A Comprehensive Guide to Shoulder Dislocation in 2023

Dr. Pamela Mehta, MD
Orthopedic Surgeon, San Jose

Everything You Need to Know About Shoulder Dislocation - Anterior, Posterior, and Inferior

Everything You Need to Know About Anterior, Posterior, and Inferior Shoulder Dislocation

The shoulder is the most likely joint in your body to dislocate, often coming out of place during contact sports such as football, rugby, and martial arts. The ball and socket mechanism of the shoulder joint makes it very mobile, which allows your arm to get into all sorts of positions, but also means it’s more vulnerable to dislocation. There are a few different types of shoulder dislocation and the treatment and complications for each type can differ.

Shoulder dislocation usually happens because of a blow to the shoulder or fall on an outstretched arm – occurring during sports injuries, falls, and trauma. Complications of shoulder dislocation can include:

  • Fracture of your clavicle (collarbone) or humerus
  • Muscle, ligament, and tendon sprains and tears
  • Damage to the nerves that pass nearby your shoulder joint, causing numbness and weakness
  • Chronic shoulder instability – which makes you prone to having further injuries and dislocations

When your shoulder dislocates, it can move forward, backward, or downward. In this guide, we will discuss these types of shoulder dislocation and the difference between a full and partial shoulder dislocation.

You can also check out our guide to the best exercises for shoulder dislocation.

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Anterior Shoulder Dislocation

Anterior shoulder dislocation, where the top of your humerus (the “ball”) moves forwards and away from the glenoid cavity (the “socket”), is by far the most common type of shoulder dislocation – making up around 97% of shoulder dislocations.

The groups most commonly affected by anterior shoulder dislocation are young men – generally from sports injuries and trauma – and older adults, often from falls. The mechanism of anterior shoulder dislocation is usually due to a high force of external rotation occurring while the arm is out.

Let’s make that easier to understand. Hold out your arm horizontally with the elbow bent at 90 degrees so that your hand is pointing at the sky with your palm facing forward.

elbow at 90 degrees

While keeping your upper arm horizontal and your elbow at 90 degrees, rotate your forearm so that it’s pointing at the ground.

shoulder abducted and internally rotated

Pretty easy, right?

Now get into the original position and try to rotate your forearm in the opposite direction. If you’re keeping everything else still, you should feel discomfort in the front of your shoulder.

shoulder abducted to 90 degrees and externally rotated

In anterior shoulder dislocation, a force is applying additional pressure in this position, but your arm can’t move any further back, and so the “ball” part of your shoulder joint dislocates forwards out of the joint.

Signs of an anterior shoulder dislocation include:

  • Pain in the shoulder with difficulty moving your arm
  • A “bump” in your shoulder, meaning it loses the normally rounded appearance
  • You may be able to feel the top of your humerus on the front of your arm, slightly below the shoulder joint
  • When the most comfortable position for your arm is to hold it slightly out from your body
  • Numbness in your arm (a sign of potential nerve damage)

You may have seen some people – those who suffer from shoulder instability and have frequent anterior shoulder dislocations – put the joint back in place themselves. This can be dangerous, especially if this is your first dislocation. Shoulder dislocations are frequently associated with fractures, nerve injuries, and rotator cuff tears. If you try to treat it yourself, you may cause further damage or miss a treatable condition.

Before being treated, an anterior shoulder dislocation requires careful examination by a healthcare professional, followed by an x-ray to check for fractures. If there are no complications, the shoulder joint can be treated using a shoulder relocation technique.

Sometimes anterior shoulder dislocation requires surgery – either when the shoulder cannot be relocated with simple techniques, or when there is associated damage to the nerves, tendons, and muscles of the shoulder. Minimally invasive shoulder surgery, such as shoulder arthroscopy, is the treatment of choice where simple measures have failed.

Recurrent dislocation of the shoulder can be a problem for anyone who suffers from an anterior shoulder dislocation, particularly if their first dislocation occurred at a young age. Those who suffered from a shoulder dislocation under the age of 25 are very likely to suffer from a further dislocation at some point in their lives.

Anterior Shoulder Dislocation X-Ray

An x-ray is the main, and often only, investigation required to diagnose an anterior shoulder dislocation. This is usually performed in the emergency room, giving your emergency medicine physician or orthopedic surgeon the ability to quickly diagnose and treat the problem without the need for more intensive tests like an MRI scan.

There are two main views that are used to diagnose shoulder dislocation: the AP (anteroposterior) view and the Y view. The AP view shows the front of the shoulder, while the Y view shows the top of the shoulder.

