What is Shoulder Instability? What Are Its Symptoms? How Is It Diagnosed and Treated?

Your shoulder joint is the most flexible joint in your body, but this feature also brings along the risk of shoulder instability. This problem, which can occur when parts of your shoulder joint are stretched or injured, can negatively affect your daily life. Falling, injuring your shoulder while playing sports, or carrying something in a way that strains your shoulder joint too much are among the main causes. In this article, you will find what you need to know about what shoulder instability is, its symptoms, causes, diagnosis, and treatment.

What is Shoulder Instability?

Shoulder instability is a condition where the head of your arm bone comes out of the shoulder socket in a controlled manner or you have the feeling that it is going to slip out. This problem occurs as a result of stretching or damage to the structures holding the shoulder joint together.

Shoulder Joint Anatomy

You can think of the shoulder joint as a ball-and-socket joint. The round head on the upper part of your arm bone (humerus) sits in a socket called the glenoid on your shoulder blade (scapula). This structure allows your arm to move in all directions.

The glenoid socket is quite shallow and flat. In fact, only 25-30% of the humeral head is in contact with this socket. Around the socket, there is a ring of cartilage called the labrum. The labrum increases the depth and surface area of the socket by approximately 50%. This ensures that the large ball safely remains within the socket.

The labrum also acts as a gasket and creates a vacuum effect within the joint. This suction force passively increases the stability of the joint by pulling the arm bone toward the socket.

Stabilizers and Their Functions

The stability of the shoulder joint is provided by passive and dynamic stabilizers. Passive stabilizers are supports originating from the joint's own structure, acting beyond your control.

Passive Stabilizers:

The joint capsule surrounds the shoulder joint like a membrane. The thickenings of this capsule in certain areas form the ligaments. Ligaments act like a seatbelt by stretching at the limits of shoulder movement. In particular, the inferior glenohumeral ligament is the critical structure that prevents the shoulder from dislocating forward when your arm is in an abducted and externally rotated position.

The ligaments holding the shoulder joint together attach directly to the labrum. Therefore, labral tears usually disrupt the function of the ligaments as well, leading to a greater instability problem.

Dynamic Stabilizers:

The rotator cuff muscles are defined as dynamic stabilizers. This muscle group consists of four muscles:

Supraspinatus: Initiates the first degrees of raising the arm upward

Infraspinatus: Provides external rotation of the shoulder

Teres Minor: Assists with external rotation

Subscapularis: Responsible for internal rotation of the shoulder

These muscles stabilize your shoulder by pushing the humeral head toward the socket when you raise your arm. The functional activity of the muscles is of vital importance for the stability of the joint.

How Does Instability Develop?

Since your shoulder joint is extremely flexible, your arm can stretch enough to push the humeral head out of the socket. A dislocation occurs when the humeral head comes completely out of the socket. When it comes out partially, a subluxation condition develops.

In the case of a dislocation or subluxation, your capsule may tear or stretch. When the humeral head comes out of the socket, it tears the labrum and ligaments as it exits. Therefore, the torn capsule and labrum cannot prevent the humeral head from slipping out again.

In the vast majority of traumatic shoulder dislocations, a Bankart tear forms in the anteroinferior part of the labrum. If a bone fragment is also torn off from the edge of the socket along with this tear, it is called a bony Bankart lesion. The compression fracture caused by the impact of the arm bone head against the hard anterior edge of the socket is called a Hill-Sachs lesion.

In some cases, instability can develop without trauma. Repetitive movements gradually cause looseness in the shoulder capsule during the chronic period. Genetic disorders affecting connective tissues can also lead to shoulder instability.

Shoulder Instability Symptoms

Shoulder instability symptoms vary from person to person. While some of you may experience a mild sense of discomfort, others may experience severe pain and limited mobility. The severity of symptoms generally depends on the type and seriousness of the instability.

