Shoulder Conditions

Shoulder Dislocation and Instability

Shoulder Dislocation and Instability: Causes, Symptoms, Diagnosis and Treatment Options

Shoulder dislocation and instability occur when the ball of the shoulder joint (the humeral head) moves partially or completely out of the socket (the glenoid). This can result in pain, weakness, loss of confidence in the shoulder, and an increased risk of further injury if not appropriately managed. Because the shoulder allows a large range of motion and has relatively little inherent bony stability, it is particularly vulnerable to instability following trauma such as a sports injury, or repetitive stress.

Why Is the Shoulder Prone to Dislocation and Instability?

The shoulder socket is naturally shallow and is often compared to a golf tee, with the ball of the shoulder joint sitting on top. There is little by way of bone structure to keep the ball in place.

Unlike joints such as the hip, shoulder stability relies heavily on soft tissue structures rather than bone.

Key soft tissue stabilising structures are:

Unlike joints such as the hip, shoulder stability relies heavily on soft tissue structures rather than bone.

When the glenoid labrum and/or ligaments are torn or stretched, the shoulder may no longer remain centred during movement, leading to instability.

Instability: Subluxation vs Shoulder Dislocation

1 Shoulder Subluxation

Occurs when the joint partially slips out of position but relocates spontaneously

2 Shoulder Dislocation

Occurs when the joint fully comes out of the socket and often requires manual reduction, sometimes in an emergency department

Both events can damage important stabilising structures within the shoulder and increase the risk of ongoing instability.

Common Causes of Shoulder Dislocation

Shoulder dislocation most commonly occurs following a traumatic incident, including:

The most frequent pattern is an anterior shoulder dislocation, where the humeral head moves forward out of the socket.

Posterior instability is when the humeral head shifts backwards. It is less common, and symptoms are more often pain with lifting or overhead use and a feeling of slipping in the shoulder rather than full dislocations. It may evade diagnosis and mimic impingement and other types of shoulder problems. There may not be a history of a specific injury.

Multi-directional instability (MDI) occurs due to loose ligaments of the shoulder an individual is born with. The labrum is not usually torn. The shoulder moves in any direction. The looseness may not cause any issues until an injury alters shoulder muscle balance following which pain or repeated dislocations and feelings of subluxation start to occur.

Injuries Associated with Shoulder Dislocation

Labral and Soft Tissue Injury (Bankart Lesions)

For a shoulder to dislocate, injury to the labrum and joint capsule almost always occurs. In anterior dislocations, this typically results in a tear of the front portion of the labrum, known as a Bankart lesion. This injury compromises the shoulder’s ability to remain centred during movement and significantly increases the risk of further dislocations if left untreated.

Bone Injury Associated with Shoulder Instability

Common examples include:

Loss of bone from either side of the joint significantly reduces shoulder stability and plays a critical role in treatment planning.

Shoulder Dislocation in Adults Over 40

In patients over the age of 40, recurrent instability is often less common. Instead, shoulder dislocation in this age group is more frequently associated with acute rotator cuff tears. Persistent pain and weakness following reduction of a dislocation may indicate rotator cuff injury. In these cases, imaging such as an MRI is commonly recommended to assess tendon integrity and guide management.

How Shoulder Instability Is Diagnosed

Assessment begins with identifying the exact cause and pattern of instability, as this directly influences treatment decisions.

Evaluation typically includes:

The goal is to determine whether instability is primarily related to soft tissue injury, bone damage, or a combination of both.

A detailed injury history and symptom review

Physical examination assessing stability, strength, and range of motion

Imaging such as X-rays, MRI, or CT scans where appropriate

How Shoulder Instability Is Diagnosed

Assessment begins with identifying the exact cause and pattern of instability, as this directly influences treatment decisions.

Evaluation typically includes:

1 A detailed injury history and symptom review

2 Physical examination assessing stability, strength, and range of motion

3 Imaging such as X-rays, MRI, or CT scans where appropriate

The goal is to determine whether instability is primarily related to soft tissue injury, bone damage, or a combination of both.

Non-Surgical Treatment Options for Rotator Cuff Tears

Non-operative management is appropriate in selected individuals.

This may include

The suitability of non-operative care depends on age, activity level, injury pattern, and recurrence risk.

MDI may require a lengthy and specialised physiotherapy program. Surgery to tighten the ligaments is possible but not often required

Surgical Treatment Options for Shoulder Instability

Surgical stabilisation may be considered when instability is recurrent, functionally limiting, or associated with structural injury such as a labral tear.

The younger and the more active an individual, the more likely the shoulder will be to dislocate repeatedly if a labral tear is present.

Surgical stabilisation, usually an arthroscopic labral repair, is strongly advised in young athletic people after a single dislocation event when the labrum is torn, to prevent repeated dislocations for which the chance is very high.

Arthroscopic Shoulder Stabilisation: For patients with isolated soft tissue injury and minimal bone loss, surgery involves repair of the labrum and ligaments /capsule using minimally invasive techniques.

Bone Reconstruction Procedures: When instability is associated with significant bone loss, procedures such as the Latarjet procedure or other bone reconstruction techniques may be recommended to restore stability.

In some cases of posterior instability the socket of the shoulder (glenoid) may be angled backward as a natural variant or as a result of numerous subluxation events, and re-shaping procedures to the bone may be advised

Individualised Shoulder Instability Management

Management of shoulder instability must be tailored to the individual. Factors such as age, sport, occupation, injury severity, and long-term joint health are carefully considered.

Specialist assessment, and often an MRI of the shoulder, is recommended if you experience:

Dr Richard Dallalana provides specialist assessment and management of shoulder impingement and bursitis, guiding treatment decisions based on symptoms, imaging findings, and functional needs. A thorough assessment can help clarify the diagnosis and guide appropriate management.

If you’re experiencing ongoing pain, stiffness, or reduced movement that is affecting your daily activities or quality of life, a thorough orthopaedic assessment can help determine the cause and guide the most appropriate treatment options for your situation.