An acromioclavicular (AC) joint separation isn’t fun, to say the least. When you get hurt, you may have many questions. What symptoms should you be on the lookout for? How long does a runner’s AC joint injury take to heal? What treatment is best? If your mind is racing faster than you are, take a moment to breathe. The process is relatively straightforward.

What Is an Acromioclavicular (AC) Joint Injury?

An AC joint separation happens when the AC ligament that connects your clavicle to the acromion of your scapula — meaning your collarbone to the back end of your shoulder blade — tears. Those two parts detach as a result.

These tears are common, making up over 40% of all shoulder injuries. They can range from a minor sprain to a severe tear. Hopefully, you have the most mild case since they are more likely.

Common AC joint injury symptoms include tenderness, swelling, tightness and loss of motion. You may see bruising or a visible lump. While the pain is often localized to your shoulder, you may feel it radiate across your arm or neck since everything is connected.

The Different Types of AC Joint Injuries

The Rockwood Classification is the most commonly used system for this kind of trauma. It has six distinct categories. Each type of AC joint injury has different symptoms.

Type I

Type I is the least severe classification, making it the best for you to have. It’s only a sprain or partial tear of the AC ligament. You don’t experience any fracture or displacement, making it the easiest to recover from. Returning to running after this AC joint injury is easy.

Type II

Type II damage involves a fully torn AC ligament and a potential coracoclavicular (CC) ligament sprain. There’s a slight increase in the space between the clavicle and the coracoid process of the scapula, which is the hook-shaped bone structure on the front end of your shoulder blade that serves as an attachment point for your ligaments.

Type III

If you experience a Type III, both your AC and CC tear. There’s a larger increase in the space between the clavicle and the coracoid process of the scapula — the coracoclavicular interspace for short.

Type IV

A Type IV separation is the displacement of your distal clavicle. Here’s the English translation — the outer end of your collarbone moves behind your upper back’s large, triangular muscles. Ouch.

Type V

Type V is a severe displacement of the clavicle. There’s a disruption of the AC and coracoclavicular ligaments, as well as the deltoid and trapezius muscle attachments.

Type VI

Type VI damage is the most extreme. It involves inferolateral displacement, meaning your ligaments become lodged below and to the side of your scapula. Thankfully, these are exceedingly rare. For reference, just 12 cases have been recorded in medical literature. One patient had fallen from the fifth floor, explaining the severity of the damage.

Common Causes of AC Joint Separations

Understanding the causes of an AC joint injury can help you speed along the road to recovery. Contributing factors like poor posture, previous scapula injuries and some medical conditions can affect the tear’s severity.

Physical trauma is the main AC joint injury cause. For example, falling directly on your shoulder or outstretched arm can cause a tear. Whether you play contact sports in your free time or are simply clumsy and don’t see a wall in time, sustaining a hard hit can injure you.

Also, lifting or throwing heavy objects like weights — especially during overhead exercises — can tear your ligaments. Your chances of injuring yourself increase during repetitive use due to continuous strain.

How to Treat an AC Joint Injury at Home

AI joint injury treatment is straightforward. Even if you’re midseason, get rest. Don’t sleep on your affected shoulder and avoid weightlifting — even if it means sacrificing your gains. You can put your arm in a brace to immobilize it, which helps the healing process along.

Ice has anti-inflammatory and pain relief effects, so using the tried-and-true ice pack method may help you get through the worst of it. However, while cold therapy has been generally accepted as the go-to treatment following soft-tissue injuries for decades, research shows it may delay healing. This can lengthen your AI joint injury recovery time.

Leaving an ice pack on the affected area for too long may reduce blood flow, potentially causing lasting tissue or nerve damage. Only hold it to your scapula for 20 minutes at a time to avoid causing more damage.

When should you seek medical attention? It’s always wise to get checked out by a professional, especially if you want to use that arm sooner rather than later. They may recommend nonsurgical AC joint injury treatment like physical therapy.

Crucially, if you have a Type III, IV or VI tear, it’s no longer a question — visit a doctor immediately. Sometimes, AC joint injury surgery is necessary for repairing your torn ligaments and restoring shoulder function.

How Long Does an AC Injury Take to Heal?

AC joint injury symptoms can resolve on their own, given enough time. Type I takes seven to 10 days to heal, while Type II usually requires four to six weeks of recovery. Living with an AC joint injury for weeks isn’t easy, but you’ve likely built up quite a bit of endurance as a runner.

How long does it take to recover from an AC joint injury fully? You should wait slightly longer to return to running and weightlifting. Overuse may degrade the bone and ligaments in your shoulder. Wait roughly eight to 12 weeks to be safe.

When is surgery needed for an AC joint injury? For anything more severe, the timeline varies depending on the type of surgical intervention you have and whether there are complications from AC joint injury surgery.

AC Joint Injury Prevention Tips for Runners

Follow these AC joint injury prevention tips to avoid another painfully long recovery process.

1.    Give Yourself Enough Time to Heal

It feels good to be symptom-free — but you shouldn’t let that feeling go to your head. You can damage your bones and cartilage unless you give yourself time to heal properly. Try not to return to your regularly scheduled activities before being medically cleared. 

2.    Strengthen Your Shoulder With Exercise

AC joint injury exercises include physical therapy, strength training, warm-ups and posture correction. They can help you avoid ligament damage in the future.

3.    Wear Protective Gear During Activities

When you tear something once, the likelihood of it happening again increases. Whether you sustained an injury by walking into a wall or falling into another runner during a race, wearing protective equipment in the future can help you avoid reinjury.

Returning to Running After an AC Joint Injury

Remember, diagnosing, treating and recovering from a runner’s AC joint injury isn’t a 100-yard sprint. Think of the process more like running a marathon. It will take time and may be painful, and you might get frustrated over your lack of progress. However, even if you don’t notice it, your body will heal gradually. Returning to running after an AC joint injury is possible.