Physical Symptoms

When your shoulder is completely dislocated, the most prominent symptom is sudden and severe pain. This pain is felt as sharp, burning, or throbbing. Muscle spasms can further increase your pain. A visible deformity occurs in your shoulder region. On the dislocated side, your shoulder flattens and your arm remains in a slightly externally rotated and abducted position.

Swelling and bruising rapidly develop around your shoulder. These symptoms are signs of inflammation. Your range of motion is severely limited. Lifting, rotation, or reaching upward becomes difficult, and you hold your arm close to your body.

In some cases, you may feel numbness or tingling in your arm or fingers. This indicates that the axillary nerve is affected and requires urgent intervention. If there is nerve damage, muscle weakness may develop. Unless there is a complete nerve rupture, this condition is usually temporary.

Symptoms Felt During Movement

In cases of partial dislocation, symptoms are milder. You may hear or feel a popping sensation or sound in the shoulder joint. You get the feeling that your shoulder is loose, going in and out of the joint. You feel weakness in your arm, especially during lifting or movements requiring muscle strength.

You may notice that your shoulder slips in certain positions. This is usually felt during a throwing motion or while raising your hand above your head. You experience a rapid and sudden pain, perceived as if a slip or impingement is occurring in the shoulder.

The feeling that your shoulder is about to dislocate creates insecurity and fear. This psychological state can limit your daily activities. The feeling as if your arm or shoulder is trapped is also a common symptom.

Chronic Symptoms

Over time, recurrent shoulder dislocations develop. Your shoulder repeatedly slips out of place or gives way during certain movements. You learn to avoid movements that cause subluxation.

As instability progresses, looseness increases and you experience frequent dislocations. You have to apply to the emergency department many times. Some individuals who experience frequent dislocations may begin to reduce (put back) their shoulders themselves. However, each dislocation causes a little more damage to the structures in the shoulder.

There is a constant feeling of looseness and insecurity in the shoulder. This condition is seen along with pain originating from the injury. In chronic cases, joint stiffness or loss of strength may become permanent.

Causes of Shoulder Instability

The causes of shoulder instability are examined in three main categories. The first group includes conditions resulting from trauma, while the second group contains problems developing without injury. The third category covers risk factors that increase the risk.

Traumatic Causes

Shoulder dislocations resulting from a fall or impact are the most frequent cause of traumatic instability. When your shoulder goes out of place, the ligaments inside and around the joint are usually injured. Specifically, the structure called the labrum, located between the glenoid and the humeral head, is torn.

More than 95% of shoulder dislocations occur in the anterior direction. Anterior dislocations occur when your arm is forced into abduction and external rotation positions. Posterior dislocations are rare and are usually seen during electrical shocks or epileptic seizures.

The risk of developing recurrent instability after the first dislocation ranges from 14% to 100%. The age at which the first dislocation occurs is the most important factor affecting this rate. When the initial dislocation is observed under the age of 20 and surgical treatment is not performed, the recurrence rate reaches 87%. After the age of 30, this rate drops to 30%.

The most common lesion in traumatic dislocations is the Bankart lesion, which is a capsulolabral detachment from the anteroinferior glenoid rim. This lesion has been reported in 97% of acute traumatic anterior dislocation cases. Bony Bankart lesions, where a bone fragment is also torn off, pose a major risk for recurrent dislocation.

Sports injuries are significant causes of traumatic instability. Collision sports such as American football and rugby carry the highest risk. The prevalence of shoulder instability is twice as high in athletes compared to the general population.

Non-Traumatic Causes

In some cases, instability can develop even if there has been no prior shoulder dislocation. The basis of this condition is usually congenital ligamentous laxity.

Repetitive overhead movements stretch the shoulder ligaments over time. Swimming, tennis, and volleyball are among sports that can stretch the shoulder ligaments. In repetitive stretching and forced occupations, ligaments become loose due to excessive stress. Frequent performance of routine chores like painting or washing a car can trigger the condition.