In a normal shoulder, the humeral head (the ball-shaped bone at the top of the arm) fits snugly into the glenoid fossa (the socket in the shoulder blade). In a shoulder dislocation, the humeral head has moved out of this socket.

On an x-ray, a shoulder dislocation will appear as a gap between the humeral head and the glenoid fossa. There may also be other signs of injury, such as fractures of the humeral head or the clavicle.

Below you can see Anterior-posterior views (AP) of two shoulder X-rays, comparing a normal shoulder X-ray with an anterior dislocation. Here you can clearly see how the head of the humerus (the “ball”) has moved anteriorly (forwards) and no longer sits nicely against the glenoid fossa (the “socket”).

Anterior shoulder dislocation x-ray

In most cases, an X-ray is the only investigation required to diagnose shoulder dislocation. However, in some cases, additional imaging tests, such as CT or MRI, may be needed to get a more detailed view of the injury.

Posterior Shoulder Dislocation

shoulder dislocation xray

Posterior shoulder dislocations, where the shoulder dislocates and moves backwards, is the second most common type of shoulder dislocation – occurring in about 2-4% of all cases.

Young adult men are the group most affected by posterior shoulder dislocation. These usually occur due to trauma, such as in sports injuries or car accidents, or seizures, where uncontrolled and violent movements of the muscles cause the shoulder to dislocate in this uncommon manner.

As posterior shoulder dislocation is less common than anterior shoulder dislocation, there is a risk that it can be misdiagnosed. If the symptoms of shoulder dislocation are present but the initial (anteroposterior) x-ray is normal, additional x-rays should be performed to check for posterior dislocation.

Signs of a posterior shoulder dislocation include:

  • Pain and loss of movement in the shoulder
  • An abnormal-looking shoulder – with bumps and dips instead of a smooth round appearance
  • When the most comfortable position for your arm is to hold it in front of your torso with your elbow bent – like someone who has their arm in a sling

Almost a third of patients with posterior shoulder dislocation have an associated fracture, and complications are more likely the longer it takes to get treatment. As there is an association with fractures, an x-ray or CT scan must be taken before there is an attempt to relocate the shoulder joint.

Treatment for posterior shoulder dislocation may require more sedation and pain relief than anterior shoulder dislocation and may sometimes require shoulder surgery – particularly if there is an associated fracture.

Posterior Shoulder Dislocation Xray and MRI

While an anterior shoulder dislocation is usually visible on an anteroposterior xray, posterior shoulder dislocations may be missed on anteroposterior x rays 50% of the time. If there are signs of a dislocation, but the frontal radiograph is normal, an axillary view xray should be taken, or an MRI scan if this is available.

AP View

x ray of a posterior shoulder dislocation - anteroposterior AP view

Lateral View

x ray of a posterior shoulder dislocation - lateral view

These x rays show a full posterior shoulder dislocation – both anteroposterior and lateral views have been obtained to confirm diagnosis. The humeral head (top of the bone in the upper arm) is fixed in internal rotation, meaning it has a rounded appearance – known as the lightbulb sign – commonly seen on posterior shoulder dislocation xray.

Posterior Dislocation X-ray Comparison

This MRI scan shows a “reverse Hills-Sachs defect” – an injury often associated with posterior shoulder dislocation. MRI and CT scans can be used to help identify posterior shoulder dislocation and rule out associated fractures.

posterior shoulder dislocation MRI scan
MRI Scan of a posterior shoulder dislocation

Inferior Shoulder Dislocation

black and white shoulder joint

Inferior shoulder dislocations are the rarest form of shoulder dislocation, accounting for roughly 0.5% of cases. The name means that the humeral head (the “ball” of the shoulder joint) dislocates downwards out of the glenoid cavity (the “socket”). This form of dislocation is often referred to as luxatio erecta, the name coming from the typical presentation where the patient’s arm is held above their head.

Trauma is the most common cause of inferior shoulder dislocation, such as when someone is holding their arm above their head to grasp something as they fall. An example of this is when a motorbike rider falls off their bike, with their arms reaching above their head so that when their arm hits the ground the arm faces extreme pressure and dislocates inferiorly (moves downwards). 

An inferior shoulder dislocation is typically very painful and is often associated with fractures and nerve injuries, causing numbness and weakness in the arm. When evaluated in a hospital, these injuries require careful clinical assessment and imaging to examine the extent of the injury. Shoulder surgery will be required if there is significant damage to the joint, or if the treating clinician cannot relocate the joint.

