Shoulder instability is classified as a condition where the ball at the top of the upper arm bone (‘humeral head’), moves outside of its normal anatomical limits. These shoulder injuries can be classified further into 2 main conditions. If the ball comes fully out of the joint capsule (aka the ‘socket’), it is referred to as a dislocation. Otherwise, subluxation is the term used to classify a situation where the ball has partially come out of the socket.
Shoulder instability is most common in patients aged younger than 40 years old. Football, surfing and skiing are the most common causes of shoulder instability, workplace injuries is another. If a patient has hypermobile joints, they are at greater risk of suffering shoulder instability.
When shoulder instability occurs the rotator cuff muscles become stretched, which can make the shoulder feel weak. Depending on the severity of the instability, symptoms such as pain, aching and feeling of looseness in the shoulder may be felt.
The shoulder joint (gleno-humeral joint) operates as a ball and socket joint. These types of joints allow for extreme ranges of motion. Some people have inherently loose shoulder joints and this places them at a greater risk of instability. For example, the ball of the joint can come out of its socket partially or completely. When either dislocation or subluxation occurs, the shoulder joint is said to be unstable.
Acute and Chronic shoulder instability
Shoulder instability can occur in both the acute and chronic phases. Acute shoulder instability occurs as a result of an accident or injury, and it results from extreme force applied to the shoulder joint. Chronic shoulder instability develops over time due to repetitive use injuries such as those experienced by athletes or those who perform frequent overhead movements. Chronic shoulder instability is also a result of aging, as the ligaments become less able to hold joints in place over time.
The symptoms of shoulder instability include pain, decreased range of motion, feeling that the shoulder “gives way” when performing certain activities, and a sensation of popping or grinding when the shoulder is moved.
Posterior shoulder instability is when the ligaments and muscles in the back of the shoulder become overstretched, resulting in instability. This type of instability is often caused by throwing motions or overhead activities. Patients with posterior instability may experience pain in the back of their shoulder when lifting or reaching for something overhead. In posterior dislocations, the shoulder blade (scapula) can move out of its normal position.
Treatment for shoulder instability can vary depending on the severity of the condition, but often includes physiotherapy exercises to strengthen and stabilize the joint as well as activities that focus on regaining range of motion. In more severe cases where damage is present, surgery may be necessary to repair or
Anterior shoulder instability is when the ligaments and shoulder muscles in the front of the shoulder become overstretched, resulting in instability. This type of instability is often caused by contact sports such as rugby. Patients with anterior instability may experience pain on the front of their shoulder when lifting or reaching for something overhead.
Treatments for an unstable shoulder joint
Usually, attendance at a hospital for treatment is recommended. Analgesic medication may be required for the next few days and a sling may be worn. An X-Ray and/or MRI (magnetic resonance imaging) of the shoulder is required in all cases of subluxation and dislocation. Shoulder dislocation may be extremely painful.
An injury of this nature may be complicated by damage to the surrounding upper arm bone or socket, cartilage of the shoulder, lining of the shoulder or surrounding muscles or nerves. If any of these symptoms have occurred, further investigations will be required. Following dislocation, surgery may be considered. This may manifest as minimally invasive surgery or surgery through an open incision. The type of surgery needed depends on the extent of damage and expected future demands on the shoulder. If significant damage has been sustained to the shoulder and the patient is active a reconstruction may be recommended.
In those less active patients who have little structural damage to the shoulder, physical therapy can help stabilize the shoulder without resorting to surgery in many cases.
The recurrence rate for shoulder instability is high: over 90% in 20 year old males. Subsequent shoulder instability can do more damage to the shoulder. This can predispose towards osteoarthritis.
Remember
All shoulder dislocations require medical assessment.
A high Recurrence rate in younger patients.
If you are inherently “loose” in the shoulder ligaments, the injury risk is greater.
Rehabilitation with a sports physiotherapist is required.
Surgery may be required depending on the extent of the injury.