In a small portion of patients, shoulder instability develops without a history of injury or repetitive strain. In these patients, the shoulder can become loose in multiple directions and result in dislocation. This condition is called multidirectional instability and is seen in individuals who naturally have loose ligaments.

Genetic disorders such as Ehlers-Danlos affect connective tissues and can lead to shoulder instability. Widespread looseness can be seen in many joints throughout the body. Individuals with this condition are sometimes referred to as double-jointed.

Risk Factors

Age is a critical factor regarding shoulder instability. Being young increases the risk of recurrent dislocation. The risk of shoulder instability is 2.7 times higher in men than in women.

Participation in contact sports significantly increases the risk. Sports like football, hockey, and basketball carry high risk. Anterior dislocation is 15-21 times more common than posterior dislocation.

A history of previous shoulder injury is a strong risk factor for recurrent instability. Joint deterioration is observed in 39% of patients with recurrent dislocations within 25 years.

Occupational factors also play a role. Occupations such as painters, mechanics, construction workers, and carpenters require the arm to be moved constantly in the same way and pose a risk. Active athletes and those who use their arms above shoulder level in their work are in the high-risk group.

Having loose ligaments, which is common in swimmers and dancers, is counted as a risk factor. Although hyperlaxity enhances performance, it also brings the risk of instability.

Diagnosis of Shoulder Instability

Your doctor performs a comprehensive evaluation before diagnosing shoulder instability. This process starts with listening to your medical history and continues with special examination techniques. Imaging methods are used to clarify the diagnosis.

Medical History and Physical Examination

Your doctor will ask you how long you have been experiencing problems with your shoulder. They will want to learn about the situations that trigger your shoulder to dislocate. What kind of work you do and whether you play any sports are important information. They will inquire whether you have experienced a shoulder injury before and, if so, what kind of treatment you received.

During the examination, your doctor wants to determine which movements cause your shoulder to lose stability. They test your arm by moving it in multiple directions. They check for tenderness points and your range of motion. Looseness in your shoulder joint is detected and evaluated during the physical examination.

General looseness in your ligaments may also be tested. You may be asked to try to touch your thumb to the underside of your forearm. This simple test shows whether you have widespread ligament laxity in your body. A comparative examination of both shoulders is performed because some differences are considered normal.

Imaging Methods

Your orthopedist may request X-rays of your shoulder taken from various positions. X-rays can show the humeral head coming out of the glenoid. Potential fractures or cracks that may have formed on the glenoid or humeral head appear in these images. In an acute dislocation, true shoulder radiographs and scapula Y radiographs are taken to make a diagnosis.

Magnetic resonance imaging uses magnetic fields and radio waves to produce an image of your shoulder. Thanks to MRI, capsule, labrum, or rotator cuff problems can be easily seen. It shows soft tissues in detail. Contrast-enhanced MRI may sometimes be necessary, especially for a Bankart lesion. Problems occurring in the bone or soft tissue are evaluated clearly as a result of MRI.

Computed tomography uses a special optical scanner and computer to produce images of bones and soft tissue. Thanks to CT, problems with the glenoid, humeral head, capsule, or labrum can be seen. Since computed tomography of the shoulder joint is more effective in showing bone lesions, the glenoid should be evaluated especially on a 3D reconstructed image to measure the defect diameter in the glenoid.

Arthrography is an X-ray imaging system performed by injecting a certain amount of dye into the shoulder. It is used to detect rotator cuff or labrum problems. Contrast is not required for every shoulder MRI, but contrast-enhanced examination may be requested in some cases.

Physical Examination Tests

The apprehension test is valuable in these patients, particularly to determine the direction and degree of instability. This test is usually performed in abduction and external rotation positions for anterior instability. For posterior instability, it is applied in adduction and internal rotation positions. The sensitivity of the apprehension test is 98% and its specificity is 72%.

The relocation test usually follows the apprehension test directly. The sensitivity of the relocation test has been determined as 97% and its specificity as 78%. The combination of apprehension and relocation tests provides a sensitivity of 67% and a specificity of 98%. These tests fundamentally confirm the presence of anterior structural instability.

