Shoulder Instability

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Dr Kau Chung Yuan (许医生)


MRCS (Ireland)

MMed (Ortho)

FRCSEd (Ortho)


What is Shoulder Instability?

Shoulder instability occurs when the structures surrounding the shoulder joint do not work to maintain the ball within its socket. This condition can lead to an increased risk of the shoulder joint becoming dislocated.

The stability of the shoulder is maintained by a balance of muscular forces, ligaments, and the bony anatomy of the joint. When any of these components are compromised, it can lead to shoulder instability. This condition can vary in severity from a feeling of the shoulder being loose to recurrent dislocations.


Understanding the causes of shoulder instability is pivotal in determining the appropriate treatment strategy.

  • Traumatic Causes
    Shoulder instability often results from a traumatic injury, particularly in athletes engaged in contact sports or activities involving overhead motions. A significant injury, like a shoulder dislocation, can impair the ligaments that secure the shoulder, leading to instability.
  • Non-Traumatic Causes
    In some instances, shoulder instability arises not from a distinct injury but due to generalised joint laxity or overuse injuries. This type of instability is more prevalent in younger individuals and may relate to specific activities or repetitive motions.
  • Muscular Imbalance or Weakness
    An imbalance or weakness in the shoulder’s surrounding muscles, notably the rotator cuff and scapular stabilisers, can contribute to instability. These muscles play a critical role in maintaining shoulder joint alignment and stability.
  • Congenital Factors
    Certain individuals are predisposed to shoulder instability due to congenital laxity of ligaments. This inherent looseness can affect multiple joints, including the shoulder.
  • Repetitive Stress
    Prolonged stress on the shoulder ligaments and muscles, often seen in athletes or individuals performing repetitive overhead activities, can lead to shoulder instability over time.
  • Age-Related Changes
    Aging can lead to less elastic ligaments and tendons around the shoulder, increasing susceptibility to injuries that may cause instability.

Types of Shoulder Instability

Shoulder instability can manifest in various forms, each characterised by the direction of instability and the underlying causes.

Traumatic Instability

This type typically occurs in younger, active individuals as a result of a significant injury or trauma. The instability is often unidirectional, meaning it occurs in a single direction, usually anterior (forward). This form of instability is frequently associated with a labral tear.

Atraumatic Instability

Atraumatic instability develops without a history of injury or trauma. It is often multidirectional, meaning the shoulder can become unstable in multiple directions. This type is more common in individuals with generalised joint laxity and can be related to repetitive overhead activities or inherent ligamentous looseness.

Voluntary Instability

In some cases, individuals can voluntarily dislocate their shoulder joint. This is often due to neuromuscular disorders or psychological issues and requires a different approach in terms of treatment and management.

Post-Surgical Instability

Shoulder instability can also occur after surgical procedures on the shoulder. This may be due to inadequate healing, failure of the surgical repair, or a new injury.

Acquired Instability

This type develops over time due to repetitive activities or overuse that gradually stretch the shoulder ligaments, leading to instability. It is commonly seen in athletes involved in sports that require repetitive shoulder motions.


The symptoms of shoulder instability can vary depending on the severity and type of the instability. Recognizing these symptoms is crucial for early diagnosis and effective management.

  • Pain
    Pain is a common symptom, particularly when performing activities that put strain on the shoulder. The pain may be a general discomfort or a sharp sensation, often worsening with specific movements.
  • Sensation of Looseness
    Individuals with shoulder instability may feel that their shoulder is loose or about to slip out of place. This sensation can be particularly noticeable during certain movements or activities.
  • Decreased Range of Motion
    Some people may experience a reduced range of motion in the shoulder, finding it difficult to perform usual tasks or movements.
  • Weakness
    Shoulder instability can lead to weakness in the shoulder joint, affecting the ability to carry objects or perform overhead activities.
  • Recurrent Dislocations
    In severe cases, the shoulder may dislocate frequently, which is a clear indication of significant instability. This can happen with everyday activities or with specific movements.
  • Popping or Clicking Sounds
    Some individuals might notice popping, clicking, or grinding sounds when moving the shoulder, indicative of joint instability.
  • Swelling and Tenderness
    The affected area may become swollen and tender, especially after a dislocation or subluxation event.

