What is Shoulder Instability?
The stability of the shoulder joint is provided by no single structure in the joint. Instead, the bony structure of the joint surfaces, the ligaments and muscles are all key components in maintaining a stable shoulder joint yet permitting a large range of movement in several directions.
Instability is often associated with subluxation (partial dislocation of the shoulder joint), which may be associated with pain and / or dead arm sensations. Indeed this is often what prompts the athlete to seek medical attention. In some people, this is not actually painful but can be quite annoying and prevent them from taking part in daily activities or sports.
The instability of the shoulder joint can be in one direction for example, anterior instability (out the front), posterior instability (out the back) or in more than one direction (known as multidirectional instability). Anterior is the most common form of instability and is probably because the joint capsule is at its weakest at the front of the joint.
This condition can be caused by a number of reasons. If the joint surfaces are shaped slightly differently for example if the glenoid fossa is slightly flatter than usual, or the head of humerus is more of an oval shape the joint may not be as stable compared with other people who have normal joint anatomy.
Other structures support the bony anatomy to help provide stability to the shoulder. These include:
Glenoid Labrum - this is a ring of cartilage which deepens the glenoid fossa, making the cupÃÂ of the socket deeper and hence improving stability
Joint Capsule - this is a membrane which encompasses the entire joint, providing stability but also maintaining the joint complex and holding the lubricating (synovial) fluid in the correct place
Ligaments - these hold the bones together and provide stability by preventing them from moving when they shouldn't.
Muscles - these work alongside the ligaments in preventing unwanted movement, but also initiate and create movement of the joint.
Treatment involves a strengthening programme to increase the stability of the joint. Rotation movements are particularly important to strengthen the rotator cuff muscles.
In severe cases where the shoulder continually subluxes, surgery may be an option to tighten the capsule and ligaments surrounding the joint.
Resistance bands are great for shoulder strengthening as they can be used to strengthen all muscle groups in all directions. They can be used anywhere and difficulty can be increased by shortening the section of band being used. Whilst wobble boards are more famously used for ankle and knee injuries, they can also be used for shoulder stability exercises.