the chest. Your therapist will also check the rotator cuff and the neck, because a fall hard enough to injure the AC joint often did something else at the same time.

If the grade is unclear or a higher type is suspected, you will be referred for X-rays, sometimes with both arms compared on one image.

Physiotherapy is a direct-access profession in British Columbia, regulated by the College of Health and Care Professionals of BC, so no physician referral is needed to book an assessment. Some extended-health plans require one for reimbursement, so check with your insurer before your first visit. If the injury happened in a motor vehicle crash, ICBC funds a set number of physiotherapy visits without pre-approval. If it happened at work, a claim goes through WorkSafeBC.

When to see a physician rather than book physiotherapy

Some presentations need medical assessment first.

Go to an emergency department if the shoulder is obviously deformed at the front and the arm is locked in position, which suggests the ball-and-socket joint has dislocated. Go if you cannot move the arm at all, if there is numbness or pins and needles down the arm or into the hand, if the hand is cold or pale, or if the skin over the collarbone is tented, white, or looks like the bone is about to break through.

Book with your physician for a suspected type IV, V or VI, meaning a large or unusual displacement, or if the collarbone appears to have moved backward. Book if pain is severe and unrelenting, if there is a fever, or if your AC injury was treated as minor and is still limiting you at 3 months.

This article is general information, not personal medical advice. A regulated practitioner can confirm whether the patterns described apply to you.

Frequently asked questions

What is an AC joint sprain?

An AC joint sprain is an injury to the ligaments of the acromioclavicular joint, the small joint on top of the shoulder where the outer end of the collarbone meets a bony shelf of the shoulder blade called the acromion. It usually happens from a direct fall onto the point of the shoulder. Most people call it a separated shoulder. Depending on how many ligaments tore, the outer end of the collarbone may ride upward and create a visible bump.

How is a separated shoulder different from a dislocated shoulder?

They involve different joints. A separated shoulder is an injury to the acromioclavicular joint on top of the shoulder, where the collarbone meets the shoulder blade, and it is a ligament injury. A dislocated shoulder means the ball of the upper arm bone has come out of its socket at the glenohumeral joint, which sits deeper and produces most of the shoulder's movement. A dislocation usually needs a physician to put the joint back in place, while an AC sprain usually does not.

What do the Rockwood grades mean?

The Rockwood classification sorts AC joint injuries into six types by how much ligament damage occurred and which way the collarbone moved. Type I is a stretch or partial tear of the ligaments at the joint with no displacement. Type II adds a torn joint ligament with the collarbone riding up a little. Type III means both sets of ligaments are torn with a clear step. Types IV, V and VI involve larger or unusual displacement and are uncommon. A 2023 study in Orthopaedic Journal of Sports Medicine found agreement between clinicians grading the same X-ray was moderate, at a kappa of 0.52.

Will the bump on my shoulder go away?

In most cases the bump stays. Once the coracoclavicular ligaments tear, the collarbone end sits higher, and rehabilitation does not change bone position. Surgery can restore the alignment, though the pooled randomised trial evidence shows it does not reliably improve function, and patient satisfaction with appearance ran at 60 to 67% after surgery against 67 to 78% without it in the 2026 meta-analysis in Orthopaedic Journal of Sports Medicine. Most people find the bump becomes something they stop noticing.

Do I need surgery for a separated shoulder?

For types I and II, almost never. For type III, current evidence supports starting without surgery in most cases. A 2024 meta-analysis in BMC Musculoskeletal Disorders pooling 4 randomised trials and 244 patients found no significant difference in Constant scores between surgical and conservative treatment, with less pain in the conservative group at 6 weeks and 3 months. Types IV, V and VI are usually referred to an orthopaedic surgeon. The decision also weighs your sport and your work demands, so it is made with your surgeon and therapist rather than from a grade alone.

How long should I wear a sling?