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Diagnosing shoulder instability involves a combination of clinical evaluation and diagnostic imaging.

Medical History and Physical Examination

The orthopaedic surgeon will ask about any previous shoulder injuries, the frequency and circumstances of shoulder dislocations or feelings of instability, and any activities that exacerbate symptoms. During the physical examination, they will assess the range of motion, strength, and stability of the shoulder.

Imaging Tests

Imaging tests play a crucial role in diagnosing shoulder instability and understanding its extent. Common imaging modalities include:

  • X-rays: These are used to visualise the bony structures of the shoulder and can show if there are any fractures or changes in the joint that may contribute to instability.
  • Magnetic Resonance Imaging (MRI): An MRI can provide detailed images of the shoulder’s soft tissues, including the ligaments, tendons, and labrum (the cartilage rim surrounding the socket of the shoulder joint). It is particularly useful for identifying injuries to these structures that may be causing instability.
  • Computed Tomography (CT) Scan: In certain cases, a CT scan may be used to get a more detailed view of the bone structure of the shoulder.

In some cases, shoulder arthroscopy may be recommended. This is a minimally invasive surgical procedure where a small camera (arthroscope) is inserted into the shoulder joint, providing a clear view of the inside of the joint to assess and possibly repair damage.

Specialised Tests

The orthopaedic surgeon may perform specific physical tests to assess the stability of the shoulder in various directions. These tests help in identifying the pattern of instability.

Non-Surgical Treatment Options

In cases where surgery is not indicated or as a first-line approach, non-surgical treatment are used in managing shoulder instability.

Rest and Activity Modification

Initially, it may be necessary to rest the shoulder and modify activities to reduce pain and prevent further injury. This involves avoiding activities that trigger symptoms or put excessive strain on the shoulder.

Physical Therapy

A cornerstone of non-surgical treatment, physical therapy aims to strengthen the muscles around the shoulder, particularly the rotator cuff and scapular stabilisers, to enhance joint stability.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

NSAIDs can be used to reduce pain and inflammation associated with shoulder instability.

Shoulder Immobilisation

In some cases, particularly after a dislocation, immobilising the shoulder with a sling or brace may be necessary to allow the injured structures to heal.

Corticosteroid Injections

Corticosteroid injections into the shoulder joint may be considered in cases with significant inflammation and pain. However, their use is generally limited due to potential adverse effects on joint structures.

Activity-Specific Training

For athletes or individuals engaged in specific activities, targeted training to improve techniques and shoulder mechanics can be crucial in preventing recurrent instability.

Pain Management Techniques

Techniques such as ice, heat, and transcutaneous electrical nerve stimulation (TENS) can be used for pain management.

Surgical Treatment Options

Surgical intervention may be considered for shoulder instability, particularly in cases where non-surgical treatments have been ineffective, or the instability is severe or recurrent.

  • Arthroscopic Surgery
    This minimally invasive surgery involves making small incisions and using an arthroscope (a small camera) and specialised instruments to repair damaged structures in the shoulder. Arthroscopic surgery can be used to repair torn ligaments, reattach the labrum, and tighten the shoulder capsule.
  • Open Surgery
    In some cases, open surgery may be necessary, particularly in complex cases or when previous arthroscopic surgery has failed. Open surgery involves a larger incision and direct access to the shoulder structures for repair.
  • Latarjet Procedure
    In cases of severe instability or when there is significant bone loss from the socket of the shoulder joint, the Latarjet procedure may be performed. This involves transferring a small piece of bone with an attached tendon to the shoulder socket to create a new barrier to dislocation.
  • Capsular Shift or Plication
    This procedure is aimed at tightening the shoulder joint capsule, which can become stretched out due to instability. It is often performed arthroscopically.
  • Bankart Repair
    A Bankart repair is commonly performed for anterior shoulder instability. It involves reattaching the torn labrum and ligaments to the front of the shoulder socket, restoring stability.

