Shoulder Instability

The shoulder is one of the body's most flexible parts, featuring a ball-and-socket joint. Here, the humeral head (the "ball" of the upper arm bone) fits into the shallow glenoid cavity (the "socket" of the shoulder blade). This design enables a wide range of motion for lifting, reaching, and throwing. However, despite its flexibility, the shoulder can lose stability, leading to pain and a persistent sensation of looseness.

What Is Shoulder Instability?

Shoulder instability describes a condition where the tissues around the shoulder joint become loose or damaged, allowing the humeral head (the "ball") to move out of its socket. This can manifest as either a partial, temporary displacement (subluxation) or a complete separation (dislocation) of the joint.

What Are the Types of Shoulder Instability?

Depending on its cause, frequency, and direction, shoulder instability can present in several distinct forms. The primary classifications of shoulder instability are:

• Traumatic

  - Traumatic instability is the most common type, typically resulting from a sudden injury that forces the shoulder out of its socket. With this, the shoulder joint either dislocates or subluxes in a single direction.

• Atraumatic

  - This type develops without a specific traumatic event. Atraumatic instability often occurs due to general joint looseness or repetitive overhead movements from activities that repeatedly stress the shoulder.

• Multidirectional

  - This means that the humeral head can be displaced or subluxed in more than one direction. People with multidirectional instability can move their arm forwards, backwards, and downwards, but their shoulder may feel unstable or loose during these movements.

What Are the Causes of Shoulder Instability?

Shoulder instability can stem from trauma, repetitive movements, and other contributing factors, such as:

• Previous Dislocations - Once a shoulder has dislocated, the risk of future dislocations or instability significantly increases, especially if the initial injury caused damage to the stabilising structures that did not heal properly.
• Labral Tears (e.g., SLAP tears, Bankart lesions) - The labrum helps to deepen the shoulder socket and provides an attachment point for ligaments. A tear in the labrum, often sustained during a dislocation or repetitive overhead activities, can compromise shoulder stability.
• Rotator Cuff Injuries - While primarily affecting movement, severe rotator cuff tears can also contribute to instability by compromising the muscles that help hold the humeral head in place.
• Bone Defects - In some cases, bone loss from the shoulder socket (glenoid) or the humeral head (Hill-Sachs lesion) due to repeated dislocations can reduce the stability of the joint.
• General Joint Looseness (Ligamentous Laxity/Hypermobility) - Some individuals are naturally born with looser ligaments throughout their body, making their joints, including the shoulder, more prone to instability. This can be due to genetic factors or connective tissue disorders (e.g., Ehlers-Danlos syndrome).

What Are the Signs and Symptoms of Shoulder Instability?

People experiencing shoulder instability might notice several symptoms and sensations, including:

• A feeling of looseness or slipping out
• Pain during certain motions or shoulder positions
• Shoulder weakness
• Bruising and swelling
• Numbness or tingling
• Limited or unstable range of motion
• Visible Deformity

How is Shoulder Instability Diagnosed?

To determine the cause of the problem, your shoulder doctor will start by discussing your medical history and symptoms. They will ask about when and how your symptoms began, any recent or past traumatic injuries, and if certain movements cause discomfort or a feeling of instability.

Next, a physical examination will be performed. This helps the doctor identify tender areas and assess your shoulder's strength. If more information is needed, your shoulder instability specialist might request an imaging test, such as an X-ray, MRI, or CT scan. These scans provide a detailed look at your shoulder's structure, helping to confirm if instability is the root cause of your symptoms or if another condition is present.

What Are the Treatment Options for Shoulder Instability?

Treatment for shoulder instability depends on the type, cause, and severity of the condition. Treatment options can range from non-surgical approaches to surgical procedures.

Non-surgical Treatments

Initially, your shoulder instability doctor will likely recommend one or more non-surgical treatments to determine how your shoulder responds. These conservative approaches can involve:

• Rest - This involves limiting activities that aggravate the shoulder joint to allow it to heal.
• Shoulder Bracing - A brace provides external support to the shoulder, helping to stabilise the joint.
• Physiotherapy and Shoulder Instability Exercises - These are crucial for strengthening the muscles surrounding the shoulder and improving overall joint stability.
• Activity Modification - Adjusting daily movements and avoiding positions that cause pain or reinjury can prevent further strain on the shoulder.
• Ice/Cold Therapy - Applying ice or cold packs helps to reduce pain and inflammation in the affected area.
• Nonsteroidal Anti-inflammatory Drugs (NSAIDs) - Medications like NSAIDs are used to manage pain and reduce swelling in the shoulder.

Surgical Treatments

In cases where conservative methods fail to alleviate symptoms, surgery may be recommended. Surgical treatments are also considered when shoulder instability is recurrent, if there is structural damage, or if the patient is not willing to give up the activities or sports that provoke their episodes.

Surgical intervention can be performed in two main ways:

• Arthroscopic Surgery - This involves inserting a small camera (arthroscope) and specialised instruments through tiny incisions to repair torn ligaments or the labrum.
• Open Surgery - A larger incision over the shoulder may be necessary to repair more severe damage or instability.

How Can Shoulder Instability Be Prevented?

While not all cases of shoulder instability can be completely avoided, several strategies can significantly reduce the risk and, importantly, minimise the possibility of recurrence. Some prevention strategies include:

• Exercising your shoulder muscles
• Maintaining proper throwing, hitting, or serving techniques
• Taking regular breaks when playing sports and avoiding overtraining
• Always warming up before engaging in strenuous activities and taking time to cool down afterwards

About Our Orthopaedic Surgeon

Dr James Tan Chung Hui

Senior Consultant
Orthopaedic Surgery, Sports & Exercise Medicine
MBBS (S’pore), MRCS (Edin), MMed (Orth), FRCS Orth & Tr (Edin)

Dr James Tan graduated from the NUS Faculty of Medicine and obtained a Master of Medicine (Orthopaedics). He is widely recognised as an orthopaedic surgeon in Singapore for his treatment techniques for shoulder pain and other shoulder conditions. With over 10 years of experience, he specialises in minimally invasive (keyhole) tendon and ligament repair, joint replacement, and muscle-tendon transfers of the shoulder joint.