Shoulder instability is a condition where the shoulder joint is unable to maintain its normal position in the socket especially during active movement of the shoulder, leading to pain, weakness, and limited function. The shoulder is a highly mobile joint, and its range of motion makes it particularly susceptible to instability. This blog post will explore the anatomy of the shoulder, risk factors, affected populations, and effective treatment options, including the vital role of physiotherapy and strengthening exercises.

Anatomy of the Shoulder
The shoulder is a ball-and-socket joint made up of two bones: the humerus – the upper arm bone, the scapula – the shoulder blade. The shoulder joint is formed where the ball (head of the humerus) fits into a shallow socket (glenoid) on the scapula. This joint is supported by a group of muscles and ligaments, known as the rotator cuff and the glenohumeral ligaments, which help stabilize and move the shoulder. Despite its mobility, the shoulder relies on these soft tissues to stay in place.

What is Shoulder Instability?
Shoulder instability occurs when the ball of the humerus slips out of or moves too easily within the shallow glenoid socket. However, there are a few different types of instability which includes:

• Unidirectional Instability: The shoulder dislocates or subluxes (partially dislocates) in one direction, typically anteriorly (forward) or inferiorly (downward).
• Multidirectional Instability: The shoulder dislocates or moves freely in multiple directions, often linked to generalized ligamentous laxity (looseness of ligaments).
• Traumatic Instability: A sudden injury or trauma, such as a fall or direct blow, causes the dislocation.
• Atraumatic Instability: Gradual stretching of the soft tissues around the shoulder joint, usually without a specific traumatic event.

Several factors increase the risk of developing shoulder instability:

• Previous Shoulder Dislocations: Individuals who have dislocated their shoulder are at a higher risk of recurrent instability, particularly in younger, active individuals.
• Sports Involving Overhead Movements: Athletes involved in sports like swimming, tennis, baseball, or gymnastics are more prone to shoulder instability due to repeated overhead
  movements.
• Age: Younger individuals, especially those in their teens or twenties, are more likely to experience shoulder instability because the ligaments and tissues around the shoulder are less
  developed.
• Genetic Factors: Some people have naturally looser ligaments, making them more susceptible to instability (a condition known as hypermobility).
• Remote trauma or Injury: Car accidents, falls, or sports-related injuries can damage the shoulder’s soft tissues, leading to instability.

Management of Shoulder Instability
Management of shoulder instability generally aims to stabilize the joint, alleviate pain, and restore function. The approach can be conservative or surgical, depending on the severity and cause of the instability. Most people with shoulder instability respond well to conservative treatments, especially when the instability is not due to a traumatic dislocation or severe damage to the joint. Physiotherapy is one of the most effective non-surgical treatments for shoulder instability is physiotherapy. A physiotherapist will design a program tailored to the individual’s needs, focusing on:

• Pain management: Activity modification and supporting the joint in a comfortable position.
• Range of motion exercises: Once pain decreases, restoring the normal range of motion is essential for overall function and to prevent stiffness.
• Improving joint stability: Strengthening the muscles around the shoulder joint, particularly the rotator cuff and scapular stabilizers, is crucial. Stronger muscles help provide better control of the joint.
• Proprioception and neuromuscular control: Exercises that improve the body’s ability to sense joint position and control movement are vital for preventing future instability, especially for athletes returning to overhead throwing sports.

If conservative treatment fails, or if the instability is caused by structural damage like torn ligaments or cartilage, surgery may be necessary. Surgical options often involve a scope (arthroscopy) where a camera is inserted into the joint, and tools are inserted through other ‘ports’ or small holes made in the skin to accommodate the camera and any tools:

• Stabilization: A procedure to repair a torn labrum (the cartilage that helps stabilize the shoulder
  socket).
• Capsular Shift: Tightening the shoulder capsule to limit excessive motion.

Shoulder instability is a challenging condition that can impact both athletes and non-athletes alike however shoulders are quite predictable and most instabilities will resolve without surgery. Understanding the anatomy of the shoulder joint and recognizing the risk factors is crucial for early intervention and prevention. Non-surgical treatment, especially physiotherapy with targeted strengthening exercises, plays a vital role in restoring stability and function. For those with more severe instability or structural damage, surgical options may be considered. If you suspect shoulder instability, it’s essential to consult your physiotherapist to determine the best course of action based on the specific cause and severity of the condition.