Most people use a sling for somewhere between a few days and 2 to 3 weeks, mainly for comfort, because it takes the weight of the arm off the injured ligaments. The exact duration depends on your grade and your pain. Wearing it longer than needed costs range of motion and shoulder blade control, both of which are harder to regain than to maintain, so gentle movement usually starts while the sling is still in use. Your physiotherapist will set the schedule after assessing you.

When can I go back to contact sport?

That depends on your grade, your sport, and how the joint responds to loading, so a date from an article would not be reliable. The usual milestones are full pain-free range of motion, strength matching the uninjured side on your therapist's tests, the ability to absorb load through the arm, and tolerance of the specific contact positions your sport demands. In the 2026 meta-analysis of type III to V injuries, return to sport within a year ran at 73 to 85% after surgery and 85% without surgery.

When can I lift overhead again?

Overhead lifting comes back in stages, and it is often slower than athletes expect. A common order is landmine and incline pressing before strict overhead pressing, then lighter overhead work well before anything near a previous maximum. Bench press and dips usually come last, because the bottom position compresses the AC joint directly. A useful guide is that pain during a movement which settles within 24 hours is acceptable, while pain that builds over the next day means dropping back a stage.

Will I get arthritis in the AC joint?

Your odds go up after an injury, though it is far from certain. In the 2016 review in Joints, one series of conservatively managed grade I and II injuries found 54% showing degenerative changes at 6.3 years, and in the type III surgical groups pooled by Xie and colleagues in 2024, posttraumatic osteoarthritis contributed to a 17% revision rate. Both come from small samples. AC joint arthritis usually shows as localised pain on top of the shoulder and discomfort reaching across the body, and it responds to strength work, load management, and sometimes an injection.

My grade 2 sprain still hurts after 3 months. Is that normal?

It is a recognised pattern rather than an unusual one. The 2016 review in Joints found 40% of one series still had significant pain at 6 months, and in another series followed for 6.3 years, 27% eventually had surgery for persistent symptoms at an average of 26 months after injury. Low-grade AC injuries are often described as minor, and the long-term data is more mixed than that word suggests. Persistent pain at 3 months deserves reassessment rather than more waiting.

Can physiotherapy help if I decide against surgery?

Yes, and for grades 1 to 3 it is the main treatment. Rehabilitation does not change the position of the collarbone, so it targets what can change: shoulder blade control, rotator cuff and deltoid strength, and tolerance for the positions and loads you need. The randomised trial evidence shows function after non-operative management matches surgery at 2 years or more for type III to V injuries, which is why a structured rehabilitation plan is a genuine treatment choice rather than a fallback.

Do I need a referral to see a physiotherapist in BC?

No. Physiotherapy is a direct-access profession in British Columbia, regulated by the College of Health and Care Professionals of BC, so you can book an assessment without a physician's referral. Some extended-health insurance plans require a referral for reimbursement even though the profession does not, so confirm with your insurer before your first visit. If your injury came from a motor vehicle crash or happened at work, ICBC and WorkSafeBC have their own processes worth checking early.

Sources

• Lameire et al., "Outcomes After Operative Versus Nonoperative Management of Type III to V Acromioclavicular Joint Dislocations: A Systematic Review and Meta-analysis of Randomized Controlled Trials," Orthopaedic Journal of Sports Medicine, 2026
• Xie et al., "Comparative efficacy of operative versus conservative treatment for Rockwood type III acromioclavicular joint dislocation: a systematic review and meta-analysis of randomized controlled trials," BMC Musculoskeletal Disorders, 2024
• North, "Rockwood grade I and II acromioclavicular injuries: as benign as commonly believed?," Joints, 2016
• Velasquez Garcia et al., "The Reliability of Acromioclavicular Joint Dislocation Classification Systems: A Comparison Between the Rockwood and Kraus Classifications," Orthopaedic Journal of Sports Medicine, 2023
• College of Health and Care Professionals of BC, physiotherapist scope of practice