The shoulder is made up of a combination of bones, tendons, ligaments, cartilage, and muscles, all working together to give us range of motion, stability, strength, and mobility.
Key to these functions is the “ball and socket”, or the head of the humerus/arm bone sitting nicely in the nook or socket of the glenoid– a shallow socket of the scapula/shoulder blade. All held together by ligaments, tendons, cartilage, and muscles which help to prevent the humerus head from slipping out of the shallow glenoid.
The shoulder joint where the humerus head sits in the shallow glenoid cavity is held together by numerous ligaments, muscles, tendons, and cartilage.
Shoulder instability occurs when the ligaments are loose and hence unable to hold the joints together, rendering them unstable. While shoulder dislocation occurs when the head of the humerus comes out of the glenoid cavity. Having shoulder instability can often lead to shoulder dislocation and vice versa.
Shoulder instability can be categorised into 3 groups, these are:
Anterior instability: the most common type of shoulder instability and is usually the result of a shoulder dislocation or subluxation.
Posterior instability: usually occurs due to a traumatic injury or rapid muscle contractions.
Multidirectional instability: due to a genetic predisposition to loose joints or in individuals commonly referred to as being “double jointed”.
What causes shoulder instability / dislocation?
Shoulder instability/dislocation can be caused by the following:
Injury: injury can cause your ligaments and muscles to become overstretched or torn. This causes them to be loose and unable to hold the humerus head in the glenoid cavity.
Overuse: with time, your ligaments and muscles can become too loose and overstretched due to repetitive movement.
Genetics: some people are born with loose joints. Shoulder instability/dislocation can occur in these individuals without any injury, overuse, or trauma to the joint.
Individuals with shoulder instability/dislocation are usually grouped into two categories: shoulder instability/dislocation due to post-traumatic shoulder injury (caused by injury or overuse) or shoulder instability/dislocation due to congenital causes (loose joints).
What are the symptoms of shoulder instability / dislocation?
Symptoms of shoulder instability/dislocation vary between individuals and may present differently depending on the cause.
General symptoms of shoulder instability include:
Popping or locking of the shoulder joint
Feeling like your shoulder is stuck in a certain position
Shoulder pain
Loose shoulder joints
Muscle weakness and reduced strength in the affected shoulder
Shoulder instability/dislocation can cause shoulder pain and loose shoulder joints.
If you notice any of the symptoms, make an appointment with an orthopaedic specialist to get an accurate diagnosis and treatment.
Dr Puah KL is our Senior Consultant Orthopaedic Surgeon at Artisan Sports & Orthopaedic Surgery. He used to serve the sports service of Singapore General Hospital - the highest volume trauma centre for orthopaedics in Singapore.
Yes, shoulder instability/dislocation is often associated with pain and the feeling like your shoulder joint is loose. Depending on the underlying cause, your shoulder instability/dislocation can also be characterised by muscle weakness and reduced range of motion.
Who is at risk of shoulder instability / dislocation in Singapore?
Shoulder instability/dislocation has a higher risk of developing in individuals with the following risk factors:
Sports/hobbies: participating in contact sports or hobbies that require repetitive movements can increase your risk of shoulder dislocation/subluxation which in turn causes shoulder instability.
Having loose joints: being genetically predisposed to loose joints or developing loose joints due to repetitive movements such as swimming, increases your risk of having shoulder instability/dislocation.
Seizures: individuals with seizure disorders such as epilepsy are at an increased risk of developing shoulder instability/dislocation.
Sports such as football can increase your risk of developing shoulder instability/dislocation.
How is shoulder instability / dislocation diagnosed?
Diagnosis of shoulder instability/dislocation involves the following:
Physical examination: your orthopaedic specialist will check your shoulder for areas of tenderness, range of motion, and strength.
X-rays: an x-ray will be performed to check for the possibility of other disorders of the shoulder.
Magnetic resonance imaging (MRI) and/or computed tomography scan (CT-scan):MRIs and CT-scans are performed to examine your bones and tissues.
What are the treatment options for shoulder instability / dislocation in Singapore?
Treatment depends on the severity and cause of your shoulder instability/dislocation.
Treatment options include:
Medication and rest: painkillers and a cold compress will be prescribed to alleviate any pain or inflammation associated with your shoulder instability/dislocation.
Physiotherapy:physiotherapy involves the use of therapeutic and gentle exercises to improve muscle strength and improve shoulder stability/dislocation.
Surgery: for severe or repeated cases of shoulder instability/dislocation.
Frequently asked questions
What does shoulder instability/dislocation feel like?
Can shoulder instability/dislocation heal on its own?
What should I look out for with shoulder instability/dislocation?
our process
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