What grade is my AC joint injury?

The Rockwood system grades AC separations from I to VI. Grade I is a sprain with no visible deformity. Grade II shows the distal clavicle slightly elevated but not above the superior border of the acromion. Grade III involves complete AC and coracoclavicular ligament disruption with clear step-off on examination. Grades IV through VI are rare high-energy injuries with the clavicle displaced posteriorly, markedly superiorly, or inferiorly, and usually go straight to surgical consultation. The ISAKOS 2014 consensus (Beitzel et al., Arthroscopy) subclassified Grade III into stable IIIA and unstable IIIB based on scapular dysfunction and overriding on the cross-body adduction view, which helps direct surgical versus conservative decisions in the grey zone.

Do I need surgery for a Grade III separation?

For most people, no. Tang et al.'s meta-analysis (Medicine, 2018) comparing surgical and conservative management of Rockwood Type III AC dislocations found no statistical difference in clinical outcomes, and conservative treatment resulted in lower rates of coracoclavicular ligament ossification and lateral clavicle osteolysis. The 2019 Cochrane review of high-grade AC injuries (types III to VI) similarly found surgery did not reliably improve shoulder function, return to activities, or quality of life at one year. I reserve surgical referral for overhead athletes, manual labourers with high demands, or patients with persistent scapular dysfunction and functional loss after 3 to 6 months of structured rehab, or an unstable pattern on cross-body adduction view.

How long until I can go back to work or sport?

Grade I injuries typically settle enough for light activity in 2 to 3 weeks, full sport in 4 to 6 weeks. Grade II usually needs 4 to 6 weeks of protected loading with return to contact sport around 6 to 8 weeks. Grade III treated conservatively often takes 8 to 12 weeks to return to full contact, though professional contact athletes frequently return faster with NFL and NCAA data showing mean loss of play around 26 to 32 days. Timelines depend less on the grade on X-ray than on whether strength and scapular control have been restored, and whether your sport involves direct contact or heavy overhead load.

Will the bump ever go away?

Probably not completely. In Grade II and Grade III separations, the visible step-off where the distal clavicle sits higher than the acromion is usually permanent, even with good functional outcomes. The bump is cosmetic, not functional. Once pain settles and the cuff and scapula are strong, most people regain full use of the shoulder with the deformity still visible. Surgery can correct the cosmetic deformity but does not reliably improve function compared to rehab, which is why it is usually not recommended on cosmetic grounds alone.

Is it safe to bench press again?

Eventually yes, with modifications. The AC joint sees high compressive and anteroposterior shear forces during pressing, especially with a wide grip and elbows flared, which is why bench press is one of the most commonly reported aggravators in recreational lifters. Early on I keep pressing out of the programme completely. As things settle I reintroduce landmine press and floor press, then close-grip bench with the elbows tucked, then full-range bench with a narrower grip. The wide-grip competition-style bench is the last movement to come back. People who rush the wide grip tend to re-flare the joint.

Why does sleeping on that side hurt?

The AC joint is just under the skin at the top of your shoulder with very little soft tissue padding, so lying on it directly compresses an already irritated joint. Most patients do better on the unaffected side with a pillow hugged under the sore arm, or on their back with a small pillow behind the affected shoulder to prevent the arm drifting into adduction. Night pain usually settles within 3 to 6 weeks if the joint is not being repeatedly re-irritated during the day.

Can AC joint arthritis develop later?

Yes, and this is part of why rehab quality matters even for a Grade I or II. The AC joint is a small, heavily loaded joint, and post-traumatic osteoarthritis or distal clavicular osteolysis can develop years later, particularly in overhead athletes and people who do high-volume bench pressing or CrossFit-style training. The risk is meaningfully higher after Grade III and above. Restoring normal scapular mechanics, building cuff capacity, and avoiding chronic low-grade overload after return to sport reduces the chance of long-term trouble.

Does a cortisone injection help?

It can help in degenerative AC arthritis or chronic post-traumatic pain, where a targeted intra-articular injection can produce meaningful short-term relief and allow loading work to progress. For acute high-grade separations, injection is not the main play since the pain reflects ligamentous injury, not joint inflammation. I use injection sparingly in the chronic setting when symptoms are blocking rehab, not as a first response.

AC Joint Sprains

Acromioclavicular joint separations and arthritis

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AC joint injuries involve damage to ligaments connecting the clavicle to the acromion. These range from sprains to complete separations. The joint is superficial and vulnerable to direct trauma.

Conditions I commonly see alongside, or confused with, this one.

Rotator Cuff Injuries
Biomechanically linked
AC joint dysfunction alters shoulder mechanics and can stress rotator cuff
Shoulder Impingement Syndrome
Biomechanically linked
AC joint pathology can contribute to subacromial impingement
Frozen Shoulder
Shares symptoms
Both cause shoulder pain; AC joint injury can lead to protective stiffness

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AC Joint Sprains

The Science of AC Joint Sprains

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