The jerk test is used to evaluate posteroinferior instability. This test yields very accurate results with 90% sensitivity and 85% specificity. Inferior instability is evaluated with the sulcus sign test. Especially in throwers, internal rotation angles should be evaluated by comparing them with the healthy shoulder. The patient should be placed lying down and a load-shift test should be performed in the anterior-posterior direction of the shoulder.

Shoulder Instability Treatment

The main goal of treatment is to ensure that you regain control of your shoulder. Your orthopedist usually examines your shoulder together with a physical therapy specialist and determines the most appropriate treatment method for your condition. In most cases, a combination of physical therapy and surgery is required.

Conservative Treatment Methods

It is usually waited for a few months to understand how effective conservative treatment is. If you have experienced a complete or partial shoulder dislocation, you should rest your affected arm and avoid strenuous activities for a few days. You should make some lifestyle changes and stay away from movements that worsen your symptoms.

If the pain is severe, immobilization with a cast and sling may be required. Applying ice compresses helps reduce swelling. Nonsteroidal anti-inflammatory drugs such as aspirin and ibuprofen relieve pain and swelling.

Physical therapy enables your shoulder to regain stability, strength, and control. By strengthening the rotator cuff and other shoulder muscles, it arranges them in a way that can replace damaged parts. The physical rehabilitation process is recommended to restore range of motion and can help you return to activities of daily living within a few weeks. Physical therapy should be continued for three to six months.

Surgical Treatment

Surgery is generally required to repair torn or stretched ligaments. Surgical intervention is indicated especially in recurrent dislocations and structural damage. Surgical treatment may be recommended for individuals who have a high risk of recurrent shoulder instability or who have previously suffered shoulder damage.

Arthroscopy is a minimally invasive surgery. A torn Bankart lesion can be repaired using this closed surgical technique. The inside of the shoulder is entered with a small camera, and the surgery is performed using special fine instruments. The patient can be discharged on the same day or the next day. Arthroscopy helps stabilize mild looseness.

Open surgery procedures may be required in some patients. The shoulder is entered through a larger incision and torn ligaments are repaired. Invasive open surgery is preferred in cases of severe shoulder instability. Post-operative hospitalization and rehabilitation are longer.

Stitches are used to perform the surgery, or metal or plastic anchors are used to reattach the ligaments and hold them in place. The probability of shoulder instability recurring after surgery is quite low, between 3-5%.

Post-Operative Recovery Process

After surgery, your shoulder is temporarily immobilized with a sling. The patient undergoes stabilization with an arm sling for a period of 3 weeks. Isometric exercises and elbow movements are permitted during this period.

With the support of physical rehabilitation, full mobility can be achieved within approximately 6-8 weeks, and a gradual return to other activities can be made. Strengthening and coordination-providing physical therapy is started simultaneously.

Physical Therapy and Rehabilitation

Exercises are initiated to rehabilitate the ligaments. This will improve the shoulder joint range of motion and prevent scarring with the healing of ligaments. Exercises for strengthening the shoulder are slowly added to your rehabilitation plan.

Following the treatment plan is crucial for success. Although the recovery process is slow and long, your commitment to physical therapy is the most important factor in returning to all the activities you enjoy. The vast majority of patients respond positively to rehabilitation and achieve good results.

Shoulder Instability in Summary

Shoulder instability is an annoying problem that can negatively affect your daily life. While it can occur as a result of a fall or sports injury, it can also develop due to repetitive movements or ligament laxity. Early diagnosis and the correct treatment approach ensure that you get successful results.

Recovery is possible with physical therapy and exercises in most cases. However, surgical intervention may be required in recurrent dislocations. It is critically important to be patient during the treatment process and continue your physical therapy program regularly. By following your doctor's recommendations, you can return to your normal activities within a few months and ensure that your shoulder regains its former strength.