Shoulder Dislocations / Instability

What is shoulder instability?.

The shoulder joint allows a huge range of motion, which allows us to position our hand in space to allow us to achieve all manner of tasks. This huge range of motion comes at the expense of shoulder stability. The shoulder is at risk of becoming unstable and slipping (subluxing) or dislocating, and is the most commonly dislocated large joint of the body.

Why do shoulders dislocate / become unstable?

Unstable shoulders can either be a result of damage to the structure of the shoulder (labrum / labral injury) or due to a mismatch in the muscle activity around the shoulder (muscle patterning). These different forms are known as traumatic and atraumatic (without trauma) respectively. There is, however, a spectrum of shoulder instability and patients can have overlapping problems.

Contact athletes, such as rugby players, can dislocate their shoulders resulting in damage to the structure of the shoulder (labral tears Fig 1 Bankart tears, bone loss) and benefit from surgical repair (arthroscopic shoulder stabilisation Fig 2 / labral repair / Latarjet procedure Fig 3) to rebuild the normal anatomy of the shoulder and restore the stability. Patients with generalised laxity (looseness) of their tissues can lose control of their shoulder and develop muscle activity mismatch (patterning) and the over-pull of certain muscles can sublux or even dislocate the shoulder.

Fig 1

Fig 2

Fig 3

Fig 1, MR Arthrogram showing an anterior labral tear (and disruption to cartilage at the front of the shoulder).

Fig 2, A keyhole repair of a torn labrum.

Fig 3, A bony block transfer (Latarjet procedure) for anterior shoulder instability.

Treatment.

Structural lesions (labral tears/bone loss) following injury are best treated with surgery, Click here for patient information regarding surgery. Muscle patterning problems are best addressed with specific guided physiotherapy (we can recommend therapists to oversee treatment).

The treatment of shoulder instability depends on the cause and will be discussed in further detail depending on the reason for your shoulder instability.