Even if your treating clinician can relocate the shoulder joint without surgery, you are likely to have limited shoulder movement for 2-6 weeks. Many of those affected by inferior shoulder dislocation will, unfortunately, suffer from recurrent shoulder dislocation.

Partial Shoulder Dislocation

Partial shoulder dislocation, also known as shoulder subluxation, is when the head of the humerus (the “ball” of the shoulder joint) partially comes out of the glenoid cavity (the “socket”) but does not completely come out of place.

Shoulder subluxation has similar symptoms to a full shoulder dislocation, but the shoulder deformity might not be as clear. Symptoms include:

  • Shoulder pain
  • Difficulty moving your shoulder
  • Swelling and deformity in the shoulder joint
  • Numbness in your arm

While with full dislocations you are often unable to move your arm at all, with partial shoulder dislocation you may be able to move your arm, albeit with some discomfort and sometimes a catching sensation – particularly for overhead movements.

Partial shoulder dislocations are caused by sports injuries, trauma, and falls. In partial dislocation, the blow to the shoulder was generally not sufficient to fully dislocate the joint.

You’re more likely to experience shoulder subluxation if you’ve previously suffered from a shoulder dislocation, or have been diagnosed with shoulder instability. This is because the ligaments, muscles, and cartilage of the shoulder joint is damaged and looser, making the movement of the humeral head out of the socket easier. 

For this reason, it is important that you seek appropriate treatment to strengthen your shoulder joint after a partial or full dislocation.

Shoulder Dislocation Treatment

patient getting treatment for shoulder dislocation

Treatment for shoulder dislocation depends on the severity of the injury, whether you’ve suffered any of the complications, and what type of dislocation has occurred. Many shoulder dislocations can be treated in the emergency department following careful assessment, using sedation and pain relief.

Here is an example of how a clinician relocates a dislocated shoulder (this should never be attempted by those without proper training):

If you’ve suffered a shoulder dislocation which has been relocated without surgery, you will have a few weeks of limited shoulder movement and rehabilitation before you can fully move your arm again. It may also be difficult to sleep.

Your doctor may place your arm in a sling for a short time following a shoulder dislocation. Other rehabilitation activities your doctor may recommend include:

  • Resting your affected arm for several weeks
  • Avoiding any heavy lifting or awkward overhead movements
  • Simple pain relief such as acetaminophen or ibuprofen
  • Ice packs placed on your shoulder several times a day for the first few days
  • Once the inflammation has improved, switching to heat packs
  • Light exercises as directed by your orthopedist or physical therapist

Sometimes shoulder dislocation requires surgery to repair damaged tissue and treat complex dislocations. You must always seek professional help following a shoulder dislocation – if you try to treat it yourself you may end up with nerve damage or an untreated fracture.

Conclusion

So that’s everything you need to know about shoulder dislocation! We’ve covered all of the different types of shoulder dislocation, as well as how to get your shoulder back to usual after you’ve suffered a dislocation.

If you suspect that you have dislocated your shoulder, please avoid treating it yourself. Instead of risking a lifelong injury, book a consultation with an orthopedic doctor near you and get your recovery off to a good start.

How Resilience Orthopedics Can Help

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Dr. Pamela Mehta is an orthopedic surgeon and a specialist in sports injuries, degenerative arthritis, and minimally invasive surgery. Dr. Mehta offers a concierge service and treats you holistically, rather than just fixing your joints. She listens to your concerns, takes time to explain how your condition and potential surgery will affect you, and works with you to create the best treatment plan.

Resilience Orthopedics is based San Jose, California. To make sure you get the right diagnosis and treatment the first time, get in touch to begin your journey to recovery.

