The shoulder is the most mobile joint in the body but is also unstable and prone to injury. Shoulder injuries cause severe pain that make even simple tasks, such as brushing your teeth or dressing, difficult. If reaching overhead makes you cry out in pain, you could have a problem with your shoulder that requires treatment. Here are six possible causes for shoulder discomfort and imaging tests that could help diagnose:

1.Broken bone. Trauma or overexertion to the shoulder can cause the bone to break and lead to bruising and disfigurement.

Diagnostic test: X-ray. X-rays provide a clear picture of the bone to see whether it is broken or remains intact. X-ray imaging can help your healthcare provider determine whether you need a cast, brace or surgery if the injury is severe.

2.Damaged cartilage. Healthy cartilage cushions the bones and helps joints move with ease. Over time, the cartilage can wear down, which is often caused by certain types of arthritis or a previous injury. Without the protection of the tissue, the bones rub against each other and cause pain and limited function of the joint.

Diagnostic test: MRI (magnetic resonance imaging). Quality MRI imaging can show lesions within the layer of cartilage. While an X-ray can show the structure of the bone and signs of osteoarthritis, cartilage damage cannot be easily seen. An MRI can help your healthcare provider determine the best course of treatment based on the size of the defect and condition of the bone.

3.Dislocation. The shoulder can twist and turn in many directions, but it can also be pushed out of the socket. This mostly occurs after a fall or sports injury, with symptoms ranging from bruising and swelling to complete deformity.

Diagnostic test: CT (computed tomography) scans. CT scans can show changes to the skeletal structure of the bone. The procedure provides detailed images of the bone that can help the radiation technologist see the position and damage to the shoulder.

4.Inflammation. Bursitis is a condition in which overuse, repetitive motion or injury causes fluid-filled sacs (bursae) in the shoulder joint to inflame. This results in pain and swelling.

Diagnostic test: If you continue to experience sudden jolts of pain in the shoulder, X-ray or MRI imaging may be useful to detect an infection and properly diagnose bursitis.

5.Tendinitis.Tendinitis is inflammation of a tendon—the tissue that connects muscles to the bone. It often develops in those who do repetitive movements, such as athletes, musicians or gardeners.

Diagnostic test: Because tendinitis is often mistaken for arthritis, proper imaging is imperative. Several different tests can be used to look for tendinitis, but an MRI will show swelling in the tendon.

6.Torn tissue. If your shoulder is weak or makes a cracking sound when you move it, you may have a rotator cuff tear. This common injury occurs when the rotator cuff, the muscles that keep your arm in the shoulder socket, tears and the tendon is no longer attached to the bone. Rotator cuff tears can be caused by a lack of blood supply in the body, shoulder impingement and repetitive stress.

Diagnostic test: MRI or ultrasound. X-rays are often the first imaging tests ordered, but an MRI or ultrasound will better show the soft tissues in the shoulder. An MRI or ultrasound can help the technologist identify a tear in the rotator cuff.