Dr. Kau Chung Yuan

MBBS (S’pore)

MRCS (Ireland)

MMed (Ortho)

FRCSEd (Ortho)

Dr Kau (许医生) is a Fellowship trained Orthopaedic Surgeon with a subspecialty interest in Hip and Knee surgery and has been in practice for more than 15 years.

He is experienced in trauma and fracture management, sports injuries, and joint replacement surgery.

  • Fellow of the Royal College of Surgeons Edinburgh, Orthopaedics (FRCS, Edin) 2014
  • Master of Medicine (Orthopaedics), Singapore (MMed) 2013
  • Member of the Royal College of Surgeons Ireland (MRCS, Ire) 2009
  • Bachelor of Medicine and Surgery (MBBS, Singapore) 2004

Prevention Measures

Prevention of shoulder instability primarily focuses on measures to strengthen the shoulder, improve joint mechanics, and avoid activities that may predispose to injury.

  • Strengthening Exercises: Regular exercises to strengthen the rotator cuff and scapular stabiliser muscles help in maintaining shoulder stability. These exercises should be a part of routine fitness or sports training programs, especially for athletes.
  • Proper Technique in Sports and Activities: Learning and maintaining proper techniques in sports and activities that involve the shoulder is crucial. This includes using proper form during overhead motions in sports like baseball, swimming, or weightlifting.
  • Warm-Up and Stretching: Incorporating a thorough warm-up and stretching routine before engaging in physical activities can help in preparing the muscles and joints, reducing the risk of injury.
  • Avoiding Repetitive Stress: Monitoring the frequency of repetitive shoulder movements and taking breaks can prevent overuse injuries that might lead to instability.
  • Use of Protective Gear: Athletes should use appropriate protective gear, such as shoulder pads in contact sports, to minimise the risk of injury.
  • Regular Check-Ups: Regular check-ups with an orthopaedic surgeon can help in the early detection and management of any shoulder issues.

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Dr. Kau is an exemplary doctor who is experienced in his field and is very patient with his patients. He walked me through the details of my knee condition and addressed all my concerns. Thanks to Dr. Kau, I had a better understanding of my ACL and MCL injury and the various treatment options available. His advice and treatment have been very valuable to me.
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    Frequently Asked Questions (FAQs)

    Can Shoulder Instability Heal on Its Own?

    Mild cases of shoulder instability may improve with rest, physical therapy, and appropriate lifestyle modifications. However, more severe cases, particularly those involving structural damage, usually require medical intervention for complete resolution.

    Is Surgery Always Required for Shoulder Instability?

    Surgery is not always necessary for shoulder instability. It is considered in cases where non-surgical treatments have failed to provide relief or stability, or when the patient experiences recurrent shoulder dislocations. The necessity for surgery also depends on the patient’s age, activity level, and overall health.

    How Long is the Recovery After Shoulder Instability Surgery?

    The recovery period after shoulder instability surgery varies based on the type of surgery performed and the patient’s adherence to a rehabilitation program. For arthroscopic procedures, the typical recovery time ranges from 4 to 6 months, while open surgeries might require 6 to 12 months for full recovery.

    Rehabilitation plays a crucial role and includes a progressive program of physical therapy focusing on gradually increasing strength and mobility in the shoulder. Return to sports or high-level activities is usually based on the successful completion of rehabilitation milestones and clearance from an orthopaedic surgeon.

    Can Shoulder Instability Lead to Other Problems?

    Untreated shoulder instability can lead to recurrent dislocations, which may cause further damage to the shoulder joint. This ongoing instability increases the risk of developing chronic shoulder pain and may accelerate the development of osteoarthritis in the joint. Repeated dislocations can also lead to a decrease in shoulder function and an increased likelihood of requiring surgery in the future.