Testimonials

Ruby G.
Ruby G.
2021-07-30
Verified
My experience with Dr Mehta was simply phenomenal. I had a cyst on my wrist and severe shoulder pain. Dr Mehta scheduled me quickly and her staff were so kind and personable.  She discussed the treatment plan with me in detail and made me comfortable with plan. Her bedside manner was kind, empathetic and thoughtful and she went out of her way to make me feel comfortable. After treatment my shoulder was pain free after months of agony, and she removed the cyst  from my wrist.   She followed up with me the next day to make sure I was ok. I can't recommend Dr Mehta highly enough, high quality, comfortable treatment from a wonderfully skilled surgeon. Thank you Dr Mehta!
S G.
S G.
2020-07-29
Verified
I highly recommend Dr. Pamela Mehta. I was recently helped by her for a broken bone that needed surgery. She is a very detailed-oriented and thorough orthopedic surgeon who thinks creatively about solving problems every step of the presurgery, surgery and recovery. She is top-notch. I had an extremely positive experience with her and would recommend her and her staff to anyone seeking a smart, professional and detailed team for a bone cast or orthopedic surgery.
Samantha L.
Samantha L.
2020-06-14
Verified
When your children like to run around barefoot it is inevitable that they will eventually get something lodged into their foot. Our daughter was climbing some trees in our backyard and wedged a couple splinters deep in her foot. After a few hours of attempts at home to remove these splinters with our own tweezers, soaking the feet, various internet remedies (and lots of scared screaming from our daughter when we got near her with tweezers) we sought the help of Dr. Mehta. Dr. Mehta's kind and calming approach was most helpful when she quickly examined the foot, spoke with our daughter, and then removed the two splinters from her foot. She helped to keep our daughter calm during the procedure and deftly pulled out the splinters. We recommend Dr. Mehta to anyone needing an expert physician who can deal with delicate patients!
Michele G.
Michele G.
2020-06-14
Verified
Dr. Pamela Mehta earned my highest MD review.  I have seen a half dozen surgeon's involving multiple surgeries for orthopedic injury and this doctor checks all the best boxes: * an emphatic listener * holistic 'whole person' treatment; much more than just a skilled surgeon * tightly networked to other excellent coordinating care MD's * recommends surgical alternatives whenever possible * real concern for functional patient outcomes * tough when needed, even when treatment is uncomfortable * solid, well organized support staff Thank You Dr. Mehta!
Aaliya Y.
Aaliya Y.
2020-06-09
Verified
I consulted Dr. Mehta after breaking my ankle in December 2019. She was extremely empathetic, knowledgeable, and took her time to explain everything to me so that I had a good understanding of my fracture and management options. She held my hand and got me comfortable with the idea of surgery and allayed my fears. Her office was very responsive, timely and  worked efficiently to help me get my imaging done in an expeditious manner. I highly recommend her for her incredible bedside manner, empathy and level of expertise. She is exactly what you want in your surgeon.
Katrina A.
Katrina A.
2020-02-12
Verified
Life is full of mishaps and great relationships. I had one really big mishap and happily stumbled into a a wonderful relationship. I've been blessed to cross paths with the beautiful professional Dr. Mehta and her wonderful staff. In a time when pain seriously interferes with manners. They were kind and gracious even when I was not. The of staff  everything they we always great.
Mike V.
Mike V.
2020-01-10
Verified
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A T.
A T.
2019-12-01
Verified
This review is long overdue from a very happy and ever so grateful patient! I was having major shoulder pain to the point where I couldn't raise my left shoulder. I decided to go to Dr. Mehta after a friend recommended me to her.  Dr. Mehta was very attentive during our initial apt. She was quickly able to diagnose the root cause of my shoulder issue and explained the how and why I ended up with this pain. Her treatment plan involved me doing various mobility exercises and after two weeks I can honestly say I am at least 50% better. I think a few other Yelp reviewers mentioned this but I have to say it again, Dr Mehta truly cares about her patients and it was very apparent from how she followed up with my recovery. She called and emailed me to make sure I was following the plan and kept up with all my progress. I'm not sure how Dr Mehta finds the time to do all this but after my experience with her, I can say with certainty that she is a very skillful doctor and I have 100% trust in her.
steve k.
steve k.
2019-11-22
Verified
I had a great experience my one time meeting Dr Mehta. She walked me through what the problem was and the course of action to fix it. She laid things out calmly with a step by step of how we get me back to 100% with no future pain. Her calm demeanor and thorough explanation made me feel at ease that everything would work out fine. I followed the steps provided and everything did work out just as she'd laid out. Should something come up again I will definitely be going to Dr Mehta again.
gajan t.
gajan t.
2019-11-19
Verified
I write only a few Yelp reviews a year, and hope that this will help anyone who is trying to find the right orthopedic doctor.  I went to 3 orthopedic doctors when I had a serious knee issue earlier this year. Although, I received good advice from all the doctors, I chose Dr. Mehta because she spent a considerable amount of time helping me to understand the root cause of my knee pain and then created a blueprint moving forward of preventative measures. She was definitely very insightful in her diagnosis and more importantly her treatment. What actually inspired me to really write this yelp review was because of her follow up calls and how much I realized that she really wanted to see me get better. I've been to many good doctors in the bay area but only a handful that offer this much personalized care. I highly recommend Dr. Mehta and happy to talk to anyone about my experience if you trying to decide on an orthopedic doctor.