What to Know About Shoulder Instability

Medically Reviewed by Dany Paul Baby, MD on November 02, 2022
5 min read

Many people have heard the term shoulder instability but have wondered what that means. So, what is shoulder instability?

Many structures are responsible for stabilizing your shoulders. This includes the joint surfaces, ligaments, capsules, and muscles. Shoulder instability is an issue affecting the structures surrounding the shoulder joint, typically when these structures do not work properly and fail to hold the ball of the shoulder in its socket.

Shoulder instability does not merely refer to one disorder. Instead, it refers to many shoulder disorders, including dislocation, subluxation, and laxity. The most common type of shoulder instability is known as anterior instability, and it is often the result of a nerve injury.

Shoulder instability can be short-term, or it can be chronic. Chronic shoulder instability occurs when the top of your arm bone, also called the head of your arm bone, slips out of its socket. This can cause your shoulder to dislocate, or it may itself be caused by a dislocated shoulder. Shoulder dislocation happens when the shoulder completely disconnects (dislocates) from the joint.

Shoulder instability can also result from strenuous activities involving your shoulders, such as sports or exercises. Untreated chronic instability can then eventually result in arthritis of the shoulder joint.

There have been efforts to categorize shoulder instability into different types depending on the laxity of the shoulder, the frequency and severity of symptoms, and the formation of particular anatomic lesions. There have also been efforts to categorize instability into directional categories: anterior, posterior, and multidirectional. 

  • Anterior instability: Anterior instability is the most common of the three instabilities and typically results from dislocation or subluxation. Between 85% and 95% of shoulder dislocations fall into the anterior category, mainly affecting men between the ages of 18 and 25.
  • Posterior instability: Posterior instability, which can follow traumatic dislocation, is a rarer form of instability and typically occurs due to athletic trauma or generalized muscle contractions from seizures or electric shocks.
  • Multidirectional instability: Multidirectional instability results less often from dislocations and more commonly from congenital hyperlaxity of the glenohumeral joint capsule, which occurs when you can move your joints behind their normal range.

The shoulder instability symptoms you experience will depend on the type of instability and its severity. For example, a patient experiencing anterior instability may have sustained an injury to their nerves. As a result, they may experience pain when rotating their arm, loss of sensation in the affected arm, and numbness or tingling. Additionally, there may be a palpable mass noticeable over the anterior shoulder. 

Those with posterior instability may experience weakness in their posterior rotator cuffs and a loss of range of motion in the affected shoulder. 

Finally, patients experiencing multidirectional instability may notice weakness and slight pain when engaging in certain activities. 

Despite these differences, a few common symptoms may be present regardless of the type of instability a patient is experiencing. These symptoms include: 

  • Repeated shoulder dislocation
  • Shoulder pain 
  • A shoulder joint that feels loose
  • A feeling that your arm bone is slipping from its joint 

If you’re experiencing shoulder dislocations, you may also have the following symptoms: 

  • Severe shoulder pain that occurs suddenly 
  • Feelings of pin and needles and numbness, especially if a nerve or blood vessel has been damaged 
  • Discoloration of the arm and hand, especially if a nerve or blood vessel has been damaged 
  • Loss of shoulder mobility, as well as experiences of difficulty and pain when trying to move the affected shoulder 
  • Deformity of the shoulder 
  • Swelling

Shoulders are among the most flexible components of the human body, able to move in various directions. Your shoulder helps you move and rotate your arm and allows you to reach above your head. Because shoulders have such great range of motion, though, they are more susceptible to instability, usually resulting when the top of the arm bone comes out of the shoulder socket, either following injury or overuse. 

Shoulder instability has two primary causes, so patients are usually divided into two categories: patients with post-traumatic shoulder instability injuries or patients who have shoulder joints that are naturally loose.

The most common shoulder instability cause is injury. Injury can occur from sports, blunt-force trauma, or simply overuse of ligaments and muscles. Other common causes include: 

  • Age 
  • Strenuous manual labor

Shoulder instability diagnosis usually occurs when you notice symptoms and go to the doctor because the pain or lack of range of motion is affecting your daily life. 

You will discuss your symptoms, medical history, and any recent traumatic injuries with your doctor, who will then perform a complete physical with a focus on your shoulder. Your doctor may check for areas of tenderness and test the strength of your shoulder.

Your doctor may also perform specific tests and shoulder instability exercises to assess your shoulder instability, such as range of motion tests, and they may look for signs that your ligaments are experiencing general looseness. You may be asked to perform simple motions like touching your thumb underneath your forearm. 

Finally, imaging tests may be used to rule out other conditions. Your doctor may order an X-ray or MRI to look at the shoulder’s structure to determine whether shoulder instability is the root cause of your symptoms or you’re experiencing another condition.

Shoulder instability treatment will vary, depending on how severe the instability is. Surgical treatment may be required. 

First, though, you should reduce the movement of your shoulder as soon as possible, especially if acute dislocation is present. Sedatives in the form of narcotics may be prescribed to help with this reduction. 

Most doctors will try to perform nonsurgical remedies before resorting to surgical treatment. Physical therapy may be required to improve strength and help you control your shoulder muscles while working to improve shoulder instability. Non-steroidal anti-inflammatory medications may also be used to help with pain and swelling. 

If nonsurgical treatments aren’t working, though, your doctor may recommend surgery, especially if your ligaments are torn or stretched.

Shoulder instability recovery time depends on how severe the condition is and whether you need surgery. Surgical recovery time can vary, too, and will depend on which procedure was performed. The hand, wrist, and elbow may have their range of motion restored on the day after surgery. You may be able to resume writing and eating with your affected shoulder, arm, and hand three to seven days after surgery. 

You’ll usually need to enroll in a physical therapy program following surgery. During physical therapy, you will work to restore range of motion and strength to your affected arm. You may find that your range of motion returns within eight weeks, while full strength returns in three months. Your doctor and physical therapist will tell you when you can return to your daily activities and work.

If you underwent surgical operations to fix your shoulder instability, there is a low chance of recurring damage, typically 3 to 5%.

If your job is the cause of your shoulder instability, you’ll need to discuss treatment and management options with your doctor, who may suggest over-the-counter medications. Sports-related shoulder instability may require you to stop playing sports. In this case, your doctor may recommend resistance and weight-lifting exercises to maintain fitness. 

If you cannot change jobs or give up the activities causing your shoulder instability, consult with your doctor and discuss further options to manage your condition.