Shoulder instability: causes, diagnosis and treatment

Written by: Mr Amit Modi
Edited by: Laura Burgess

The shoulder is one of the most commonly dislocated joints in the body and when instability occurs, individuals may feel as if the shoulder has ‘given way’. We spoke to one of our expert orthopaedic surgeons Mr Amit Modi about what causes shoulder instability and how it is treated.



What is shoulder instability?

The shoulder is a shallow ball and socket joint designed for movement and is held in place by soft tissues - capsule, ligaments and muscles. Shoulder instability is a problem that occurs when the function of the soft tissue is impaired. If the joint is lax, it may slide out partially (subluxation) or completely (dislocation).

What causes shoulder instability?

The following are the possible causes of shoulder instability:


The most common cause of shoulder instability is trauma. This could be sports-related, accidents or following seizures and/or electrocution.


This is seen in throwing athletes and swimmers where the capsule of the joint stretches out due to repeated microtrauma and results in a lax joint.

Muscle Imbalance

More commonly seen in individuals who are hypermobile. Some patients can have a combination of the above.

What symptoms of shoulder instability can I look out for?

The traumatic variety is usually obvious after an injury episode that forces the joint out and often requires attendance to A & E to put the shoulder back in joint.

The cartilage rim (labrum) which is damaged with the trauma often does not heal, especially in younger people. It can result in instability with the shoulder subluxing or dislocation with overhead activity.

One can get a ‘dead arm,’ which results from the ball coming out of the socket and pressing on the nerves in the armpit. Some patients complain of the joint slipping out of place and not feeling secure.

In the more elderly patient, a shoulder dislocation can cause weakness of the joint resulting from a rotator cuff tear.

How does a specialist diagnose shoulder instability?

Your surgeon can diagnose your type of instability with a good history and clinical examination. They may request an MRI scan with an injection of a dye to assess the extent of the soft tissue damage. Sometimes a CT scan is required to assess the extent of bone damage.

What happens if shoulder instability is left untreated?

Every episode of dislocation increases the risk of arthritis in the shoulder joint and this risk increases in proportion to the number of dislocations. Symptoms of the joint feeling insecure can affect work and sporting pursuits.

How is shoulder instability treated?

Instability that is atraumatic or due to muscle imbalance often responds well to a good rehabilitation programme. This would require a referral to a specialist physiotherapist. For the traumatic variety, most surgeons would recommend surgery after two or more episodes of dislocation.

The surgery to repair the soft tissue is usually done by a keyhole procedure (arthroscopic Bankart repair). Occasionally, when there is bone loss from the socket due to multiple episodes of dislocation, a more extensive open bone procedure is required (Bristow Laterjet procedure).

If you would like to discuss your shoulder pain with Mr Modi, you can book an appointment with him via his Top Doctor’s profile here.

By Mr Amit Modi
Orthopaedic surgery

Mr Amit Modi is a highly trained and skilled consultant orthopaedic surgeon with a sub-speciality interest in the diagnosis and management of conditions involving the shoulder and elbow. His specialist training in trauma and orthopaedics in India and the UK has given him a strong orthopaedic background.

Mr Modi's areas of expertise include, but are not limited to, shoulder surgery, shoulder arthroscopy, shoulder replacement, shoulder instability and elbow surgery and rotator cuff reconstruction. In fact, he has the world’s largest case series using acellular dermal matrix graft for reconstructing massive irreparable rotator cuff tears, for which he has received national and international recognition. His objective concerning all patients is to provide high quality, personalised and comprehensive orthopaedic services. 

Not only does he dedicate his career to first-class patient care, but also to the education and training of medical professionals. He conducts workshops and lectures overseas. This includes conducted surgeon visitations, cadaveric workshops and webinars for use of Graft Jacket in Rotator Cuff reconstruction. He has a special interest in rotator cuff reconstruction and have the world’s largest case series using acellular dermal matrix graft for reconstructing massive irreparable rotator cuff tears for which he has received national and international recognition He regularly returns to India to lecture and promote shoulder and elbow surgery.

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