AC Joint Sprains

The Rockwood system grades AC separations from I to VI. Grade I is a sprain with no visible deformity. Grade II shows the end of the collarbone sitting slightly higher, but not above the top edge of the acromion (the bony point of the shoulder). In Grade III both the AC ligaments and the strong ligaments holding the collarbone down (coracoclavicular ligaments) are fully torn, with a clear step on examination. Grades IV to VI are rare, high-force injuries where the collarbone is pushed backward, far upward or downward, and they usually go straight to a surgical consultation. The ISAKOS 2014 consensus (Beitzel et al., Arthroscopy) split Grade III into stable IIIA and unstable IIIB, based on how well the shoulder blade is working and whether the collarbone overlaps the acromion on a cross-body X-ray. This helps decide between surgery and non-surgical care in the grey zone.

For most people, no. Tang et al.'s meta-analysis (Medicine, 2018) comparing surgery and non-surgical care for Rockwood Type III AC dislocations found no statistical difference in clinical outcomes, and non-surgical care led to lower rates of bone forming in the ligaments (coracoclavicular ligament ossification) and bone loss at the end of the collarbone (lateral clavicle osteolysis). The 2019 Cochrane review of higher-grade AC injuries similarly found, with low-certainty evidence, that surgery did not clearly 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 people whose shoulder blade control and function are still poor after 3 to 6 months of structured rehab, or an unstable pattern on a cross-body X-ray.

It depends on the grade and on what you are returning to. Light daily activity and desk work usually come back first. Heavy lifting at work, pressing in the gym, overhead sport and contact sport take longer, and higher-grade injuries take longer still. In two studies of college and military academy athletes, low-grade (Grade I and II) sprains cost an average of about 10 to 11 days of sport or training (Pallis et al., 2012; Dragoo et al., 2012). Higher-grade injuries took longer, and some of those athletes had surgery. These figures come from young athletes and may not match a manual job or a recreational player. Within each grade, the timeline depends on whether strength and shoulder blade control have been restored, and on whether your sport involves direct contact or heavy overhead load.

Probably not completely. In Grade II and Grade III separations, the visible step where the end of the collarbone sits higher than the acromion often remains, even when the shoulder works well. Once pain settles and the cuff and shoulder blade muscles are strong, many people regain full use of the shoulder with the bump still visible. Ongoing pain or a feeling of instability deserves reassessment. 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.

Eventually yes, with modifications. The AC joint is squeezed and pushed forward and back with high force 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 program 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.

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 people do better on the other side with a pillow hugged under the sore arm, or on their back with a small pillow behind the sore shoulder to stop the arm drifting across the body. Night pain usually settles within 3 to 6 weeks if the joint is not being repeatedly re-irritated during the day.

It can. Arthritis after an injury (post-traumatic arthritis) or bone loss at the end of the collarbone (distal clavicular osteolysis) can develop years later, particularly in people who press heavily or do a lot of overhead work. It is not known whether rehabilitation changes that long-term risk, but building shoulder strength and returning to heavy pressing gradually can help the joint cope with the demands you put on it. If pain at the top of the shoulder comes back, it is worth having it reassessed.

It can help with wear-related AC arthritis or long-standing pain after an injury, where an injection into the joint can give meaningful short-term relief and allow loading work to progress. For a fresh, high-grade separation, an injection is not the main option, since the pain comes from torn ligaments, not joint inflammation. Injection is worth considering sparingly for long-standing pain when symptoms are blocking rehab, not as a first response. Injection itself is something I coordinate with a sports medicine physician. They perform the procedure, and I plan the loading work around it.