Your shoulder is comprised of three bones, your upper arm bone (humerus), your shoulder blade (scapula), and your collarbone (clavicle).
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A socket called the ‘glenoid’ is where the head of your upper arm bone fits into a rounded socket in your shoulder blade. Through a combination of muscles and tendons your arm bone is kept centred in your shoulder socket. These tissues are called the rotator cuff and cover the head of your upper arm bone and attach it to your shoulder blade.
Causes Of Shoulder Pain
Shoulder problems fall into four major categories:
- Tendon inflammation (bursitis or tendinitis) or tendon tear
- Fracture (broken bone)
Tumours, infection, and nerve-related problems are other far less common causes of shoulder pain.
Small fluid-filled sacs are located in joints throughout your body, including the shoulder; these are called Bursae.
Bursae act as cushions between bones and the overlying soft tissues, helping to reduce friction between the gliding muscles and the bone.
In certain cases excessive use of the shoulder can lead to inflammation and swelling of the bursa between the rotator cuff and part of the shoulder blade known as the acromion. The result of this inflammation is known as subacromial bursitis.
Bursitis often occurs in association with rotator cuff tendinitis. Many tissues in the shoulder can become inflamed and painful. When suffering from this condition many simple daily activities, such as combing your hair or getting dressed may become difficult to execute.
A tendon is a cord that connects muscle to bone. In most cases, tendinitis is caused as a result of a wearing down of the tendon. This can occur slowly over time.
Tendinitis is generally placed within two categories:
- Acute. Can be caused by excessive ball throwing or other overhead activities during work or sport.
- Chronic. Degenerative diseases like arthritis or repetitive wear and tear due to age, can lead to chronic tendinitis.
The four rotator cuff tendons and one of the biceps tendons are the most commonly affected tendons in the shoulder area.
The rotator cuff is made up of four small muscles and their tendons. These muscles and tendons cover the head of your upper arm bone and keep it in the shoulder socket. Your rotator cuff helps provide shoulder motion and stability.
(Image Source: https://www.webmd.com/pain-management/what-is-my-rotator-cuff)
Acute injury or degenerative changes in the tendons can be due to advancing age, long-term overuse and wear and tear, or a sudden injury. These tears may be partial or may completely split the tendon into two pieces. In most cases of complete tears, the tendon is pulled away from its attachment to the bone. Rotator cuff and biceps tendon injuries are among the most common of these injuries.
When the arm is lifted away from the body and the top of the shoulder blade (acromion) puts pressure on the underlying soft tissues, this can cause shoulder impingement. When the arm is lifted, the acromion rubs, or "impinges" on, the rotator cuff tendons and bursa. This can lead to bursitis and tendinitis, causing pain and limiting movement. Over time, severe impingement can even lead to a rotator cuff tear.
When the head of the upper arm bone is forced out of the shoulder socket this is when shoulder instability occurs This can happen as a result of a sudden injury or from overuse.
When the ball of the upper arm is just partially coming out of the socket, this is called a partial dislocation or subluxation. A complete dislocation means the ball comes all the way out of the socket.
Once the ligaments, tendons, and muscles around the shoulder become loose or torn, dislocations can occur repeatedly. Recurring dislocations, which may be partial or complete, cause pain and unsteadiness when you raise your arm or move it away from your body. Repeated episodes of subluxations or dislocations lead to an increased risk of developing arthritis in the joint.
Shoulder pain can also result from arthritis. The most common type of arthritis in the shoulder is osteoarthritis, also known as "wear and tear" arthritis. Symptoms, such as swelling, pain, and stiffness, typically begin during middle age. Osteoarthritis develops slowly and the pain it causes worsens over time.
Osteoarthritis, may be related to sports or work injuries and chronic wear and tear. Other types of arthritis can be related to rotator cuff tears, infection, or an inflammation of the joint lining.
Fractures are broken bones. Shoulder fractures commonly involve the clavicle (collarbone), humerus (upper arm bone), and scapula (shoulder blade).
Shoulder fractures in older patients are often the result of a fall from standing height. In younger patients, shoulder fractures are often caused by a high-energy injury, such as a motor vehicle accident or contact sports injury.
If you are experiencing any of the above conditions or symptoms please contact MG Orthopaedics here to find out how we can help you.